Population Genetic Structure of the Tiger Salamander (Ambystoma tigrinum) in the Canadian Prairies: Insights into the Spread of Ranaviruses
Mihelich, Brittany; Schock, Danna; and Collins, James
School of Life Sciences, Arizona State University
Ranaviruses (Family Iridoviridae) are the causative agent of mass die-offs of tiger salamanders (Ambystoma tigrinum) across North America. Laboratory-based studies have demonstrated marked differences among tiger salamander populations from the Canadian prairies (study area = 450km x 800km) in terms of outcome of exposure to ranaviruses. Ranaviruses are widespread across the Canadian prairies yet some tiger salamander populations experience very high mortality rates when exposed to ranaviruses whereas others experience almost no mortality at all. Since migrating tiger salamanders are thought to be the main way in which ranaviruses are moved among populations, we seek to characterize the population genetic structure of this species on the Canadian prairies and thereby estimate how readily ranaviruses are moved among populations. It will also allow us to estimate how frequently tiger salamanders that are potentially genetically resistant to ranaviruses may move among populations. To understand the population genetic structure of tiger salamanders, we are using several previously published microsatellite markers. To date, we have been able to optimize and collect data for two markers. Preliminary analyses reveal that tiger salamander populations in the south-west part of the study area are completely homozygous at both markers for each marker's respective most common allele. In contrast, tiger salamander populations in the eastern part of the study area have two or three alleles at each marker. Our study suggests that there may be important structure to tiger salamanders populations across the Canadian prairies, perhaps driven by western populations being founded by migrants from more eastern populations.