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1.
We report complete mitochondrial genomic sequences for Crocodylus acutus and Crocodylus novaeguineae, whose gene orders match those of other crocodilians. Phylogenetic analyses based on the sequences of 12 mitochondrial protein-coding genes support monophyly of two crocodilian taxonomic families, Alligatoridae (genera Alligator, Caiman, and Paleosuchus) and Crocodylidae (genera Crocodylus, Gavialis, Mecistops, Osteolaemus, and Tomistoma). Our results are consistent with monophyly of all crocodilian genera. Within Alligatoridae, genus Alligator is the sister taxon of a clade comprising Caiman and Paleosuchus. Within Crocodylidae, the basal phylogenetic split separates a clade comprising Gavialis and Tomistoma from a clade comprising Crocodylus, Mecistops, and Osteolaemus. Mecistops and Osteolaemus form the sister taxon to Crocodylus. Within Crocodylus, we sampled five Indopacific species, whose phylogenetic ordering is ((C. mindorensis, C. novaeguineae), (C. porosus, (C. siamensis, C. palustris))). The African species C. niloticus and New World species C. acutus form the sister taxon to the Indopacific species, although our sampling lacks three other New World species and an Australian species of Crocodylus.  相似文献   

2.
BrachyorrhosSchlegel, 1826a is a terrestrial-fossorial snake genus endemic to eastern Indonesia that has been assigned to six different families and subfamilies within Colubroidea (advanced snakes) over the past ~200 years. Here we report the first molecular sequences for Brachyorrhos and use them to test the position of the genus within snake phylogeny. Our Bayesian and Maximum Likelihood analyses of three mitochondrial and one nuclear gene strongly resolve Brachyorrhos within the rear-fanged semiaquatic Homalopsidae (Colubroidea), as the sister taxon to all other genera and sampled species.  相似文献   

3.
Chinese species of the genus Niviventer, predominantly distributed in the southeastern Tibetan Plateau and in Taiwan, are a diverse group and have not yet received a thorough molecular phylogenetic analysis. Here, we reconstructed the phylogenetic relationships of 32 specimens representing nine Chinese species of Niviventer, based on sequences of the complete mitochondrial cytochrome b gene. Maximum parsimony, maximum likelihood and Bayesian analysis resulted in three consistent trees, each supported by high bootstrap values. The results showed that the Niviventer species included here are monophyletic. The nine species were classified into three distinct clades: clade A with Niviventer brahma, N. confucianus, N. coxingi, N. culturatus, N. eha and N. fulvescens; clade B with N. andersoni and N. excelsior; clade C with N. cremoriventer. Our results also suggested that N. culturatus should be a valid species rather than a subspecies of N. confucianus. Divergence times among species were calibrated according to the middle-late Pleistocene (1.2-0.13 Mya) fossil records of N. confucianus. The results demonstrated that the first radiation event of the genus Niviventer occurred in early Pleistocene (about 1.66 Mya), followed by the divergence of clades A and B at about 1.46 Mya. Most of the extant Niviventer species appeared during early to middle Pleistocene (about 1.29-0.67 Mya). These divergence times are coincidental with the last uplift events of the Tibetan Plateau, Kun-Huang movement, Pleistocene glaciations and the vicariant formation of Taiwan Strait. Consequently geographical events and Pleistocene glaciations have played a great role in the diversification of Niviventer.  相似文献   

4.
The phylogenetic relationships of nine species of freshwater sponges, representing the families Spongillidae, Lubomirskiidae, and Metaniidae, were inferred from analyses of 18S rDNA, cytochrome oxidase subunit I (COI) mtDNA, and internal transcribed spacer 2 (ITS2) rDNA sequences. These species form a strongly supported monophyletic group within the Demospongiae, with the lithistid Vetulina stalactites as the sister taxon. Within the freshwater sponge clade, the basal taxon is not resolved. Depending upon the method of analysis and sequence, the metaniid species, Corvomeyenia sp., or the spongillid species, Trochospongilla pennsylvanica , emerges as the basal species. Among the remaining freshwater sponge species, the spongillids, Spongilla lacustris and Eunapius fragilis , form a sister group to a clade comprised of the spongillid species, Clypeatula cooperensis , Ephydatia fluviatilis , and Ephydatia muelleri , and the lubomirskiid species, Baikalospongia bacillifera and Lubomisrkia baicalensis . C. cooperensis is the sister taxon of E. fluvialitis , and E. muelleri is the sister taxon of ( B. bacillifera + L. baicalensis ). The family Spongillidae and the genus Ephydatia are thus paraphyletic with respect to the lubomirskiid species; Ephydatia is also paraphyletic to C. cooperensis . We suggest that C. cooperensis be transferred to the genus Ephydatia and that the family Lubomirskiidae be subsumed into the Spongillidae.  相似文献   

