A morphologically cryptic salamander reveals additional hidden diversity: evidence for ancient genetic divergence in Webster’s salamander, Plethodon websteri
We investigated the genetic diversity and phylogenetic structure of Webster’s salamander (Plethodon websteri), an understudied species of conservation concern and one of the first morphologically cryptic salamander species described solely on the basis of molecular techniques. Using a combination of mitochondrial and microsatellite data, we discovered significant genetic differentiation across the known distribution (ɸST > 0.868 and FST = 0.261−0.652, p < 0.001), and identified at least two highly divergent clades. These clades, referenced herein as the Semlitsch and Type Locality clades, are of late Miocene origin (approximately 5.3 million years old) and are composed of several geographically and genetically distinct populations. Together, our observations suggest that previously unrecognized species-level diversity may exist in P. websteri, with populations potentially representing distinct but undescribed taxa. We hypothesize that divergence within P. websteri likely resulted from a culmination of radical changes in climate, hydrology, and geology over deep time. Moreover, our results add to mounting evidence suggesting that P. websteri does not belong within the P. welleri group, but instead forms its own discrete species complex separate and genetically distant from P. welleri. This study provides a starting point for future work and reiterates that relationships among, and species-level diversity within, eastern species of Plethodon require additional investigation and potential reevaluation.
KeywordsPhylogeography Population genetics Cryptic Plethodon Webster’s salamander Rock
Salamanders were handled and tail clips collected under the authority granted by the following scientific collection permits: United States National Park Service #NATR-2011-SCI-0005 and #NATR-2013-SCI-0001; United States Fish and Wildlife Service (USFWS) #43665-15-001 and #43665-16-001; State of Alabama #2014012054668680, #2015050109068680, #2016062270668680. Transport of tissues and DNA extracts were covered under an injurious salamander permit from USFWS (MA19723C-0). This project was made possible by State Wildlife Grant funds provided by USFWS, and was additionally partially supported by the Mississippi INBRE, funded by an Institutional Development AWARD (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under Grant #P20GM103476. We thank the following people for either contributing to fieldwork or for supplying tissue samples utilizing their own permits/authority: Elizabeth Timpe, John Jensen, Megan Gibbons, Ken Marion, Adrienne Duvall, Jeff Boundy, Jennifer Lamb, Jennifer Frey, Mike Stegall, K. Bakkegard, and Will Dillman.
Funding was provided by U.S. Fish and Wildlife Service (Grant Nos. MS-T-F17AF01210, MS-T-F16AF01209, MS-T-F15AF00032, MS-T-F14AF01350, MS-T-F13AF01252) and Foundation for the National Institutes of Health (Grant No. P20GM103476)
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