BMC Evolutionary Biology最新文献

{"title":"Clonal evolution driven by superdriver mutations.","authors":"Patrick Grossmann,&nbsp;Simona Cristea,&nbsp;Niko Beerenwinkel","doi":"10.1186/s12862-020-01647-y","DOIUrl":"https://doi.org/10.1186/s12862-020-01647-y","url":null,"abstract":"<p><strong>Background: </strong>Tumors are widely recognized to progress through clonal evolution by sequentially acquiring selectively advantageous genetic alterations that significantly contribute to tumorigenesis and thus are termned drivers. Some cancer drivers, such as TP53 point mutation or EGFR copy number gain, provide exceptional fitness gains, which, in time, can be sufficient to trigger the onset of cancer with little or no contribution from additional genetic alterations. These key alterations are called superdrivers.</p><p><strong>Results: </strong>In this study, we employ a Wright-Fisher model to study the interplay between drivers and superdrivers in tumor progression. We demonstrate that the resulting evolutionary dynamics follow global clonal expansions of superdrivers with periodic clonal expansions of drivers. We find that the waiting time to the accumulation of a set of superdrivers and drivers in the tumor cell population can be approximated by the sum of the individual waiting times.</p><p><strong>Conclusions: </strong>Our results suggest that superdriver dynamics dominate over driver dynamics in tumorigenesis. Furthermore, our model allows studying the interplay between superdriver and driver mutations both empirically and theoretically.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"89"},"PeriodicalIF":3.4,"publicationDate":"2020-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01647-y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38176298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ancient DNA of northern China Hystricidae sub-fossils reveals the evolutionary history of old world porcupines in the Late Pleistocene.","authors":"Guilian Sheng,&nbsp;Jiaming Hu,&nbsp;Haowen Tong,&nbsp;Bastien Llamas,&nbsp;Junxia Yuan,&nbsp;Xindong Hou,&nbsp;Shungang Chen,&nbsp;Bo Xiao,&nbsp;Xulong Lai","doi":"10.1186/s12862-020-01656-x","DOIUrl":"https://doi.org/10.1186/s12862-020-01656-x","url":null,"abstract":"<p><strong>Background: </strong>Old World porcupines (Family: Hystricidae) are the third-largest rodents and inhabit southern Europe, Asia, and most regions of Africa. They are a typical indicator of warm climate and their distribution is restricted to tropical and subtropical zones. In China, porcupines are widely distributed in southern areas of the Yangtze River. However, fossil remains have been identified in a few sites in northern China, among which Tianyuan Cave-near Zhoukoudian site-represents the latest known porcupine fossil record. So far, studies have focused mainly on porcupines' husbandry and domestication but little is known about their intrafamilial phylogenetic relationships and evolutionary history.</p><p><strong>Results: </strong>In this study, we sequence partial mitochondrial 12S rRNA and cyt b genes for seven Late Pleistocene porcupine individuals from Northern, Southern and Central China. Phylogenetic analyses show that the Tianyuan Cave porcupines, which had been morphologically identified as Hystrix subcristata, have a closer relationship to Hystrix brachyura.</p><p><strong>Conclusion: </strong>Together with morphological adaptation characteristics, associated fauna, and climate change evidence, the molecular results reveal that a Late Quaternary extirpation has occurred during the evolutionary history of porcupines.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"88"},"PeriodicalIF":3.4,"publicationDate":"2020-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01656-x","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38166796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expansions and contractions in gene families of independently-evolved blood-feeding insects.","authors":"Lucas Freitas, Mariana F Nery","doi":"10.1186/s12862-020-01650-3","DOIUrl":"10.1186/s12862-020-01650-3","url":null,"abstract":"<p><strong>Background: </strong>The blood-feeding behavior evolved multiple times in Insecta lineages and it represents an excellent opportunity to study patterns of convergent molecular evolution regarding this habit. In insects the expansion of some gene families is linked with blood-feeding behavior, but a wide study comparing the evolution of these gene families among different lineages is still missing. Here we gathered genomic data from six independently-evolved hematophagous lineages, aiming to identify convergent expansions and/or contractions of gene families in hematophagous lineages of insects.