Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

We combine morphological (qualitative and quantitative data) and genetic (one mitochondrial and one nuclear gene) data from a large set of specimens of Octodon from the four currently recognized living species of the genus. The integration of the results (qualitative assessment, multivariate analysis of cranial measurements, and gene trees) allows us to state that 1) the current taxonomic scheme does not reflect the species diversity of Octodon; 2) in particular, as currently understood O. bridgesii likely is a complex of three species; 3) one of these, encompassing the southern populations of the genus, in the Araucanía Region (Chile) and Neuquén Province (Argentina), is named and described here as a new species; and 4) the mitochondrial gene tree departs from the nuclear gene tree with respect to O. pacificus and the new species here described.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The taxonomic history of the species of Octodon is relatively simple as only a handful of studies have tackled the taxonomy of the genus. In fact, only three taxonomic studies centered on the genus have been published over the last 100 years; in each of these tree studies (i.e., Osgood, 1943;Hutterer, 1994;D'Elía et al., 2020a) a new species was described (O. lunatus, O. pacificus, and O. ricardojeda respectively). ...
... This decision is based on the problems discussed regarding the Cyt-b locus and since the results of the nuclear dataset analyzed with BPP are the ones that depart least from the current taxonomic scheme it implies the recognition of less cryptic species. With this perspective, the genus Octodon is composed of eight species, a significant departure from the number of currently recognized species (Díaz et al., 2015;D'Elía et al., 2020a). ...
... However, both species are strongly supported as being distinct when the analyses includes nuclear sequences, either analyzed alone or along with the Cyt-b gene (Fig. 2, Table 1). In addition, both species are qualitatively and morphometrically different (Fig. 3;D'Elía et al., 2020a; see also Hutterer, 1994). As such, we recognize O. pacificus and Argentinean Octodon as distinct species. ...
Article
As currently understood, the genus Octodon contains five species degus, lunatus, bridgesii, pacificus, and ricardojeda. Previous phylogenetic studies suggest that genus specific diversity is underestimated. In order to evaluate the taxonomic diversity of Octodon, we implemented unilocus (cytochrome-b) and multilocus (cytochrome-b + 4 nuclear genes) species delimitation methods. Octodon degus was recovered as a sister of the other species of the genus. The unilocus bGMYC and mPTP methods, based on cytochrome-b sequences, delimits 11 and 7 candidate species respectively, and both methods fail to recognize O. pacificus from O. ricardojeda. Results of the multilocus analysis (BPP) vary as a function of the dataset used. When the five genes are used 11 species are delimited, while eight species are delimited when only the nuclear genes are used. Octodon bridgesii is shown as comprising at least two species (one on the Pacific coast and the typical form found on the Andean slopes), while O. ricardojeda may comprise two species (one on the Chilean side of the Andes and the other in Argentina). Likewise, both multilocus matrices recover O. pacificus as a distinct species. This shows that species diversity of Octodon is underestimated. Remarkably, many of the delimited species based on genetic data are morphologically differentiated in cranio-dental characteristics. However, a pair of species has not achieved morphological differentiation, being cryptic species. Finally, the incongruence between mitochondrial and nuclear phylogenies suggests that processes such as incomplete lineage sorting and/or introgression have been present during the radiation of the genus.
... Teta y D'Elía (2020b) sinonimizaron C. coyhaiquensis Kelt y Gallardo 1994 bajo C. sericeus Allen 1903, considerándose a esta última una de las tres especies de Ctenomys distribuidas en la Región de Aysén. Las otras dos especies registradas en dicha región son C. magellanicus y C. fodax, esta última citada por primera vez para el país por Teta et al. (2020). ...
... Octodon.-La especie Octodon ricardojeda fue recientemente descrita y comprende poblaciones de áreas pre-andinas de la Región de la Araucanía, Chile y de la Provincia de Neuquén, Argentina, hasta entonces asignadas a O. bridgesii (D'Elía et al. 2020). ...
... El orden Rodentia, con 14 especies endémicas, constituye el orden con mayor riqueza de estas especies; el segundo orden con mayor número de especies endémicas es Carnivora (tres); finalmente, los órdenes Artiodactyla, Didelphimorphia y Microbiotheria poseen una especie endémica cada uno. La presente lista de endemismos incluye a Octodon bridgesii porque las poblaciones de áreas pre-andinas de la Región de la Araucanía que junto a las de Neuquén, Argentina que eran previamente asignadas a esta especie, se refieren a la recientemente descrita especie O. ricardojeda (D'Elía et al. 2020). Por otra parte, la lista de endemismos no incluye a Spalacopus cyanus dado que recientemente el género ha sido reportado para áreas andinas de Argentina (Pardiñas et al. 2020). ...
Article
Full-text available
Se presenta una lista actualizada de los mamíferos vivientes con registros en Chile, compilada en diciembre de 2020. La lista incluye 163 especies silvestres agrupadas en 85 géneros, 31 familias y ocho órdenes. De estas especies, 20 son endémicas del país. También se provee la lista de 22 especies exóticas con poblaciones silvestres en Chile. Dado que aún persisten áreas de Chile que no han sido suficientemente exploradas, al tiempo que varios géneros no han sido adecuadamente revisados, y debido a que el estatus de algunas formas nominales es debatido, avizoramos que esta lista deberá ser actualizada en el futuro cercano.
... Morphotypes were no recovered monophyletic (Fig. 6) but they account for 69.67% of the observed genetic variation. The observed value of genetic distance between both clades of O. degus (0.69%) is low, being similar to those recorded within species of distinct octodontoid species (e.g., Vianna et al. 2017;Londoño-Gaviria et al. 2019;D'Elía et al. 2020). The crown age of O. degus was inferred at 0.46 (0.21e0.79) ...
Article
The caviomorph Octodon degus is likely the most studied Chilean mammal species. Several studies have centered in its natural history, ecology, behavior, and physiology; in addition, the species is used as model organism in biomedicine and neurobiology research. However, basic aspects such as its genetic and morphological variation throughout its distribution have not been adequately assessed. In fact, the last taxonomic study focused on populations of O. degus dates to the first half of the last century. Here we integrate morphologic (137 specimens from 23 localities) and genetic (cytochrome b gene sequences of 47 individuals from 17 localities) evidence to assess the level and pattern of geographic variation along the whole species distribution. We found that specimens of O. degus present one of two morphotypes that are quali and quatitative differentiable. A gracile morphotype is found towards the north and a robust morphotype towards the south. Skull size variation correlates with precipitation, temperature and primary productivity. In addition, genealogical analysis uncovered two mains clades, one of them formed by haplotypes from specimens from the north and the other formed by haplotypes from specimens from the south of the distribution. We consider these differences warrant recognition at the subspecies level. As such, after assigning a neotype for Sciurus degus (= O. degus) that attaches this name to the southern morph, we described and named a new subspecies for the northern populations of O. degus.
