How species will respond to the shifting climate is poorly understood, but will become increasingly important as the climate changes further, particularly in alpine areas, which will experience some of the most dramatic changes in temperature and precipitation. To track responses to climate change, the National Park System has identified “sentinel” species, such as the American pika (Ochotona princeps). Pikas typically occur in alpine habitats and are “cold adapted” to survive long winters without hibernating. These adaptations make it easy for pikas to overheat in the summer, which is when juveniles must disperse to find their own territories. Warmer summers might reduce the chances of successful dispersal, reducing gene flow and local genetic diversity. Previous studies of genetic diversity in pikas have focused on measures like microsatellites that give inflated estimates. Our study used a novel genetic analysis based on SNPs (Single Nucleotide Polymorphisms) from RADseq (Restriction site Associated DNA sequencing), to analyze the genetic composition of pikas in three habitat patches just south of Rocky Mountain National Park. The aim of this study was to get a clear picture of pika population dynamics in an area that is relatively stable under current climatic conditions, and to get a more robust idea of the current genetic structure of pika in the Colorado Rocky Mountains. This will give us a baseline for predicted changes in pika population structure due to climate change, as well as providing insight into the genetic stability of the american pika and how to preserve it.
Results/Conclusions
Although these patches were 1-3 km apart, we found little genetic differentiation among the pikas from each patch with the mean pairwise Fst values being 0.015, 0.0057, and 0.013 between our three sites, suggesting high levels of dispersal under current climatic conditions over these distances. However, one component of genetic diversity--heterozygosity--was much lower than reported in a recent study of pikas in the Rocky Mountain National Park. The average heterozygosity based on SNPs and RADseq was .280, less than half the value reported in a 2018 study based on microsatellites (Castillo et al. 2018). These results should be considered when defining populations for conservation, as low heterozygosity values are predicted to result in quicker genetic bottlenecks after isolation due to climate change.