Combining genetic structure and ecological niche modeling to establish units of conservation: A case study of an imperiled salamander

Identification of conservation units below the species level has been difficult for researchers and conservation planners. Methods reliant solely on genetics to identify conservation units are widely used but have limited scope. Additionally, methods used to assess ecological distinctness are typically difficult to interpret, and hence not broadly applicable. Here, we attempt to reconcile these problems by defining conservation units utilizing both genetic and ecological methods. This study suggests a framework to evaluate discreteness and significance among populations for assessment of distinct population segments (DPSs). Specifically, we highlight a methodology that incorporates genetic analyses and niche-based distribution modeling to identify conservation units. As a case study, we sought to determine whether populations of an imperiled salamander (Notophthalmus perstriatus), appearing to exist in two regions separated by 125. km, exhibited genetic and ecological distinctness such that the regions demarcate separate conservation units. Using mtDNA (cyt-b), we found that haplotypes were shared between localities within each region but none were shared between regions. Niche-based distribution modeling revealed significant differences in the ecological setting between the two regions. In combination, the absence of evidence for recent genetic exchange and model-based support for differing ecological conditions utilized by newts between regions provides evidence that eastern and western populations are both distinct and significant. This study formalizes a method to assess DPS distinctness and significance providing general utility for this methodology as a conservation tool for many species.