5.
Plant disjunctions have provided some of the most intriguing distribution patterns historically addressed by biogeographers. We evaluated the three hypotheses that have been postulated to explain these patterns [vicariance, stepping‐stone dispersal and long‐distance dispersal (LDD)] using Munroa, an American genus of grasses with six species and a disjunct distribution between the desert regions of North and South America. The ages of clades, cytology, ancestral characters and areas of distribution were investigated in order to establish relationships among species, to determine the time of divergence of the genus and its main lineages, and to understand further the biogeographical and evolutionary history of this genus. Bayesian inference recovered the North American M. pulchella as sister species to the rest. Molecular dating and ancestral area analyses suggest that Munroa originated in North America in the late Miocene–Pliocene (7.2 Mya; 8.2–6.5 Mya). Based on these results, we postulate that two dispersal events modelled the current distribution patterns of Munroa: the first from North to South America (7.2 Mya; 8.2–6.5 Mya) and the second (1.8 Mya; 2–0.8 Mya) from South to North America. Arid conditions of the late Miocene–Pliocene in the Neogene and Quaternary climatic oscillations in North America and South America were probably advantageous for the establishment of populations of Munroa. We did not find any relationship between ploidy and dispersal events, and our ancestral character analyses suggest that shifts associated with dispersal and seedling establishment, such as habit, reproductive system, disarticulation of rachilla, and shape and texture of the glume, have been important in these species reaching new areas. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 110–125.  相似文献   

6.
Hydraena is the largest genus within the water beetle family Hydraenidae, with ca. 1000 species distributed worldwide. Within this large genus some monophyletic groups of species are recognised, among them the "Haenydra" lineage, including ca. 90 species distributed in the western Palaearctic from the Iberian peninsula to Iran. Species of "Haenydra" have often very restricted distributions, and are typical of clean small rivers and streams. We obtained ca. 2.5Kb of mitochondrial and nuclear protein-code and ribosomal markers of 101 specimens of 69 species of "Haenydra", and used Bayesian and Maximum Likelihood phylogenetic methods to reconstruct their phylogeny and diversification history. We found a derived phylogenetic position of the "Haenydra" lineage within the genus Hydraena, as sister to the species of the Hydraenabisulcata group. Within "Haenydra" three main lineages were recognised, with poorly resolved relationships among them: the Hydraena iberica, Hydraena gracilis and Hydraena dentipes lineages, the former restricted to the Iberian peninsula but the latter two distributed through the whole north-Mediterranean area. A Bayesian relaxed molecular clock approach using a combined mitochondrial rate of 2% divergence per MY estimated the origin of "Haenydra" in the Tortonian, ca. 8Mya, and the main diversification and the origin of most extant species in the Pliocene and Pleistocene. We did not found evidence of a phylogenetic connection between the western and eastern species that could be traced to the Messinian salinity crisis, with dispersal only at small geographical scales (e.g. the colonisation of Corsica and Sardinia from NW Italy and SW France). The H. gracilis and H. iberica lineages were estimated to have diversified under a pure birth model with a speciation rate of 0.64 and 0.23 species/MY respectively, while the H. dentipes lineage was estimated to have a decreasing diversification rate with time, with an average rate of 0.29 sp/MY.  相似文献   

7.
Stingless bees (Meliponini) are one of only two highly eusocial bees, the other being the well studied honey bee (Apini). Unlike Apini, with only 11 species in the single genus Apis, stingless bees are a large and diverse taxon comprising some 60 genera, many of which are poorly known. This is the first attempt to infer a phylogeny of the group that includes the world fauna and extensive molecular data. Understanding the evolutionary relationships of these bees would provide a basis for behavioural studies within an evolutionary framework, illuminating the origins of complex social behaviour, such as the employment of dance and sound to communicate the location of food or shelter. In addition to a global phylogeny, we also provide estimates of divergence times and ancestral biogeograhic distributions of the major groups. Bayesian and maximum likelihood analyses strongly support a principal division of Meliponini into Old and New World groups, with the Afrotropical+Indo‐Malay/Australian clades comprising the sister group to the large Neotropical clade. The meliponine crown clade is inferred to be of late Gondwanan origin (approximately 80 Mya), undergoing radiations in the Afrotropical and Indo‐Malayan/Australasian regions, approximately 50–60 Mya. In the New World, major diversifications occurred approximately 30–40 Mya. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 206–232.  相似文献   

