Article

Spider‐specific probe set for ultraconserved elements offers new perspectives on the evolutionary history of spiders (Arachnida, Araneae)

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Abstract

Phylogenomic methods have proven useful for resolving deep nodes and recalcitrant groups in the spider tree of life. Across arachnids, transcriptomic approaches may generate thousands of loci, and target‐capture methods, using the previously designed arachnid‐specific probe‐set, can target a maximum of about 1,000 loci. Here, we develop a specialized target‐capture probe set for spiders that contains over 2,000 ultraconserved elements (UCEs) and then demonstrate the utility of this probe set through sequencing and phylogenetic analysis. We designed the “spider‐specific” probe set using three spider genomes (Loxosceles, Parasteatoda and Stegodyphus) and ensured that the newly designed probe‐set include UCEs from the previously designed Arachnida probe set. The new “spider‐specific” probes were used to sequence UCE loci in 51 specimens. The remaining samples included five spider genomes and taxa that were enriched using Arachnida probe set. The “spider‐specific” probes were also used to gather loci from a total of 84 representative taxa across Araneae. On mapping these 84 taxa to the Arachnida probe set, we captured at most 710 UCE loci, while the spider specific probe set captured up to 1,547 UCE loci from the same taxon sample. Phylogenetic analyses using Maximum Likelihood and coalescent methods corroborate most nodes resolved by recent transcriptomic analyses, but not all (e.g., UCE data suggests monophyly of “symphytognathoids”). Our preferred analysis based on topology tests, suggests monophyly of the “symphytognathoids” (the miniature orb‐weavers), which in previous studies has only been supported by a combination of morphological and behavioral characters.

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... Because some taxa were captured using the arachnid probeset (outgroups Attulus, Breda, Colonus, Salticus), and others using the spider probeset (remaining outgroups, and all baviines), a blended probeset file was needed to best pull out UCE contigs, because each of the arachnid and spider probesets includes loci not included by the other. Kulkarni et al.'s (2019) spider probeset includes (i) some of Starrett et al.'s (2017) arachnid probes directly, (ii) others for the same loci but modified to target spiders better, and (iii) others for new loci. Because Kulkarni et al. do not identify probes of the second category as such, we sought to identify whether spider probes are orthologous to arachnid probes. ...
... files, was taken as indicating homology between the probes. Arachnid probes that showed no such hint of homology to spider probes were then added to Kulkarni et al.'s (2019) spider probeset to generate the blended probeset (see Suppl. material 1). ...
... This resulted in resulting in a final set of 1313 loci, in which the 16 spider-probeset taxa had on average 1076 loci and 775,244 base pairs of sequence; the four arachnid-probeset taxa had on average 104 loci and 53,936 base pairs. The strong decline in arachnid-probeset taxa from 415 loci to 104 after occupancy filtering suggests that Kulkarni et al.'s (2019) incorporation of arachnid-unique probes into the spider probeset included only a portion. The 1313 loci were concatenated into a single alignment with 1,050,217 sites. ...
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The systematics and taxonomy of the tropical Asian jumping spiders of the tribe Baviini is reviewed, with a molecular phylogenetic study (UCE sequence capture, traditional Sanger sequencing) guiding a reclassification of the group’s genera. The well-studied members of the group are placed into six genera: Bavia Simon, 1877, Indopadilla Caleb & Sankaran, 2019, Padillothorax Simon, 1901, Piranthus Thorell, 1895, Stagetillus Simon, 1885, and one new genus, Maripanthus Maddison, gen. nov. The identity of Padillothorax is clarified, and Bavirecta Kanesharatnam & Benjamin, 2018 synonymized with it. Hyctiota Strand, 1911 is synonymized with Stagetillus. The molecular phylogeny divides the baviines into three clades, the Piranthus clade with a long embolus (Piranthus, Maripanthus), the genus Padillothorax with a flat body and short embolus, and the Bavia clade with a higher body and (usually) short embolus (remaining genera). In general, morphological synapomorphies support or extend the molecularly delimited groups. Eighteen new species are described: Bavia nessagyna, Indopadilla bamilin, I. kodagura, I. nesinor, I. redunca, I. redynis, I. sabivia, I. vimedaba, Maripanthus draconis (type species of Maripanthus), M. jubatus, M. reinholdae, Padillothorax badut, P. mulu, Piranthus api, P. bakau, P. kohi, P. mandai, and Stagetillus irri, all sp. nov., with taxonomic authority W. Maddison. The distinctions between baviines and the astioid Nungia Żabka, 1985 are reviewed, leading to four species being moved into Nungia from Bavia and other genera. Fifteen new combinations are established: Bavia maurerae (Freudenschuss & Seiter, 2016), Indopadilla annamita (Simon, 1903), I. kahariana (Prószyński & Deeleman-Reinhold, 2013), I. sonsorol (Berry, Beatty & Prószyński, 1997), I. suhartoi (Prószyński & Deeleman-Reinhold, 2013), Maripanthus menghaiensis (Cao & Li, 2016), M. smedleyi (Reimoser, 1929), Nungia hatamensis (Thorell, 1881), N. modesta (Keyserling, 1883), N. papakula (Strand, 1911), N. xiaolonghaensis (Cao & Li, 2016), Padillothorax casteti (Simon, 1900), P. exilis (Cao & Li, 2016), P. flavopunctus (Kanesharatnam & Benjamin, 2018), Stagetillus banda (Strand, 1911), all comb. nov. One combination is restored, Bavia capistrata (C. L. Koch, 1846). Five of these new or restored combinations correct previous errors of placing species in genera that have superficially similar palps but extremely different body forms, in fact belonging in distantly related tribes, emphasizing that the general shape of male palps should be used with caution in determining relationships. A little-studied genus, Padillothorus Prószyński, 2018, is tentatively assigned to the Baviini. Ligdus Thorell, 1895 is assigned to the Ballini.
... The design of taxon-specific UCE probes is a growing field, which is rapidly developing a body of knowledge (Branstetter et al., 2017;Gustafson et al., 2019a;Gustafson et al., 2019b;Kulkarni et al., 2020). Recent literature justified the use of tailored UCE probes as they frequently outperform general (i.e. ...
... Recent literature justified the use of tailored UCE probes as they frequently outperform general (i.e. universal) probes and should aid in locus recovery (Branstetter et al., 2017;Gustafson et al., 2019a;Gustafson et al., 2019b;Kulkarni et al., 2020). Previous molecular studies on Oestroidea (Kutty et al., 2010;Buenaventura et al., 2017;Buenaventura & Pape, 2017a;Buenaventura et al., 2019) and similar radiations predict that reconstructing a strong phylogeny would require a large increase in molecular data (Dell'Ampio et al., 2014; Giarla & Esselstyn, 2015) and the combination of information from multiple genome regions to attempt to produce accurate species tree estimates (Degnan & Rosenberg, 2009). ...
... General UCE probe sets designed to work across larger taxonomic groups have proven successful at resolving phylogeny in various groups (Faircloth et al., 2015;Starrett et al., 2016;Van Dam et al., 2017), but there is growing evidence for improved locus recovery through the use of probe sets tailored to focal taxa (Baca et al., 2017;Branstetter et al., 2017;Van Dam et al., 2019;Gustafson et al., 2019a; Gustafson et al., 2019b;Kulkarni et al., 2020). An increase in locus recovery is especially important in the study of rapid radiations (Dell'Ampio et al., 2014;Giarla & Esselstyn, 2015), such as that of Oestroidea. ...
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The diverse superfamily Oestroidea with more than 15 000 known species includes among others blow flies, flesh flies, bot flies and the diverse tachinid flies. Oestroidea exhibit strikingly divergent morphological and ecological traits, but even with a variety of data sources and inferences there is no consensus on the relationships among major Oestroidea lineages. Phylogenomic inferences derived from targeted enrichment of ultraconserved elements or UCEs have emerged as a promising method for resolving difficult phylogenetic problems at varying timescales. To reconstruct phylogenetic relationships among families of Oestroidea, we obtained UCE loci exclusively derived from the transcribed portion of the genome, making them suitable for larger and more integrative phylogenomic studies using other genomic and transcriptomic resources. We analysed datasets containing 37–2077 UCE loci from 98 representatives of all oestroid families (except Ulurumyiidae and Mystacinobiidae) and seven calyptrate outgroups, with a total concatenated aligned length between 10 and 550 Mb. About 35% of the sampled taxa consisted of museum specimens (2–92 years old), of which 85% resulted in successful UCE enrichment. Our maximum likelihood and coalescent‐based analyses produced well‐resolved and highly supported topologies. With the exception of Calliphoridae and Oestridae all included families were recovered as monophyletic with the following conclusions: Oestroidea is monophyletic with Mesembrinellidae as sister to the remaining oestroid families; Oestridae is paraphyletic with respect to Sarcophagidae; Polleniidae is sister to Tachinidae; Rhinophoridae sister to (Luciliinae (Toxotarsinae (Melanomyinae + Calliphorinae))); Phumosiinae is sister to Chrysomyinae and Bengaliinae is sister to Rhiniidae. These results support the ranking of most calliphorid subfamilies as separate families.
... In recent studies on the spider tree of life, phylogenies resulting from the analysis of either transcriptomes or ultraconserved elements (UCEs) have largely converged on similar topologies (e.g., Garrison et al. 2016;Fernández et al. 2018;Kulkarni et al. 2020;Dimitrov & Hormiga 2021;Kallal et al. in press). However, incongruence persists in some recalcitrant nodes, receiving high support for contradicting hypotheses. ...
... Lopardo et al.'s (2011) extensive Sanger-based data set supported "symphytognathoid" monophyly only when the nucleotide data were analyzed in combination with phenotypic data. Recently, an analysis using target enrichment methods to capture ultraconserved elements (UCEs) provided the first molecular support for the monophyly of "symphytognathoids" (ultrafast bootstrap >95), although only with the analyzed low occupancy data sets (Kulkarni et al. 2020). This result was surprising, given the lack of support for symphytognathoid monophyly in all prior molecular analyses, including phylogenomic data sets analyzed as amino acid data in a maximum likelihood framework (Kallal et al. in press). ...
... The present study aims to identify the causes of incongruence amongst transcriptomebased and UCE-based sequences in phylogenetic analyses of spiders by leveraging data from recent studies (e.g., Garrison et al. 2016;Fernández et al. 2018;Kulkarni et al. 2020;Kallal et al. in press). Our approach was to reconstruct phylogenies using sequences from transcriptomes, UCEs, and a combination of data sources, at both the amino acid and Downloaded from https://academic.oup.com/mbe/advance-article/doi/10.1093/molbev/msaa251/5912541 by guest on 08 November 2020 nucleotide level. ...
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Genome-scale data sets are converging on robust, stable phylogenetic hypotheses for many lineages; however, some nodes have shown disagreement across classes of data. We use spiders (Araneae) as a system to identify the causes of incongruence in phylogenetic signal between three classes of data: exons (as in phylotranscriptomics), non-coding regions (included in ultraconserved elements [UCE] analyses), and a combination of both (as in UCE analyses). Gene orthologs, coded as amino acids and nucleotides (with and without third codon positions), were generated by querying published transcriptomes for UCEs, recovering 1,931 UCE loci (codingUCEs). We expected that congeners represented in the codingUCE and UCEs data would form clades in the presence of phylogenetic signal. Non-coding regions derived from UCE sequences were recovered to test the stability of relationships. Phylogenetic relationships resulting from all analyses were largely congruent. All nucleotide data sets from transcriptomes, UCEs, or a combination of both recovered similar topologies in contrast with results from transcriptomes analyzed as amino acids. Most relationships inferred from low occupancy data sets, containing several hundreds of loci, were congruent across Araneae, as opposed to high occupancy data matrices with fewer loci, which showed more variation. Furthermore, we found that low occupancy data sets analyzed as nucleotides (as is typical of UCE data sets) can result in more congruent relationships than high occupancy data sets analyzed as amino acids (as in phylotranscriptomics). Thus, omitting data, through amino acid translation or via retention of only high occupancy loci, may have a deleterious effect in phylogenetic reconstruction.
... This grade, along with the retrolateral tibial apophysis clade (RTA) constitute a monophyletic clade. Nevertheless, the interfamilial relationship of the UDOH grade remains unclear when comparing the published phylogenies (Bond et al., 2014;Dimitrov et al., 2017;Fernández et al., 2018;Kulkarni et al., 2019Kulkarni et al., , 2020. ...
... Among the spider families phylogenetically close to Deinopidae, according to the most recent phylogenies (Bond et al., 2014;Dimitrov et al., 2017;Fernández et al., 2018;Kulkarni et al., 2019Kulkarni et al., , 2020, the diploid number varies from 2n♂ = 10, in Uloborus danolius Tikader, 1969 (Uloboridae, belonging to the UDOH grade) to 2n♂ = ±52 in Agelenopsis naevia (Walckenaer, 1841) (Agelenidae, belonging to the RTA clade) (Wallace, 1909;Parida and Sharma, 1987;Sharma and Parida, 1987). The predominant chromosomal morphology is acro/telocentric and the most common sex chromosome system (SCS) is of the type ♂X 1 X 2 0 / ♀X 1 X 1 X 2 X 2 0 (Araujo et al., 2021). ...
... Recent phylogenies bring three families as close to the Deinopidae: Hersiliidae, Oecobiidae and Uloboridae (UDOH grade), and together with the RTA clade, they form a monophyletic group (Bond et al., 2014;Dimitrov et al., 2017;Fernández et al., 2018;Kulkarni et al., 2019Kulkarni et al., , 2020. Based on the few cytogenetic studies on species of the UDOH grade (see Araujo et al., 2021), the 2n♂ = 40 (36 + X 1 X 2 X 3 X 4 ) of Deinopis biaculeata and D. plurituberculata (present work) are among the highest diploid number, with Uroctea compactilis L. Kock, 1878 (Oecobiidae) presenting 2n♂ = 42 = 40 + X 1 X 2 with acro / telocentric morphology (Suzuki, 1954) being the highest diploid number within the species of the UDOH grade. ...
