Nd DMRT1 [16?23]. Using this approach, a recent study that included genetic data from four of the new species described here proposed that tetraploidization occurred at least once in subgenus Silurana and once in subgenus Xenopus, octoploidization occurred at least three times in subgenus Xenopus, and that (R)-K-13675 site dodecaploidization occurred at least three times in subgenus Xenopus [21].PLOS ONE | DOI:10.1371/journal.pone.0142823 December 16,2 /Six New Species of African Clawed Frog (Xenopus)Phylogenetic analyses indicate that all of these genome duplication events were definitively by allopolyploidization jir.2010.0097 rather than autopolyploidization, except tetraploidization in subgenus Xenopus. The ancestral (2n = 18) diploid(s) is/are not available for comparison, and possibly extinct, although allopolyploidization seems to be the most likely mechanism of tetraploidization based on its role in other genome duplications in this group [10]. Alternative scenarios for allotetraploidization involving more than one allopolyploidization event in Xenopus are discussed in Supplementary Information of Bewick et al. [18]. Not all examples of hybridization in African clawed frogs are associated with genome duplication, and naturally occurring hybrids that have the same ploidy level as the parental species have been reported between X. laevis and X. muelleri, between X. laevis and X. gilli, and between X. 1,1-Dimethylbiguanide hydrochlorideMedChemExpress 1,1-Dimethylbiguanide hydrochloride victorianus and X. borealis [24?8]. Additional species pairs have been observed in the same body of water, but no hybrids were detected, including X. clivii and X. largeni [19, 29], X. victorianus and X. wittei [30], and X. vestitus and X. wittei [30].ObjectivesThe principal objective of this study is to describe several new species of African clawed frog and to provide information about the evolutionary history of these species. Because many species of Xenopus are highly similar in external morphology, we take a multi-faceted approach, first by using molecular phylogenetics to identify distinct lineages and then using vocal characteristics, karyotypes, and both external and internal morphology (including measurements and skeletal anatomy) to provide diagnoses for lineages that we recognize as species. We explicitly compare our data to those for other described species of Xenopus that are closely related, morphologically similar, or distributed in the same region. In several cases, we also provide more detail on the distribution and morphology of previously proposed species, and in one case resurrect a taxon long synonymized with Xenopus tropicalis. By examining type material of Xenopus fraseri, we substantially revise the previous concepts for this species and suggest that this is among the most poorly known of all living Xenopus species. We provide updates on evolutionary relationships and genome duplication events as well as refinements of previously proposed species groups. For the species groups for which we describe new species, we also provide short summaries of their evolution, diversity, and distinguishing characteristics.Materials and Methods SpecimensOur analyses are based on extensive collections of the genus Xenopus that 17470919.2015.1029593 are currently available in museum collections. Many of these specimens derive from our field research (BJE, EG, VG, DBK, PJM, OSGP, DMP, RCT, MLT, and DCB), including those with associated vocalization data and tissue samples used for genetic analyses. We made a special effort to include type specimens in our morphological studies and.Nd DMRT1 [16?23]. Using this approach, a recent study that included genetic data from four of the new species described here proposed that tetraploidization occurred at least once in subgenus Silurana and once in subgenus Xenopus, octoploidization occurred at least three times in subgenus Xenopus, and that dodecaploidization occurred at least three times in subgenus Xenopus [21].PLOS ONE | DOI:10.1371/journal.pone.0142823 December 16,2 /Six New Species of African Clawed Frog (Xenopus)Phylogenetic analyses indicate that all of these genome duplication events were definitively by allopolyploidization jir.2010.0097 rather than autopolyploidization, except tetraploidization in subgenus Xenopus. The ancestral (2n = 18) diploid(s) is/are not available for comparison, and possibly extinct, although allopolyploidization seems to be the most likely mechanism of tetraploidization based on its role in other genome duplications in this group [10]. Alternative scenarios for allotetraploidization involving more than one allopolyploidization event in Xenopus are discussed in Supplementary Information of Bewick et al. [18]. Not all examples of hybridization in African clawed frogs are associated with genome duplication, and naturally occurring hybrids that have the same ploidy level as the parental species have been reported between X. laevis and X. muelleri, between X. laevis and X. gilli, and between X. victorianus and X. borealis [24?8]. Additional species pairs have been observed in the same body of water, but no hybrids were detected, including X. clivii and X. largeni [19, 29], X. victorianus and X. wittei [30], and X. vestitus and X. wittei [30].ObjectivesThe principal objective of this study is to describe several new species of African clawed frog and to provide information about the evolutionary history of these species. Because many species of Xenopus are highly similar in external morphology, we take a multi-faceted approach, first by using molecular phylogenetics to identify distinct lineages and then using vocal characteristics, karyotypes, and both external and internal morphology (including measurements and skeletal anatomy) to provide diagnoses for lineages that we recognize as species. We explicitly compare our data to those for other described species of Xenopus that are closely related, morphologically similar, or distributed in the same region. In several cases, we also provide more detail on the distribution and morphology of previously proposed species, and in one case resurrect a taxon long synonymized with Xenopus tropicalis. By examining type material of Xenopus fraseri, we substantially revise the previous concepts for this species and suggest that this is among the most poorly known of all living Xenopus species. We provide updates on evolutionary relationships and genome duplication events as well as refinements of previously proposed species groups. For the species groups for which we describe new species, we also provide short summaries of their evolution, diversity, and distinguishing characteristics.Materials and Methods SpecimensOur analyses are based on extensive collections of the genus Xenopus that 17470919.2015.1029593 are currently available in museum collections. Many of these specimens derive from our field research (BJE, EG, VG, DBK, PJM, OSGP, DMP, RCT, MLT, and DCB), including those with associated vocalization data and tissue samples used for genetic analyses. We made a special effort to include type specimens in our morphological studies and.
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