8.
逗亚科似逗属鱼类的物种界定保持争议, 系统发育关系尚待解决。研究取样似逗属鱼类所有种, 使用核基因多位点序列重建似逗属鱼类的系统发育关系, 运用分子的物种界定方法并结合形态特征分析厘定我国似逗属鱼类的分类。贝叶斯系统发育树结果表明: 桂林似逗与平江似逗是单系种; 似逗与扁嘴似逗是多系种, 前者包括五个谱系A至E, 后者包括两个谱系A与B。POFAD距离分析和Structurama分析的结果表明似逗和扁嘴似逗的每个谱系是独立遗传种群, BP & P分析结果强烈支持它们是不同种。*Beast物种树结果揭示: 扁嘴似逗谱系B位于似逗属鱼类的基部位置; 似逗谱系A与B是姊妹群关系, 似逗谱系C是扁嘴似逗谱系A的姊妹群, 它们一起与桂林似逗形成姊妹群关系; 似逗谱系D与E是姊妹群关系, 它们一起是平江似逗的姊妹群。结合形态证据, 对我国似逗属鱼类分类厘定如下: 限定严格意义似逗包括似逗谱系A+B; 恢复长吻似逗(Pseudogobio longirostris Mori, 1934)给予似逗谱系C分类名; 似逗谱系D与E是隐存种, 桂林似逗与平江似逗是有效种。  相似文献   

9.
The subgenus Mesocarabus Thomson, 1875 is a western Palaearctic group that currently includes five species: four of them inhabiting western Europe (Carabus lusitanicus Fabricius, 1801, Carabus problematicus Herbst, 1786, Carabus dufourii Dejean & Boisduval, 1829, and Carabus macrocephalus Dejean, 1826) and one found in the Rif Mountains in northern Morocco (Carabus riffensis Fairmaire, 1872). Representatives of Mesocarabus have been included in previous molecular phylogenetic studies, but taxon‐ or gene‐sampling limitations yielded inconclusive results regarding its monophyly and sister relationship. Here we perform molecular phylogenetic analyses based on five mitochondrial (3625 nt) and eight nuclear (5970 nt) genes sequenced in many Mesocarabus populations, and in related western Palaearctic Carabus Linnaeus, 1758. We conducted parsimony, maximum‐likelihood, and Bayesian analyses and found a well‐supported sister relationship between a monophyletic Mesocarabus with Iberian species of the subgenus Oreocarabus Géhin, 1876. Within Mesocarabus, the European species form a monophyletic lineage sister to Moroccan C. riffensis. A time‐calibrated phylogeny suggests the split between Mesocarabus and Oreocarabus occurred at 11.8 Mya (95% highest posterior density, HPD, 8.7–15.3 Mya), and the divergence between C. riffensis and European Mesocarabus at 9.5 Mya (95% HPD 7.0–12.5 Mya). The early diversification of Mesocarabus and related subgenera during the Miocene, and alternative hypotheses concerning the origin of Mesocarabus in the Iberian Peninsula and the Betic‐Riffian plate are discussed using calibration data and dispersal–vicariance biogeographic analyses. Finally, we found instances of incongruence between mitochondrial DNA and nuclear‐based phylogenies of Mesocarabus, which are hypothesized to be the result of introgressive hybridization. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 787–804.  相似文献   

