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Systematics and subjectivity: the phylogeny and classification of iguanian lizards revisited
... Tropidurinae* was designated as a metataxon, which is defined as a traditionally recognized group whose monophyly is statistically equivocal. This metataxon definition adds a statistical criterion to its usage as discussed by Schwenk (1994). ...
... This is important as it is likely that additional data will not recover Anolis and Polychrus as sister taxa, a result consistent with our analyses except the morphological data alone and the analysis of molecular data by Frost et al. (2001a). Because monophyly is equivocal, the taxon names Polychrotinae* and Tropidurinae* may be retained as a metataxa Gauthier et al., 1988;Schwenk, 1994;Schulte et al., 1998). ...
... An important motivation for the latter study to suggest such a radical taxonomic revision was the lack of morphological evidence to support monophyly of Iguanidae and Agamidae*. This proposal generated a flurry of discussion in the literature (reviewed in Schwenk, 1994). Nonetheless, the eight family system for the former Iguanidae was gradually embraced by the herpetological community, whereas their proposal to combine Agamidae* and Chamaeleonidae into one family has never become established. ...
We present phylogenetic analyses of 42 new partial mitochondrial-DNA sequences in combination with 28 previously published sequences representing all eight major groups of the lizard clade Iguanidae (sensu lato). These sequences include 1838 aligned positions (1013 parsimony informative for ingroup taxa) extending from the protein-coding gene ND1 (subunit one of NADH dehydrogenase) through the genes encoding tRNAIle, tRNAGln, tRNAMet, ND2 (NADH dehydrogenase subunit two), tRNATrp, tRNAAla, tRNAAsn, tRNACys, tRNATyr, to the protein-coding gene COI (subunit I of cytochrome c oxidase). These data,analyzed in combinationwith 67 previouslypublishedmorphologicalcharacters,providestatistical support for monophyly of iguanid clades Corytophaninae, Crotaphytinae, Hoplocercinae, Iguaninae, Oplurinae, and Phrynosomatinae. Monophyly is neither supported nor statistically rejected for Polychrotinae and Tropidurinae. Polychrotinae* and Tropidurinae* may be recognized as metataxa, to denote the fact that evidence for their monophyly is equivocal, or replaced by recognizing constituent groups whose monophyly has stronger empirical support. A phylogenetically (non-ranked) based, statistically robust taxonomy of iguanian lizards is proposed. The Old World lizard clade, Acrodonta, is composed of Chamaeleonidae and Agamidae* with the Agaminae, Amphibolurinae, Draconinae, Hydrosaurinae, Leiolepidinae, and Uromastycinae nested within Agamidae*. The predominately New World clade, Iguanidae, contains the groups Corytophaninae,Crotaphytinae,Hoplocercinae, Iguaninae,Oplurinae,Phrynosomatinae, Polychrotinae*, and Tropidurinae*; with Anolis, Leiosaurini (composed of the Leiosaurae and Anisolepae), and Polychrus as the subgroups of Polychrotinae*; and Leiocephalus, Liolaemini, and Tropidurini as the subgroups of Tropidurinae*.
... The iguanines, consisting of the extant genera Amblyrhynchus and Conolophus (Galápagos Islands), Cyclura (West Indies), Brachylophus (Fiji), Dipsosaurus, Sauromalus, Ctenosaura, and Iguana (southwestern North America, the latter two extending south to Central America and Northern South America, respectively) were elevated to Iguanidae (sensu stricto). This cladistic reanalysis, along with the new taxonomy for Iguanidae, proved highly controversial because of its principles, methodology, interpretations, and its direct challenge to deeply entrenched informal nomenclature (see Lazell 1992;Schwenk 1994;Frost and Etheridge 1993). Nevertheless, their study proved instrumental in providing workable hypotheses for subsequent systematic investigations. ...
... Frequency data indicate that the taxonomy of Frost and Etheridge (1989) peaked in 1996, representing 84% of publications that year (Fig. 1B). This lag could be an artifact of the highly controversial nature of the reclassification (see Schwenk 1994), the result of less advanced communication technology (i.e., email and Internet), or the often-lengthy lag from manuscript acceptance to time of publication. ...