Article
Here we present the first cytogentic study concerning Deinopidae and their controversial phylogenetic position. This study karyologically analyzed one population of Deinopis biaculeata Simon, 1906 and five populations of Deinopis plurituberculata Mello-Leitão, 1925. The majority of specimens of D. plurituberculata exhibited 2n♂ = 40 and 2n♀ = 44 telocentric chromosomes (however some of them showed B chromosomes, belongs to Aquidauana and Botucatu population). The Deinopis biaculeata and D. plurituberculata meiosis of males showed 18 autosomal bivalents + X1X2X3X4, n = 22 and n = 18, a rare sex chromosome system (SCS) in spiders. Some individuals of D. plurituberculata from the Campo Grande population exhibited 2n♂ = 39 and 2n♀ = 43, with a metacentric chromosome (heterozygotes for centric fusion). The D. plurituberculata males with the rearrangement exhibit diplotenes with 16 autosomal bivalents + 1 autosomal trivalent + X1X2X3X4 and metaphases II with n = 22 (18 telocentric autosomes + X1X2X3X4), n = 21 (16 telocentric autosomes + a metacentric autosome + X1X2X3X4), n = 18 (18 telocentric autosomes) and n = 17 (16 telocentric autosomes + a metacentric autosome). The Ag-NORs (silver impregnation) are terminally located in a pair, coinciding with secondary constriction, which is the most common configuration for Araneae. The relatively high diploid number in Deinopis corroborates phylogenies that place it in a basal position among Entelegynes, in the UDOH grade (Uloboridae, Deinopidae, Oecobiidae and Hersiliidae). Centric fusion in only one population of D. plurituberculata suggests low dispersion capacity of this species and an absence of homozygotes for fusion suggests their low viability or a need to increase the population sampling of D. plurituberculata exhibiting the rearrangement. B chromosomes were detected in D. plurituberculata, with interpopulacional, intrapopulacional and intraindividual numerical variation, with cells presenting 0 - 3 and 0 - 6 B chromosomes in populations of Aquidauana and Botucatu, respectively.
... family-level) of analyses of spider interfamilial relationships have increased (e.g. Garrison et al., 2016;Cheng and Piel, 2018;Hedin et al., 2018;Kallal et al., 2018;Shao and Li, 2018;Wood et al., 2018;Fern andez et al., 2018a;Hedin et al., 2019;Kuntner et al., 2019;Michalik et al., 2019;Kulkarni et al., 2019;Opatova et al., 2020). The increasing consensus has led to more resolved and robust trees at various phylogenetic scales, making comparative questions interpretable in new ways. ...
... Our study, with strategically increased taxon sampling to maximize web diversity across lineages and a variety of analytical methods produced a well-resolved spider tree-of-life. For the overlapping taxa, results recovered most of the phylogenetic relationships established by previous works (Garrison et al., 2016;Dimitrov et al., 2017;Wheeler et al., 2017;Cheng and Piel, 2018;Kallal et al., 2018;Shao and Li, 2018;Fern andez et al., 2018a;Hedin et al., 2019;Kulkarni et al., 2019;Michalik et al., 2019;Kulkarni et al., 2020), reinforcing several previous topologies. For this reason, we limit our discussion of relationships to highlight areas in which our results are novel. ...
... (2018a) as well as palpimanoid-specific analyses using Sanger markers and morphology (Wood et al., 2012) or UCEs (Wood et al., 2018;Kulkarni et al., 2019). Our taxon sampling is more limited than that of Wood et al. (2018), and the degree of difference suggests that sampling, data type and analysis type are very important for resolving palpimanoid relationships. ...
Article
High throughput sequencing and phylogenomic analyses focusing on relationships among spiders have both reinforced and upturned long‐standing hypotheses. Likewise, the evolution of spider webs—perhaps their most emblematic attribute—is being understood in new ways. With a matrix including 272 spider species and close arachnid relatives, we analyze and evaluate the relationships among these lineages using a variety of orthology assessment methods, occupancy thresholds, tree inference methods and support metrics. Our analyses include families not previously sampled in transcriptomic analyses, such as Symphytognathidae, the only araneoid family absent in such prior works. We find support for the major established spider lineages, including Mygalomorphae, Araneomorphae, Synspermiata, Palpimanoidea, Araneoidea and the Retrolateral Tibial Apophysis Clade, as well as the uloborids, deinopids, oecobiids and hersiliids Grade. Resulting trees are evaluated using bootstrapping, Shimodaira–Hasegawa approximate likelihood ratio test, local posterior probabilities and concordance factors. Using structured Markov models to assess the evolution of spider webs while accounting for hierarchically nested traits, we find multiple convergent occurrences of the orb web across the spider tree‐of‐life. Overall, we provide the most comprehensive spider tree‐of‐life to date using transcriptomic data and use new methods to explore controversial issues of web evolution, including the origins and multiple losses of the orb web.
... Despite the importance of the UCE approach in phylogenomics, the design of ad hoc probe sets remains a technical gap such that many researchers are forced to use probe sets designed for similar taxa or for different taxonomic levels. In the current study, we compared the effectiveness of an ad hoc probe set for spiders in the superfamily Araneoidea to the existing probe sets that are known to be applicable to higher taxonomic levels in arachnids [9,11]. ...
... The UCE approach was first applied to arachnids by Starrett et al. [23], and to Araneae by Kulkarni et al. [11]. Note that the order Araneae includes 49,877 species [24] in three subclades, suborder Mesothelae, infraorder Mygalomorphae, and infraorder Araneomorphae, with evolutionary time extending back to more than 300 MYA [25,26]. ...
... As data sources for our in silico testing, we employed two published probe sets for ultraconserved elements [9,11], including 14 published genomes (Table 1) and 1 de novo assembled genome (Argyrodes miniaceus). ...
Article
Full-text available
Reduced-representation sequencing (RRS) has made it possible to identify hundreds to thousands of genetic markers for phylogenomic analysis for the testing of phylogenetic hypotheses in non-model taxa. The use of customized probes to capture genetic markers (i.e., ultraconserved element (UCE) approach) has further boosted the efficiency of collecting genetic markers. Three UCE probe sets pertaining to spiders (Araneae) have been published, including one for the suborder Mesothelae (an early diverged spider group), one for Araneae, and one for Arachnida. In the current study, we developed a probe set specifically for the superfamily Araneoidea in spiders. We then combined the three probe sets for Araneoidea, Araneae, and Arachnid into a fourth probe set. In testing the effectiveness of the 4 probe sets, we used the captured loci of the 15 spider genomes in silico (6 from Araneoidea). The combined probe set outperformed all other probe sets in terms of the number of captured loci. The Araneoidea probe set outperformed the Araneae and Arachnid probe sets in most of the included Araneoidea species. The reconstruction of phylogenomic trees using the loci captured from the four probe sets and the data matrices generated from 50% and 75% occupancies indicated that the node linked to the Stegodyphus + RTA (retrolateral tibial apophysis) clade has unstable nodal supports in the bootstrap values, gCFs, and sCFs. Our results strongly indicate that developing ad hoc probe sets for sub-lineages is important in the cases where the origins of a lineage are ancient (e.g., spiders ~380 MYA).
... The Symphytognathidae has traditionally been put together with other small size araneoids (Anapidae, Mysmenidae, and Theridiosomatidae, sometimes with synaphrids and micropholcommatids) in a group informally called the symphytognathoids (Griswold et al. 1998;Hormiga and Griswold 2014). Although phylogenetic relationships among the Symphytognathidae have not been directly studied, some representatives have been used as part of other phylogenetic studies targeting the family Mysmenidae (Lopardo et al. 2011;Feng et al. 2019), as well as a broad scope analysis of the whole order Araneae (Wheeler et al. 2017;Kulkarni et al. 2020). Symphytognathids can be separated from other relatives by the following combination of characters: the loss of the posterior median eyes, reducing eye number to six (with the further loss of the anterior median eyes in the case of the foureyed genus Anapistula), fusion of the chelicerae (but see below), extreme reduction or loss of female pedipalp, the labium being much wider than long, loss of the colulus, sternum broadly truncated posteriorly, the absence of book lungs, and the presence of one or two promarginal cheliceral teeth originating from a common base (Forster and Platnick 1977;Wunderlich 2004;Miller et al. 2009;Lopardo et al. 2011;Hormiga and Griswold 2014). ...
... The symphytognathoids were first recognized in a morphological study being formed by four putatively monophyletic families Anapidae, Symphytognathidae, Mysmenidae and Theridiosomatidae (Griswold et al. 1998). The monophyly of this clade has been tested several times using different molecular approaches targeting specific families (Rix et al. 2008;Lopardo et al. 2011;Feng et al. 2019), the Orbiculariae (Fernández et al. 2014), and the whole order Araneae (Wheeler et al. 2017;Kulkarni et al. 2020). However, only a few representatives of the family Symphytognathidae have been used rendering their position and relations largely unexplored. ...
... This has been explained by either the limited set of loci and the relatively low taxon sampling (Feng et al. 2019) or an indication of the polyphyly of the "symphytognathoids" as suggested by three broad scoped phylogenies (Dimitrov et al. 2012;Fernández et al. 2014;Wheeler et al. 2017). Nevertheless, Symphytognathoids were found to be a highly supported monophyletic group in a recent study that used ultraconserved elements (UCE) from 16 species across the four principal symphytognathoid families (Kulkarni et al. 2020) The internal relations of the Symphytognathidae in our analyses are still unresolved. Most of Lopardo's identifications (pers. ...
Article
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The family Symphytognathidae is reported from Thailand for the first time. Three new species: Anapistula choojaiae sp. nov., Crassignatha seeliam sp. nov., and Crassignatha seedam sp. nov. are described and illustrated. Distribution is expanded and additional morphological data are reported for Patu shiluensis Lin & Li, 2009. Specimens were collected in Thailand between July and August 2018. The newly described species were found in the north mountainous region of Chiang Mai, and Patu shiluensis was collected in the coastal region of Phuket. DNA sequences are provided for all the species here studied. The relations of these symphytognathid species were tested using previously published phylogenetic analyses on micro orb-weavers. Also, we used mi-cro CT analysis to build 3D models of the male genitalia and somatic characters of two species of Crassignatha Wunderlich, 1995. The molecular phylogeny and 3D models were used to discuss the taxonomy and circum-scription of the currently valid symphytognathid genera, with focus on Crassignatha and Patu Marples, 1951. Based on this, three new combinations are suggested: Crassignatha bicorniventris (Lin & Li, 2009), comb. nov., Crassignatha quadriventris (Lin & Li, 2009), comb. nov., and Crassignatha spinathoraxi (Lin & Li, 2009), comb. nov. A new record of Crassignatha danaugirangensis Miller et al. 2014 is reported from Brunei.
... In other spheres of evolution we recollect that the Basque and Etruscan systems of speech, which can claim kindred with no existing family of language, are excellent instances of the same phenomenon. Mello-Leitão (1946) and Lehtinen (1986) considered filistatids as the sister group of Pholcidae; Eskov and Zonshtein (1990) placed them next to mygalomorphs; the morphological data from Platnick et al. (1991) recovered them as a sister group to other spiders with simple genitalia; and NGS data recovered a close relationship to Hypochilidae (Fern andez et al., 2018;Kulkarni et al., 2020Kulkarni et al., , 2021Ram ırez et al., 2021). For a long time, they were considered closely related to the clade of spiders with simple genitalia that is now called Synspermiata (Michalik and Ram ırez, 2014), a position supported by classic characters, such as the fusion of tegulum and subtegulum and a cheliceral lamina (Platnick et al., 1991). ...
... However, filistatids present typical plesiomorphic characters, such as an M-shaped midgut (Griswold et al., 2005), retention of the posterior lungs in the first instars (Ram ırez, 2014), coenospermia (several sperm cells in the same capsule; Michalik et al., 2003), ecdysis after sexual maturity in females, copulation and spermatic web similar to that of mygalomorphs ( Barrantes and Ram ırez, 2013) and the behaviour of combing cribellate silk using leg III as support (Lopardo and Ram ırez, 2007). Finally, independent sources of NGS data strongly suggest Filistatidae are closely related to Hypochilidae, another family that has many plesiomorphic characters (Fern andez et al., 2018;Kulkarni et al., 2020Kulkarni et al., , 2021Ram ırez et al., 2021). All this suggests an adequate knowledge of the morphology and internal relationships of filistatids could have a great impact on our knowledge of the evolution of early-diverging araneomorphs. ...
Article
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Filistatids, the crevice weavers, are an ancient family of cribellate spiders without extant close relatives. As one of the first lineages of araneomorph spiders, they present a complicated mixture of primitive and derived characters that make them a key taxon to elucidate the phylogeny of spiders, as well as the evolution of phenotypic characters in this group. Their moderate diversity (187 species in 19 genera) is distributed mainly in arid and semi‐arid subtropical zones of all continents, except Antarctica. The objective of this paper is to generate a comprehensive phylogenetic hypothesis for this family to advance the understanding of its morphological evolution and biogeography, as well as lay the basis for a natural classification scheme. By studying the morphology using optical and electronic microscopy techniques, we produced a matrix of 302 morphological characters coded for a sample of 103 species of filistatids chosen to represent the phylogenetic diversity of the family. In addition, we included sequences of four molecular markers (COI, 16S, H3 and 28S; 3787 aligned positions) of 70 filistatid species. The analysis of the data (morphological, molecular, and combined) consistently indicates the separation of the Filistatidae into two subfamilies, Prithinae and Filistatinae, in addition to supporting several groups of genera: Filistata, Zaitunia and an undescribed genus from Madagascar; Sahastata and Kukulcania; all Prithinae except Filistatinella and Microfilistata; Antilloides and Filistatoides; a large Old World group including Pritha, Tricalamus, Afrofilistata, Labahitha, Yardiella, Wandella and putative new genera; and a South American group formed by Lihuelistata, Pikelinia and Misionella. Pholcoides is transferred to Filistatinae and Microfilistata is transferred to Prithinae, and each represents the sister group to the remaining genera of its own subfamily. Most genera are valid, although Pikelinia is paraphyletic with respect to Misionella, so we consider the two genera as synonyms and propose a few new generic combinations. Considering the new phylogenetic hypothesis, we discuss the evolution of some morphological character systems and the biogeography of the family. The ages of divergence between clades were estimated using a total‐evidence tip‐dating approach by including fossils of Filistatidae and early spider clades; this approach resulted in younger age estimates than those obtained with traditional node‐dating. Filistatidae is an ancient family that started diversifying in the Mesozoic and most genera date to the Cretaceous. Clades displaying transcontinental distributions were most likely affected by continental drift, but at least one clade shows unequivocal signs of transoceanic long‐distance dispersal.