10.
We present the first phylogenetic study on the widespread Middle American microhylid frog genus Hypopachus. Partial sequences of mitochondrial (12S and 16S ribosomal RNA) and nuclear (rhodopsin) genes (1275 bp total) were analyzed from 43 samples of Hypopachus, three currently recognized species of Gastrophryne, and seven arthroleptid, brevicipitid and microhylid outgroup taxa. Maximum parsimony (PAUP), maximum likelihood (RAxML) and Bayesian inference (MrBayes) optimality criteria were used for phylogenetic analyses, and BEAST was used to estimate divergence dates of major clades. Population-level analyses were conducted with the programs NETWORK and Arlequin. Results confirm the placement of Hypopachus and Gastrophryne as sister taxa, but the latter genus was strongly supported as paraphyletic. The African phrynomerine genus Phrynomantis was recovered as the sister taxon to a monophyletic Chiasmocleis, rendering our well-supported clade of gastrophrynines paraphyletic. Hypopachus barberi was supported as a disjunctly distributed highland species, and we recovered a basal split in lowland populations of Hypopachus variolosus from the Pacific versant of Mexico and elsewhere in the Mesoamerican lowlands. Dating analyses from BEAST estimate speciation within the genus Hypopachus occurred in the late Miocene/early Pliocene for most clades. Previous studies have not found bioacoustic or morphological differences among these lowland clades, and our molecular data support the continued recognition of two species in the genus Hypopachus.  相似文献   

11.
We present a revised molecular phylogeny of the Drosophila repleta group including 62 repleta group taxa and nine outgroup species based on four mitochondrial and six nuclear DNA sequence fragments. With ca. 100 species endemic to the New World, the repleta species group represents one of the major species radiations in the genus Drosophila. Most repleta group species are associated with cacti in arid or semiarid regions. Contrary to previous results, maximum likelihood and Bayesian phylogenies of the 10-gene dataset strongly support the monophyly of the repleta group. Several previously described subdivisions in the group were also recovered, despite poorly resolved relationships between these clades. Divergence time estimates suggested that the repleta group split from its sister group about 21millionyears ago (Mya), although diversification of the crown group began ca. 16Mya. Character mapping of patterns of host plant use showed that flat leaf Opuntia use is common throughout the phylogeny and that shifts in host use from Opuntia to the more chemically complex columnar cacti occurred several times independently during the history of this group. Although some species retained the use of Opuntia after acquiring the use of columnar cacti, there were multiple, phylogenetically independent instances of columnar cactus specialization with loss of Opuntia as a host. Concordant with our proposed timing of host use shifts, these dates are consistent with the suggested times when the Opuntioideae originated in South America. We discuss the generally accepted South American origin of the repleta group.  相似文献   

12.
To explore the spatio-temporal dynamics of endangered fin whales (Balaenoptera physalus) within the baleen whale (Mysticeti) lineages, we analyzed 148 published mitochondrial genome sequences of baleen whales. We used a Bayesian coalescent approach as well as Bayesian inferences and maximum likelihood methods. The results showed that the fin whales had a single maternal origin, and that there is a significant correlation between geographic location and evolution of global fin whales. The most recent common female ancestor of this species lived approximately 9.88 million years ago (Mya). Here, North Pacific fin whales first appeared about 7.48 Mya, followed by a subsequent divergence in Southern Hemisphere approximately 6.63 Mya and North Atlantic about 4.42 Mya. Relatively recently, approximately 1.76 and 1.42 Mya, there were two additional occurrences of North Pacific populations; one originated from the Southern Hemisphere and the other from an uncertain location. The evolutionary rate of this species was 1.002?×?10?3 substitutions/site/My. Our Bayesian skyline plot illustrates that the fin whale population has the rapid expansion event since ~?2.5 Mya, during the Quaternary glaciation stage. Additionally, this study indicates that the fin whale has a sister group relationship with humpback whale (Meganoptera novaeangliae) within the baleen whale lineages. Of the 16 genomic regions, NADH5 showed the most powerful signal for baleen whale phylogenetics. Interestingly, fin whales have 16 species-specific amino acid residues in eight mitochondrial genes: NADH2, COX2, COX3, ATPase6, ATPase8, NADH4, NADH5, and Cytb.  相似文献   

13.
The timing and order of divergences within the genus Rattus have, to date, been quite speculative. In order to address these important issues we sequenced six new whole mitochondrial genomes from wild-caught specimens from four species, Rattus exulans, Rattus praetor, Rattus rattus and Rattus tanezumi. The only rat whole mitochondrial genomes available previously were all from Rattus norvegicus specimens. Our phylogenetic and dating analyses place the deepest divergence within Rattus at approximately 3.5 million years ago (Mya). This divergence separates the New Guinean endemic R. praetor lineage from the Asian lineages. Within the Asian/Island Southeast Asian clade R. norvegicus diverged earliest at approximately 2.9Mya. R. exulans and the ancestor of the sister species R. rattus and R. tanezumi subsequently diverged at approximately 2.2Mya, with R. rattus and R. tanezumi separating as recently as approximately 0.4Mya. Our results give both a better resolved species divergence order and diversification dates within Rattus than previous studies.  相似文献   