The contemporary increase in character data, especially the advent of rapid DNA sequencing, has provided taxonomists new tools for delimiting monophyletic groups. However, controversy concerning analytical techniques or data interpretation, as well as resistance to modifying established uses of names, may delay the acceptance of new phylogenies or taxonomic reclassifications. Additionally, new or revised classifications may take years to become established because of the time lapse between publication date and widespread use. Consequently, the proliferation of novel phylogenies and taxonomic revisions may prove confusing to comparative biologists, ecologists, and students. The taxonomy of the lizard lineage Iguanidae (sensu lato Boulenger 1884; Camp 1923; Etheridge and de Queiroz 1988) has been both dynamic and controversial in the last 15 years. Since 1989, two familial taxonomic revisions (Frost and Etheridge 1989; Macey et al. 1997) and two expansions (Frost et al. 2001; Schulte et al. 2003), have been published for Iguanidae (sensu lato), and the current scientific literature is replete with conflicting taxono-mies concerning this family. It may be bewildering to students when contemporary herpetology textbooks (e.g., Pough et al. 2001, 2004; Zug et al. 2001) report a particular classification scheme when other classifications might be more prominent in the literature. Further confusion ensues when the taxonomy of iguanid lizards in herpetological peer-reviewed journals often does not adhere to a consistent classification scheme—even in the same issue. In an attempt to clarify the taxonomic record of Iguanidae (sensu lato), we summarize the taxonomic history and current status of the lineage. Additionally, because some authors of reclassifica-tions have defended their taxonomic revisions by claiming that they have " widespread recognition and usage " (Frost et al. 2001: p. 13), we test this by analyzing nomenclature use in the scientific literature since 1990. Another interesting artifact of a dynamic taxo-nomic history is the time lapse between reclassifications and widespread adoption among biologists. To test this phenomenon, we statistically compare the use of different classifications (Boulenger 1884; Frost and Etheridge 1989; Frost et al. 2001; Macey et al. 1997) in terms of their citation frequency per year and by journal type. Taxonomic Summary.—Iguanidae (sensu lato Boulenger 1884; Camp 1923; Etheridge and de Queiroz 1988) is the largest (ca. 51 genera and 908 species; Pough et al. 2001) and most widely distributed family of lizards in the Western Hemisphere. Iguanids are found throughout the Americas including the West Indies and Galápagos Archipelago. Two extralimital genera occur on Mada-gascar and the Comoro Archipelago, and another in the Fiji and Tonga Islands (Etheridge and de Queiroz 1988). The disjunct distribution of the family was thought to be a potential artifact of paraphyly (Frost and Etheridge 1989) because morphological evidence of either monophyly or paraphyly for Iguanidae* was ambiguous , and the family was thus considered a metataxon (denoted with an asterisk; Estes et al. 1988). Etheridge and de Queiroz (1988) were the first to attempt a phy-logenetic reconstruction of iguanid lizards using outgroup comparisons and modern character-based phylogenetic methods. Their analysis of morphological characters suggested that iguanid species could be placed in one of eight major groups (Anoloids, Basiliscines, Crotaphytines, Iguanines, Morunasaurs, Oplurines, Sceloporines, Tropidurines). However, they acknowledged that they could not identify any synapomorphies for Iguanidae (sensu lato) indicating that it may be paraphyletic. Based on a cladistic analysis of morphological characters, Frost and Etheridge (1989) did not find evidence of monophyly for Iguanidae (sensu lato). They also failed to resolve the intergroup relationships within iguanids, but claimed that their data supported monophyly for the previously recognized informal groups of Etheridge and de Queiroz (1988). With intent to reform named but potentially misleading groupings, they recognized as families (sedis metabilis) the largest historical groups that were consistent with the strict consensus tree generated by their phylogenetic analysis of Iguania (Table 1). The iguanines, consisting of the extant genera Amblyrhynchus and Conolophus (Galápagos Islands), Cyclura (West Indies), Brachylophus (Fiji), Dipsosaurus, Sauromalus, Ctenosaura, and Iguana (southwestern North America, the latter two extending south to Central America and Northern South America, respectively) were elevated to Iguanidae (sensu stricto). This cladistic reanalysis, along with the new tax-onomy for Iguanidae, proved highly controversial because of its principles, methodology, interpretations, and its direct challenge to deeply entrenched informal nomenclature (see Lazell 1992; Schwenk 1994; Frost and Etheridge 1993). Nevertheless, their study proved instrumental in providing workable hypotheses for subsequent systematic investigations. Macey