Range‐wide phylogeography of the four‐toed salamander: out of Appalachia and into the glacial aftermath

Abstract

AimWe assessed the phylogeography of Hemidactylium scutatum across the entire range of the species, quantifying the diversity of populations, and identifying extrinsic factors that may have generated observed patterns of genetic connectivity and distribution.Location North America. MethodsWe performed DNA sequence analysis of the mitochondrial cytochrome oxidase 1 gene of 335 samples collected from 79 field locations distributed throughout the species range. Phylogenetic analyses, patterns of haplotype distribution, DNA mismatch distributions, and partial Mantel tests were performed to estimate divergence times of major clades, identify geographical barriers that determined phylogenetic breaks, and describe a potential scenario for the radiation of the species.Results Phylogenetic analyses showed deep sequence divergences with strong support for regional monophyletic groups. Patterns of haplotype distribution suggest that both ancient and modern river drainages acted as barriers to dispersal. Two distinct allopatric clades accounted for all sampling sites within glaciated areas of North America yet showed distinct patterns of recolonization. High levels of haplotype diversity were detected in the southern Appalachians, with several members of widely ranging clades as well as other unique, endemic, and highly divergent lineages. Bayesian analyses estimated the common ancestor of all living Hemidactylium at roughly 8 Ma, with the most basal splits confined to the Blue Ridge Mountains. Main conclusionsOur results are consistent with the 'Out of Appalachia' hypothesis for the origin of Hemidactylium scutatum, lending further support to the importance of this region as a generator of biodiversity in eastern North America.

Post‐Pleistocene differentiation in a Central Interior Highlands endemic salamander

“…Figure 3); however, this relationship was not significant. Further, previous studies of CIH caudates identified the Arkansas River Valley to be a phylogeographic barrier between the Ozarks and Ouachitas(Herman & Bouzat, 2016;Martin et al, 2016); however, the Arkansas River Basin was not a phylogeographic barrier for A. annulatum in our study.Although we surveyed a number of sites in the Ouachitas, we were only able to obtain a limited number of individuals and we were only able to obtain >10 individuals at one sampling site. Further, previous studies of CIH caudates identified the Arkansas River Valley to be a phylogeographic barrier between the Ozarks and Ouachitas(Herman & Bouzat, 2016;Martin et al, 2016); however, the Arkansas River Basin was not a phylogeographic barrier for A. annulatum in our study.Although we surveyed a number of sites in the Ouachitas, we were only able to obtain a limited number of individuals and we were only able to obtain >10 individuals at one sampling site.…”

Biogeographical evidence for common vicariance and rare dispersal in a southern Appalachian harvestman (Sabaconidae, Sabacon cavicolens)

“…Vertebrate examples are numerous in salamanders (e.g. Weisrock & Larson, 2006;Kozak & Wiens, 2010;Herman & Bouzat, 2016), whereas arthropod examples include other harvestmen (Thomas & Hedin, 2008;Hedin & Thomas, 2010), spiders (Hedin, 1997(Hedin, , 2001Hendrixson & Bond, 2005;Keith & Hedin, 2012;Hedin et al, 2015) and others. Also, intraspecific phylogeographical fragmentation is evident within more wide-ranging species, with many taxa including divergent populations on distinct massifs, separated by lowland riverine barriers.…”

Cyto‐nuclear discordance suggests complex evolutionary history in the cave‐dwelling salamander, Eurycea lucifuga

“…The results we see in the case of E. lucifuga suggest that mitochondrial gene loci reflects a more ancient evolutionary history, wherein the central and eastern/western lineages diverged during the climatic shifts of the Pleistocene, possibly taking refuge in two locations as has been seen in other species (Phillips 1994;Zamudio and Savage 2003;Herman and Bouzat 2015). However, following expansion from Pleistocene refugia and establishment in present-day localities, there may have been secondary contact between central and eastern populations leading to introgression seen in the microsatellites and the POMC gene trees.…”

“…The sharing of haplotypes among localities in concert with the departures from neutrality we observe in estimates of Tajima's D and Fu's F and reduced nucleotide diversity suggests further recent expansion within the eastern and western regions. Lineage divergence during the turbulent Pleistocene reflects what we know about other North American salamanders (Church et al 2003;Herman and Bouzat 2015;Newman and Austin 2015) as well as other cave-dwelling species (Niemiller et al 2013;Bryson et al 2014), and in particular, other troglophilic salamanders (Cimmaruta et al 2015;Kuchta et al 2016). However, this estimation is much more recent than the dispersal event predicted by Martin et al (2015), which they estimated to have occurred approximately 4 Ma.…”

“…Published information about the evolutionary history of other salamanders and other cave-dwelling species reveals some general phylogeographic patterns that shape our expectations. Many North American salamander species experienced ancient divergence from sister taxa, on the order of millions of years (Bonett and Chippindale 2004;Kozak et al 2006;Reilly and Wake 2014;Folt et al 2016), but in most species, intraspecific divergences reflect the impacts of climatic fluctuations throughout the Pleistocene (approximately 2.5 Ma-10 Ka; Church et al 2003;Herman and Bouzat 2015;Newman and Austin 2015). The evolutionary history of troglophilic salamanders tends to reflect these same patterns, for example, Hydromantes strinatii, a native to Southern Europe, experienced divergence among major lineages during the Pleistocene (Cimmaruta et al 2015).…”