Molecular Phylogeographic Methods Reveal the Identity and Origin of a Dusky Salamander (Genus Desmognathus) Population in Southern Illinois, USA

Introduced species can negatively affect natural communities and ecosystems through interactions with native species. Dusky salamanders (genus Desmognathus) are commonly collected from the wild and used as fishing bait, which can result in release outside their native population or beyond the limits of the range of the species. Desmognathus conanti is the only species of the genus native to Illinois, where it occurs in Pulaski County in the extreme southern tip of the state. In 1986, a population of Desmognathus was discovered at Jug Spring, Johnson County, about 32 km north of previously known Illinois populations. We generated mitochondrial DNA sequence data for Jug Spring Desmognathus and D. conanti from Pulaski County, and combined them with DNA sequences from GenBank to determine the species identity and geographic origin of Jug Spring Desmognathus. Our analyses confirmed the species identity of Pulaski County D. conanti and showed that Jug Spring Desmognathus are D. fuscus, a species that ranges throughout the eastern U.S. but is not previously known from Illinois. Jug Spring Desmognathus were most closely related to haplotypes of D. fuscus from the Cumberland Plateau of Tennessee, pointing to this region as the likely source of the Jug Spring population. The impacts of the introduced D. fuscus on the Jug Spring ecosystem are unknown, but their presence may negatively affect invertebrates and other salamanders occupying the spring and adjacent habitats. We recommend the population be monitored and that surveys be conducted to determine if this introduced species is expanding its range.