14.
Phylogenetic relationships and biogeography of the genus Cerastium were studied using sequences of three noncoding plastid DNA regions (trnL intron, trnL-trnF spacer, and psbA-trnH spacer). A total of 57 Cerastium taxa was analyzed using two species of the putative sister genus Stellaria as outgroups. Maximum parsimony analyses identified four clades that largely corresponded to previously recognized infrageneric groups. The results suggest an Old World origin and at least two migration events into North America from the Old World. The first event possibly took place across the Bering land bridge during the Miocene. Subsequent colonization of South America occurred after the North and South American continents joined during the Pliocene. A more recent migration event into North America probably across the northern Atlantic took place during the Quaternary, resulting in the current circumpolar distribution of the Arctic species. Molecular clock dating of major biogeographic events was internally consistent on the phylogenetic trees. The arctic high-polyploid species form a polytomy together with some boreal and temperate species of the C. tomentosum group and the C. arvense group. Lack of genetic variation among the arctic species probably indicates a recent origin. The annual life form is shown to be of polyphyletic origin.  相似文献   

15.
The family Microhylidae has a large circumtropic distribution and contains about 400 species in a highly subdivided taxonomy. Relationships among its constituent taxa remained controversial due to homoplasy in morphological characters, resulting in conflicting phylogenetic hypotheses. A phylogeny based on four nuclear genes (rag-1, rag-2, tyrosinase, BDNF) and one mitochondrial gene (CO1) of representatives of all currently recognized subfamilies uncovers a basal polytomy between several subfamilial clades. A sister group relationship between the cophylines and scaphiophrynines is resolved with moderate support, which unites these endemic Malagasy taxa for the first time. The American members of the subfamily Microhylinae are resolved to form a clade entirely separate from the Asian members of that subfamily. Otophryne is excluded from the subfamily Microhylinae, and resolved as a basal taxon. The placement of the Asian dyscophine Calluella nested within the Asian Microhyline clade rather than with the genus Dyscophus is corroborated by our data. Bayesian estimates of the divergence time of extant Microhylidae (47-90 Mya) and among the subclades within the family are discussed in frameworks of alternative possible biogeographic scenarios.  相似文献   

16.
The South American iguanian lizard genus Stenocercus includes 54 species occurring mostly in the Andes and adjacent lowland areas from northern Venezuela and Colombia to central Argentina at elevations of 0-4000m. Small taxon or character sampling has characterized all phylogenetic analyses of Stenocercus, which has long been recognized as sister taxon to the Tropidurus Group. In this study, we use mtDNA sequence data to perform phylogenetic analyses that include 32 species of Stenocercus and 12 outgroup taxa. Monophyly of this genus is strongly supported by maximum parsimony and Bayesian analyses. Evolutionary relationships within Stenocercus are further analyzed with a Bayesian implementation of a general mixture model, which accommodates variability in the pattern of evolution across sites. These analyses indicate a basal split of Stenocercus into two clades, one of which receives very strong statistical support. In addition, we test previous hypotheses using non-parametric and parametric statistical methods, and provide a phylogenetic classification for Stenocercus.  相似文献   

17.
This study constitutes the first evolutionary investigation of the snake family Psammophiidae--the most widespread, most clearly defined, yet perhaps the taxonomically most problematic of Africa's family-level snake lineages. Little is known of psammophiid evolutionary relationships, and the type genus Psammophis is one of the largest and taxonomically most complex of the African snake genera. Our aims were to reconstruct psammophiid phylogenetic relationships and to improve characterisation of species boundaries in problematic Psammophis species complexes. We used approximately 2500 bases of DNA sequence from the mitochondrial and nuclear genomes, and 114 terminals covering all psammophiid genera and incorporating approximately 75% of recognised species and subspecies. Phylogenetic reconstructions were conducted primarily in a Bayesian framework and we used the Wiens/Penkrot protocol to aid species delimitation. Rhamphiophis is diphyletic, with Rhamphiophis acutus emerging sister to Psammophylax. Consequently we transfer the three subspecies of Rhamphiophis acutus to the genus Psammophylax. The monotypic genus Dipsina is sister to Psammophis. The two species of Dromophis occupy divergent positions deeply nested within Psammophis, and we therefore relegate Dromophis to the synonymy of Psammophis. Our results allow division of the taxonomically problematic Psammophis 'sibilans' species complex into two monophyletic entities, provisionally named the 'phillipsii' and 'subtaeniatus' complexes. Within these two clades we found support for the status of many existing species, but not for a distinction between P.p. phillipsii and P. mossambicus. Additionally, P. cf. phillipsii occidentalis deserves species status as the sister taxon of P. brevirostris.  相似文献   