... Nevertheless, we recovered hits for a total of 1,895 (46%) of our target UCEs, which is comparable to values obtained in some previous UCE studies (e.g. Kulkarni et al., 2020;Starrett et al., 2017;Streicher et al., 2018), indicating that our design worked. As is regularly the case in UCE studies (Buenaventura et al., 2021;Faircloth et al., 2012;Kulkarni et al., 2020;Quattrini et al., 2018;Starrett et al., 2017), the number of UCEs that can eventually be included in the alignment for phylogenetic inference was a restricted subset of the recovered UCEs, here n = 276 (but see Branstetter et al., 2017). ...
... Kulkarni et al., 2020;Starrett et al., 2017;Streicher et al., 2018), indicating that our design worked. As is regularly the case in UCE studies (Buenaventura et al., 2021;Faircloth et al., 2012;Kulkarni et al., 2020;Quattrini et al., 2018;Starrett et al., 2017), the number of UCEs that can eventually be included in the alignment for phylogenetic inference was a restricted subset of the recovered UCEs, here n = 276 (but see Branstetter et al., 2017). Nevertheless, this restricted set of UCEs allowed to unambiguously reconstruct the backbone phylogeny of Coelaturini. ...
Preprint
Despite the increasing accessibility of high-throughput sequencing, obtaining high-quality genomic data on non-model organisms without proximate well-assembled and annotated genomes remains challenging. Here we describe a workflow that takes advantage of distant genomic resources and ingroup transcriptomes to select and jointly enrich long open reading frames (ORFs) and ultraconserved elements (UCEs) from genomic samples for integrative studies of microevolutionary and macroevolutionary dynamics. This workflow is applied to samples of the African unionid bivalve tribe Coelaturini (Parreysiinae) at basin and continent-wide scales. Our results indicate that ORFs are efficiently captured without prior identification of intron-exon boundaries. The enrichment of UCEs was less successful, but nevertheless produced a substantial dataset. Exploratory continent-wide phylogenetic analyses with ORF supercontigs (>515,000 parsimony informative sites) resulted in a fully resolved phylogeny, the backbone of which was also retrieved with UCEs (>11,000 informative sites), although some branches lack support in the latter case. Variant calling on the exome of Coelaturini from the Malawi Basin produced ~2,000 SNPs per population pair. Nucleotide diversity and population differentiation was low compared to previous estimates in mollusks, but comparable to those in recently diversifying Malawi cichlids and other taxa at an early stage of speciation. Skimming non-specific sequence data obtained for Coelaturini of the Malawi Basin, we reconstructed the maternally-inherited mitogenome, which displays an identical gene order to that of the most recent common ancestor of Unionidae. Overall, our workflow and results provide exciting perspectives for the development of integrative genomic studies on micro- and macroevolutionary dynamics in non-model organisms.
... Transcriptomic analyses of extensive taxonomic samples of araneoids and thousands of loci (Fernández et al., 2018;Kallal et al., 2021) have also refuted symphytognathoid monophyly with high nodal support values. Surprisingly, the most recent phylogenomic analyses (Kulkarni et al., 2020, using ultraconserved elements (UCEs) and up to 26 symphytognathoid representatives, suggest (and paradoxically also with high nodal support values) that when the sequence data are analyzed as nucleotides, rather than as amino acids, and when about a hundred or more loci are used, symphytognathoids are indeed monophyletic. We take this latter proposal as the best supported phylogenetic hypothesis of symphytognathoid relationships. ...
... The second hypothesis uses the interfamilial relationships of the UCE topology of Kulkarni et al. (2021: fig. 4b), which results from a dataset that included a combination of the taxon sample of UCEs recovered from the transcriptomic study of Fernández et al. (2018) and the UCEs of Kulkarni et al. (2020). This second topology is based on the same taxon sample as the first tree with the symphytognathoid intrafamilial relationships also taken from Lopardo et al. (2011: fig. ...
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Spiders are unique in having a dual respiratory system with book lungs and tracheae, and most araneomorph spiders breathe simultaneously via book lungs and tracheae, or tracheae alone. The respiratory organs of spiders are diverse but relatively conserved within families. The small araneoid spiders of the symphytognathoid clade exhibit a remarkably high diversity of respiratory organs and arrangements, unparalleled by any other group of ecribellate orb weavers. In the present study, we explore and review the diversity of symphytognathoid respiratory organs. Using a phylogenetic comparative approach, we reconstruct the evolution of the respiratory system of symphytognathoids based on the most comprehensive phylogenetic frameworks to date. There are no less than 22 different respiratory system configurations in symphytognathoids. The phylogenetic reconstructions suggest that the anterior tracheal system evolved from fully developed book lungs and, conversely, reduced book lungs have originated independently at least twice from its homologous tracheal conformation. Our hypothesis suggests that structurally similar book lungs might have originated through different processes of tracheal transformation in different families. In symphytognathoids, the posterior tracheal system has either evolved into a highly branched and complex system or it is completely lost. No evident morphological or behavioral features satisfactorily explains the exceptional variation of the symphytognathoid respiratory organs.
... Phylogenomic and transcriptomic methods have (Ramírez, 2014); (b) Sanger molecular data (Wheeler et al., 2017); (c) Sanger molecular (Moradmand et al., 2014); (d) total evidence ; (e) genomic (UCE) data . also recently been applied in higher-level systematics and evolutionary studies of spiders (Fernández et al., 2018;Garrison et al., 2016;Kallal et al., 2020;Kulkarni et al., 2020;Opatova et al., 2020;Ramírez et al., 2021;Xu et al., 2020). Although some spider clades have been studied using a combined analysis of morphology and traditional molecular markers (Blackledge et al., 2009;Bond et al., 2012;Polotow et al., 2015), none have yet been explored using the combination of genomic, transcriptomic, traditional loci and morphological data. ...
... One of the key families to understanding dionychan evolution is Sparassidae. This family has been phylogenetically placed in Dionycha (Ramírez, 2014), as sister to the RTA clade (Moradmand et al., 2014), as sister to Dionycha + OCC (Wheeler et al., 2017) and as sister to marronoids (Fernández et al., 2018;Kallal et al., 2020;Kulkarni et al., 2020). Here we corroborated the latter hypothesis with strong support. ...
Article
The importance of morphology in the phylogenomic era has recently gained attention, but relatively few studies have combined both types of information when inferring phylogenetic relationships. Sanger sequencing legacy data can also be important for understanding evolutionary relationships. The possibility of combining genomic, morphological and Sanger data in one analysis seems compelling, permitting a more complete sampling and yielding a comprehensive view of the evolution of a group. Here we used these three data types to elucidate the systematics and evolution of the Dionycha, a highly diverse group of spiders relatively underrepresented in phylogenetic studies. The datasets were analyzed separately and combined under different inference methods, including a novel approach for analyzing morphological matrices with commonly used evolutionary models. We tested alternative hypotheses of relationships and performed simulations to investigate the accuracy of our findings. We provide a comprehensive and thorough phylogenetic hypothesis for Dionycha that can serve as a robust framework to test hypotheses about the evolution of key characters. We also show that morphological data might have a phylogenetic impact, even when massively outweighed by molecular data. Our approach to analyze morphological data may serve as an alternative to the proposed practice of arbitrarily partitioning, weighting, and choosing between parsimony and stochastic models. As a result of our findings, we propose Trachycosmidae new rank for a group of Australian genera formerly included in Trochanteriidae and Gallieniellidae, and consider Ammoxenidae as a junior synonym of Gnaphosidae. We restore the family rank for Prodidomidae, but transfer the subfamily Molycriinae to Gnaphosidae. Drassinella is transferred to Liocranidae, Donuea to Corinnidae, and Mahafalytenus to Viridasiidae.
... An alternative is to target a large sample of representative loci, for example, by using hybrid enrichment to sequence ultraconserved elements (UCEs) across the genome (Faircloth et al. 2012). Although a few UCE probe sets have been designed for arachnids and spiders, these enriched only a small number of loci from the liphistiid species, Liphistius malayanus (Starrett et al. 2017;Kulkarni et al. 2020). ...
... The liphistiid-specific probe set that we have developed here has targeted a larger number of UCE loci than any existing spider-specific or Arachnida probe set (Faircloth 2017;Starrett et al. 2017;Kulkarni et al. 2020). The novel probe set is also likely to be suitable for mygalomorphs, given the UCEs targeted for seven mygalomorphs in this study. ...
Article
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The segmented trapdoor spiders (Liphistiidae) are the sole surviving family of the suborder Mesothelae, which forms the sister lineage to all other living spiders. Liphistiids have retained a number of plesiomorphic traits and their present-day distribution is limited to East and Southeast Asia. Studying this group has the potential to shed light on the deep evolutionary history of spiders, but the phylogeny and divergence times of the family have not been resolved with confidence. We performed phylogenomic and molecular dating analyses of 2,765 ultraconserved element loci from 185 liphistiid taxa. Our analyses show that the crown group of Liphistiidae appeared in the mid-Cretaceous at 102 Ma (95% credibility interval 92–113 Ma), but it was not until the Neogene that much of the diversification within the family occurred in mainland Southeast and East Asia. This diversification was coincident with tectonic events such as the extension of the East Asian continental margin, as well as geological upheavals in Indochina induced by the collision between India and Asia. Our study highlights the important role of major tectonic events in shaping the evolutionary history, present-day diversity, and geographical distribution of mesothele and liphistiid spiders.
... An alternative is to target a large sample of representative loci, for example, by using hybrid enrichment to sequence ultraconserved elements (UCEs) across the genome (Faircloth et al. 2012). Although a few UCE probe sets have been designed for arachnids and spiders, these enriched only a small number of loci from the liphistiid species, Liphistius malayanus (Starrett et al. 2017;Kulkarni et al. 2020). ...
... The liphistiid-specific probe set that we have developed here has targeted a larger number of UCE loci than any existing spider-specific or Arachnida probe set (Faircloth 2017;Starrett et al. 2017;Kulkarni et al. 2020). The novel probe set is also likely to be suitable for mygalomorphs, given the UCEs targeted for seven mygalomorphs in this study. ...
... Knowing the evolutionary relationships among taxa in a community is critical for understanding the processes underlying community assembly (Barker 2002). Currently, phylogenetic analyses often rely on information from hundreds or thousands of loci, for example, inferred from whole transcriptome sequencing (Foley et al. 2019) or the targeted enrichment of ultra-conserved elements (Kulkarni et al. 2020). While such data offer unprecedented phylogenetic resolution, their generation is expensive and laborious. ...
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Large-scale studies on community ecology are highly desirable but often difficult to accomplish due to the considerable investment of time, labor and, money required to characterize richness, abundance, relatedness, and interactions. Nonetheless, such large-scale perspectives are necessary for understanding the composition, dynamics, and resilience of biological communities. Small invertebrates play a central role in ecosystems, occupying critical positions in the food web and performing a broad variety of ecological functions. However, it has been particularly difficult to adequately characterize communities of these animals because of their exceptionally high diversity and abundance. Spiders in particular fulfill key roles as both predator and prey in terrestrial food webs and are hence an important focus of ecological studies. In recent years, large-scale community analyses have benefitted tremendously from advances in DNA barcoding technology. High-throughput sequencing (HTS), particularly DNA metabarcoding, enables community-wide analyses of diversity and interactions at unprecedented scales and at a fraction of the cost that was previously possible. Here, we review the current state of the application of these technologies to the analysis of spider communities. We discuss amplicon-based DNA barcoding and metabarcoding for the analysis of community diversity and molecular gut content analysis for assessing predator-prey relationships. We also highlight applications of the third generation sequencing technology for long read and portable DNA barcoding. We then address the development of theoretical frameworks for community-level studies, and finally highlight critical gaps and future directions for DNA analysis of spider communities.
... We assembled a new genomic-scale data set that complements previous phylogenies reconstructed mostly using transcriptomes. The high congruence with these prior studies and strong support for both deep and shallow branches indicate that UCE-based sequence capture is a good strategy when paired with dense taxon sampling, without the stringent sampling conditions of transcriptomes Kulkarni et al. 2020). Our results indicate that the posterior book lungs of spiders were transformed six times into tracheal systems after the origin of aerial webs and the evolution Cataleptoneta semipinnata CR2020 of the ampullate + piriform gland system of true spiders. ...
Article
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The common ancestor of spiders likely used silk to line burrows or make simple webs, with specialized spinning organs and aerial webs originating with the evolution of the megadiverse "true spiders" (Araneomorphae). The base of the araneomorph tree also concentrates the greatest number of changes in respiratory structures, a character system whose evolution is still poorly understood, and that might be related to the evolution of silk glands. Emphasizing a dense sampling of multiple araneomorph lineages where tracheal systems likely originated, we gathered genomic-scale data and reconstructed a phylogeny of true spiders. This robust phylogenomic framework was used to conduct maximum likelihood and Bayesian character evolution analyses for respiratory systems, silk glands, and aerial webs, based on a combination of original and published data. Our results indicate that in true spiders, posterior book lungs were transformed into morphologically similar tracheal systems six times independently, after the evolution of novel silk gland systems and the origin of aerial webs. From these comparative data we put forth a novel hypothesis that early-diverging web building spiders were faced with new energetic demands for spinning, which prompted the evolution of similar tracheal systems via convergence; we also propose tests of predictions derived from this hypothesis.