Article
Full-text available
Addressed here is the biogeographical‐vexing question of why the guanaco (Lama guanicoe) is the only large mammal on the big island of Tierra del Fuego, answered by comparing alternative colonisation hypotheses. A multidisciplinary examination was conducted into the archaeological, ecological, evolutionary, geographical, genomic, glacial and zoological past, plus distribution of native terrestrial vertebrates in the Patagonia of southern South America. Notable disparities exist between main Patagonia (2.5 species/10,000 km2) compared with Tierra del Fuego (1.8). In the similar‐sized area of mainland Patagonia just north of the Strait of Magellan there are 12 reptiles, 7 amphibians and 34 mammals = 53 total species; Tierra del Fuego has 13. Despite being the size of Switzerland and only 3.1 km from the mainland, Tierra del Fuego has no species of snakes, salamanders, frogs or turtles, only one lizard, one toad, nine small mammals, one carnivore and one ungulate, the Guanaco. An innovative proposal is made contrary to traditional thinking: Tierra del Fuego has relatively few native‐terrestrial vertebrates because they were decimated by major tephra‐ash fallout (2 to >15 cm) from the Holocene 7750 YBP (years before present) Hudson volcano, the biggest and most destructive eruption in Patagonia during the past 10,000 years that eradicated indigenous peoples, most terrestrial vertebrates and all Guanacos. Neither terrestrial vertebrates nor man were replenished from the adjacent mainland for 1000 years because the Strait of Magellan was a complete biogeographical barrier. Guanacos on Tierra del Fuego have lower genetic diversity compared with the mainland, suggesting it is a younger population. Empirical evidence and pivotal events of Patagonia's prehistory support one of three hypotheses: guanacos were introduced to Tierra del Fuego by early Holocene, guanaco‐dependent, indigenous peoples from the mainland who repopulated Tierra del Fuego utilising the newly invented, skilfully crafted, seaworthy bark canoe (Appendix S1–Resumen en Español). A geographical and biological puzzle that has perplexed scientists since the late 1800s working in southern South America: why are there so few vertebrates on the island of Tierra del Fuego compared to the adjacent Patagonia mainland, including the absence of the ubiquitous Guanaco (Lama guanicoe), wild camelid of the south? An interdisciplinary search favors the hypothesis that the Guanaco, most other wildlife, and early man were decimated by an early Holocene volcano and not replenished for a 1000 years because of the physical barrier Strait of Magellan. But then with the local invention of the bark canoe, an indigenous stone‐age, hunter‐gather culture not only crossed the Strait and re‐inhabited the island, but introduced their primary game animal, the Guanaco.
Article
Full-text available
Abstract Temporal differences in fossil assemblages of small mammals can generate important insights into associated environmental conditions. Moreover, by including modern assemblages in such comparisons, it may also be possible to identify the effects of recent human colonization on mammal communities and their habitats. To explore potential signals of European colonization in northwestern Patagonia, we compared fossil and modern assemblages of small mammals from two newly characterized paleontological sites in the Limay Valley region of Río Negro Province, Argentina. The material analyzed consisted of 18 species of small-bodied terrestrial mammals identified from a sample of 27,992 specimens. Fossil assemblages dating from 6453 to 1002 calibrated years before present were relatively stable in taxonomic composition and displayed only minor differences in relative species abundances. In contrast, the modern assemblages examined were clearly distinct, containing a different suite of numerically dominant taxa and lacking three previously abundant grassland species that are presumed to have gone extinct in the vicinity of our study sites. We suggest that these changes reflect substantial post-colonization modifications of surrounding landscapes, including establishment of pine plantations, changes in fire regimes, and introductions of livestock and invasive species of plants. If correct, this supposition raises important concerns regarding the use of modern assemblages as a baseline for reconstructing paleoenvironmental conditions. To avoid potential misinterpretations associated with the use of modern faunal assemblages, we suggest two potential alternative strategies for inferring temporal changes in environmental conditions.
Article
Full-text available
The combination of morphometrics, phylogenetic comparative methods, and open data sets has renewed interest in relating morphology to adaptation and ecological opportunities. Focusing on the Caviomorpha, a well-studied mammalian group, we evaluated patterns in research and data sharing in studies relating form and function. Caviomorpha encompasses a radiation of rodents that is diverse both taxonomically and ecologically. We reviewed 41 publications investigating ecomorphology in this group. We recorded the type of data used in each study and whether these data were made available, and we re-digitized all provided data. We tracked two major lines of information: collections material examined and trait data for morphological and ecological traits. Collectively, the studies considered 63% of extant caviomorph species; all extant families and genera were represented. We found that species-level trait data rarely were provided. Specimen-level data were even less common. Morphological and ecological data were too heterogeneous and sparse to aggregate into a single data set, so we created relational tables with the data. Additionally, we concatenated all specimen lists into a single data set and standardized all relevant data for phylogenetic hypotheses and gene sequence accessions to facilitate future morphometric and phylogenetic comparative research. This work highlights the importance and ongoing use of scientific collections, and it allows for the integration of specimen information with species trait data.
Article
Full-text available
Adaptation and evolution of terrestrial vertebrates inhabiting islands have been the topic of many studies, particularly those seeking to identify trends or patterns in body size in mammals, albeit not necessarily in shape, in relation to mainland populations. The spiny pocket mouse, Chaetodipus spinatus, is distributed in the Baja California peninsula and its surrounding islands. Insular populations became isolated ~12,000 due to changes in sea level; these populations’ matrilinear (mitochondrial) DNA shows minor interpopulation variation. We tested the hypothesis that adaptation and evolution in these island populations involve variation in both skull size and skull shape (using geometric morphometrics) relative to mainland populations, rather than only in size as previously assumed. A total of 363 specimens from 15 insular and peninsular populations were used in analysis of the skull length and geometric morphometric analyses. Our findings revealed significant differences related to skull size among population. The skull shape analyses showed two significantly different morphotypes: one for all island specimens and one for all mainland samples. Our analyses support the hypothesis that insular populations may not only vary in size relative to mainland populations, but may also show variations in shape, regardless of differing conditions across islands.
