Document Type



Genetic diversity is important to the long-term survival of a species. Populations with low genetic diversity are more likely to go extinct due to an inability to adapt to environmental changes or accumulation of deleterious alleles. Habitat fragmentation may result in lower genetic diversity by disrupting gene flow between subpopulations caused by urbanization and development (e.g., roads, buildings, and agricultural fields). This study explored the effects of habitat fragmentation on the genetic diversity of the eastern red-back salamander (Plethodon cinereus). I collected tissue samples from 20-30 individuals from 1-3 different subpopulations within four larger forest sites that differed in their total area (i.e., >1000 hectares or 3-60 hectares). Two sites were small fragments that are completely surrounded by suburban or agricultural areas in eastern Massachusetts (“fragmented” forest; three subpopulations). The other two sites were large, continuous forests located in western Massachusetts (“continuous” forest; four subpopulations). DNA was extracted and amplified at five to seven microsatellite loci. I calculated heterozygosity, allelic richness, and overall population differentiation. Two out of three fragmented subpopulations had significantly lower than average allelic richness, while one out of four continuous subpopulations had significantly higher than average allelic richness. I also found stronger differentiation (higher FST) between fragmented subpopulations than expected from simply isolation-by-distance, and evidence of secondary structure between the fragmented sites. This suggests that while genetic diversity in this species may not yet be directly affected by habitat fragmentation, dispersal is limited between fragmented subpopulations (reflected in their higher FST compared to continuous subpopulations).



Thesis Comittee

M. Caitlin Fisher-Reid (Thesis Director)

Christopher Bloch

Jonathan Rolling

Copyright and Permissions

Original document was submitted as an Honors Program requirement. Copyright is held by the author.

Included in

Biology Commons