Genetics, geographics, and prairie dogs: A landscape model of prairie dog (Cynomys ludovicianus) dispersal

How populations are arranged on a landscape and how individuals move among those populations are important questions for population biology. There are several aspects of population dynamics that can address these questions: temporal distribution, genetic differentiation, and animal dispersal. The first element, temporal changes within populations, describes how populations are placed on a landscape over time. The second element, the genetic differentiation among populations, is a measure of the exchange of individuals among different populations. Finally, the third element, the dispersal distance of animals (defined as the distance an individual animal would travel between two populations), describes how spatial arrangement of environmental features can influence animal dispersal between Populations. In this study, the temporal distribution of populations of prairie dogs (Cynomys ludovicianus) was described along with a genetic study and a model of dispersal paths. Prairie dogs are fossorial colonial rodents on the Great Plains of North America. Several colonies of prairie dogs in Badlands National Park, South Dakota were used in this study to describe temporal, genetic, and spatial parameters of colonies in and around the park. These colonies were distinct and could be detected in aerial photography dating back to 1954. The colonies were also potential reintroduction sites for the federally endangered black-footed ferret (Mustela nigripes) an obligate predator of prairie dogs. Protein electrophoresis from twenty-two presumptive loci was combined with a Geographic Information Systems (GIS) model of the landscape elements around each population. The GIS modeling consisted of constructing least-cost paths across weighted surfaces where the weights are defined by prairie dog ecological preferences. These surfaces were used to create a path between two populations where the length of the path was analogous to the separation between populations (as compared to the Euclidean distances between the same two populations). The correlation between genetics and geographics demonstrates that population distribution can be explained not by the physical separation among populations (as in the island model of genetic differentiation), but by the physical barriers that isolate populations. This study found some landscape features (such as roads) correlate with genetic differentiation patterns and may be more effective in isolating populations than Euclidean distances. By including human-influences such as roads or the park boundary, the GIS model has direct application to the conservation of populations in reserves and national parks.