Article
Full-text available
With almost 2,600 species, Rodentia is the most diverse order of mammals. Here, we provide an overview of changes in our understanding of the systematics of living rodents, including species recognition and delimitation, phylogenetics, and classi cation, with emphasis on the last three decades. Roughly, this corresponds to the DNA sequencing era of rodent systematics, but the eld is undergoing a transition into the genomic era. At least 248 species were newly described in the period 2000–2017, including novelties such as the rst living member of Diatomyidae and a murid species without molars (Paucidentomys vermidax), thus highlighting the fact that our understanding of rodent diversity is going through an age of discovery. Mito-nuclear discordance (including that resulting from mitochondrial introgression) has been detected in some of the few taxonomic studies that have assessed variation of two or more unlinked loci. As studies incorporate more loci, incomplete lineage sorting and introgression are likely to gain recognition as widespread phenomena in the near future. Molecular phylogenetics has had a major impact in rodent phylogeny and allowed the identi cation of three major rodent clades, here recognized as suborders: 1) the Hystricomorpha (sometimes referred as the Ctenohystrica) and including two infraorders, Hystricognathi and Ctenodactylomorphi; 2) the Sciuromorpha; and 3) the Supramyomorpha, a new suborder that comprises the infraorders Castorimorphi, Anomalurimorphi, and Myomorphi. In spite of the greater understanding and ensuing stability of rodent phylogeny gained during the last three decades, several major areas of the rodent tree remain unresolved or poorly supported. We expect that the analysis of genomic-scale data will help resolve those areas of the radiation of Rodentia that still remain poorly understood.
Article
Full-text available
Bayesian inference of phylogeny using Markov chain Monte Carlo (MCMC) (Drummond et al., 2002; Mau et al., 1999; Rannala and Yang, 1996) flourishes as a popular approach to uncover the evolutionary relationships among taxa, such as genes, genomes, individuals or species. MCMC approaches generate samples of model parameter values - including the phylogenetic tree -drawn from their posterior distribution given molecular sequence data and a selection of evolutionary models. Visualising, tabulating and marginalising these samples is critical for approximating the posterior quantities of interest that one reports as the outcome of a Bayesian phylogenetic analysis. To facilitate this task, we have developed the Tracer (version 1.7) software package to process MCMC trace files containing parameter samples and to interactively explore the high-dimensional posterior distribution. Tracer works automatically with sample output from BEAST (Drummond et al., 2012), BEAST2 (Bouckaert et al., 2014), LAMARC (Kuhner, 2006), Migrate (Beerli, 2006), MrBayes (Ronquist et al., 2012), RevBayes (Höhna et al., 2016) and possibly other MCMC programs from other domains.
Article
Full-text available
Caviomorph rodents are one of the most diverse mammalian groups in the Neotropics; they display astonishing eco-morphological variation, including unparalleled size range. Here we analyze evolutionary patterns among extant caviomorphs, particularly their rates of diversification and size evolution. The results show large heterogeneity in the evolutionary dynamics of caviomorphs. Three clear episodes of rapid increase of the diversification rate were detected; two of them during the Oligocene were related to the diversification of major clades; a third one, in the late Miocene, was related to the diversification of the genus Ctenomys. Regarding size, relatively low rates characterized much of Octodontoidea, the most speciose among the main caviomorph clades. Other clades, especially Cavioidea and Chinchilloidea, showed much accelerated evolutionary rates and the highest number of size changes, particularly increases; furthermore, they include extinct representatives that reached very large to gigantic size. Thus, although the macroevolutionary dynamics of caviomorphs were complex and heterogeneous in our study, the pathways followed by different clades seem to display their own particular characteristics. This should be analyzed in greater depth through new, greater-scale analyses incorporating the rich fossil record of caviomorphs, which contributes essential information to understand the evolution of these peculiar rodents
Article
Full-text available
Octodon (Octodontidae) is an endemic genus of rodents that is typical of southwestern South America and represented by 4 species. Octodon pacificus, commonly referred to as the Mocha Island degu, was initially described from specimens collected in 1959 at Mocha Island, a small coastal island located along the central coast of Chile. Fifty-seven years after its original collection, we report the discovery of a female O. pacificus carcass, identified by its morphological characteristics and its specific locality. In addition, based on the cytochrome b (Cytb) gene of the mitochondrial DNA obtained from O. pacificus and other congeneric species, we assessed phylogenetic relationships within the Octodontidae. Bayesian phylogenetic reconstruction indicated that O. degus represented the basal Octodon sp., followed by O. lunatus; O. bridgesii and O. pacificus were identified as sister taxa. Remarkably, the genetic divergence between O. bridgesii and O. pacificus is low, which suggests that 1 of 2 scenarios may be at play: the occurrence of a recent peripatric speciation process in O. pacificus, or the presence of O. bridgesii on Mocha Island. Documented collections of archeozoological material obtained from Mocha Island only include specimens of O. pacificus, a finding that supports our 1st proposed scenario. While the core of Mocha Island is a national reserve, strong anthropogenic landscape modifications have affected the coastal plains—the only known habitat of O. pacificus. Rodent control using killing traps and poison is a common practice on the island; therefore, population surveys and conservation initiatives are needed to conserve this endangered species. El género Octodon (Octodontidae) se compone por cuatro especies de roedores endémicos del suroeste de América del Sur. Ocotodon pacificus fue descrito a partir de especímenes colectados en 1959 en Isla Mocha, una pequeña isla ubicada en la costa de Chile Central. Cincuenta y siete años después de su único registro, mediante un estudio morfológico, reportamos la identificación de una carcasa de una hembra de O. pacificus colectada en la localidad tipo para la especie. Adicionalmente, utilizando secuencias parciales del gen mitocondrial Cytb de esta y las otras tres especies del género, mediante un análisis Bayesiano se reconstruyeron las relaciones filogenéticas dentro de la familia Octodontidae. Con un elevado soporte de valores de probabilidad posterior, Octodon degu figura en un clado basal separado de un grupo hermano compuesto por Octodon lunatus, Octodon bridgesii y O. pacificus. La alta similitud genética observada entre O. bridgesii y O. pacificus es sugestivo de dos posibles escenarios: la ocurrencia de un evento de especiación peripátrica, o que O. brigdesii posee una población en la Isla Mocha. Análisis de osamentas de roedores en restos arqueológicos colectados en la isla, solo incluyen el diagnóstico de
Article
Full-text available
A previous study showed that Dromiciops gliroides has deep phylogeographic structure, with 3 allopatric and highly differentiated groups. Here, we constructed on that study by assessing the morphologic variation of D. gliroides . Our results show that along its distribution Dromiciops is morphologically highly variable and that the geographic pattern of morphologic variation matches the phylogeographic pattern. Taken together, morphological and molecular data indicate the existence of 2 unrecognized and unnamed species of monito del monte, which are here named and described. Cranial and dental features can easily distinguish species of Dromiciops . One of the new species is endemic of Chile, and the other new species occurs in Argentina and Chile. D. gliroides s.s. is restricted to the southern part of the genus distribution including Chiloé Island. We comment on the conservation significance of our findings and on the need of continuing with field- and collection-based research in order to characterize the richness of the Chilean mammal assemblage. Un estudio previo mostró que Dromiciops gliroides tiene una marcada estructura filogeográfica con 3 grupos alopátridos bien diferenciados. Dado esos resultados, en el presente estudio analizamos la variación morfológica de D. gliroides . Nuestros resultados indican que D. gliroides es, a través de su distribución, altamente variable y que el patrón geográfico de la variación morfológica es congruente con el patrón filogeografico. Considerada en conjunto, la evidencia morfológica y molecular indica la existencia de dos especies de monito del monte que no han sido reconocidas, las que son aca descritas y nominadas. Las tres especies de Dromiciops se pueden distinguir fácilmente por características craneales y dentales. Una de las nuevas especies es endémica de Chile y la otra se distribuye en Argentina y Chile. D. gliroides s.s. se restringe a la porción sur del área distribucional del género, incluyendo la Isla de Chiloé. Cerramos el trabajo comentado sobre la necesidad de continuar realizando colectas y trabajo basado en colecciones con el fin de caracterizar la diversidad del ensamble de mamíferos de Chile.
