Modeling occurrence of the green salamander, Aneides aeneus, in the Blue Ridge Escarpment

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Rebecca Hale Hardman (Creator)
Western Carolina University (WCU )
Web Site:
Joseph Pechmann

Abstract: Amphibian species have experienced global declines since the 1970s andplethodontid salamanders are no exception. The green salamander, Aneides aeneus, is aplethodontid salamander that has experienced declines throughout its range in the BlueRidge Escarpment.Species distribution models are algorithms that predict occurrences of a speciesacross a landscape and can be used to determine conservation priority areas. However,there are commonly only presence locations without corresponding absence locationsavailable to a researcher. These presence-only datasets can present a challenge whentrying to depict reliable distributions for a species of concern. Maximum Entropy(MaxEnt) is an algorithm empirically tested to model species distributions givenpresence-only datatsets.I used landscape-level species distribution models including MaxEnt and logisticregression to model the occurrence of green salamanders across the Blue RidgeEscarpment of North Carolina. These models were used to assess particular featuresassociated with A. aeneus presence as well used to search for new localities. MaxEnt models outperformed logistic regressions for all methods of evaluation.MaxEnt models had fairly low omission (false negative) and commission (false positive)rates whereas my logistic regression had extremely high error rates for both. “Area Underthe Receiver Operator Curve” evaluation scores were excellent (0.96) and good (0.81) forthe top Maxent model and logistic regression, respectively.Aneides aeneus is known to be associated with habitat that includes rockoutcroppings with thin, deep crevices. My models indicated that forested areas,intermediate elevations, and shallow soils of particular types are desirable landscapefeatures for A. aeneus. Soil was the most important variable in all models, accounting foralmost half of the variation in MaxEnt models. Elevation accounted for most of theremaining variation. Percent canopy cover accounted for 4-6.5% of the variation inMaxent models. While these models did not specifically predict presence of outcrops,they were extremely helpful in identifying habitat with conditions supportive for A.aeneus if a rock outcrop was present. With the help of these models I discovered onepreviously unknown locality for A. aeneus and am confident addition locations can befound.

Additional Information

Language: English
Date: 2014
Aneides aeneus, Green salamander, Maxent, Plethodontidae, SDM, Species distribution model
Salamander populations -- Blue Ridge Mountains -- Mathematical models
Lungless salamanders -- Blue Ridge Mountains -- Geographical distribution -- Mathematical models

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