</p><p><strong>Results: </strong>We found four rapidly evolving gene families shared by at least two hematophagous independently-evolved lineages, including a heat-shock and a chemosensory protein. On the expression of these four rapidly evolving gene families we found more genes expressed in mated individuals compared with virgin individuals in rapidly-expanded families and more genes expressed in non-blood-feeding individuals compared with blood-feeding individuals in rapidly-contracted families.</p><p><strong>Conclusion: </strong>Our results reveal a new set of candidate genes to be explored in further analysis to help the development of new strategies to deal with blood-feeding vectors and also presents a new perspective to study the evolution of hematophagy identifying convergent molecular patterns.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"87"},"PeriodicalIF":3.4,"publicationDate":"2020-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7367253/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38165312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the utility of Hsp90 gene for inferring evolutionary relationships within the ciliate subclass Hypotricha (Protista, Ciliophora).","authors":"Qi Zhang,&nbsp;Jiahui Xu,&nbsp;Alan Warren,&nbsp;Ran Yang,&nbsp;Zhuo Shen,&nbsp;Zhenzhen Yi","doi":"10.1186/s12862-020-01653-0","DOIUrl":"https://doi.org/10.1186/s12862-020-01653-0","url":null,"abstract":"<p><strong>Background: </strong>Although phylogenomic analyses are increasingly used to reveal evolutionary relationships among ciliates, relatively few nuclear protein-coding gene markers have been tested for their suitability as candidates for inferring phylogenies within this group. In this study, we investigate the utility of the heat-shock protein 90 gene (Hsp90) as a marker for inferring phylogenetic relationships among hypotrich ciliates.</p><p><strong>Results: </strong>A total of 87 novel Hsp90 gene sequences of 10 hypotrich species were generated. Of these, 85 were distinct sequences. Phylogenetic analyses based on these data showed that: (1) the Hsp90 gene amino acid trees are comparable to the small subunit rDNA tree for recovering phylogenetic relationships at the rank of class, but lack sufficient phylogenetic signal for inferring evolutionary relationships at the genus level; (2) Hsp90 gene paralogs are recent and therefore unlikely to pose a significant problem for recovering hypotrich clades; (3) definitions of some hypotrich orders and families need to be revised as their monophylies are not supported by various gene markers; (4) The order Sporadotrichida is paraphyletic, but the monophyly of the \"core\" Urostylida is supported; (5) both the subfamily Oxytrichinae and the genus Urosoma seem to be non-monophyletic, but monophyly of Urosoma is not rejected by AU tests.</p><p><strong>Conclusions: </strong>Our results for the first time demonstrate that the Hsp90 gene is comparable to SSU rDNA for recovering phylogenetic relationships at the rank of class, and its paralogs are unlikely to pose a significant problem for recovering hypotrich clades. This study shows the value of careful gene marker selection for phylogenomic analyses of ciliates.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"86"},"PeriodicalIF":3.4,"publicationDate":"2020-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01653-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38162840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Directional divergence of Ep300 duplicates in teleosts and its implications","authors":"Xianzong Wang, Junli Yan","doi":"10.21203/rs.3.rs-42120/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-42120/v1","url":null,"abstract":"Background EP300 is a conserved protein in vertebrates, which serves as a key mediator of cellular homeostasis. Mutations and dysregulation of EP300 give rise to severe human developmental disorders and malignancy. Danio rerio is a promising model organism to study EP300 related diseases and drugs; however, the effect of EP300 duplicates derived from teleost-specific whole genome duplication should not just be neglected. Results In this study, we obtained EP300 protein sequences of representative teleosts, mammals and sauropsids, with which we inferred a highly supported maximum likelihood tree. We observed that Ep300 duplicates (Ep300a and Ep300b) were widely retained in teleosts and universally expressed in a variety of tissues. Consensus sequences of Ep300a and Ep300b had exactly the same distribution of conserved domains, suggesting that their functions should still be largely overlapped. We analyzed the molecular evolution of Ep300 duplicates in teleosts, using branch-site models, clade models and site models. The results showed that both duplicates were subject to strong positive selection; however, for an extant species, generally at most one copy was under positive selection. At the clade level, there were evident positive correlations between evolutionary rates, the number of positively selected