... In recent years, we have seen an important increase in phylogenomic studies, and these studies are starting to converge on a relatively stable picture of the higher-level phylogenetic relationships of spiders (55,57,80,122), but relationships at a finer taxonomic scale often remain contentious; phylogenomic efforts should continue in that direction. Advances in high-throughput sequencing methods have also facilitated microbiome studies, leading to some exciting results (e.g., 124), but these studies are limited to a handful of species. ...
Article
Spiders (Araneae) make up a remarkably diverse lineage of predators that have successfully colonized most terrestrial ecosystems. All spiders produce silk, and many species use it to build capture webs with an extraordinary diversity of forms. Spider diversity is distributed in a highly uneven fashion across lineages. This strong imbalance in species richness has led to several causal hypotheses, such as codiversification with insects, key innovations in silk structure and web architecture, and loss of foraging webs. Recent advances in spider phylogenetics have allowed testing some of these hypotheses, but results are often contradictory, highlighting the need to consider additional drivers of spider diversification. The spatial and historical patterns of diversity and diversification remain contentious. Comparative analyses of spider diversification will advance only if we continue to make progress with studies of species diversity, distribution, and phenotypic traits, together with finer-scale phylogenies and genomic data. Expected final online publication date for the Annual Review of Entomology, Volume 66 is January 11, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... Given the promise of this phylogenetic data class, efforts to improve the recovery of UCE data sets in sea spiders should target the generation of high-quality sea spider genomes, with downstream improvements in the design of sea spider-specific UCE probes. Such strategies have been shown to overcome limitations inherent to the arachnid UCE bait set for spiders (Kulkarni et al. 2020). ...
Article
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Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. Previous efforts based on a handful of genes have yielded unstable tree topologies. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and 3 nuclear ribosomal genes. We inferred molecular divergence times by integrating morphological data for fossil species to calibrate 15 nodes in the arthropod tree of life. This integration of data classes resolved the basal topology of sea spiders with high support. The enigmatic family Austrodecidae was resolved as the sister group to the remaining Pycnogonida and the small-bodied family Rhynchothoracidae as the sister group of the robust-bodied family Pycnogonidae. Molecular divergence time estimation recovered a basal divergence of crown group sea spiders in the Ordovician. Comparison of diversification dynamics with other marine invertebrate taxa that originated in the Paleozoic suggests that sea spiders and some crustacean groups exhibit resilience to mass extinction episodes, relative to mollusk and echinoderm lineages.
... We lacked samples of Barraina Richardson 2013, Maileus Peckham & Peckham 1907 and Prostheclina Keyserling 1882, all hypothesized members of the Saitis Clade (Zhang & Maddison (2013. We used the MYbaits Spider v.1 kit (Arbor Biosciences, Ann Arbor, MI, USA; Kulkarni et al., 2020) to capture UCE loci, using methods of library preparation as in recent publications (Starrett et al., 2017;Hedin et al., 2019). Sequencing was conducted on an Illumina HiSeq400 at the U.C. Davis Genome Center with 150-bp paired-end reads. ...
Article
Understanding diversity has been a pursuit in evolutionary biology since its inception. A challenge arises when sexual selection has played a role in diversification. Questions of what constitutes a ‘species’, homoplasy vs. synapomorphy, and whether sexually selected traits show phylogenetic signal have hampered work on many systems. Peacock spiders are famous for sexually selected male courtship dances and peacock-like abdominal ornamentation. This lineage of jumping spiders currently includes over 90 species classified into two genera, Maratus and Saratus. Most Maratus species have been placed into groups based on secondary sexual characters, but evolutionary relationships remain unresolved. Here we assess relationships in peacock spiders using phylogenomic data (ultraconserved elements and RAD-sequencing). Analyses reveal that Maratus and the related genus Saitis are paraphyletic. Many, but not all, morphological groups within a ‘core Maratus’ clade are recovered as genetic clades but we find evidence for undocumented speciation. Based on original observations of male courtship, our comparative analyses suggest that courtship behaviour and peacock-like abdominal ornamentation have evolved sequentially, with some traits inherited from ancestors and others evolving repeatedly and independently from ‘simple’ forms. Our results have important implications for the taxonomy of these spiders, and provide a much-needed evolutionary framework for comparative studies of the evolution of sexual signal characters.
... The transcriptomic analyses of Fernández et al. (2018) and Kallal et al. (2021) support the monophyly of linyphioids but place Weintrauboa as a sister group to the linyphiid clade, rather than to Pimoa. Analyses of ultraconserved elements (Kulkarni et al. 2020 have also supported the monophyly of linyphioids, based on representation of a single pimoid genus (Pimoa). ...
Article
We address the phylogenetic relationships of pimoid spiders (Pimoidae) using a standard target-gene approach with an extensive taxonomic sample, which includes representatives of the four currently recognized pimoid genera, 26 linyphiid genera, a sample of Physoglenidae, Cyatholipidae and one Tetragnathidae species. We test the monophyly of Pimoidae and Linyphiidae and explore the biogeographic history of the group. Nanoa Hormiga, Buckle and Scharff, 2005 and Pimoa Chamberlin & Ivie, 1943 form a clade which is the sister group of a lineage that includes all Linyphiidae, Weintrauboa Hormiga, 2003 and Putaoa Hormiga and Tu, 2008. Weintrauboa, Putaoa, Pecado and Stemonyphantes form a clade (Stemonyphantinae) sister to all remaining linyphiids. We use the resulting optimal molecular phylogenetic tree to assess hypotheses on the male palp sclerite homologies of pimoids and linyphiids. Pimoidae is redelimited to only include Pimoa and Nanoa. We formalize the transfer from Pimoidae of the genera Weintrauboa and Putaoa to Linyphiidae, re-circumscribe the linyphiid subfamily Stemonyphantinae, and offer revised morphological diagnoses for Pimoidae and Linyphiidae.
... Molecular studies, as well as classical morphological work and integrative "whole-evidence" analyses, are covering large parts of spider diversity with increasing density. The last years have seen the publication of several comprehensive phylogenetic studies of the entire order, based on continuously increasing species coverage and ever-larger amounts of (mostly molecular) data (e.g., Agnarsson et al. 2013;Bond et al. 2014;Dimitrov et al. 2017;Fernandez et al. 2014Fernandez et al. , 2018Garrison et al. 2016;Hedin et al. 2019;Kulkarni et al. 2020;Opatova et al. 2020;Ramírez 2014;Ramírez et al. 2019Ramírez et al. , 2021Shao & Li 2018;Wheeler et al. 2017). Subsets of the order, from superfamilies to individual groups of genera, have also been the target of various analyses (e.g., Crews et al. 2020;Godwin et al. 2018;Hedin et al. 2018;Kallal et al. 2020; and numerous publications cited below for individual families). ...
Article
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The recent accumulation of increasingly densely sampled phylogenetic analyses of spiders has greatly advanced our understanding of evolutionary relationships within this group. Here, this diverse literature is reviewed and combined with earlier morphological analyses in an attempt to reconstruct the first fully resolved phylogeny for the spider fauna of the British Isles. The resulting tree highlights parts of the group where data are still too limited for a confident assessment of relationships, proposes a number of deviations from previously suggested phylogenetic hypotheses, and can serve as a framework for evolutionary and ecological interpretations of the biology of British spiders, as well as a starting point for future studies on a larger geographical scale.
... The ultraconserved sequences (UCEs) for this study were obtained from publicly available transcriptomes and UCEs (we sequenced some of these) that were targeted using Arachnida and the 'spider-specific' Spider2Kv1 probe sets (Starrett et al. 2017;Kulkarni et al. 2020). Because the aim of this study is to assess the placement of Hickmania troglodytes, we sampled lineages from the families Austrochilidae, Gradungulidae, Leptonetidae and Archoleptonetidae. ...
Article
Hickmania troglodytes is an emblematic cave spider representing a monotypic cribellate spider genus. This is the only Australian lineage of Austrochilidae while the other members of the family are found in southern South America. In addition to being the largest spider in Tasmania, Hickmania is an oddity in Austrochilidae because this is the only lineage in the family bearing posterior book lungs, tarsal spines and an embolar process on male pedipalps. Six-gene Sanger sequences and genome scale data such as ultraconserved elements (UCEs) and transcriptomes have suggested that Hickmania troglodytes is not nested with the family of current classification, Austrochilidae. We studied the phylogenetic placement of Hickmania troglodytes using an increased taxon sample by combining publicly available UCE and UCEs recovered from transcriptomic data in a parsimony and maximum likelihood framework. Based on our phylogenetic results we formally transfer Hickmania troglodytes from Austrochilidae to the family Gradungulidae. The cladistic placement of Hickmania in the family Gradungulidae fits the geographic distribution of both gradungulids (restricted to Australia and New Zealand) and austrochilids (restricted to southern South America) more appropriately.
... Given the promise of this phylogenetic data class, efforts to improve the recovery of UCE datasets in sea spiders should target the generation of high-quality sea spider genomes, with downstream improvements in the design of sea spider-specific UCE probes. Such strategies have been shown to overcome limitations inherent to the arachnid UCE bait set for spiders [46]. to the present as only four species that diverged in the Cretaceous [47]. ...
Preprint
Full-text available
Despite significant advances in invertebrate phylogenomics over the past decade, the higher-level phylogeny of Pycnogonida (sea spiders) remains elusive. This group of arthropods appeared early in the fossil record, with the oldest unambiguous fossils dating to the Silurian. Due to the inaccessibility of some small-bodied lineages, few phylogenetic studies have sampled all sea spider families. In addition, previous efforts based on a handful of genes have yielded unstable tree topologies from one analytical approach to the next. Here, we inferred the relationships of 89 sea spider species using targeted capture of the mitochondrial genome, 56 conserved exons, 101 ultraconserved elements, and three nuclear ribosomal genes. We inferred molecular divergence times by integrating morphological data for fossil species to calibrate 15 nodes in the arthropod tree of life. This integration of data classes resolved the basal topology of sea spiders with high support. The enigmatic family Austrodecidae was resolved as the sister group to the remaining Pycnogonida and the small-bodied family Rhynchothoracidae as the sister group of the Page 3 of 31 robust-bodied family Pycnogonidae. This stable, dated phylogeny of Pycnogonida enables confident polarization of of cephalic appendage loss across pycnogonid families, with the consistent lack of the adult chelifore in a grade of basally diverging lineages. Molecular divergence time estimation recovered a basal divergence of crown group sea spiders in the Ordovician. Comparison of diversification dynamics with other marine invertebrate taxa that originated in the Paleozoic suggests that sea spiders and some crustacean groups exhibit resilience to mass extinction episodes, relative to mollusk and echinoderm lineages.
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Synopsis To capture prey otherwise unattainable by muscle function alone, some animal lineages have evolved movements that are driven by stored elastic energy, producing movements of remarkable speed and force. One such example that has evolved multiple times is a trap-jaw mechanism, in which the mouthparts of an animal are loaded with energy as they open to a wide gape and then, when triggered to close, produce a terrific force. Within the spiders (Araneae), this type of attack has thus far solely been documented in the palpimanoid family Mecysmaucheniidae but a similar morphology has also been observed in the distantly related araneoid subfamily Pararchaeinae, leading to speculation of a trap-jaw attack in that lineage as well. Here, using high-speed videography, we test whether cheliceral strike power output suggests elastic-driven movements in the pararchaeine Pararchaea alba. The strike speed attained places P. alba as a moderately fast striker exceeding the slowest mecysmaucheniids, but failing to the reach the most extreme high-speed strikers that have elastic-driven mechanisms. Using microcomputed tomography, we compare the morphology of P. alba chelicerae in the resting and open positions, and their related musculature, and based on results propose a mechanism for cheliceral strike function that includes a torque reversal latching mechanism. Similar to the distantly related trap-jaw mecysmaucheniid spiders, the unusual prosoma morphology in P. alba seemingly allows for highly maneuverable chelicerae with a much wider gape than typical spiders, suggesting that increasingly maneuverable joints coupled with a latching mechanism may serve as a precursor to elastic-driven movements.
Article
This paper addresses the systematics of the New Zealand spiders of the family Malkaridae. Malkarids are small araneoid spiders that live primarily in the leaf litter and mosses of temperate and tropical wet forests in Australia and New Zealand, with the exception of a single species in southern South America and another in New Caledonia. We treat the New Zealand species of Malkaridae that are not members of the subfamily Pararchaeinae, a monophyletic group of 11 new species that we classify in 2 new genera (Tingotingo, gen. nov. and Whakamoke, gen. nov.) and a new subfamily (Tingotinginae, subfam. nov.). We describe, diagnose, illustrate and map the distribution of specimen records of these 11 new species of New Zealand Malkaridae: Tingotingo porotiti, sp. nov., T. pouaru, sp. nov., T. tokorera, sp. nov., T. aho, sp. nov., Whakamoke orongorongo, sp. nov.; W. tarakina, sp. nov.; W. guacamole, sp. nov.; W. hunahuna, sp. nov.; W. paoka, sp. nov.; W. heru, sp. nov.; and W. rakiura, sp. nov. We also treat the phylogenetic relationships of Malkaridae and use the results of our previous work on the molecular phylogeny of Araneoidea as the bases for the classification of the family. Tingotingo, gen. nov. and Whakamoke, gen. nov. are sister clades. Tingotinginae, subfam. nov. is the sister group of the Malkarinae plus Pararchaeinae clade. We further hypothesise and discuss the morphological synapomorphies of Malkaridae, Tingotinginae, subfam. nov. and the two new genera.
Article
The tetragnathid genus Leucauge includes some of the most common orb-weaving spiders in the tropics. Although some species in this genus have attained relevance as model systems for several aspects of spider biology, our understanding of the generic diversity and evolutionary relationships among the species is poor. In this study we present the first attempt to determine the phylogenetic structure within Leucauge and the relationship of this genus with other genera of Leucauginae. This is based on DNA sequences from the five loci commonly used and Histone H4, used for the first time in spider phylogenetics. We also assess the informativeness of the standard markers and test for base composition biases in the dataset. Our results suggest that Leucauge is not monophyletic since species of the genera Opas, Opadometa, Mecynometa and Alcimosphenus are included within the current circumscription of the genus. Based on a phylogenetic re-circumscription of the genus to fulfil the requirement for monophyly of taxa, Leucauge White, 1841 is deemed to be a senior synonym of the genera Opas Pickard-Cambridge, 1896 revalidated synonymy, Mecynometa Simon, 1894 revalidated synonymy, Opadometa Archer, 1951 new synonymy and Alcimosphenus Simon, 1895 new synonymy. We identify groups of taxa critical for resolving relationships within Leucauginae and describe the limitations of the standard loci for accomplishing these resolutions.
