Connectivity and Gene Flow Among Eastern Tiger Salamander (Ambystoma tigrinum) Populations in Highly Modified Anthropogenic Landscapes
Valorie R. Titus
ABSTRACT: Fragmented landscapes resulting from anthropogenic habitat modification can have significant impacts on dispersal, gene flow, and persistence of wildlife populations. Therefore, quantifying population connectivity across a mosaic of habitats in highly modified landscapes is critical for the development of conservation management plans for threatened populations. The eastern tiger salamander (Ambystoma tigrinum) is listed as endangered in New York and New Jersey and remaining populations persist in highly developed landscapes in both states. We used landscape genetic approaches to examine regional genetic population structure and potential barriers to migration among remaining populations. Salamander populations in each state belong to distinct genetic demes, consistent with the large geographic distance that separates these isolated, range-edge populations. We found overall low genetic diversity and high relatedness within populations, likely due to isolation and relatively small population sizes in each state. Nonetheless, landscape connectivity analyses reveal habitat corridors among remaining breeding ponds within each state. Furthermore, molecular estimates of population connectivity among ponds indicate that gene flow still occurs at regional scales. Further fragmentation of remaining habitat will potentially restrict dispersal among breeding ponds, cause the erosion of genetic diversity, and exacerbate already high levels of inbreeding. We recommend the continued management and maintenance of habitat corridors to ensure long-term viability of these endangered populations.
Valorie is a graduate of Binghamton University where she studied the movements and population genetics of the eastern tiger salamander on Long Island. The majority of her work was completed on Brookhaven National Laboratory property. She is currently working for the Wildlife Conservation Society- formerly at the Bronx Zoo as a curatorial science fellow in the herpetology department, and presently as a postdoctoral associate in Montana. Her main focus is the conservation and management of reptiles and amphibians, and is now looking at the impacts of bison reintroduction in Montana on aquatic communities.