sites and gene expression levels. In Ostariophysi, Ep300a were under stronger positive selection than Ep300b; in Neoteleostei, another species-rich teleost clade, the contrary was the case. We also modeled 3D structures of zf-TAZ domain and its flanking regions of Ep300a and Ep300b of D. rerio and Oryzias latipes and found that in either species the faster evolving copy had more short helixes. Conclusions Collectively, the two copies of Ep300 have undoubtedly experienced directional divergence in main teleost clades. The divergence of EP300 between teleosts and mammals should be greater than the divergence between different teleost clades. Further studies are needed to clarify to what extent the EP300 involved regulatory network has diverged between teleosts and mammals, which would also help explain the huge success of teleosts.","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":" ","pages":""},"PeriodicalIF":3.4,"publicationDate":"2020-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44159781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating cellular and molecular mechanisms of neurogenesis in Capitella teleta sheds light on the ancestor of Annelida.","authors":"A Sur, A Renfro, P J Bergmann, N P Meyer","doi":"10.1186/s12862-020-01636-1","DOIUrl":"10.1186/s12862-020-01636-1","url":null,"abstract":"<p><strong>Background: </strong>Diverse architectures of nervous systems (NSs) such as a plexus in cnidarians or a more centralized nervous system (CNS) in insects and vertebrates are present across Metazoa, but it is unclear what selection pressures drove evolution and diversification of NSs. One underlying aspect of this diversity lies in the cellular and molecular mechanisms driving neurogenesis, i.e. generation of neurons from neural precursor cells (NPCs). In cnidarians, vertebrates, and arthropods, homologs of SoxB and bHLH proneural genes control different steps of neurogenesis, suggesting that some neurogenic mechanisms may be conserved. However, data are lacking for spiralian taxa.</p><p><strong>Results: </strong>To that end, we characterized NPCs and their daughters at different stages of neurogenesis in the spiralian annelid Capitella teleta. We assessed cellular division patterns in the neuroectoderm using static and pulse-chase labeling with thymidine analogs (EdU and BrdU), which enabled identification of NPCs that underwent multiple rounds of division. Actively-dividing brain NPCs were found to be apically-localized, whereas actively-dividing NPCs for the ventral nerve cord (VNC) were found apically, basally, and closer to the ventral midline. We used lineage tracing to characterize the changing boundary of the trunk neuroectoderm. Finally, to start to generate a genetic hierarchy, we performed double-fluorescent in-situ hybridization (FISH) and single-FISH plus EdU labeling for neurogenic gene homologs. In the brain and VNC, Ct-soxB1 and Ct-neurogenin were expressed in a large proportion of apically-localized, EdU⁺ NPCs. In contrast, Ct-ash1 was expressed in a small subset of apically-localized, EdU⁺ NPCs and subsurface, EdU^- cells, but not in Ct-neuroD⁺ or Ct-elav1⁺ cells, which also were subsurface.</p><p><strong>Conclusions: </strong>Our data suggest a putative genetic hierarchy with Ct-soxB1 and Ct-neurogenin at the top, followed by Ct-ash1, then Ct-neuroD, and finally Ct-elav1. Comparison of our data with that from Platynereis dumerilii revealed expression of neurogenin homologs in proliferating NPCs in annelids, which appears different than the expression of vertebrate neurogenin homologs in cells that are exiting the cell cycle. Furthermore, differences between neurogenesis in the head versus trunk of C. teleta suggest that these two tissues may be independent developmental modules, possibly with differing evolutionary trajectories.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"84"},"PeriodicalIF":3.4,"publicationDate":"2020-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7362552/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38152398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular evolution of the ATP-binding cassette subfamily G member 2 gene subfamily and its paralogs in birds.","authors":"Shengchao Ma,&nbsp;Hehe Liu,&nbsp;Wenqiang Sun,&nbsp;Ahsan Mustafa,&nbsp;Yang Xi,&nbsp;Fajun Pu,&nbsp;Yanying Li,&nbsp;Chunchun Han,&nbsp;Lili Bai,&nbsp;He Hua","doi":"10.1186/s12862-020-01654-z","DOIUrl":"https://doi.org/10.1186/s12862-020-01654-z","url":null,"abstract":"<p><strong>Background: </strong>ATP-binding cassette (ABC) transporters are involved in the active transportation of various endogenous or exogenous substances. Two ABCG2 gene subfamily members have been identified in birds. A detailed comparative study of the ABCG2 and ABCG2-like genes aid our understanding of their evolutionary history at the molecular level and provide a theoretical reference for studying the specific functions of ABCG2 and ABCG2-like genes in birds.