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Natural history collections play a crucial role in biodiversity research and museum specimens are increasingly being incorporated into modern genetics‐based studies. Sequence capture methods have proven incredibly useful for phylogenomics, providing the additional ability to sequence historical museum specimens with highly degraded DNA, which until recently have been deemed less valuable for genetic work. The successful sequencing of ultraconserved elements (UCEs) from historical museum specimens has been demonstrated on multiple tissue types including dried bird skins, formalin‐fixed squamates, and pinned insects. However, no study has thoroughly demonstrated this approach for historical ethanol‐preserved museum specimens. Alongside sequencing of “fresh” specimens preserved in >95% ethanol and stored at ‐80 ºC, we used extraction techniques specifically designed for degraded DNA coupled with sequence capture protocols to sequence UCEs from historical museum specimens preserved in 70–80% ethanol and stored at room temperature, the standard for such ethanol‐preserved museum collections. Across 35 fresh and 15 historical museum samples of the arachnid order Opiliones, an average of 345 UCE loci were included in phylogenomic matrices, with museum samples ranging from 6–495 loci. We successfully demonstrate the inclusion of historical ethanol‐preserved museum specimens in modern sequence capture phylogenomic studies, show high frequency of variant bases at the species and population‐level, and from off‐target reads successfully recover multiple loci traditionally sequenced in multi‐locus studies including mitochondrial loci and nuclear rRNA loci. The methods detailed in this study will allow researchers to potentially acquire genetic data from millions of ethanol‐preserved museum specimens held in collections worldwide. This article is protected by copyright. All rights reserved.
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Instances of sexual size dimorphism (SSD) provide the context for rigorous tests of biological rules of size evolution, such as Cope's rule (phyletic size increase), Rensch's rule (allometric patterns of male and female size), as well as male and female body size optima. In certain spider groups, such as the golden orbweavers (Nephilidae), extreme female-biased SSD (eSSD, female:male body length $\ge$2) is the norm. Nephilid genera construct webs of exaggerated proportions, which can be aerial, arboricolous, or intermediate (hybrid). First, we established the backbone phylogeny of Nephilidae using 367 anchored hybrid enrichment markers, then combined these data with classical markers for a reference species-level phylogeny. Second, we used the phylogeny to test Cope and Rensch's rules, sex specific size optima, and the coevolution of web size, type, and features with female and male body size and their ratio, SSD. Male, but not female, size increases significantly over time, and refutes Cope's rule. Allometric analyses reject the converse, Rensch's rule. Male and female body sizes are uncorrelated. Female size evolution is random, but males evolve toward an optimum size (3.2-4.9 mm). Overall, female body size correlates positively with absolute web size. However, intermediate sized females build the largest webs (of the hybrid type), giant female Nephila and Trichonephila build smaller webs (of the aerial type), and the smallest females build the smallest webs (of the arboricolous type). We propose taxonomic changes based on the criteria of clade age, monophyly and exclusivity, classification information content, and diagnosability. Spider families, as currently defined, tend to be between 37 million years old and 98 million years old, and Nephilidae is estimated at 133 Ma (97-146), thus deserving family status. We, therefore, resurrect the family Nephilidae Simon 1894 that contains Clitaetra Simon 1889, the Cretaceous GeratonephilaPoinar and Buckley (2012), Herennia Thorell 1877, IndoetraKuntner 2006, new rank, Nephila Leach 1815, Nephilengys L. Koch 1872, Nephilingis Kuntner 2013, Palaeonephila Wunderlich 2004 from Tertiary Baltic amber, and TrichonephilaDahl 1911, new rank. We propose the new clade Orbipurae to contain Araneidae Clerck 1757, Phonognathidae Simon 1894, new rank, and Nephilidae. Nephilid female gigantism is a phylogenetically ancient phenotype (over 100 Ma), as is eSSD, though their magnitudes vary by lineage.
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The atypoid mygalomorphs include spiders from three described families that build a diverse array of entrance web constructs, including funnel-and-sheet webs, purse webs, trapdoors, turrets and silken collars. Molecular phylogenetic analyses have generally supported the monophyly of Atypoidea, but prior studies have not sampled all relevant taxa. Here we generated a dataset of ultraconserved element loci for all described atypoid genera, including taxa (Mecicobothrium and Hexurella) key to understanding familial monophyly, divergence times, and patterns of entrance web evolution. We show that the conserved regions of the arachnid UCE probe set target exons, such that it should be possible to combine UCE and transcriptome datasets in arachnids. We also show that different UCE probes sometimes target the same protein, and under the matching parameters used here show that UCE alignments sometimes include non-orthologs. Using multiple curated phylogenomic matrices we recover a monophyletic Atypoidea, and reveal that the family Mecicobothriidae comprises four separate and divergent lineages. Fossil-calibrated divergence time analyses suggest ancient Triassic (or older) origins for several relictual atypoid lineages, with late Cretaceous/early Tertiary divergences within some genera indicating a high potential for cryptic species diversity. The ancestral entrance web construct for atypoids, and all mygalomorphs, is reconstructed as a funnel-and-sheet web.
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The Infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3,000 nominal species. This ancient group has a world-wide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here we present the most comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae conducted to date. We employ 472 loci obtained through Anchored Hybrid Enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We performed an extensive generic sampling of all currently recognized families, which has allowed us to assess their status, and as a result, propose a new classification scheme. Our generic-level sampling has also provided an evolutionary framework for revisiting questions regarding silk use in mygalomorph spiders. The first such analysis for the group within a strict phylogenetic framework shows that a sheet web is likely the plesiomorphic condition for mygalomorphs, as well as providing hints to the ancestral foraging behavior for all spiders. Our divergence time estimates, concomitant with detailed biogeographic analysis, suggest that both ancient continental-level vicariance and more recent dispersal events have played an important role in shaping modern day distributional patterns. Based on our results, we relimit the generic composition of the Ctenizidae, Cyrtaucheniidae, Dipluridae and Nemesiidae. We also elevate five subfamilies to family rank: Anamidae (NEW RANK), Euagridae (NEW RANK), Ischnothelidae (NEW RANK), Pycnothelidae (NEW RANK), and Bemmeridae (NEW RANK). The three families Hermachidae (NEW FAMILY), Microhexuridae (NEW FAMILY), and Stasimopidae (NEW FAMILY) are newly proposed. Such a major rearrangement in classification, recognizing eight newly established family-level rank taxa, is the largest the group has seen in over three decades since Raven's (1985) taxonomic treatment.
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The genomics revolution has initiated a new era of population genetics where genome‐wide data are frequently used to understand complex patterns of population structure and selection. However, the application of genomic tools to inform management and conservation has been somewhat rare outside a few well‐studied species. Fortunately, two recently developed approaches, amplicon sequencing and sequence capture, have the potential to significantly advance the field of conservation genomics. Here, amplicon sequencing refers to highly multiplexed PCR followed by high‐throughput sequencing (e.g. GTseq), and sequence capture refers to using capture probes to isolate loci from reduced‐representation libraries (e.g. Rapture). Both approaches allow sequencing of thousands of individuals at relatively low costs, do not require any specialized equipment for library preparation, and generate data that can be analyzed without sophisticated computational infrastructure. Here, we discuss the advantages and disadvantages of each method and provide a decision framework for geneticists who are looking to integrate these methods into their research program. While it will always be important to consider the specifics of the biological question and system, we believe that amplicon sequencing is best suited for projects aiming to genotype < 500 loci on many individuals (> 10,000) or for species where continued monitoring is anticipated (e.g. long‐term pedigrees). Sequence capture, on the other hand, is best applied to projects including fewer individuals or where > 500 loci are required. Both of these techniques should smooth the transition from traditional genetic techniques to genomics, helping to usher in the conservation genomics era. This article is protected by copyright. All rights reserved.
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Mites (Acari) are one of the most diverse groups of life on Earth, yet their evolutionary relationships are poorly understood. Also, the resolution of broader arachnid phylogeny has been hindered by an underrepresentation of mite diversity in phylogenomic analyses. To further our understanding of Acari evolution, we design targeted ultraconserved genomic elements (UCEs) probes, intended for resolving the complex relationships between mite lineages and closely related arachnids. We then test our Acari UCE baits in‐silico by constructing a phylogeny using 13 existing Acari genomes, as well as 6 additional taxa from a variety of genomic sources. Our Acari‐specific probe kit improves the recovery of loci within mites over an existing general arachnid UCE probe set. Our initial phylogeny recovers the major mite lineages, yet finds mites to be non‐monophyletic overall, with Opiliones (harvestmen) and Ricinuleidae (hooded tickspiders) rendering Parasitiformes paraphyletic. This article is protected by copyright. All rights reserved.
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Morphological, mitochondrial, and nuclear phylogenomic data were combined to address phylogenetic and species delimitation questions in cave-limited Cicurina spiders from central Texas. Special effort was focused on specimens and cave locations in the San Antonio region (Bexar County), home to four eyeless species listed as US Federally Endangered. Sequence capture experiments resulted in the recovery of ~200–400 homologous ultra-conserved element (UCE) nuclear loci across taxa, and nearly complete COI mitochondrial DNA sequences from the same set of individuals. Some of these nuclear and mitochondrial sequences were recovered from “standard” museum specimens without special preservation of DNA material, including museum specimens preserved in the 1990s. Multiple phylogenetic analyses of the UCE data agree in the recovery of two major lineages of eyeless Cicurina in Texas. These lineages also differ in mitochondrial clade membership, female genitalic morphology, degree of troglomorphy (as measured by relative leg length), and are mostly allopatric across much of Texas. Rare sympatry was confirmed in Bexar County, where members of the two major clades sometimes co-exist in the same karst feature. Both nuclear phylogenomic and mitochondrial data indicate the existence of undescribed species from the San Antonio region, although further sampling and collection of adult specimens is needed to explicitly test these hypotheses. Our data support the two following species synonymies ( Cicurinavenii Gertsch, 1992 = Cicurinamadla Gertsch, 1992; Cicurinaloftini Cokendolpher, 2004 = Cicurinavespera Gertsch, 1992), formally proposed here. Overall, our taxonomy-focused research has many important conservation implications, and again highlights the fundamental importance of robust taxonomy in conservation research.
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Background: Evolutionary histories can be discordant across the genome, and such discordances need to be considered in reconstructing the species phylogeny. ASTRAL is one of the leading methods for inferring species trees from gene trees while accounting for gene tree discordance. ASTRAL uses dynamic programming to search for the tree that shares the maximum number of quartet topologies with input gene trees, restricting itself to a predefined set of bipartitions. Results: We introduce ASTRAL-III, which substantially improves the running time of ASTRAL-II and guarantees polynomial running time as a function of both the number of species (n) and the number of genes (k). ASTRAL-III limits the bipartition constraint set (X) to grow at most linearly with n and k. Moreover, it handles polytomies more efficiently than ASTRAL-II, exploits similarities between gene trees better, and uses several techniques to avoid searching parts of the search space that are mathematically guaranteed not to include the optimal tree. The asymptotic running time of ASTRAL-III in the presence of polytomies is [Formula: see text] where D=O(nk) is the sum of degrees of all unique nodes in input trees. The running time improvements enable us to test whether contracting low support branches in gene trees improves the accuracy by reducing noise. In extensive simulations, we show that removing branches with very low support (e.g., below 10%) improves accuracy while overly aggressive filtering is harmful. We observe on a biological avian phylogenomic dataset of 14K genes that contracting low support branches greatly improve results. Conclusions: ASTRAL-III is a faster version of the ASTRAL method for phylogenetic reconstruction and can scale up to 10,000 species. With ASTRAL-III, low support branches can be removed, resulting in improved accuracy.
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Here we show that the most venomous spiders in the world are phylogenetically misplaced. Australian atracine spiders (family Hexathelidae), including the notorious Sydney funnel-web spider Atrax robustus, produce venom peptides that can kill people. Intriguingly, eastern Australian mouse spiders (family Actinopodidae) are also medically dangerous, possessing venom peptides strikingly similar to Atrax hexatoxins. Based on the standing morphology-based classification, mouse spiders are hypothesized distant relatives of atracines, having diverged over 200 million years ago. Using sequence-capture phylogenomics, we instead show convincingly that hexathelids are non-monophyletic, and that atracines are sister to actinopodids. Three new mygalomorph lineages are elevated to the family level, and a revised circumscription of Hexathelidae is presented. Re-writing this phylogenetic story has major implications for how we study venom evolution in these spiders, and potentially genuine consequences for antivenom development and bite treatment research. More generally, our research provides a textbook example of the applied importance of modern phylogenomic research.
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The standard bootstrap (SBS), despite being computationally intensive, is widely used in maximum likelihood phylogenetic analyses. We recently proposed the ultrafast bootstrap approximation (UFBoot) to reduce computing time while achieving more unbiased branch supports than SBS under mild model violations. UFBoot has been steadily adopted as an efficient alternative to SBS and other bootstrap approaches. Here, we present UFBoot2, which substantially accelerates UFBoot and reduces the risk of overestimating branch supports due to polytomies or severe model violations. Additionally, UFBoot2 provides suitable bootstrap resampling strategies for phylogenomic data. UFBoot2 is 778 times (median) faster than SBS and 8.4 times (median) faster than RAxML rapid bootstrap on tested datasets. UFBoot2 is implemented in the IQ-TREE software package version 1.6 and freely available at http://www.iqtree.org.