et al. (1997) performed a phylogenetic analysis of Iguanidae (sensu lato) and Acrodonta (Agamidae + Chamaeleonidae) using mtDNA sequences and the morphological data of Frost and Etheridge (1989). Analyzed separately, the morphological and molecular data suggested different phyloge-netic hypotheses with the morphological data recovering a weakly paraphyletic Iguanidae (sensu lato), and the sequence data recovering a strongly supported monophyletic Iguanidae (sensu lato). The monophyly of the family, however, also was supported by (1) separate analyses of protein-coding and t-RNA-coding subsets of the DNA sequences; (2) analysis of amino acids from protein-coding regions; (3) analysis of the total DNA sequence data with silent transitions removed from the protein-coding sequences; and (4) use of transversion parsimony on the total DNA sequence data. Although their sampling was not adequate to establish monophyly of Frost and Etheridge's (1989) eight families, these authors sug
... The use o f 'Acrodonta' (e.g.Estes et al, 1988) was not consistent with their method of recognising the largest monophyletic groups as families within the Iguania, and 'Chamaeleonidae' has age superiority over 'Agamidae'. They also provided evidence for a closer relationship between the nonacrodont oplurids, phrynosomatids, tropidurids and possibly the polychrids, than between the other suprageneric groups.The formalisation o f previously recognised groups inFrost and Etheridge (1989) is seen by some authors as unhelpful (e.g.Lazell, 1992), and their discontinuation o f using the term metataxon was disputed by various authors (e.g.Schwenk, 1994), as the term should be used in order call our attention to the uncertain status o f a taxon.Because the convention for referring to the various iguanian groups is as yet unformalised, this study follows the example o f previous works on fossil iguanians (e.g. Borsuk-Bialynicka andAlifanov, 1991;Gao and Hou, 1995a;Gao and Fox, 1996). ...
The Hampshire Basin, Southern England, contains three geological Formations, known as the 'Solent Group' (Headon Hill Formation, Bembridge Limestone Formation, Bouldnor Formation), spanning the Upper Eocene to the early Lower Oligocene. These sites are known for their diverse mammal assemblages, permitting detailed palaeoenvironmental analyses and investigations of migration and evolution patterns of mammals across Europe in the Palaeogene. This thesis focuses on the fossil lizard assemblages from the Solent group, describing the taxa present, cataloguing changes through time, and attempting to correlate patterns of change with the changing palaeoenvironment. Information from late Middle Eocene (Creechbarrow Limestone Formation; Barton Clay Formation) lizard assemblages has also been included. The 'Grande Coupure', an event notable for an overturn in the mammal assemblage of Europe, occurs near the end of Solent Group deposition. A number of mammal families (seven), which were previously unknown in Continental Europe, appear in the Hampshire Basin. At the same time, the Continental European lizard assemblage saw a reduction in diversity, and subsequent diversity has remained low. The lizard assemblage of the Hampshire Basin is compared to those of Continental Europe in terms of diversity and structure. Many families are found in common, although differences occur at a generic level. The horizons in the Hampshire Basin vary in the quality, quantity and diversity of lizard material present. The reasons for these differences are discussed and appear to be due to a combination of characters aside from the life-assemblage, including taphonomy and preservation. These may account for the apparent fall in diversity which occurs in the lizards throughout the Hampshire Basin sequence. Despite the difficulty of observing changes linked to the 'Grande Coupure', the lizard fossils of the Hampshire Basin Solent Group provide an important addition to our knowledge of squamates at the beginning of the Tertiary.
... The use of the phylogenetic concept of taxa (monophyly) and statistical criteria supporting the recognition of higher taxa within the iguanian lizards ensures stability of the developed system. Moreover, the use of the concept of metataxa (Schwenk, 1994;Schulte et al., 1998Schulte et al., , 2003 more accurately reflects the statistical significance of distinguishing the main subgroups of these reptiles. Thus, the current taxonomy retains historical continuity in the context of a stringent criterion for monophyly by considering reliably supported groups with morphological and molecular data. ...
The results of recent phylogenetic studies of the main groups of squamate reptiles are summarized.
The contributions of various methodological approaches to modern patterns in the analysis of these vertebrates,
including the positions of different groups on the phylogenetic tree of reptiles, are considered. Modern
patterns in the integrated analysis of the structure of phylogenetic and taxonomic diversity and ecogeographical
patterns in its formation are discussed.