18.
Abstract—Cyttaria Berkeley (Cyttariaceae, Cyttariales, Class Discomycetes), is a genus of eleven species, seven from South America and four from Australasia (Australia, Tasmania, and New Zealand). Cyttaria is a monophyletic genus defined by the following synapomorphies: fleshy to gelatinous stromata with endostromatic apothecia; and complete lack of fungal chitin in the cell walls, having instead β-1–3-glucan. All Cyttaria are exclusive parasites of Nothofagus species. A cladistic analysis of the genus was performed using 18 characters from macromorphology, micro-morphology, and phenology. Polarity of characters is based on the outgroup comparison method (using the Class Discomycetes as a whole) and on the ontogenetic criterion. A hypothetical outgroup was constructed using all plesiomorphic states. Two equally parsimonious cladograms were produced, each with 40 steps and a consistency index of 0.70. These differed in the position of the South American species C. hookeri and C. johowii. In one cladogram, C. hookeri is the sister group to the rest of the genus, and in the other, both species form a monophyletic group (ascospores ovoid) that is the sister group of the rest of the genus. Our analysis of the two characters causing this difference (position of apothecia on stroma, and shape of ascospores) supports the latter hypothesis. In both cladograms, all of the Australasian species form a monophyletic group (thick ectostroma), and, within that, two subgroups are defined: C. gunnii-C. pallida (papillae present), and C. nigra-C. septentrionalis (ectostroma with black incrustations). The Australasian species form a monophyletic group (spermatangia absent) with C. berteroi , and this last group forms a monophyletic group (conidia absent) with C. espinosae. Cytlaria darwimi and C. exigua form another monophyletic group (very thick ectostroma). Excluding C. hookeri and C. johowii, C. hariotii is the sister group to the remaining eight species.  相似文献   

19.
The bee-eaters (family Meropidae) comprise a group of brightly colored, but morphologically homogeneous, birds with a wide variety of life history characteristics. A phylogeny of bee-eaters was reconstructed using nuclear and mitochondrial DNA sequence data from 23 of the 25 named bee-eater species. Analysis of the combined data set provided a well-supported phylogenetic hypothesis for the family. Nyctiornis is the sister taxon to all other bee-eaters. Within the genus Merops, we recovered two well-supported clades that can be broadly separated into two groups along geographic and ecological lines, one clade with mostly African resident species and the other clade containing a mixture of African and Asian taxa that are mostly migratory species. The clade containing resident African species can be further split into two groups along ecological lines by habitat preference into lowland forest specialists and montane forest and forest edge species. Intraspecific sampling in several of the taxa revealed moderate to high (3.7-6.5%, ND2) levels of divergence in the resident taxa, whereas the lone migratory taxon showed negligible levels of intraspecific divergence. This robust molecular phylogeny provides the phylogenetic framework for future comparative tests of hypotheses about the evolution of plumage patterns, sociality, migration, and delayed breeding strategies.  相似文献   

20.
Morphological and molecular studies have inferred multiple hypotheses for the phylogenetic relationships of Testudines. The hypothesis that Testudines are the only extant anapsid amniotes and the sister taxon of diapsid amniotes is corroborated by morphological studies, while the hypothesis that Testudines are diapsid amniotes is corroborated by more recent molecular and morphological studies. In this study, the placement of Testudines is tested using the full length cDNA sequence of the polypeptide hormone precursor proopiomelanocortin (POMC). Because only extant taxa have been used, the hypotheses being tested are limited to the following (1) Testudines as the sister taxon of Archosauria, (2) Testudines included in Archosauria and the sister taxon of Crocodilia, (3) Testudines as the sister taxon of Lepidosauria, (4) Testudines as the sister taxon of Sauria, and (5) Testudines as the sister taxon of a monophyletic Mammalia–Sauria clade. Neither Maximum likelihood, Bayesian, or maximum parsimony analyses are able to falsify the hypothesis of (Archosauria (Lepidosauria, Testudines)) and as such is the preferred inference from the POMC data.  相似文献   

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