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We present the first genome-wide molecular phylogeny of jumping spiders (Araneae: Salticidae), inferred from Anchored Hybrid Enrichment (AHE) sequence data. From 12 outgroups plus 34 salticid taxa representing all but one subfamily and most major groups recognized in previous work, we obtained 447 loci totalling 96,946 aligned nucleotide sites. Our analyses using concatenated likelihood, parsimony, and coalescent methods (ASTRAL and SVDQuartets) strongly confirm most previous results, resolving as monophyletic the Spartaeinae, Salticinae (with the hisponines sister), Salticoida, Amycoida, Saltafresia, and Simonida. The agoriines, previously difficult to place beyond subfamily, are finally placed confidently within the saltafresians as relatives of the chrysillines and hasariines. Relationships among the baviines, astioids, marpissoids, and saltafresians remain uncertain, though our analyses tentatively conclude the first three form a clade together. Deep relationships, among the seven subfamilies, appear to be largely resolved, with spartaeines, lyssomanines, and asemoneines forming a clade. In most analyses, Onomastus (representing the onomastines) is strongly supported as sister to the hisponines plus salticines. Overall, the much-improved resolution of many deep relationships despite a relatively sparse taxon sample suggests AHE is a promising technique for salticid phylogenetics.
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Background: The duplication of genes can occur through various mechanisms and is thought to make a major contribution to the evolutionary diversification of organisms. There is increasing evidence for a large-scale duplication of genes in some chelicerate lineages including two rounds of whole genome duplication (WGD) in horseshoe crabs. To investigate this further, we sequenced and analyzed the genome of the common house spider Parasteatoda tepidariorum. Results: We found pervasive duplication of both coding and non-coding genes in this spider, including two clusters of Hox genes. Analysis of synteny conservation across the P. tepidariorum genome suggests that there has been an ancient WGD in spiders. Comparison with the genomes of other chelicerates, including that of the newly sequenced bark scorpion Centruroides sculpturatus, suggests that this event occurred in the common ancestor of spiders and scorpions, and is probably independent of the WGDs in horseshoe crabs. Furthermore, characterization of the sequence and expression of the Hox paralogs in P. tepidariorum suggests that many have been subject to neo-functionalization and/or sub-functionalization since their duplication. Conclusions: Our results reveal that spiders and scorpions are likely the descendants of a polyploid ancestor that lived more than 450 MYA. Given the extensive morphological diversity and ecological adaptations found among these animals, rivaling those of vertebrates, our study of the ancient WGD event in Arachnopulmonata provides a new comparative platform to explore common and divergent evolutionary outcomes of polyploidization events across eukaryotes. Keywords: Parasteatoda tepidariorum, Genome, Centruroides sculpturatus, Gene duplication, Evolution, Hox genes
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The beetle suborder Adephaga has been the subject of many phylogenetic reconstructions utilizing a variety of data sources and inference methods. However, no strong consensus has yet emerged on the relationships among major adephagan lineages. Ultraconserved elements (UCEs) have proved useful for inferring difficult or unresolved phylogenies at varying timescales in vertebrates, arachnids and Hymenoptera. Recently, a UCE bait set was developed for Coleoptera using polyphagan genomes and a member of the order Strepsiptera as an outgroup. Here, we examine the utility of UCEs for reconstructing the phylogeny of adephagan families, in the first in vitro application a UCE bait set in Coleoptera. Our final dataset included 305 UCE loci for 18 representatives of all adephagan families except Aspidytidae, and two polyphagan outgroups, with a total concatenated length of 83 547 bp. We inferred trees using maximum likelihood analyses of the concatenated UCE alignment and coalescent species tree methods (astral ii, ASTRID, svdquartets). Although the coalescent species tree methods had poor resolution and weak support, concatenated analyses produced well-resolved, highly supported trees. Hydradephaga was recovered as paraphyletic, with Gyrinidae sister to Geadephaga and all other adephagans. Haliplidae was recovered as sister to Dytiscoidea, with Hygrobiidae and Amphizoidae successive sisters to Dytiscidae. Finally, Noteridae was recovered as monophyletic and sister to Meruidae. Given the success of UCE data for resolving phylogenetic relationships within Adephaga, we suggest the potential for further resolution of relationships within Adephaga using UCEs with improved taxon sampling, and by developing Adephaga-specific probes.
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Spider silks are the toughest known biological materials, yet are lightweight and virtually invisible to the human immune system, and they thus have revolutionary potential for medicine and industry. Spider silks are largely composed of spidroins, a unique family of structural proteins. To investigate spidroin genes systematically, we constructed the first genome of an orb-weaving spider: the golden orb-weaver (Nephila clavipes), which builds large webs using an extensive repertoire of silks with diverse physical properties. We cataloged 28 Nephila spidroins, representing all known orb-weaver spidroin types, and identified 394 repeated coding motif variants and higher-order repetitive cassette structures unique to specific spidroins. Characterization of spidroin expression in distinct silk gland types indicates that glands can express multiple spidroin types. We find evidence of an alternatively spliced spidroin, a spidroin expressed only in venom glands, evolutionary mechanisms for spidroin diversification, and non-spidroin genes with expression patterns that suggest roles in silk production.
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Museum specimens provide a wealth of information to biologists, but obtaining genetic data from formalin-fixed and fluid-preserved specimens remains challenging. While DNA sequences have been recovered from such specimens, most approaches are time-consuming and produce low data quality and quantity. Here we use a modified DNA extraction protocol combined with high-throughput sequencing to recover DNA from formalin-fixed and fluid-preserved snakes that were collected over a century ago and for which little or no modern genetic materials exist in public collections. We successfully extracted DNA and sequenced ultraconserved elements (x̄ = 2,318 loci) from 10 fluid-preserved snakes and included them in a phylogeny with modern samples. This phylogeny demonstrates the general use of such specimens in phylogenomic studies and provides evidence for the placement of enigmatic snakes, such as the rare and never-before sequenced Indian Xylophis stenorhynchus. Our study emphasizes the relevance of museum collections in modern research and simultaneously provides a protocol that may prove useful for specimens that have been previously intractable for DNA sequencing. This article is protected by copyright. All rights reserved.
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We present a phylogenetic analysis of spiders using a dataset of 932 spider species, representing 115 families (only the family Synaphridae is unrepresented), 700 known genera, and additional representatives of 26 unidentified or undescribed genera. Eleven genera of the orders Amblypygi, Palpigradi, Schizomida and Uropygi are included as outgroups. The dataset includes six markers from the mitochondrial (12S, 16S, COI) and nuclear (histone H3, 18S, 28S) genomes, and was analysed by multiple methods, including constrained analyses using a highly supported backbone tree from transcriptomic data. We recover most of the higher-level structure of the spider tree with good support, including Mesothelae, Opisthothelae, Mygalomorphae and Araneomorphae. Several of our analyses recover Hypochilidae and Filistatidae as sister groups, as suggested by previous transcriptomic analyses. The Synspermiata are robustly supported, and the families Trogloraptoridae and Caponiidae are found as sister to the Dysderoidea. Our results support the Lost Tracheae clade, including Pholcidae, Tetrablemmidae, Diguetidae, Plectreuridae and the family Pacullidae (restored status) separate from Tetrablemmidae. The Scytodoidea include Ochyroceratidae along with Sicariidae, Scytodidae, Drymusidae and Periegopidae; our results are inconclusive about the separation of these last two families. We did not recover monophyletic Austrochiloidea and Leptonetidae, but our data suggest that both groups are more closely related to the Cylindrical Gland Spigot clade rather than to Synspermiata. Palpimanoidea is not recovered by our analyses, but also not strongly contradicted. We find support for Entelegynae and Oecobioidea (Oecobiidae plus Hersiliidae), and ambiguous placement of cribellate orb-weavers, compatible with their non-monophyly. Nicodamoidea (Nicodamidae plus Megadictynidae) and Araneoidea composition and relationships are consistent with recent analyses. We did not obtain resolution for the titanoecoids (Titanoecidae and Phyxelididae), but the Retrolateral Tibial Apophysis clade is well supported. Penestomidae, and probably Homalonychidae, are part of Zodarioidea, although the latter family was set apart by recent transcriptomic analyses. Our data support a large group that we call the marronoid clade (including the families Amaurobiidae, Desidae, Dictynidae, Hahniidae, Stiphidiidae, Agelenidae and Toxopidae). The circumscription of most marronoid families is redefined here. Amaurobiidae include the Amaurobiinae and provisionally Macrobuninae. We transfer Malenellinae (Malenella, from Anyphaenidae), Chummidae (Chumma) (new syn.) and Tasmarubriinae (Tasmarubrius, Tasmabrochus and Teeatta, from Amphinectidae) to Macrobuninae. Cybaeidae are redefined to include Calymmaria, Cryphoeca, Ethobuella and Willisius (transferred from Hahniidae), and Blabomma and Yorima (transferred from Dictynidae). Cycloctenidae are redefined to include Orepukia (transferred from Agelenidae) and Pakeha and Paravoca (transferred from Amaurobiidae). Desidae are redefined to include five subfamilies: Amphinectinae, with Amphinecta, Mamoea, Maniho, Paramamoea and Rangitata (transferred from Amphinectidae); Ischaleinae, with Bakala and Manjala (transferred from Amaurobiidae) and Ischalea (transferred from Stiphidiidae); Metaltellinae, with Austmusia, Buyina, Calacadia, Cunnawarra, Jalkaraburra, Keera, Magua, Metaltella, Penaoola and Quemusia; Porteriinae (new rank), with Baiami, Cambridgea, Corasoides and Nanocambridgea (transferred from Stiphidiidae); and Desinae, with Desis, and provisionally Poaka (transferred from Amaurobiidae) and Barahna (transferred from Stiphidiidae). Argyroneta is transferred from Cybaeidae to Dictynidae. Cicurina is transferred from Dictynidae to Hahniidae. The genera Neoramia (from Agelenidae) and Aorangia, Marplesia and Neolana (from Amphinectidae) are transferred to Stiphidiidae. The family Toxopidae (restored status) includes two subfamilies: Myroinae, with Gasparia, Gohia, Hulua, Neomyro, Myro, Ommatauxesis and Otagoa (transferred from Desidae); and Toxopinae, with Midgee and Jamara, formerly Midgeeinae, new syn. (transferred from Amaurobiidae) and Hapona, Laestrygones, Lamina, Toxops and Toxopsoides (transferred from Desidae). We obtain a monophyletic Oval Calamistrum clade and Dionycha; Sparassidae, however, are not dionychans, but probably the sister group of those two clades. The composition of the Oval Calamistrum clade is confirmed (including Zoropsidae, Udubidae, Ctenidae, Oxyopidae, Senoculidae, Pisauridae, Trechaleidae, Lycosidae, Psechridae and Thomisidae), affirming previous findings on the uncertain relationships of the “ctenids” Ancylometes and Cupiennius, although a core group of Ctenidae are well supported. Our data were ambiguous as to the monophyly of Oxyopidae. In Dionycha, we found a first split of core Prodidomidae, excluding the Australian Molycriinae, which fall distantly from core prodidomids, among gnaphosoids. The rest of the dionychans form two main groups, Dionycha part A and part B. The former includes much of the Oblique Median Tapetum clade (Trochanteriidae, Gnaphosidae, Gallieniellidae, Phrurolithidae, Trachelidae, Gnaphosidae, Ammoxenidae, Lamponidae and the Molycriinae), and also Anyphaenidae and Clubionidae. Orthobula is transferred from Phrurolithidae to Trachelidae. Our data did not allow for complete resolution for the gnaphosoid families. Dionycha part B includes the families Salticidae, Eutichuridae, Miturgidae, Philodromidae, Viridasiidae, Selenopidae, Corinnidae and Xenoctenidae (new fam., including Xenoctenus, Paravulsor and Odo, transferred from Miturgidae, as well as Incasoctenus from Ctenidae). We confirm the inclusion of Zora (formerly Zoridae) within Miturgidae.
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Background Despite considerable effort, progress in spider molecular systematics has lagged behind many other comparable arthropod groups, thereby hindering family-level resolution, classification, and testing of important macroevolutionary hypotheses. Recently, alternative targeted sequence capture techniques have provided molecular systematics a powerful tool for resolving relationships across the Tree of Life. One of these approaches, Anchored Hybrid Enrichment (AHE), is designed to recover hundreds of unique orthologous loci from across the genome, for resolving both shallow and deep-scale evolutionary relationships within non-model systems. Herein we present a modification of the AHE approach that expands its use for application in spiders, with a particular emphasis on the infraorder Mygalomorphae. Results Our aim was to design a set of probes that effectively capture loci informative at a diversity of phylogenetic timescales. Following identification of putative arthropod-wide loci, we utilized homologous transcriptome sequences from 17 species across all spiders to identify exon boundaries. Conserved regions with variable flanking regions were then sought across the tick genome, three published araneomorph spider genomes, and raw genomic reads of two mygalomorph taxa. Following development of the 585 target loci in the Spider Probe Kit, we applied AHE across three taxonomic depths to evaluate performance: deep-level spider family relationships (33 taxa, 327 loci); family and generic relationships within the mygalomorph family Euctenizidae (25 taxa, 403 loci); and species relationships in the North American tarantula genus Aphonopelma (83 taxa, 581 loci). At the deepest level, all three major spider lineages (the Mesothelae, Mygalomorphae, and Araneomorphae) were supported with high bootstrap support. Strong support was also found throughout the Euctenizidae, including generic relationships within the family and species relationships within the genus Aptostichus. As in the Euctenizidae, virtually identical topologies were inferred with high support throughout Aphonopelma. Conclusions The Spider Probe Kit, the first implementation of AHE methodology in Class Arachnida, holds great promise for gathering the types and quantities of molecular data needed to accelerate an understanding of the spider Tree of Life by providing a mechanism whereby different researchers can confidently and effectively use the same loci for independent projects, yet allowing synthesis of data across independent research groups. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0769-y) contains supplementary material, which is available to authorized users.