</p><p><strong>Results: </strong>We first identified 77 ABCG2/ABCG2-like gene sequences in the genomes of 41 birds. Further analysis showed that both the nucleic acid and amino acid sequences of ABCG2 and ABCG2-like genes were highly conserved and exhibited high homology in birds. However, significant differences in the N-terminal structure were found between the ABCG2 and ABCG2-like amino acid sequences. A selective pressure analysis showed that the ABCG2 and ABCG2-like genes were affected by purifying selection during the process of bird evolution.</p><p><strong>Conclusions: </strong>We believe that multiple members of the ABCG2 gene subfamily exist on chromosome 4 in the ancestors of birds. Over the long course of evolution, only the ABCG2 gene was retained on chromosome 4 in birds. The ABCG2-like gene on chromosome 6 might have originated from chromosome replication or fusion. The structural differences between the N terminus of ABCG2 protein and those of ABCG2-like proteins might lead to functional differences between the corresponding genes.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"85"},"PeriodicalIF":3.4,"publicationDate":"2020-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01654-z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38151842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic legacy of cultures indigenous to the Northeast Asian coast in mitochondrial genomes of nearly extinct maritime tribes.","authors":"Stanislav V Dryomov,&nbsp;Elena B Starikovskaya,&nbsp;Azhar M Nazhmidenova,&nbsp;Igor V Morozov,&nbsp;Rem I Sukernik","doi":"10.1186/s12862-020-01652-1","DOIUrl":"https://doi.org/10.1186/s12862-020-01652-1","url":null,"abstract":"<p><strong>Background: </strong>We have described the diversity of complete mtDNA sequences from 'relic' groups of the Russian Far East, primarily the Nivkhi (who speak a language isolate with no clear relatedness to any others) and Oroki of Sakhalin, as well as the sedentary Koryak from Kamchatka and the Udegey of Primorye. Previous studies have shown that most of their traditional territory was dramatically reshaped by the expansion of Tungusic-speaking groups.</p><p><strong>Results: </strong>Overall, 285 complete mitochondrial sequences were selected for phylogenetic analyses of published, revised and new mitogenomes. To highlight the likely role of Neolithic expansions in shaping the phylogeographical landscape of the Russian Far East, we focus on the major East Eurasian maternal lineages (Y1a, G1b, D4m2, D4e5, M7a2, and N9b) that are restricted to the coastal area. To obtain more insight into autochthonous populations, we removed from the phylogeographic analysis the G2a, G3a2, M8a1, M9a1, and C4b1 lineages, also found within our samples, likely resulting from admixture between the expanding proto-Tungus and the indigenous Paleoasiatic groups with whom they assimilated. Phylogenetic analysis reveals that unlike the relatively diverse lineage spectrum observed in the Amur estuary and northwestern Sakhalin, the present-day subpopulation on the northeastern coast of the island is relatively homogenous: a sole Y1a sublineage, conspicuous for its nodal mutation at m.16189 T > C!, includes different haplotypes. Sharing of the Y1a-m.16189 T > C! sublineages and haplotypes among the Nivkhi, Ulchi and sedentary Koryak is also evident. Aside from Y1a, the entire tree approach expands our understanding of the evolutionary history of haplogroups G1, D4m, N9b, and M7a2. Specifically, we identified the novel haplogroup N9b1 in Primorye, which implies a link between a component of the Udegey ancestry and the Hokkaido Jomon.</p><p><strong>Conclusions: </strong>Through a comprehensive dataset of mitochondrial genomes retained in autochthonous populations along the coast between Primorye and the Bering Strait, we considerably extended the sequence diversity of these populations to provide new features based on the number and timing of founding lineages. We emphasize the value of integrating genealogical information with genetic data for reconstructing the population history of indigenous groups dramatically impacted by twentieth century resettlement and social upheavals.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"83"},"PeriodicalIF":3.4,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01652-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38148516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Last Glacial Maximum led to community-wide population expansion in a montane songbird radiation in highland Papua New Guinea.","authors":"Kritika M Garg, Balaji Chattopadhyay, Bonny Koane, Katerina Sam, Frank E Rheindt","doi":"10.1186/s12862-020-01646-z","DOIUrl":"10.1186/s12862-020-01646-z","url":null,"abstract":"<p><strong>Background: </strong>Quaternary climate fluctuations are an engine of biotic diversification. Global cooling cycles, such as the Last Glacial Maximum (LGM), are known to have fragmented the ranges of higher-latitude fauna and flora into smaller refugia, dramatically reducing species ranges. However, relatively less is known about the effects of cooling cycles on tropical biota.