Analyses of Genetic Variation in Populations of Oregon Chub, a Threatened Floodplain Minnow in a Highly Altered Environment

作者：DeHaan Patrick W^*; Scheerer Paul D; Rhew Ron; Ardren William R

来源：Transactions of the American Fisheries Society, 2012, 141(2): 533-549.

DOI：10.1080/00028487.2012.670184

The Oregon chub Oregonichthys crameri is a small floodplain minnow endemic to the Willamette River basin of western Oregon. Historically the species was widely abundant and probably relied on periodic floods for dispersal and genetic exchange among populations. The species has declined substantially in the past 100 years due to habitat alterations and the introduction of nonnative species and is currently listed as threatened under the U.S. Endangered Species Act. Information on the level of genetic variation within and among populations did not exist when the species was listed or when a recovery plan was being developed. In this study, we used a suite of nine microsatellite loci to characterize genetic variation within and among 16 sampling locations and provide information to help guide future recovery efforts. Even though many locations are presently isolated from one another, we observed relatively high levels of genetic variation within collections. Temporal samples revealed that the levels of genetic variation were stable over time despite fluctuations in abundance. Estimates of effective population size (N-e) for three sampling locations ranged from approximately 120 to 220 and suggest that there is no immediate threat from inbreeding or genetic drift. We observed a significant level of genetic variation among sampling locations (global F-ST = 0.078) and significant differences in allele frequencies among all sampling locations. Our results suggest that the different locations represent distinct populations of Oregon chub and that greater levels of gene flow occur among populations within the Santiam and Middle Fork Willamette River subbasins. The information presented in this study will help guide Oregon chub recovery efforts, including the refinement of recovery areas and future population introduction efforts, and will help address the challenge of managing populations largely in isolation from one another in order to minimize threats from nonnative species.

• 出版日期2012-3