FrogEyes
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The following paper appeared today, although it is unpaginated and may not be the final published version. It concludes that South American salamanders originated up to 30 million years ago, rather than 3 million, and consist of many cryptic unnamed species. From the authors' explicit conclusions, references to undiscussed specimens, and my own comparison of their data to type localities, it appears they reference as many as two undescribed Oedipina species and 14 undescribed Bolitoglossa (Eladinea). Some of these have been referenced in previous papers. While I still need to combine my previous checklist with my update list, it appears that the number of known salamander species and subspecies is approaching or surpassing 1000 (my update list for the last 10 years is close to 400. My previous complete list, which overlaps, was close to 800). Given the shortage of South American specimens of Oedipina, their low ability to disperse, the topographic diversity of the region, and their broad range in South America, it seems likely to me that there may be dozens more of this genus to be discovered there still.
The paper is open access and can be obtained here:
BMC Evolutionary Biology | Abstract | Early Miocene origin and cryptic diversification of South American salamanders
Kathryn R Elmer, Ronald M Bonett, David B Wake and Stephen C Lougheed, 2013. Early Miocene origin and cryptic diversification of South American salamanders. BMC Evolutionary Biology, 13:59.
Abstract (provisional)
Background
The currently recognized species richness of South American salamanders is surprisingly low compared to North and Central America. In part, this low richness may be due to the salamanders being a recent arrival to South America. Additionally, the number of South American salamander species may be underestimated because of cryptic diversity. The aims of our present study were to infer evolutionary relationships, lineage diversity, and timing of divergence of the South American Bolitoglossa using mitochondrial and nuclear sequence data from specimens primarily from localities in the Andes and upper Amazon Basin. We also estimated time of colonization of South America to test whether it is consistent with arrival via the Panamanian land bridge connection at its traditionally assumed age of 3 million years.
Results
Divergence time estimates suggest that Bolitoglossa arrived in South America from Central America by at least the Early Miocene, ca. 23.6 MYA (95% HPD 15.9-30.3 MYA), and subsequently diversified. South American salamanders of the genus Bolitoglossa show strong phylogeographic structure at fine geographic scales and deep divergences at the mitochondrial gene cytochrome b (Cytb) and high diversity at the nuclear recombination activating gene-1 (Rag1). Species often contain multiple genetically divergent lineages that are occasionally geographically overlapping. Single specimens from two southeastern localities in Ecuador are sister to the equatoriana-peruviana clade and genetically distinct from all other species investigated to date. Another single exemplar from the Andes of northwestern Ecuador is highly divergent from all other specimens and is sister to all newly studied samples. Nevertheless, all sampled species of South American Bolitoglossa are members of a single clade that is one of several constituting the subgenus Eladinea, one of seven subgenera in this large genus.
Conclusions
The ancestors of South American salamanders likely arrived at least by the Early Miocene, well before the completion of the Late Pliocene Panamanian land bridge (widely accepted as ca. 3 MYA). This date is in agreement with recent, controversial, arguments that an older, perhaps short-lived, land connection may have existed between South America and present-day Panama 23--25 MYA. Since its arrival in South America, Bolitoglossa has diversified more extensively than previously presumed and currently includes several cryptic species within a relatively small geographic area. Rather than two upper Amazonian species currently recorded for this region, we propose that at least eight should be recognized, although these additional lineages remain to be formally described.
The paper is open access and can be obtained here:
BMC Evolutionary Biology | Abstract | Early Miocene origin and cryptic diversification of South American salamanders
Kathryn R Elmer, Ronald M Bonett, David B Wake and Stephen C Lougheed, 2013. Early Miocene origin and cryptic diversification of South American salamanders. BMC Evolutionary Biology, 13:59.
Abstract (provisional)
Background
The currently recognized species richness of South American salamanders is surprisingly low compared to North and Central America. In part, this low richness may be due to the salamanders being a recent arrival to South America. Additionally, the number of South American salamander species may be underestimated because of cryptic diversity. The aims of our present study were to infer evolutionary relationships, lineage diversity, and timing of divergence of the South American Bolitoglossa using mitochondrial and nuclear sequence data from specimens primarily from localities in the Andes and upper Amazon Basin. We also estimated time of colonization of South America to test whether it is consistent with arrival via the Panamanian land bridge connection at its traditionally assumed age of 3 million years.
Results
Divergence time estimates suggest that Bolitoglossa arrived in South America from Central America by at least the Early Miocene, ca. 23.6 MYA (95% HPD 15.9-30.3 MYA), and subsequently diversified. South American salamanders of the genus Bolitoglossa show strong phylogeographic structure at fine geographic scales and deep divergences at the mitochondrial gene cytochrome b (Cytb) and high diversity at the nuclear recombination activating gene-1 (Rag1). Species often contain multiple genetically divergent lineages that are occasionally geographically overlapping. Single specimens from two southeastern localities in Ecuador are sister to the equatoriana-peruviana clade and genetically distinct from all other species investigated to date. Another single exemplar from the Andes of northwestern Ecuador is highly divergent from all other specimens and is sister to all newly studied samples. Nevertheless, all sampled species of South American Bolitoglossa are members of a single clade that is one of several constituting the subgenus Eladinea, one of seven subgenera in this large genus.
Conclusions
The ancestors of South American salamanders likely arrived at least by the Early Miocene, well before the completion of the Late Pliocene Panamanian land bridge (widely accepted as ca. 3 MYA). This date is in agreement with recent, controversial, arguments that an older, perhaps short-lived, land connection may have existed between South America and present-day Panama 23--25 MYA. Since its arrival in South America, Bolitoglossa has diversified more extensively than previously presumed and currently includes several cryptic species within a relatively small geographic area. Rather than two upper Amazonian species currently recorded for this region, we propose that at least eight should be recognized, although these additional lineages remain to be formally described.