</p><p><strong>Results: </strong>We analyzed thousands of genome-wide DNA markers across an assemblage of three closely related understorey-inhabiting scrubwrens (Sericornis and Aethomyias; Aves) from montane forest along an elevational gradient on Mt. Wilhelm, the highest mountain of Papua New Guinea. Despite species-specific differences in elevational preference, we found limited differentiation within each scrubwren species, but detected a strong genomic signature of simultaneous population expansions at 27-29 ka, coinciding with the onset of the LGM.</p><p><strong>Conclusion: </strong>The remarkable synchronous timing of population expansions of all three species demonstrates the importance of global cooling cycles in expanding highland habitat. Global cooling cycles have likely had strongly different impacts on tropical montane areas versus boreal and temperate latitudes, leading to population expansions in the former and serious fragmentation in the latter.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"82"},"PeriodicalIF":3.4,"publicationDate":"2020-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353695/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38149150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phylogenetic and spatial distribution of evolutionary diversification, isolation, and threat in turtles and crocodilians (non-avian archosauromorphs).","authors":"Timothy J Colston,&nbsp;Pallavi Kulkarni,&nbsp;Walter Jetz,&nbsp;R Alexander Pyron","doi":"10.1186/s12862-020-01642-3","DOIUrl":"https://doi.org/10.1186/s12862-020-01642-3","url":null,"abstract":"<p><strong>Background: </strong>The origin of turtles and crocodiles and their easily recognized body forms dates to the Triassic and Jurassic. Despite their long-term success, extant species diversity is low, and endangerment is extremely high compared to other terrestrial vertebrate groups, with ~ 65% of ~ 25 crocodilian and ~ 360 turtle species now threatened by exploitation and habitat loss. Here, we combine available molecular and morphological evidence with statistical and machine learning algorithms to present a phylogenetically informed, comprehensive assessment of diversification, threat status, and evolutionary distinctiveness of all extant species.</p><p><strong>Results: </strong>In contrast to other terrestrial vertebrates and their own diversity in the fossil record, the recent extant lineages of turtles and crocodilians have not experienced any global mass extinctions or lineage-wide shifts in diversification rate or body-size evolution over time. We predict threat statuses for 114 as-yet unassessed or data-deficient species and identify a concentration of threatened turtles and crocodilians in South and Southeast Asia, western Africa, and the eastern Amazon. We find that unlike other terrestrial vertebrate groups, extinction risk increases with evolutionary distinctiveness: a disproportionate amount of phylogenetic diversity is concentrated in evolutionarily isolated, at-risk taxa, particularly those with small geographic ranges. Our findings highlight the important role of geographic determinants of extinction risk, particularly those resulting from anthropogenic habitat-disturbance, which affect species across body sizes and ecologies.</p><p><strong>Conclusions: </strong>Extant turtles and crocodilians maintain unique, conserved morphologies which make them globally recognizable. Many species are threatened due to exploitation and global change. We use taxonomically complete, dated molecular phylogenies and various approaches to produce a comprehensive assessment of threat status and evolutionary distinctiveness of both groups. Neither group exhibits significant overall shifts in diversification rate or body-size evolution, or any signature of global mass extinctions in recent, extant lineages. However, the most evolutionarily distinct species tend to be the most threatened, and species richness and extinction risk are centered in areas of high anthropogenic disturbance, particularly South and Southeast Asia. Range size is the strongest predictor of threat, and a disproportionate amount of evolutionary diversity is at risk of imminent extinction.</p>","PeriodicalId":9111,"journal":{"name":"BMC Evolutionary Biology","volume":"20 1","pages":"81"},"PeriodicalIF":3.4,"publicationDate":"2020-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/s12862-020-01642-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"38140414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}