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We test the limits of the spider superfamily Araneoidea and reconstruct its interfamilial relationships using standard molecular markers. The taxon sample (363 terminals) comprises for the first time representatives of all araneoid families, including the first molecular data of the family Synaphridae. We use the resulting phylogenetic framework to study web evolution in araneoids. Araneoidea is monophyletic and sister to Nicodamoidea rank. n. Orbiculariae are not monophyletic and also include the RTA clade, Oecobiidae and Hersiliidae. Deinopoidea is paraphyletic with respect to a lineage that includes the RTA clade, Hersiliidae and Oecobiidae. The cribellate orb-weaving family Uloboridae is monophyletic and is sister group to a lineage that includes the RTA Clade, Hersiliidae and Oecobiidae. The monophyly of most Araneoidea families is well supported, with a few exceptions. Anapidae includes holarchaeids but the family remains diphyletic even if Holarchaea is considered an anapid. The orb-web is ancient, having evolved by the early Jurassic; a single origin of the orb with multiple “losses” is implied by our analyses. By the late Jurassic, the orb-web had already been transformed into different architectures, but the ancestors of the RTA clade probably built orb-webs. We also find further support for a single origin of the cribellum and multiple independent losses. The following taxonomic and nomenclatural changes are proposed: the cribellate and ecribellate nicodamids are grouped in the superfamily Nicodamoidea rank n. (Megadictynidae rank res. and Nicodamidae stat. n.). Araneoidea includes 17 families with the following changes: Araneidae is re-circumscribed to include nephilines, Nephilinae rank res., Arkyidae rank n., Physoglenidae rank n., Synotaxidae is limited to the genus Synotaxus, Pararchaeidae is a junior synonym of Malkaridae (syn. n.), Holarchaeidae of Anapidae (syn. n.) and Sinopimoidae of Linyphiidae (syn. n.).
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Species tree reconstruction is complicated by effects of incomplete lineage sorting, commonly modeled by the multi-species coalescent model (MSC). While there has been substantial progress in developing methods that estimate a species tree given a collection of gene trees, less attention has been paid to fast and accurate methods of quantifying support. In this article, we propose a fast algorithm to compute quartet-based support for each branch of a given species tree with regard to a given set of gene trees. We then show how the quartet support can be used in the context of the MSC to compute (1) the local posterior probability (PP) that the branch is in the species tree and (2) the length of the branch in coalescent units. We evaluate the precision and recall of the local PP on a wide set of simulated and biological datasets, and show that it has very high precision and improved recall compared with multi-locus bootstrapping. The estimated branch lengths are highly accurate when gene tree estimation error is low, but are underestimated when gene tree estimation error increases. Computation of both the branch length and local PP is implemented as new features in ASTRAL.
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Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the “usual suspect” genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125–90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results challenge the monophyly of Eresoidea, Orbiculariae, and Deinopoidea. The composition of the major paleocribellate and neocribellate clades, the basal divisions of Araneomorphae, appear to be falsified. Traditional Haplogynae is in need of revision, as our findings appear to support the newly conceived concept of Synspermiata. The sister pairing of filistatids with hypochilids implies that some peculiar features of each family may in fact be synapomorphic for the pair. Leptonetids now are seen as a possible sister group to the Entelegynae, illustrating possible intermediates in the evolution of the more complex entelegyne genitalic condition, spinning organs and respiratory organs.
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Background Ultraconserved elements (UCEs) have been successfully used in phylogenomics for a variety of taxa, but their power in phylogenetic inference has yet to be extensively compared with that of traditional Sanger sequencing data sets. Moreover, UCE data on invertebrates, including insects, are sparse. We compared the phylogenetic informativeness of 959 UCE loci with a multi-locus data set of ten nuclear markers obtained via Sanger sequencing, testing the ability of these two types of data to resolve and date the evolutionary history of the second most species-rich subfamily of ants in the world, the Formicinae. Results Phylogenetic analyses show that UCEs are superior in resolving ancient and shallow relationships in formicine ants, demonstrated by increased node support and a more resolved phylogeny. Phylogenetic informativeness metrics indicate a twofold improvement relative to the 10-gene data matrix generated from the identical set of taxa. We were able to significantly improve formicine classification based on our comprehensive UCE phylogeny. Our divergence age estimations, using both UCE and Sanger data, indicate that crown-group Formicinae are older (104–117 Ma) than previously suggested. Biogeographic analyses infer that the diversification of the subfamily has occurred on all continents with no particular hub of cladogenesis. Conclusions We found UCEs to be far superior to the multi-locus data set in estimating formicine relationships. The early history of the clade remains uncertain due to ancient rapid divergence events that are unresolvable even with our genomic-scale data, although this might be largely an effect of several problematic taxa subtended by long branches. Our comparison of divergence ages from both Sanger and UCE data demonstrates the effectiveness of UCEs for dating analyses. This comparative study highlights both the promise and limitations of UCEs for insect phylogenomics, and will prove useful to the growing number of evolutionary biologists considering the transition from Sanger to next-generation sequencing approaches. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0552-5) contains supplementary material, which is available to authorized users.
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New DNA sequencing technologies are allowing researchers to explore the genomes of the millions of natural history specimens collected prior to the molecular era. Yet, we know little about how well specific next-generation sequencing (NGS) techniques work with the degraded DNA typically extracted from museum specimens. Here, we use one type of NGS approach, sequence capture of ultraconserved elements (UCEs), to collect data from bird museum specimens as old as 120 years. We targeted 5,060 UCE loci in 27 Western Scrub-Jays (Aphelocoma californica) representing three evolutionary lineages that could be species, and we collected an average of 3,749 UCE loci containing 4,460 single nucleotide polymorphisms (SNPs). Despite older specimens producing fewer and shorter loci in general, we collected thousands of markers from even the oldest specimens. More sequencing reads per individual helped to boost the number of UCE loci we recovered from older specimens, but more sequencing was not as successful at increasing the length of loci. We detected contamination in some samples and determined that contamination was more prevalent in older samples that were subject to less sequencing. For the phylogeny generated from concatenated UCE loci, contamination led to incorrect placement of some individuals. In contrast, a species tree constructed from SNPs called within UCE loci correctly placed individuals into three monophyletic groups, perhaps because of the stricter analytical procedures we used for SNP calling. This study and other recent studies on the genomics of museums specimens have profound implications for natural history collections, where millions of older specimens should now be considered genomic resources. This article is protected by copyright. All rights reserved.
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High-throughput genomic sequencing is rapidly changing the field of phylogenetics by decreasing the cost and increasing the quantity and rate of data collection by several orders of magnitude. This deluge of data is exerting tremendous pressure on downstream data-analysis methods providing new opportunities for method development. In this review, we present (a) recent advances in laboratory methods for collection of high-throughput phylogenetic data and(b) challenges and constraints for phylogenetic analysis of these data. We compare the merits of multiple laboratory approaches, compare methods of data analysis, and offer recommendations for the most promising protocols and data-analysis workflows currently available for phylogenetics. We also discuss several strategies for increasing accuracy, with an emphasis on locus selection and proper model choice.
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Large phylogenomics data sets require fast tree inference methods, especially for maximum-likelihood (ML) phylogenies. Fast programs exist, but due to inherent heuristics to find optimal trees, it is not clear whether the best tree is found. Thus, there is need for additional approaches that employ different search strategies to find ML trees and that are at the same time as fast as currently available ML programs. We show that a combination of hill-climbing approaches and a stochastic perturbation method can be time-efficiently implemented. If we allow the same CPU time as RAxML and PhyML, then our software IQ-TREE found higher likelihoods between 62.2% and 87.1% of the studied alignments, thus efficiently exploring the tree-space. If we use the IQ-TREE stopping rule, RAxML and PhyML are faster in 75.7% and 47.1% of the DNA alignments and 42.2% and 100% of the protein alignments, respectively. However, the range of obtaining higher likelihoods with IQ-TREE improves to 73.3–97.1%. IQ-TREE is freely available at http://www.cibiv.at/software/iqtree.
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Gaining a genomic perspective on phylogeny requires the collection of data from many putatively independent loci collected across the genome. Among insects, an increasingly common approach to collecting this class of data involves transcriptome sequencing, because few insects have high-quality genome sequences available; assembling new genomes remains a limiting factor; the transcribed portion of the genome is a reasonable, reduced subset of the genome to target; and the data collected from transcribed portions of the genome are similar in composition to the types of data with which biologists have traditionally worked (e.g., exons). However, molecular techniques requiring RNA as a template are limited to using very high quality source materials, which are often unavailable from a large proportion of biologically important insect samples. Recent research suggests that DNA-based target enrichment of conserved genomic elements offers another path to collecting phylogenomic data across insect taxa, provided that conserved elements are present in and can be collected from insect genomes. Here, we identify a large set (n$=$1510) of ultraconserved elements (UCE) shared among the insect order Hymenoptera. We use in silico analyses to show that these loci accurately reconstruct relationships among genome-enabled Hymenoptera, and we design a set of baits for enriching these loci that researchers can use with DNA templates extracted from a variety of sources. We use our UCE bait set to enrich an average of 721 UCE loci from 30 hymenopteran taxa, and we use these UCE loci to reconstruct phylogenetic relationships spanning very old ($\geq$220 MYA) to very young ($\geq$1 MYA) divergences among hymenopteran lineages. In contrast to a recent study addressing hymenopteran phylogeny using transcriptome data, we found ants to be sister to all remaining aculeate lineages with complete support.
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Spiders are ecologically important predators with complex venom and extraordinarily tough silk that enables capture of large prey. Here we present the assembled genome of the social velvet spider and a draft assembly of the tarantula genome that represent two major taxonomic groups of spiders. The spider genomes are large with short exons and long introns, reminiscent of mammalian genomes. Phylogenetic analyses place spiders and ticks as sister groups supporting polyphyly of the Acari. Complex sets of venom and silk genes/proteins are identified. We find that venom genes evolved by sequential duplication, and that the toxic effect of venom is most likely activated by proteases present in the venom. The set of silk genes reveals a highly dynamic gene evolution, new types of silk genes and proteins, and a novel use of aciniform silk. These insights create new opportunities for pharmacological applications of venom and biomaterial applications of silk.
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The infraorder Mygalomorphae is one of the three main lineages of spiders comprising over 3000 nominal species. This ancient group has a worldwide distribution that includes among its ranks large and charismatic taxa such as tarantulas, trapdoor spiders, and highly venomous funnel-web spiders. Based on past molecular studies using Sanger-sequencing approaches, numerous mygalomorph families (e.g., Hexathelidae, Ctenizidae, Cyrtaucheniidae, Dipluridae, and Nemesiidae) have been identified as non-monophyletic. However, these data were unable to sufficiently resolve the higher-level (intra- and interfamilial) relationships such that the necessary changes in classification could be made with confidence. Here, we present a comprehensive phylogenomic treatment of the spider infraorder Mygalomorphae. We employ 472 loci obtained through anchored hybrid enrichment to reconstruct relationships among all the mygalomorph spider families and estimate the timeframe of their diversification. We sampled nearly all currently recognized families, which has allowed us to assess their status, and as a result, propose a new classification scheme. Our generic-level sampling has also provided an evolutionary framework for revisiting questions regarding silk use in mygalomorph spiders. The first such analysis for the group within a strict phylogenetic framework shows that a sheet web is likely the plesiomorphic condition for mygalomorphs, as well as providing insights to the ancestral foraging behavior for all spiders. Our divergence time estimates, concomitant with detailed biogeographic analysis, suggest that both ancient continental-level vicariance and more recent dispersal events have played an important role in shaping modern day distributional patterns. Based on our results, we relimit the generic composition of the Ctenizidae, Cyrtaucheniidae, Dipluridae, and Nemesiidae. We also elevate five subfamilies to family rank: Anamidae (NEW RANK), Euagridae (NEW RANK), Ischnothelidae (NEW RANK), Pycnothelidae (NEW RANK), and Bemmeridae (NEW RANK). Three families Entypesidae (NEW FAMILY), Microhexuridae (NEW FAMILY), and Stasimopidae (NEW FAMILY), and one subfamily Australothelinae (NEW SUBFAMILY) are newly proposed. Such a major rearrangement in classification, recognizing nine newly established family-level rank taxa, is the largest the group has seen in over three decades. [Biogeography; molecular clocks; phylogenomics; spider web foraging; taxonomy.].
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We address some of the taxonomic and classification changes proposed by Kuntner et al. (in press) in a comparative study on the evolution of sexual size dimorphism in nephiline spiders. Their proposal to re-circumscribe araneids and to rank the subfamily Nephilinae is fundamentally flawed as it renders the family Araneidae paraphyletic. We discuss the importance of monophyly, outgroup selection and taxon sampling, the subjectivity of ranks, and the implications of the age of origin criterion to assign categorical ranks in biological classifications. We explore the outcome of applying the approach of Kuntner et al. (in press) to the classification of spiders with emphasis on the ecribellate orb-weavers (Araneoidea) using a recently published dated phylogeny. We discuss the implications of including the putative sister group of Nephilinae (the sexually dimorphic genus Paraplectanoides) and the putative sister group of Araneidae (the miniature, monomorphic family Theridiosomatidae). We propose continuation of the phylogenetic classification put forth by Dimitrov et al. (2017) and we formally rank Nephilinae and Phonognathinae as subfamilies of Araneidae. Our classification better reflects the understanding of the phylogenetic placement and evolutionary history of nephilines and phonognathines while maintaining the diagnosability of Nephilinae. It also fulfills the fundamental requirement that taxa must be monophyletic, and thus avoids the paraphyly of Araneidae implied by Kuntner et al. (in press).