Keywords: squamate reptiles, lizards, snakes, amphisbaenians, biogeography, phylogenetic relationships,
molecular phylogeny
... The true iguanas represent an assemblage of relatively large, mostly herbivorous lizards that has long been recognized as being monophyletic (Etheridge 1964). However, controversy exists (reviewed by Knapp and Gomez-Zlatar 2006) concerning whether the radiation should be ranked as a family (e.g., Hollingsworth 1998Hollingsworth , 2004Wiens and Hollingsworth 2000;Frost et al. 2001;Conrad 2008), or as a subfamily (e.g., Pough et al. 2004;Townsend et al. 2004;Smith 2009;Vitt and Caldwell 2009), or whether maintaining the associations between names and clades (monophyletic groups) is more important than reflecting taxonomic ranks (e.g., de Queiroz 1995;Schulte et al. 2003; see also de Queiroz and Gauthier 1990;Schwenk 1994). Considerable controversy also surrounds 5 the phylogenetic relationships among the eight genera in this family (e.g., see reviews in Hollingsworth 2004;Pyron et al. 2013). ...
This annotated checklist of the world's iguanas (Iguanidae; Iguaninae) represents an update by the Iguana Taxonomy Working Group (ITWG) of its 2011 list. We recognize 44 extant species (19 subspecies across six species) in eight genera. Ctenosaura (as currently recognized) is the most diverse, with 18 species, and Amblyrhynchus is the least diverse, with only one species, but seven subspecies. The list provides a comprehensive inventory of the taxonomy, common names, holotype(s), type locality, and distribution of all named taxa of iguanas. Extensive comments clarify contentious issues of nomenclature and/or distribution. Recently published papers suggest that additional diversity of iguanas remains to be described. Of the 44 included species, eight are listed as Critically Endangered (CR) on the IUCN Red List of Threatened Species, 11 as Endangered (EN), nine as Vulnerable (VU), two as Near Threatened (NT), three as Least Concern (LC), and one as Data Deficient (DD). Ten are not yet listed. Thus, over 82% of listed taxa are Threatened (28 of 34: CR, EN, or VU), placing this distinctive group among the most threatened vertebrate groups on the planet (surpassing turtles [50–58%], primates [ca. 49%], and amphibians [ca. 41%]).
... Iguanidae has undergone considerable systematic revision and debate (Etheridge 1982, Frost and Etheridge 1989, Lazell 1992, Schwenk 1994, Macey et al. 1997, Frost et al. 2001. Under the classification of Frost and Etheridge (1989), green iguanas are in the subfamily Iguaninae, which contains eight extant genera and approximately 35 species. ...
The Green Iguana can be found through the Caribbean basin, as an invader and as a native species. As most invaders, Iguana iguana (Linnaeus) has the tendency to be found in high densities and expand its range in a short period of time. Lessons from Florida and Puerto Rico has teach us that Green Iguanas are opportunistic omnivores that can pose a threat to agriculture, ornamental and native plants, mollusks and birds. In Florida the Hibiscus Garden at the Fairchild Tropical Garden was overgrazed by Green Iguanas and eventually relocated into an Iguana iguana free-zone. Green Iguanas have also been documented to consume and disperse invasive species seeds. In the Lesser Antilles there are concerns about Iguana iguana populations out-breeding with the endangered Iguana delicatissima. Given this background; can Green Iguana have suitable environmental conditions in the Pacific Islands for its survival? And what are the implications of this hypothetical scenario? We used the Maximum entropy method (MaxEnt) for niche modeling to predict the distribution of the Green Iguana in the Pacific islands. The distribution maps showed suitability for Green Iguana in different islands of the Pacific. The threat to the Pacific islands is latent, with sightings in Hawai’i, and growing populations in Fiji. The Pacific islands have species related to species in the Caribbean that the Green Iguana affects, such as other Iguanidae species, species of the Malvaceae family, ornamental species, and forth. Therefore efforts to prevent their introduction and spread to other islands should be a priority.
... Previously known as Basiliscinae (basiliscines) (Etheridge & de Queiroz 1988;Lang 1989), the taxonomic status of Corytophanidae has changed over the decades. The group was recognized as a family (along with seven more iguanid sensu lato lineages) by Frost & Etheridge (1989) but the taxonomy of Iguania is a quodlibet (see Schwenk 1994;Macey et al . 1997;Schulte et al . ...