Chapter
Full-text available
The Caviomorpha is a diverse lineage of hystricognath rodents endemic to the Americas and Caribbean islands. We analyzed evolutionary relationships within 11 families of caviomorphs and their relatives in the suborder Ctenohystrica using a supermatrix of 199 taxa and DNA sequences from five genes. New gene sequences were generated for 33 genera, including 12 genera newly available for molecular analysis. Presented here are the analyses pruned to a single representative for each genus, totaling 68 of the 70 living genera in Ctenohystrica. Our analyses recovered strong support for Hystricognathi containing the monophyletic groups Hystricidae, Phiomorpha, and Caviomorpha, with the latter two groups as well- supported sister taxa. The analyses also strongly supported the monophyly of the four traditional superfamilies of caviomorphs, with Cavioidea + Erethizontoidea and Chinchilloidea (including Dinomyidae) + Octodontoidea. Cuniculidae + Dasyproctidae are recovered as sister to Caviidae (including Hydrochoerus). Abrocomidae (including Cuscomys) is sister to the remaining octodontoid families, consisting of the dyads Octodontidae + Ctenomyidae and Echimyidae (including Myocastor) + Capromyidae. The five genera of capromyids form a robustly monophyletic group, but they are allied to a group of Brazilian echimyids, rendering Echimyidae paraphyletic. We dated nodes in our tree by comparing eight sets of fossil calibrations, identifying a set of 22 calibrations that minimized internal age conflicts.The resulting timetree dates the Hystricognathi crown to the Middle Eocene, 44.9 Ma, and the phiomorph-caviomorph split to 42.0 Ma. Crown caviomorphs diverged at 35.7 Ma, and splits of Cavioidea-Erethizontoidea and Chinchilloidea-Octodontoidea occurred at 32.4 Ma and 32.8 Ma, respectively. Most families appeared in the late Oligocene-Early Miocene and virtually all genera are of Middle-Late Miocene age, with a few exceptions. We briefly consider geo-climatic changes that might have influenced the evolution of hystricognath rodents, deferring to another work a detailed analysis of their rates and ecological drivers of diversification.
Article
Full-text available
The family Octodontidae (Rodentia, Hystricognatha) is an old group of low diversity, currently found on both sides of the Andean mountains between 16°S and 41°S. Information on the geographic distribution of the octodontid genera is presented and discussed, and the systematic status of each species and subspecies is given. An explanation is also proposed for the present distribution of the family, considering geological, climatic, floristic, faunistic, and ecological events that occurred after the first appearance of octodontids in the Deseaden age (early Oligocene) in Bolivia and Patagonia. Uplift of the Andes, formation of Patagonian pampas, disappearance of echimyids from the Patagonian Subregion, and appearance of ctenomyids seem to be the most important factors determining the present distribution of octodontids. -from Authors
Article
Full-text available
Phylogeny and evolutionary patterns of South American octodontoid rodents. Acta Palaeontologica Polonica 59 (4): 757–769. Octodontoidea is the most diverse clade of hystricognath rodents, and is richly recorded in South America since at least the Oligocene. A parsimony-based morphological phylogenetic analysis of a wide range of extant and extinct octodon-toids recovered three major clades, here recognised as Echimyidae, Octodontidae, and Abrocomidae. Taxa previously assigned to Echimyidae or Octodontoidea incertae sedis are here interpreted for the first time as early representatives of Ctenomyinae (Octodontidae), Octodontinae or Abrocomidae. Based on our results, we estimate the divergence of octodontoid families and subfamilies to have occurred during the Late Oligocene, which is consistent with molecular estimates, but older than previous inferences based on the fossil record. Contrary to previous suggestions, we show the first appearances of modern members of Abrocomidae, Octodontinae and Ctenomyinae to be distinctly decoupled from the origin of these clades, with different stages in the evolutionary history of octodontoids seemingly following distinct phases of palaeoenvironmental change. Depending on the phylogenetic pattern, fossils from the stage of differentiation bear evolutionary information that may not be provided by crown groups, thus highlighting the unique and important contribution of fossils to our understanding of macroevolutionary patterns.
Article
Full-text available
Karyotypic evolution in the Octodontidae and Abrocomidae is examined by use of C-bands. Karyotypic pathways illustrate chromosomal rearrangements that are more varied than previously thought. A superimposition of tandem fusions and non-Robertsonian mechanisms involving euchromatic segments accounts for the pattern of variation observed. Heterochromatic short arms, although present, do not explain the general biarmed karyotypic condition observed across the genera. Evolution of heterochromatin has proceeded through whole-arm additions and euchromatin transformation, and has been independent of the bidirectional changes in diploid number. The magnitude of the karyotypic differences within the Octodontidae reflects its extensive adaptive radiation in the past, although the family is now represented by relatively few species.
Article
Full-text available
Species definitions are commonly based on documentation either of genetic or ecologic cohesion (biological species models) or of phylogenetic relationship (phylogenetic species concept). However, these philosophical positions are often incompatible with data on genealogical relationship of and genetic/reproductive interactions among member populations. The difficulty in defining species in nature based on either viewpoint is exacerbated when times between divergence events are short, when differentiation among populations prior to speciation is extensive, and when reticulation events persist subsequent to speciation. We illustrate this set of problems with data on mitochondrial DNA sequences and both nuclear sequences and allozyme electromorphs for sets of populations of two currently recognized species of pocket gophers,Thomomys bottae andT. townsendii in the western United States. These molecular perspectives give somewhat conflicting views of polyphyly, paraphyly, and monophyly at the population and species level due, in part, to probable differences in times to monophyly, differential lineage sorting, retention of ancestral polymorphisms, and/or episodes of asymmetrical introgressive hybridization. As a consequence, strict adherence to any species concept in the objective recognition of evolutionary units within this complex is difficult at best.
