Genetic Divergence Inferred from Nested Phylogenetic Analysis of the Green Salamander: Aneides aeneus
Maxson, Laura S.
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The concept of species has been a highly debated subject in recent years, especially in the context of conservation biology. What is the minimum unit that should be considered for conservation measures? The species Aneides aeneus, the green salamander found in the Appalachian region of the eastern United States presents an accurate illustration of this problem. The International Union for Conservation of Nature and Natural Resources (IUCN) is presently considering the entire metapopulation of A. aeneus for conservation. However, Sessions and Kezer discovered that A. aeneus exists in two chromosomally distinct populations (Sessions and Kezer, 1987). One of these karyotypes is also found in a disjunct population in North and South Carolina. The purpose of this study was to use cytochrome b mitochondrial DNA sequence to reanalyze the intraspecific phylogenetic relationships of A. aeneus to a degree that was not methodologically possible in the previous karyotype study of Sessions and Kezer. A nested cladistic analysis was used to resolve relationships within A. aeneus populations. Following initial phylogenetic analysis, gene flow between populations was estimated from the phylogeny generated with the Cyt b sequences. The mitochondrial sequence data demonstrated that A. aeneus is represented by at least three genetically distinct populations. Gene flow estimates indicated that little migration has occurred between the three populations in recent years. According to the Endangered Species Act and several species concepts, these distinct populations are the taxa that should be considered for conservation. Therefore, this phylogenetic data should be seriously considered in formulating necessary conservation measures to protect these populations of A. aeneus.