Habitat fragmentation and woodland amphibians: Consequences for distribution, genetic diversity and fitness responses to UV-B radiation

Recent declines in amphibian populations have heightened the importance of understanding amphibian/habitat relationships. Because of poor dispersal abilities and physiological constraints, amphibians may be especially susceptible to the effects of habitat fragmentation. In this dissertation, I investigate landscape-level influences of fragmentation on woodland amphibian species distributions, as well as population-level impacts on genetic diversity and related fitness consequences for wood frogs (Rana sylvatica).; For the first part of my research, I surveyed 25 woodlots and one area of continuous forest in Crawford County, Ohio for amphibians and evaluated 13 models concerning amphibian species richness and the presence of individual species in woodlots. I found 13 species of amphibians within the study plot, indicating that small woodlots within an agricultural matrix are important amphibian refuges. Hydroperiod was the most important habitat characteristic for predicting species richness. Landscape characteristics were relatively unimportant.; Next, I analyzed the genetic diversity of wood frog populations in relation to characteristics of their local habitat and landscape, to determine whether populations within woodlots have become genetically differentiated and/or have lost genetic diversity. I found genetic distance to be correlated with geographical distance. Populations from breeding ponds with longer hydroperiods were more genetically diverse. I also assessed the genetic diversity of eight wood frog populations, and compared the genetic diversity of each population with the mortality and deformity rates of lab-reared eggs and larvae. Although there were weak negative correlations, my analyses failed to find a significant relationship between genetic diversity and deformity or mortality rates.; The final component of my research was an investigation of a synergism between UV-B radiation and genetic diversity, influencing mortality and deformity rates in wood frogs. I measured the genetic diversity of 12 populations, and exposed eggs/larvae from those populations to three different UV-B treatments. UV-B exposure significantly increased larval mortality and deformity rates. Populations with low genetic diversity suffered greater egg and larval mortality rates and deformity rates. Further, the interaction between UV-B treatment and genetic diversity significantly influenced larval mortality rates. This is the first study to document such an interaction between genetic diversity and resistance to an environmental stressor.