Population genetics of Ash Meadows pupfish

Authors: Andrew P. Martin

Year: 2008 (xl)

Abstract

Ash Meadows harbors a large number of pupfish (Cyprinodon nevadensis) distributed across multiple springs and their outflows. Using a battery of 10 polymorphic microsatellite loci and ND2 mitochondrial DNA sequences I inferred the present and historical connectivity among populations and estimated effective population size for populations based on collections spanning a decade. Several inferences from the molecular data are noteworthy. First, there is robust separation of the two subspecies C. n. mionectes and C. n. pectoralis; however, assignment tests suggest South Scruggs may provide a conduit for migration between the lower elevation springs harboring mionectes and the upper elevation springs supporting pectoralis. Second, there is clear evidence for strong differentiation among spring pools and that these pools export individuals to the outflow system and lower elevation marshes; nonetheless, there is evidence for distinct outflow and marsh gene pools. Third, there is some indication that springs without flumes that channelize water from the spring exhibit greater connectivity than those with flumes. Fourth, individuals springs harbor modest effective population sizes, yet the two subspecies are characterized by enormous amounts of genetic diversity, a situation best explained by the effects of moderate population structure determined by the geographic configuration of springs. Finally, there is evidence for recent migration between North Indian and School springs sometime between 1998 and 2007, perhaps as a consequence of flooding. Interestingly, it appears movement was upstream. These and other inferences gained from analysis of molecular variation will be discussed in the light of planned restoration efforts.