Phylogenetic relationships of corytophanid lizards (Iguania, Squamata, Reptilia) based on partitioned and total evidence analyses of sperm morphology, gross morphology, and DNA data. — Zoologica Scripta , 34 , 605– 625. We conducted partitioned and combined Bayesian and parsimony phylogenetic analyses of corytophanid lizards (Iguania) using mtDNA, gross morphology, and sperm ultrastructure data sets. Bayesian and parsimony hypotheses showed little disagreement. The combined analysis, but not any of the partitioned ones, showed strong support for the monophyly of Corytophanidae and its three genera, Basiliscus , Corytophanes , and Laemanctus . Basiliscus is the sister taxon of a well-supported clade formed by Corytophanes and Laemanctus . The relation-ships of species within Basiliscus and Corytophanes received weak support, regardless of the method used. We defend those relationships as feasible and open to further testing. Data derived from the ultrastructure of spermatozoa are potentially a good source of characters for systematic inferences of Iguania and its major lineages. A Brooks Parsimony Analysis based on the geographic distributions of corytophanids and the phylogenetic tree obtained from the combined analysis suggested a Central American origin of the group, a recent colonization of northern South America, and the role of epeirogenic uplifts and the formation of lowlands during the late Tertiary in the differentiation of corytophanids. Gustavo H. C. Vieira, Pós-graduação em Biologia Animal, Instituto de Ciências Biológicas, Universi-dade de Brasília, Brasília/DF, Brazil.
This checklist was compiled by the Iguana Taxonomy Working Group (ITWG) of the IUCN SSC Iguana Specialist Group (ISG), and was based primarily on Etheridge (1982), Hollingsworth (2004), and Etheridge and Frost (http://research.amnh.org/vz/herpetology). Common names represent our recommendations, and they attempt to establish consistency in their construction. Content: Nine living genera and 44 living species are currently recognized; however, undescribed species are known to exist (e.g., see Zarza et al. 2008; Malone and Davis 2004; Gentile et al. 2009). We also include here the one species that has been extirpated in the last century (). Comment: This assemblage of relatively large, mostly herbivorous iguanas has long been recognized as being monophyletic (including all descendants of a single common ancestor). However, controversy exists (reviewed by Knapp and Gomez-Zlatar 2006) concerning whether the radiation should be ranked as a family (e.g., Wiens and Hollingsworth 2000; Frost et al. 2001; Hollingsworth 1998, 2004; Conrad 2008), or as a subfamily (e.g., Pough et al. 2004; Townsend et al. 2004; Vitt and Caldwell 2009), or whether maintaining the associations between names and clades (monophyletic groups) is more important than reflecting taxonomic ranks (e.g., de Queiroz 1995; Schulte et al. 2003; see also de Queiroz and Gautier 1990; Schwenk 1994). Considerable controversy also surrounds the phylogenetic relationships among the genera in this family (e.g., see review in Hollingsworth 2004). The most recent published list of synonymies is by Hollingsworth (2004), but see also Etheridge and Frost (op. cit.). Distribution: New World tropics and subtropics including the West Indies and Galápagos Islands, and the Fiji and Tonga Islands (Pough et al. 2004; Vitt and Caldwell 2009).
Phenotypic evolution has been studied since Darwin established the fact of evolution. In contrast, molecular evolution has been a subject of study since the mid-1960s. Nevertheless, our understanding of the mechanisms of phenotypic evolution is far less developed than our knowledge of molecular evolution. This fact is often attributed to the greater “complexity” of phenotypic characters, although it is not always clear what complexity means. More specifically, there are two features of phenotypic evolution that make molecular and phenotypic evolution quite distinct problems. First, molecular evolution is a continuing process, often occurring over long periods of time at a nearly constant rate, even if there are variations in rate among lineages. In contrast, phenotypic evolution is perceived as a highly irregular process with long periods of stasis interrupted by short bursts of change (Gould and Eldredge, 1977; Kimura, 1983). Second, most phenotypic characters comprise many levels of organization from the molecular to the behavioral and the population level, and the rate of change is nonuniform across these levels of organization. Some attributes of the phenotype, such as color and size, vary widely and evolve rapidly whereas other aspects of the phenotype, such as mode of food acquisition, are remarkably stable. Furthermore, even the conservative elements of the phenotype are not immutable because they have evolved in ancestral lineages and may become variable in a descendant lineage. Molecular evolution, on the other hand, pertains to evolutionary change on only one level of organization.
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