Article
Full-text available
Abrotrichini is a recently defined and diagnosed tribe of Sigmodontinae with a complex taxonomy. Abrotrichine genera, Abrothrix (including Chroeomys), Chelemys, Geoxus, Notiomys and Pearsonomys, are mostly distributed in the central and southern Andes and adjacent lowlands and show terrestrial and fossorial habits. Recent studies have evidenced some incongruence between current taxonomy and abrotrichine phylogeny, such as the polyphyly of Chelemys and paraphyly of Geoxus respect to Pearsonomys. We used DNA sequence data of six loci (one mitochondrial and five nuclear) to resolve the relationships within the tribe. Independent and combined analyses of these loci were carried out using parsimony, maximum likelihood and Bayesian inference. Estimates of divergence time of the main lineages of abrotrichines were calculated with a molecular clock using as calibration, a fossil recently found. The concatenated data set increased the resolution and defined the relationships within the tribe. Our phylogenetic analyses corroborate that Abrothrix is sister of a clade containing the long-clawed abrotrichines. We recovered two main clades within Abrothrix that match morphologic variation and geographic distribution of its species. In addition, we corroborated the lack of monophyly of Chelemys and the lack of monophyly of Geoxus. We discuss different taxonomic scenarios to abrotrichine classification reflects the phylogenetic relationships obtained in this study. Our molecular clock estimated the Abrotrichini crown age to be around the early Pliocene (4.4 Ma) and suggest that the tribe diversified over a short period of time.
Article
Full-text available
†Eumysops is a peculiar representative of the currently tropical family Echimyidae, which evolved in increasingly dry and cold Plio–Pleistocene environments of southern South America. The results of a systematic and stratigraphic review of the genus, and of phylogenetic analyses based on both morphology and a combined morphological–molecular dataset in the context of extant representatives, are presented here. Recognised diversity includes four previously described species plus a new one from the late Pliocene. These species form a well-supported monophyletic clade, sister to the late Miocene †Pampamys and the extant Thrichomys. The position of †Eumysops–†Pampamys–Thrichomys in a major clade including non-‘eumysopine’ echimyids constrains the traditional taxon Eumysopinae only to these three genera. Phylogeny and stratigraphic distribution of †Eumysops species suggest an essentially cladogenetic evolutionary pattern. Beyond this, a gradual directional change, involving increase in size and in molar hypsodonty, is shown by †Eumysops chapalmalensis as part of a late Pliocene faunal turnover interpreted as a local representation of the 2.5-Ma cooling global event. Distinctive skeletal and dental anatomy of †Eumysops, including large orbits, shortened braincase, marked hypsodonty and postcranial specialisations, would be a result of its southern history related to a particular palaeoclimatic context.
Article
Full-text available
We present a new open source, extensible and flexible software platform for Bayesian evolutionary analysis called BEAST 2. This software platform is a re-design of the popular BEAST 1 platform to correct structural deficiencies that became evident as the BEAST 1 software evolved. Key among those deficiencies was the lack of post-deployment extensibility. BEAST 2 now has a fully developed package management system that allows third party developers to write additional functionality that can be directly installed to the BEAST 2 analysis platform via a package manager without requiring a new software release of the platform. This package architecture is showcased with a number of recently published new models encompassing birth-death-sampling tree priors, phylodynamics and model averaging for substitution models and site partitioning. A second major improvement is the ability to read/write the entire state of the MCMC chain to/from disk allowing it to be easily shared between multiple instances of the BEAST software. This facilitates checkpointing and better support for multi-processor and high-end computing extensions. Finally, the functionality in new packages can be easily added to the user interface (BEAUti 2) by a simple XML template-based mechanism because BEAST 2 has been re-designed to provide greater integration between the analysis engine and the user interface so that, for example BEAST and BEAUti use exactly the same XML file format.
Article
Full-text available
We announce the release of an advanced version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which currently contains facilities for building sequence alignments, inferring phylogenetic histories, and conducting molecular evolutionary analysis. In version 6.0, MEGA now enables the inference of timetrees, as it implements our RelTime method for estimating divergence times for all branching points in a phylogeny. A new Timetree Wizard in MEGA6 facilitates this timetree inference by providing a graphical user interface (GUI) to specify the phylogeny and calibration constraints step-by-step. This version also contains enhanced algorithms to search for the optimal trees under evolutionary criteria and implements a more advanced memory management that can double the size of sequence data sets to which MEGA can be applied. Both GUI and command-line versions of MEGA6 can be downloaded from www.megasoftware.net free of charge.
Article
Full-text available
Two new genera and species of rodents are described from isolated salt pans in far northwestern Argentina. Both are members of the hystricognath family, Octodontidae. The tow new genera are both specialized for life in zones of high salinity with halophytic vegetation growing at the periphery of saline flats. The new taxa are most closely related to Tympanoctomys barrerae, the Red Vizcacha Rat, with occurs in salt flats in central Argentina further to the south. One of the new mammals is restricted to an isolated salt flat lying within an enclosed bolson in Catamarca province. The other is limited to habitat islands that occur within the vast Salinas Grandes (great salt flat) of La Rioja Province in central Argentina. Taxonomic description are included, as is information on relationships within the familiy Octodontidae. The biogeographic history of the group, and an evolutionary scenario for the evolution of the two new genera, are also discussed.
Article
Full-text available
Reports on Octodon bridgesi in 2 Argentinian areas of the Province of Neuquen. -from Authors
Article
Full-text available
in spring of 2000, Chusquea culeou bamboo, the dominant understory plant in Valdivian forest habitat in southwestern argentina, flowered over a latitudinal range of 100 km and produced a massive amount of seed. reproductive activity of rodents in the area continued into the subsequent autumn and winter, when rodent numbers reached peak levels and large numbers of drowned rodents appeared on beaches. Owls and foxes reached high numbers, and the mean age in populations of Oligoryzomys longicaudatus and Abrothrix longipilis declined. In the following (second) spring, reproduction was delayed or suppressed, and by the following (second) autumn populations had declined to unusually low levels. By the third year after the flowering, rodent numbers had returned to levels characteristic of populations in this area. Oligoryzomys longicaudatus, Abrothrix longipilis, Loxodontomys micropus, irenomys tarsalis, and the introduced Rattus rattus increased in numbers following the bamboo bloom; numbers of Chelemys macronyx and Geoxus valdivianus, species that eat invertebrates, were not affected. these observations strongly imply that the abundance of bamboo seed caused this outbreak, and suggest that food availability is the main factor limiting numbers of rodents in these forests.