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Target enrichment of conserved genomic regions facilitates collecting sequences of many orthologous loci from non-model organisms to address phylogenetic, phylogeographic, population genetic, and molecular evolution questions. Bait sets for sequence capture can simultaneously target thousands of loci, which opens new avenues of research on speciose groups. Current phylogenetic hypotheses on the >103,000 species of Hemiptera have failed to unambiguously resolve major nodes, suggesting that alternative datasets and more thorough taxon sampling may be required to resolve relationships. We here use a recently designed ultraconserved element (UCE) bait set for Hemiptera, with a focus on the suborder Heteroptera, or the true bugs, to test previously proposed relationships. We present newly generated UCE data for 36 samples representing three suborders, all seven heteropteran infraorders, 23 families, and 34 genera of Hemiptera and one thysanopteran outgroup. To improve taxon sampling, we also mined additional UCE loci in silico from published hemipteran genomic and transcriptomic data. We obtained 2,271 UCE loci for newly sequenced hemipteran taxa, ranging from 265 to 1,696 (average 904) per sample. These were similar in number to the data mined from transcriptomes and genomes, but with fewer loci overall. The amount of missing data correlates with greater phylogenetic divergence from taxa used to design the baits. This bait set hybridizes to a wide range of hemipteran taxa and specimens of varying quality, including dried specimens as old as 1973. Our estimated phylogeny yielded topologies consistent with other studies for most nodes and was strongly-supported. We also demonstrate that UCE loci are almost exclusively from the transcribed portion of the genome, thus data can be successfully integrated with existing genomic and transcriptomic resources for more comprehensive phylogenetic sampling, an important feature in the era of phylogenomics. UCE approaches can be used by other researchers for additional studies on hemipteran evolution and other research that requires well resolved phylogenies.
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The Cretaceous experienced one of the most remarkable greenhouse periods in geological history. During this time, ecosystem reorganizations significantly impacted the diversification of many groups of organisms. The rise of angiosperms marked a major biome turnover. Notwithstanding, relatively little remains known about how the Cretaceous global ecosystem impacted the evolution of spiders, which constitute one of the most abundant groups of predators. Herein, we evaluate the transcriptomes of 91 taxa representing more than half of the spider families. We add 23 newly sequenced taxa to the existing database to obtain a robust phylogenomic assessment. Phylogenetic reconstructions using different datasets and methods obtain novel placements of some groups, especially in the Synspermiata and the group having a retrolateral tibial apophysis (RTA). Molecular analyses indicate an expansion of the RTA clade at the Early Cretaceous with a hunting predatory strategy shift. Fossil analyses show a 7-fold increase of diversification rate at the same period, but this likely owes to the first occurrences spider in amber deposits. Additional analyses of fossil abundance show an accumulation of spider lineages in the Early Cretaceous. We speculate that the establishment of a warm greenhouse climate pumped the diversification of spiders, in particular among webless forms tracking the abundance of insect prey. Our study offers a new pathway for future investigations of spider phylogeny and diversification.
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Dating back to almost 400 mya, spiders are among the most diverse terrestrial predators [1]. However, despite considerable effort [1-9], their phylogenetic relationships and diversification dynamics remain poorly understood. Here, we use a synergistic approach to study spider evolution through phylogenomics, comparative transcriptomics, and lineage diversification analyses. Our analyses, based on ca. 2,500 genes from 159 spider species, reject a single origin of the orb web (the "ancient orb-web hypothesis") and suggest that orb webs evolved multiple times since the late Triassic-Jurassic. We find no significant association between the loss of foraging webs and increases in diversification rates, suggesting that other factors (e.g., habitat heterogeneity or biotic interactions) potentially played a key role in spider diversification. Finally, we report notable genomic differences in the main spider lineages: while araneoids (ecribellate orb-weavers and their allies) reveal an enrichment in genes related to behavior and sensory reception, the retrolateral tibial apophysis (RTA) clade-the most diverse araneomorph spider lineage-shows enrichment in genes related to immune responses and polyphenic determination. This study, one of the largest invertebrate phylogenomic analyses to date, highlights the usefulness of transcriptomic data not only to build a robust backbone for the Spider Tree of Life, but also to address the genetic basis of diversification in the spider evolutionary chronicle.
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The orb-weaving spider family Araneidae is extremely diverse (> 3,100 spp.) and its members can be charismatic terrestrial arthropods, many of them recognizable by their iconic orbicular snare web, such as the common garden spiders. Despite considerable effort to better understand their backbone relationships based on multiple sources of data (morphological, behavioral and molecular), pervasive low support remains in recent studies. In addition, no overarching phylogeny of araneids is available to date, hampering further comparative work. In this study, we analyze the transcriptomes of 33 taxa, including 19 araneids - 12 of them new to this study - representing most of the core family lineages, to examine the relationships within the family using genomic-scale datasets resulting from various methodological treatments, namely ortholog selection and gene occupancy as a measure of matrix completion. Six matrices were constructed to assess these effects by varying orthology inference method and gene occupancy threshold. Orthology methods used are the benchmarking tool BUSCO and the tree-based method UPhO; three gene occupancy thresholds (45%, 65%, 85%) were used to assess the effect of missing data. Gene tree and species tree-based methods (including multi-species coalescent and concatenation approaches, as well as maximum likelihood and Bayesian inference) were used totalling 17 analytical treatments. The monophyly of Araneidae and the placement of core araneid lineages were supported, together with some previously unsound backbone divergences; these include high support for Zygiellinae as the earliest diverging subfamily (followed by Nephilinae), the placement of Gasteracanthinae as sister group to Cyclosa and close relatives, and close relationships between the Araneus + Neoscona clade and Cyrtophorinae + Argiopinae clade. Incongruences were relegated to short branches in the clade comprising Cyclosa and its close relatives. We found congruence between most of the completed analyses, with minimal topological effects from occupancy/missing data and orthology assessment. The resulting number of genes by certain combinations of orthology and occupancy thresholds being analyzed had the greatest effect on the resulting trees, with anomalous outcomes concluding from analysis of lower numbers of genes.
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Capturing conserved genomic elements to shed light on deep evolutionary history is becoming the new gold standard for phylogenomic research. Ultraconserved elements are shared among distantly related organisms, allowing the capture of unpreceded amounts of genomic data of non-model taxa. 2.An underappreciated consequence of hybrid enrichment methods is the potential of introducing undetected DNA sequences from organisms outside the lineage of interest, facilitated through the high degree of conservation of the target regions. In this in-silico study, we quantify ultraconserved loci using a data set of 400 published genomes. We utilized six newly designed UCE bait sets, tailored to various arthropod groups, and screened for shared conserved elements in all 244 currently published arthropod genomes. Additionally, we included a diverse set of other potential contaminating organisms, such as various species of fungi and bacteria. 3.Our results show that specific UCE bait sets can capture genomic elements from vastly divergent lineages, including human DNA. Nonetheless, our in-silico modeling demonstrates that sufficiently strict bioinformatic processing parameters effectively filter out unintentionally targeted DNA from taxa other than the focus group. Lastly, we characterize all the 100 most widely shared UCE loci as highly conserved exonic regions. 4.We give practical recommendations to address contamination in data sets generated through targeted-enrichment. This article is protected by copyright. All rights reserved.
Article
Model-based molecular phylogenetics plays an important role in comparisons of genomic data, and model selection is a key step in all such analyses. We present ModelFinder, a fast model-selection method that greatly improves the accuracy of phylogenetic estimates by incorporating a model of rate heterogeneity across sites not previously considered in this context and by allowing concurrent searches of model space and tree space.
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1.Targeted enrichment of conserved genomic regions is a popular method for collecting large amounts of sequence data from non-model taxa for phylogenetic, phylogeographic, and population genetic studies. For example, two available bait sets each allow enrichment of thousands of orthologous loci from >20,000 species (Faircloth et al. 2012, 2015). Unfortunately, few open-source workflows are available to identify conserved genomic elements shared among divergent taxa and to design enrichment baits targeting these regions. Those that do exist require extensive bioinformatics expertise and significant amounts of time to use. These shortcomings limit the application of targeted enrichment methods to additional organismal groups.
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Targeted enrichment of conserved genomic regions (e.g., ultraconserved elements or UCEs) has emerged as a promising tool for inferring evolutionary history in many organismal groups. Because the UCE approach is still relatively new, much remains to be learned about how best to identify UCE loci and design baits to enrich them. 2.We test an updated UCE identification and bait design workflow for the insect order Hymenoptera, with a particular focus on ants. The new strategy augments a previous bait design for Hymenoptera by (a) changing the parameters by which conserved genomic regions are identified and retained, and (b) increasing the number of genomes used for locus identification and bait design. We perform in vitro validation of the approach in ants by synthesizing an ant-specific bait set that targets UCE loci and a set of “legacy” phylogenetic markers. Using this bait set, we generate new data for 84 taxa (16/17 ant subfamilies) and extract loci from an additional 17 genome-enabled taxa. We then use these data to examine UCE capture success and phylogenetic performance across ants. We also test the workability of extracting legacy markers from enriched samples and combining the data with published data sets. 3.The updated bait design (hym-v2) contained a total of 2,590-targeted UCE loci for Hymenoptera, significantly increasing the number of loci relative to the original bait set (hym-v1; 1,510 loci). Across 38 genome-enabled Hymenoptera and 84 enriched samples, experiments demonstrated a high and unbiased capture success rate, with the mean locus enrichment rate being 2,214 loci per sample. Phylogenomic analyses of ants produced a robust tree that included strong support for previously uncertain relationships. Complementing the UCE results, we successfully enriched legacy markers, combined the data with published Sanger data sets, and generated a comprehensive ant phylogeny containing 1,060 terminals. 4.Overall, the new UCE bait design strategy resulted in an enhanced bait set for genome-scale phylogenetics in ants and other Hymenoptera. Our in vitro tests demonstrate the utility of the updated design workflow, providing evidence that this approach could be applied to any organismal group with available genomic information. This article is protected by copyright. All rights reserved.
Article
Arachnida is an ancient, diverse, and ecologically important animal group that contains a number of species of interest for medical, agricultural, and engineering applications. Despite their importance, many aspects of the arachnid tree of life remain unresolved, hindering comparative approaches to arachnid biology. Biologists have made considerable efforts to resolve the arachnid phylogeny; yet, limited and challenging morphological characters, as well as a dearth of genetic resources, have hindered progress. Here, we present a genomic toolkit for arachnids featuring hundreds of conserved DNA regions (ultraconserved elements or UCEs) that allow targeted sequencing of any species in the arachnid tree of life. We used recently developed capture probes designed from conserved regions of available arachnid genomes to enrich a sample of loci from 32 diverse arachnids. Sequence capture returned an average of 487 UCE loci for all species, with a range from 170 to 722. Phylogenetic analysis of these UCEs produced a highly resolved arachnid tree with relationships largely consistent with recent transcriptome-based phylogenies. We also tested the phylogenetic informativeness of UCE probes within the spider, scorpion, and harvestman orders, demonstrating the utility of these markers at shallower taxonomic scales, and suggesting that these loci will be useful for species-level differences. This probe set will open the door to phylogenomic and population genomic studies across the arachnid tree of life, enabling systematics, species delimitation, species discovery, and conservation of these diverse arthropods. This article is protected by copyright. All rights reserved.
Article
Acropyga ants are a widespread clade of small subterranean formicines that live in obligate symbiotic associations with root mealybugs. We generated a data set of 944 loci of ultraconserved elements (UCEs) to reconstruct the phylogeny of 41 representatives of 23 Acropyga species using both concatenation and species-tree approaches. We investigated the biogeographic history of the genus through divergence dating analyses and ancestral range reconstructions. We also explored the evolution of the Acropyga-mealybug mutualism using ancestral state reconstruction methods. We recovered a highly supported species phylogeny for Acropyga with both concatenation and species-tree analyses. The age for crown-group Acropyga is estimated to be around 30 Ma. The geographic origin of the genus remains uncertain, although phylogenetic affinities within the subfamily Formicinae point to a Paleotropical ancestor. Two main Acropyga lineages are recovered with mutually exclusive distributions in the Old World and New World. Within the Old World clade, a Palearctic and African lineage is suggested as sister to the remaining species. Ancestral state reconstructions indicate that Old World species have diversified mainly in close association with xenococcines from the genus Eumyrmococcus, although present-day associations also involve other mealybug genera. In contrast, New World Acropyga predominantly evolved with Neochavesia until a recent (10-15 Ma) switch to rhizoecid mealybug partners (genus Rhizoecus). The striking mandibular variation in Acropyga evolved most likely from a 5-toothed ancestor. Our results provide an initial evolutionary framework for extended investigations of potential co-evolutionary interactions between these ants and their mealybug partners.
Article
Availability and implementation: PHYLUCE is written for Python 2.7. PHYLUCE is supported on OSX and Linux (RedHat/CentOS) operating systems. PHYLUCE source code is distributed under a BSD-style license from https://www.github.com/faircloth-lab/phyluce/. PHYLUCE is also available as a package (https://binstar.org/faircloth-lab/phyluce) for the Anaconda Python distribution that installs all dependencies, and users can request a PHYLUCE instance on iPlant Atmosphere (tag: phyluce). The software manual and a tutorial are available from http://phyluce.readthedocs.org/en/latest/ and test data are available from doi: 10.6084/m9.figshare.1284521. Contact: brant@faircloth-lab.org SUPPLEMENTARY INFORMATION: Supplementary Figure 1.
Article
Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported [1]. Current working hypotheses for a spider “backbone” phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype—the spider web.
Article
Spiders constitute one of the most successful clades of terrestrial predators [1]. Their extraordinary diversity, paralleled only by some insects and mites [2], is often attributed to the use of silk, and, in one of the largest lineages, to stereotyped behaviors for building foraging webs of remarkable biomechanical properties [1]. However, our understanding of higher-level spider relationships is poor and is largely based on morphology [2, 3 and 4]. Prior molecular efforts have focused on a handful of genes [5 and 6] but have provided little resolution to key questions such as the origin of the orb weavers [1]. We apply a next-generation sequencing approach to resolve spider phylogeny, examining the relationships among its major lineages. We further explore possible pitfalls in phylogenomic reconstruction, including missing data, unequal rates of evolution, and others. Analyses of multiple data sets all agree on the basic structure of the spider tree and all reject the long-accepted monophyly of Orbiculariae, by placing the cribellate orb weavers (Deinopoidea) with other groups and not with the ecribellate orb weavers (Araneoidea). These results imply independent origins for the two types of orb webs (cribellate and ecribellate) or a much more ancestral origin of the orb web with subsequent loss in the so-called RTA clade. Either alternative demands a major reevaluation of our current understanding of the spider evolutionary chronicle.