From Earth-observing space satellites to nuclear microsatellites: Amphibian conservation in the Northern Great Plains

Amphibian conservation can be facilitated by the use of conceptual models, knowledge of spatial and temporal distributions of key habitat features, spatially explicit habitat suitability maps, and increased understanding of the mechanisms by which genetic diversity is maintained. To facilitate amphibian conservation and management in the Northern Great Plains (NGP), I present a conceptual model linking drivers, stressors, and effects to key habitat attributes influencing population viability and genetic diversity (chapter 2). Using this model as scaffolding, I focus three additional chapters on specific case studies. In chapter 3, I evaluate how extreme droughts alter the distribution of suitable winter habitat for the northern leopard frog (Rana pipiens). Northern leopard frogs successfully overwinter only in wetlands with sufficient water depth to avoid complete freezing. These deep-water wetlands can become rare and widely separated during periods of drought. Through the use of satellite imagery and remote sensing data manipulation techniques, I show that these potential "drought refugia" can be identified for conservation purposes. In chapter 4, I apply an emerging tool developed from ecological niche theory to map overall habitat suitability for five amphibian species. I used species occurrence information acquired from amphibian call surveys and environmental data derived from various GIS sources to develop these species specific habitat suitability maps. Suitable habitat for northern leopard frogs and wood frogs (Rana sylvatica) was closely tied to the presence of intact grasslands. Contrastingly, habitat for Great Plains toads (Bufo cognatus) and Woodhouse's toads ( Bufo woodhousii) was linked to areas of agricultural croplands. Boreal chorus frogs (Pseudocorus triserata) were habitat generalist encountered throughout the study area. Persistence of amphibian populations is tied not just to the maintenance of individuals, but also to maintenance of genetic diversity. In chapter 5, I use nuclear microsatellites to study the genetic diversity of northern leopard frog populations separated by up to 68 km. While habitat alterations and climate variability within the region have been severe, the northern leopard frog populations I sampled have maintained an exceptionally high level of genetic diversity comparable to that of eastern populations where climate dynamics are less extreme.