Multiple Translocations and Founder Events Cause Bottlenecks and Genetic Drift In Endangered Owens Pupfish Populations

The Owens pupfish (Cyprinodon radiosus) historically ranged throughout the Owens Valley, California, and numbered in the millions. The species declined in the first half of the 20th century, and was deemed extinct in 1942.  In 1964, a small, isolated population was discovered in BLM Spring near Bishop, California, and the Owens pupfish became one of the original species listed under the 1967 Endangered Species Act. A few years later, in 1969, the spring feeding the last population began to run dry, and 800 fish were rescued. These 800 fish are the parent population to all Owens pupfish surviving today. Since this original founder event, Owens pupfish have been reintroduced, serially transplanted, and extirpated many times in a number of different refuge locations. This history culminated in the existence of five refuge populations.

We used microsatellite data to examine the genetic divergencewithin and among the Owens pupfish populations in 2007, and again in 2010, and compared these populations over the intervening three years. Preliminary results revealed private alleles in each population, evidence of bottlenecks, and low effective population sizes. We also examined museum specimens to compare mitochondrial DNA diversity from the 1940s, 1970s and 2011 to explore the potential loss of diversity over time. These data will be used to inform potential future reintroductions and explore how assisted migration can be used to manage the Owens pupfish.