Article
Full-text available
Many rodents have large body sizes on islands, and there are many hypotheses that try to explain this observed pattern. Using body size data on Apodemus in Europe as an example, I try to evaluate the main hypotheses. These can be divided in four different categories. 1) Hypothesesa ssumingc limaticd ifferencesb etweeni slandsa nd mainland:n o trend in body size on islandsi n the Mediterraneani,n Britaino r in the Baltic area is observed. 2) Hypotheses based on island size: no trend is observed in the data analysed. 3) Hypotheses based on distance to mainland: no general effect is found, although there is an effect in the British material. 4) Hypothesesb asedo n faunisticd ifferences:c onsistentr elationshipas re foundi n all areas. A. sylvaticus shows larger body size when lacking competition from A. flavicolliso r Clethrionomygsl areoluso r whenp redationi s absent.A . flavicollisi s larger when predators are lacking, and smaller when no competitors are present. This is in agreementw ith characterd isplacement heory.
Article
Full-text available
Background The hystricognath rodents of the New World, the Caviomorpha, are a diverse lineage with a long evolutionary history, and their representation in South American fossil record begins with their occurrence in Eocene deposits from Peru. Debates regarding the origin and diversification of this group represent longstanding issues in mammalian evolution because early hystricognaths, as well as Platyrrhini primates, appeared when South American was an isolated landmass, which raised the possibility of a synchronous arrival of these mammalian groups. Thus, an immediate biogeographic problem is posed by the study of caviomorph origins. This problem has motivated the analysis of hystricognath evolution with molecular dating techniques that relied essentially on nuclear data. However, questions remain about the phylogeny and chronology of the major caviomorph lineages. To enhance the understanding of the evolution of the Hystricognathi in the New World, we sequenced new mitochondrial genomes of caviomorphs and performed a combined analysis with nuclear genes. Results Our analysis supports the existence of two major caviomorph lineages: the (Chinchilloidea + Octodontoidea) and the (Cavioidea + Erethizontoidea), which diverged in the late Eocene. The Caviomorpha/phiomorph divergence also occurred at approximately 43 Ma. We inferred that all family-level divergences of New World hystricognaths occurred in the early Miocene. Conclusion The molecular estimates presented in this study, inferred from the combined analysis of mitochondrial genomes and nuclear data, are in complete agreement with the recently proposed paleontological scenario of Caviomorpha evolution. A comparison with recent studies on New World primate diversification indicate that although the hypothesis that both lineages arrived synchronously in the Neotropics cannot be discarded, the times elapsed since the most recent common ancestor of the extant representatives of both groups are different.
Article
Full-text available
Nesse estudo descreve-se a fauna de mamíferos não-voadores do Rio Juruá, situado a oeste da Amazônia brasileira, por meio das coletas realizadas ao longo desse rio durante levantamento de aproximadamente um ano. Os trabalhos de campo foram planejados para examinar os efeitos do rio na estrutura dos vertebrados terrestres, inclusive dos mamíferos, tanto no que se refere às comunidades quanto aos padrões de diferenciação geográfica para espécies individuais. Dezesseis sítios de coleta primários foram inventariados segundo desenho experimental constituido por dois pares de sítios situados em margens opostas, em cada uma das quatro regiões distribuidas das proximidades da foz até a região da cabeceira do rio. Um total de 81 espécies foram obtidas, e inclui nove espécies novas para a ciência. Quarto delas estão descritas neste estudo; as outras encontram-se descritas em outros trabalhos. A estrutura das comunidades foi determinada a partir de um protocolo de amostragem padronizado para cada um dos 16 sítios que incluia estações de captura, com armadilhas terrestres e arbóreas, nas matas de várzea e de terra firme. Capturas adicionais foram realizadas em habitats considerados secundários em todos os sítios de amostragem. Descrevem-se esses sítios, o esforço de amostragem e a localização das estações de captura correspondentes aos habitats locais. Também descreve-se cada uma das espécies de marsupiais e de roedores murídeos e equimídeos encontradas, comenta-se sobre sua sistemática, e sumarizam-se aspectos relativos ao uso de habitat, história natural, distribuição geográfica, e diferenciação geográfica baseada em caracteres morfológicos e moleculares. A variação nas sequências do gene mitocondrial citocromo-b foi examinada para amostras de 41 das 45 espécies de marsupiais e roedores obtidas. Para cada um dos táxons, cujas amostras eram suficientes, examinaram-se os padrões de diferenciação na bacia do Rio Juruá, e discutiram-se esses padrões para toda a Amazônia e, em alguns casos, incluiu-se também a Mata Atlântica. Posteriormente, examinaram-se os padrões de organização das comunidades na bacia do Rio Juruá e em toda a Amazônia, chamando atenção sobre a distribuição geográfica do que aparentemente representam unidades faunística maiores, independentes das diferenças no habitat. Retorna-se, então, ao objetivo original e utilizam-se os princípios filogeográficos para analisar os padrões geográficos de diferenciação entre os mamíferos não-voadores com referência à Hipótese dos Rios. Mostra-se que embora para alguns táxons o Rio Juruá funcione como barreira, a maioria dos táxons ou é largamente indiferenciada em toda a bacia ou marcadamente dividida em clades de haplotipos monofiléticos separáveis em duas unidades distintas, uma rio-acima e outra rio-abaixo. Argumenta-se que essa concordância na localização geográfica dos limites dos clados indicam uma história comum e, tanto a idade desses clados quanto suas posições geográficas em relação às estruturas geológicas subjacentes sugerem que a evolução das paisagens tem sido um componente importante, embora desconsiderado dos processos de diversificação no oeste da Amazônia.
Article
Full-text available
Species are routinely used as fundamental units of analysis in biogeog-raphy, ecology, macroevolution, and conservation biology. A large literature focuses on defining species conceptually, but until recently little attention has been given to the issue of empirically delimiting species. Researchers confronted with the task of delimiting species in nature are often unsure which method(s) is (are) most appropriate for their system and data type collected. Here, we review twelve of these methods organized into two general categories of tree-and nontree-based approaches. We also summarize the relevant biological properties of species amenable to empirical evalu-ation, the classes of data required, and some of the strengths and limitations of each method. We conclude that all methods will sometimes fail to delimit species bound-aries properly or will give conflicting results, and that virtually all methods require researchers to make qualitative judgments. These facts, coupled with the fuzzy nature of species boundaries, require an eclectic approach to delimiting species and caution against the reliance on any single data set or method when delimiting species. No one definition has as yet satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species.
