Publication Date


Advisor(s) - Committee Chair

Jarrett R. Johnson (Director), Carl W. Dick, Lawrence Alice

Degree Program

Department of Biology

Degree Type

Master of Science


Habitat connectivity is important to maintain in order to prevent loss of genetic diversity, reduce inbreeding depression, and decrease extinction risk in threatened or endangered species. Here I present a landscape genetics study on marbled salamanders (Ambystoma opacum) in highly connected forested habitat at Mammoth Cave National Park. This investigation of gene flow among ponds within a mostly continuous landscape provides data that can be compared with patterns observed in more fragmented landscapes. These comparisons can provide a means of investigating the separate effects of structural and functional habitat connectivity on amphibian genetic population structure. Structural connectivity refers to the pattern of available habitat, and functional connectivity refers to the organism’s response to the available habitat (i.e., use of alternative habitat types). Five hundred fifty-six individuals were sampled from 50 ponds and screened at eight microsatellite loci to look for genetic population structure. Structure did exist at the park, with the best predictor of breeding pond isolation being interpond distance. Wet deciduous forest appears to offer lower resistance to gene flow in this species than dry deciduous or coniferous forest habitat, while the Green River appears to serve as a partial barrier to gene flow. Overall, my data suggest that marbled salamanders at Mammoth Cave National Park frequently move among breeding ponds, and these individuals within these ponds experience extensive amounts of gene flow. This confirms that the seemingly continuous pattern of habitat at Mammoth Cave National Park has resulted in well-connected subpopulations that frequently share genetic material.


Animal Sciences | Biodiversity | Biology | Ecology and Evolutionary Biology | Zoology