Although many studies have examined how taxa responded to Pleistocene climate fluctuations in the Appalachian Mountains, impacts on high-elevation endemics of Central Appalachia are not yet understood. We use mitochondrial (ND4 & Cytb) and nuclear (GAPD) DNA sequences to investigate the phylogeography of the Cow Knob Salamander ( Plethodon punctatus ), a woodland species from Central Appalachian highlands thought to have origins in the Pleistocene. Data from 72 tail tips representing 25 sites revealed that the species comprises two geographically cohesive mitochondrial clades with a narrow, putative contact zone on Shenandoah Mountain. Molecular clock estimates indicate the clades diverged in the Middle Pleistocene. The population size of the Southern clade appears to have remained stable for at least 50,000 years. Despite spanning several isolated mountain systems, the Northern clade has exceptionally low genetic diversity, probably due to recent demographic expansion. Palaeodemographic hypothesis testing supported a scenario in which a founder effect characterized the Northern clade as it diverged from the Southern clade. Species distribution models predicted no suitable habitat for the species during the Last Glacial Maximum. Ultimately, Pleistocene glacial climates may have driven the species from the northern half of its current range, with recolonization events by members of the Northern clade as climates warmed. Density dependent processes may now maintain a narrow contact zone between the two clades.
Rapid contemporary climate change is a potential threat to long-term persistence of montane wildlife species because they often have narrow thermal tolerances and have limited potential to shift their distributions. The Appalachian Mountain region in the eastern United States is a global biodiversity hotspot for woodland salamanders (genus Plethodon), many of which are high-elevation endemic species. Robust assessments of the vulnerability of high-elevation endemic salamanders to climate change, including delineation of future potential climate refugia, are needed to guide climate change adaptations strategies. The Cow Knob Salamander (Plethodon punctatus) is a species of conservation concern found at high elevations in the Valley and Ridge Province of western Virginia and eastern West Virginia. We used habitat suitability models to examine relationships between landscape characteristics, climate variables, and P. punctatus occurrence, and estimated effects of future climate scenarios on the species’ climatic niche. We found that elevation, slope, aspect, and hillshade were influential landscape predictors of species occurrence, and that mean annual temperature was the most influential climate variable. Future climate projections indicated this species will likely lose most of its climatic niche by mid-century, and that amount of suitable habitat will continue to decline through 2100. We identified several pockets of habitat that may represent climate change refugia for P. punctatus due to cooler microclimates from greater hillshade and aspects that receive less direct solar radiation; however, we found these refugia exist in small, isolated habitat patches. Our study provides quantitative estimates that support the general concern that high-elevation endemic salamanders are particularly vulnerable to climate change. Our models can be used by natural resource managers to guide current P. punctatus monitoring and habitat conservation efforts, as well as to identify focal areas that will likely serve as refugia for the species as the climate continues to change over this century.
DNA evidence is often critical for taxonomic studies; however, many historical type specimens lack corresponding genetic samples, which limits contemporary molecular research questions and may restrict conservation and management decisions. We conducted a pilot Type Locality Project to collect voucher specimens and genomic-grade samples from amphibian type localities in the state of Virginia, USA. These samples can serve as proxies for cases in which obtaining genomic data from the type specimen is not possible. Undergraduate students participated in all aspects of the project including fieldwork, DNA barcoding, and incorporating specimens into the Smithsonian Institution’s National Museum of Natural History research collection. The Type Locality Project is an excellent platform for providing undergraduate students with hands-on research experience and training in taxonomy and systematics. Other institutions could easily adapt our approach to obtain genomic-quality, topotypic vouchers for other taxa and simultaneously create authentic undergraduate research experiences in field, laboratory, and natural history museum settings.
Prescribed fire is used in the central Appalachians to promote and maintain mixed-oak and pine forests, create open forest conditions, improve habitat for wildlife, and to reduce the risk of impact of higher intensity wildfires on human development. Few studies have investigated responses of terrestrial salamander populations to habitat management using fire, and estimated responses have been neutral, negative, and positive depending on geography, species, and fire-severity. We examined woodland salamander (genus Plethodon) population responses to habitat management using prescribed fire on Shenandoah Mountain in the George Washington National Forest in West Virginia and Virginia, USA. We focused on responses of the Cow Knob Salamander (P. punctatus), a talus specialist and species of high conservation concern, but also examined responses of the Eastern Red-Backed Salamander (P. cinereus), a widespread habitat generalist. Three burn units were subjected to two low-severity burns and one unit was burned five times with ca. 40% tree mortality. Using a combination of nighttime visual encounter surveys and coverboard surveys, we compared terrestrial salamander abundance and body condition in unburned and burned areas. We also measured habitat characteristics at sampling sites to determine if prescribed burn histories were correlated with habitat conditions important to woodland salamanders. Mean abundance for P. punctatus was lower at sites that were burned, but there was not a strong burn effect for P. cinereus. Abundance of both species was positively correlated with canopy cover. Mean and median body condition index (BCI) score was higher for P. punctatus and lower for P. cinereus on the West Virginia side of Shenandoah Mountain, and lower in burned areas for both species. However, the most parsimonious BCI models did not contain the burn predictor. Management using prescribed fire altered microhabitat conditions that are important for woodland salamanders, such as canopy cover, leaf litter depth, and vegetation groundcover. Our study suggests that woodland salamanders in the central Appalachians can persist in forests managed using prescribed fire, but also indicates that prescribed fire can result in reduced habitat quality for some woodland salamander species.
A recent review on the climbing behavior of plethodontid salamanders (McEntire 2016. Copeia 104:124–131) reported that many Plethodon are facultatively arboreal. Here, we report observations of climbing behavior for Plethodon punctatus, a species of conservation concern that is only found on Shenandoah Mountain and Great North Mountain in eastern West Virginia and western Virginia, USA.
Effective monitoring of population size is critically important for endemic species with specialized habitat requirements so that timely remedial steps can be taken when declines are detected. We initiated a monitoring study of the endemic plethodontid salamander, Plethodon punctatus, which is generally found in talus habitats over 1000 M in elevation in a narrow range on Shenandoah Mountain on the border of Virginia and West Virginia. We tested congruence of nighttime visual encounter surveys (VES) and mark-recapture estimates of population size. VES was a valid index of the abundances of P. punctatus in the two habitats we surveyed. Sites on the eastern and western sides of Shenandoah Mountain were surveyed, and both methods estimated that population size on the west was approximately twice as high as that on the east. Individuals of this species exhibited a high degree of site fidelity. Cover object searches for species in talus habitats are expected to be of limited value, and we conclude that nighttime visual encounter surveys are most effective for population size monitoring of P. punctatus and other species that live in talus.