Article
Using computer simulations, we generated and analyzed genetic distances among selectively neutral haplotypes transmitted through gene genealogies with random-mating organismal pedigrees. Constraints and possible biases on haplotype distances due to correlated ancestry were evaluated by comparing observed distributions of distances to those predicted from an inbreeding theory that assumes independence among haplotype pairs. Results suggest that: 1) mean time to common ancestry of neutral haplotypes can be a reasonably good predictor of evolutionary effective population size; 2) the nonindependence of haplotype paths of descent within a given gene genealogy typically produces significant departures from the theoretical probability distributions of haplotype distances; 3) frequency distributions of distances between haplotypes drawn from "replicate" organismal pedigrees or from multiple unlinked loci within an organismal pedigree exhibit very close agreement with the theory for independent haplotypes. These results are relevant to interpretations of current molecular data on genetic distances among nonrecombining haplotypes at either nuclear or cytoplasmic loci.
Article
When lineages diverge in allopatry and come into secondary contact, we have a unique opportunity to examine the degree to which they have become reproductively isolated from one another and the mechanisms that contribute to rates of interspecific gene flow. If hybridization and introgression have occurred in the past or are ongoing, examining patterns of variation in differentially inherited genetic markers can provide insight into underlying mechanisms determining interspecific reproductive interactions. We investigated genetic variation in a recently discovered contact zone between two species of woodrats (Neotoma fuscipes and N.macrotis) in central coastal California. Previous studies have found evidence of historic hybridization between these species, but an active site of sympatry had yet to be discovered. Here, we describe the first known area of sympatry between the two species and present evidence of ongoing hybridization at this site. We intensively sampled throughout the narrow area of interspecific contact and continuously into the adjacent areas where each taxon existed largely in isolation of the other. We genotyped 851 individuals sampled in a single year at 15 nuclear microsatellite loci and sequenced a portion of the cytochrome b gene in a subset of these to examine patterns of introgression. We find that the area of sympatry is less than 1km in length, but hybridization appeared to be fairly common, with 15% of the woodrats being of hybrid origin. At least some hybrids are fertile because introgression was evident. However, introgression appeared to be asymmetric with backcrosses toward N.macrotis being more common, a pattern we suspect is due in part to directional mate choice related to differential body size. This study adds to our growing understanding of the nature of species boundaries, especially between lineages that are far along the continuum towards speciation.
Article
The insular body size trends for different vertebrate families are compared. Certain groups such as lagomorphs, bats, artiodactyls, elephants, foxes, raccoons, snakes, and teiid and lacertid lizards are habitually represented by relatively smaller forms on islands. On the other hand, cricetid rodents, iguanid lizards, tortoises, and bears often have races with larger body sizes on islands. Contrary to conventional niche theoretic concepts, in many instances knowledge of the body sizes of some of these animals' insular and mainland competitors does not help explain the difference in that species body size in the 2 places. To account for these divergent size changes I examine optimum body size models that use as the optimization criterion the net energy gained by an organism over a given time period. These models predict that increases in the mean amount of available food should lead to evolutionary increases in body size, but only if body size is not tightly constrained by additional physical or biotic factors: such additional factors might be important if a change in body size alters an animal's effectiveness in finding or handling preferred food items or increases competition with its neighbors. Next using arguments derived from simple non-age-structured 2 species predator-prey models, the availability of food for a given consumer species at equilibrium is compared in theoretical island and mainland situations. Because islands usually contain fewer competitors and the insular physical environment is often more moderate, food availability for colonists is initially expected to be high. On the other hand, as the population grows resources will become depleted. Further, the loss of many predator species on islands may allow consumer densities to increase to such an extent that at equilibrium food may become relatively more limiting for consumers on islands than on the mainland. Whether the supply to demand ratio (S:D) of consumers for their food is ultimately greater or lower will depend on the relative magnitude of these various factors. Within this framework, a necessary condition for island S:D ratios to be greater than on the mainland is that the consumers maintain individual feeding territories. For animals whose body sizes are not tightly bound within narrow limits by physical or competitive restraints, an increase in S:D should lead to an evolutionary increase in body size. Accordingly, a good association is found between the presence or absence of territoriality and the direction of the insular body size shift in a number of different vertebrate groups. Yet there are exceptions which fall into 2 categories: First, if a species' mainland predators preferentially take larger individuals, selection favoring small size may override selection based on optimizing energy input. Such may have been the case for the now extinct mainland relatives of certain giant relictual insular reptiles. Secondly, an animal's body size may be tightly constrained by physical or competitive factors. The body size of island foxes, rattlesnakes, and some lizards appears to be primarily adjusted to the competitive milieu along typical niche theoretic lines. That is, body size may be predicted quite well from knowing the size class of competitors which are absent from an island or from differences in the species' prey-size distribution between island and mainland sites.
Article
Using computer simulations, we generated and analyzed genetic distances among selectively neutral haplotypes transmitted through gene genealogies with random-mating organismal pedigrees. Constraints and possible biases on haplotype distances due to correlated ancestry were evaluated by comparing observed distributions of distances to those predicted from an inbreeding theory that assumes independence among haplotype pairs. Results suggest that: 1) mean time to common ancestry of neutral haplotypes can be a reasonably good predictor of evolutionary effective population size; 2) the nonindependence of haplotype paths of descent within a given gene genealogy typically produces significant departures from the theoretical probability distributions of haplotype distances; 3) frequency distributions of distances between haplotypes drawn from "replicate" organismal pedigrees or from multiple unlinked loci within an organismal pedigree exhibit very close agreement with the theory for independent haplotypes. These results are relevant to interpretations of current molecular data on genetic distances among nonrecombining haplotypes at either nuclear or cytoplasmic loci.
Article
Sooretamys is a monotypic genus of the family Cricetidae, subfamily Sigmodontinae, that is distributed throughout eastern South America in the Atlantic Forest Biome, including Argentina, Brazil, and Paraguay. The taxonomic history of the forms associated with this genus is long and relatively complex, and few studies have evaluated the taxonomic problems of this genus. To this end, our goal was to describe the degree and geographical pattern of morphological and molecular variation in this genus to test the current hypothesis that the genus is monotypic, and, as a consequence, to determine the status of the nominal forms associated with Sooretamys. Accordingly, we employed morphometric, morphological, and molecular tools, according to an integrative taxonomy approach. The results show that some level of morphometric discontinuity is present between the individuals from Paraguay and those from adjacent localities in Brazil and Argentina; sharp discontinuities were not observed in qualitative traits. Molecular analyses of the mitochondrial cytochrome b gene showed that the Paraguayan populations have some degree of genetic differentiation, but the haplotypic variants do not form a monophyletic group. Thus, the evidence so far suggests a difference in the genes and morphology of the Paraguayan population, but there is no consistent resolution (e.g. lack of monophyly) to show that specimens from Paraguay represent a distinct population that would merit taxonomic recognition. Thus, we recognize a single species within the genus Sooretamys, named Sooretamys angouya. The pattern of morphological and genetic differentiation of Sooretamys could be the result of divergence with gene flow. However, our data also correspond in some aspects with the model advanced by Carnaval & Moritz, which claims the existence of stable Atlantic Forest areas where the forest biota persisted during the Quaternary climatic fluctuations. Whatever process has occurred, S. angouya represents one species with a complex evolutionary history, and the analysis of additional samples would be welcome to further elucidate the process of diversification of this taxon. © 2014 The Linnean Society of London
Article
Sooretamysis a monotypic genus of the family Cricetidae, subfamily Sigmodontinae, that is distributed throughout eastern South America in the Atlantic Forest Biome, including Argentina, Brazil, and Paraguay. The taxonomic history of the forms associated with this genus is long and relatively complex, and few studies have evaluated the taxonomic problems of this genus. To this end, our goal was to describe the degree and geographical pattern of morphological and molecular variation in this genus to test the current hypothesis that the genus is monotypic, and, as a consequence, to determine the status of the nominal forms associated withSooretamys. Accordingly, we employed morphometric, morphological, and molecular tools, according to an integrative taxonomy approach. The results show that some level of morphometric discontinuity is present between the individuals from Paraguay and those from adjacent localities in Brazil and Argentina; sharp discontinuities were not observed in qualitative traits. Molecular analyses of the mitochondrial cytochromebgene showed that the Paraguayan populations have some degree of genetic differentiation, but the haplotypic variants do not form a monophyletic group. Thus, the evidence so far suggests a difference in the genes and morphology of the Paraguayan population, but there is no consistent resolution (e.g. lack of monophyly) to show that specimens from Paraguay represent a distinct population that would merit taxonomic recognition. Thus, we recognize a single species within the genus Sooretamys, named Sooretamys angouya. The pattern of morphological and genetic differentiation of Sooretamyscould be the result of divergence with gene flow. However, our data also correspond in some aspects with the model advanced by Carnaval & Moritz, which claims the existence of stable Atlantic Forest areas where the forest biota persisted during the Quaternary climatic fluctuations. Whatever process has occurred,S. angouyarepresents one species with a complex evolutionary history, and the analysis of additional samples would be welcome to further elucidate the process of diversification of this taxon.
Article
Chromosomes obtained from bone-marrow, spleen and testes were studied in samples from five populations of Spalacopus cyanus of Central Chile. Animals of four low-land coastal localities and animals of a high Andean valley showed a karyotype of 2n = 58 chromosomes, with almost no variation, either in number or in structure, both within each population or among the various populations. This karyotype was found to be very similar to that of Octodon degus, but very different to those in species of Ctenomys. The evolutionary and systematic significance of these results is discussed. The lack of karyotypic variation found in Spalacopus is correlated with its taxonomic uniformity, and both could be the result of the high vagility of the populations of this rodent, suggested by previous studies. This high capacity of dispersal is supposed to have enhanced gene flow, and therewith chromosome uniformity and low taxonomic diversification. The occurrence of a case of dimorphism for the presence of a secondary constriction in one of the autosome pairs is reported and discussed.
Article
Deep misunderstandings still besiege taxonomy after more than 200 years of fruitful output. It has been asserted in this journal that taxonomy should be integrative and conform to a series of restrictive guidelines. We show that taxonomy has been integrative for most of its history although, in our sense, integrative does not mean the indiscriminate pooling of any source of data. The guidelines proposed are not founded in good scientific rationale and can have, if followed, a detrimental effect not only on taxonomy, but also on biology as a whole. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 211–216.
Article
Delineating species boundaries correctly is crucial to the discovery of life's diversity because it determines whether or not different individual organisms are members of the same entity. The gap in communication between the dif-ferent disciplines currently involved in delimiting species is an important and overlooked problem in the so-called 'taxonomy crisis'. To solve this problem, it is suggested that taxonomy become integrative, and this integration is seen as the real challenge for the future of taxonomy. 'Integrative taxonomy' is defined as the science that aims to delimit the units of life's diversity from multiple and complementary perspectives (phylogeography, comparative morphology, population genetics, ecology, development, behaviour, etc.). Some workers have already collaborated and successfully adopted an integrative approach to taxonomy. However, it is now time for the whole discipline to evolve. A radical change in mentality is needed concerning the creation of names in order to achieve this integration and to prevent the over-abundance of both synonyms and names of doubtful application from worsening. Integrative tax-onomy gives priority to species delineation over the creation of new species names. Furthermore, it is emphasized that describing morphological diversity, referred to as 'morphodiversity', does not require the naming of any single set of specimens. Seven guidelines are proposed to help integrative taxonomists recognize cases when species are supported by broad biological evidence and therefore are deserving of an official name.
Article
Progress in molecular techniques together with the incorporation of phylogenetic analyses of DNA into taxonomy have caused an increase in the number of species’ discoveries in groups with morphological characters that are difficult to study or in those containing polytypic species. But some emerged criticisms plead for a taxonomic conservatism grounded either on the requirement of providing evidences of morphological distinctiveness or reproductive barriers to erect new species names. In a case study of taxonomic research on Neotropical frogs, we combine several lines of evidence (morphological characters, prezygotic reproductive isolation and phylogenetic analyses of mitochondrial DNA) to test the status of 15 nominal species and to assess the degree of agreement of the different lines of evidence. Our study reveals that morphology alone is not sufficient to uncover all species, as there is no other single line of evidence independently. Full congruence between lines of evidence is restricted to only four out of the 15 species. Five species show congruence of two lines of evidence, whereas the remaining six are supported by only one. The use of divergence in morphological characters seems to be the most conservative approach to delineate species boundaries because it does not allow the identification of some sibling reciprocally monophyletic species differing in their advertisement calls. The separate analysis of differences in advertisement calls (evidence of reproductive isolation) or of phylogenetic data alone also shows limitations, because they do not support some morphological species. Our study shows that only an integrative approach combining all sources of evidence provides the necessary feedback to evaluate the taxonomic status of existing species and to detect putative new ones. Furthermore, the application of integrative taxonomy enables the identification of hypotheses about the existence of species that will probably be rejected or changed, and those that can be expected to persist.