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Past and Present Processes Influencing Genetic Diversity and Effective Population Size in a Natural Population of Atlantic Sturgeon
Author(s) -
Moyer G. R.,
Sweka J. A.,
Peterson D. L.
Publication year - 2012
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1080/00028487.2011.651073
Subject(s) - overexploitation , effective population size , biology , population size , endangered species , genetic diversity , population , acipenser , ecology , extinction (optical mineralogy) , fishery , sturgeon , geography , habitat , demography , fish <actinopterygii> , paleontology , sociology
Abstract Threats such as habitat loss, invasive species, and overexploitation cause species extinctions; however, stochastic processes can accelerate extinction rates as census sizes decline. Using molecular and ecological data, we explored the influence of these processes on the demography of a candidate species under the U.S. Endangered Species Act—the Atlantic sturgeon Acipenser oxyrinchus oxyrinchus . We used molecular microsatellite markers to estimate the effective population size ( N e ) and effective number of breeders ( N b ) and we used mark–recapture data to estimate the number of spawners ( N a ) for Atlantic sturgeon of the Altamaha River, Georgia. We found that estimates of N b were 7–45% less than the estimated N a over four consecutive cohorts and that skewed sex ratios could explain the relative decrease of N b to N a . Our estimate of contemporary N e was 125 (95% confidence interval = 75–348) and was at least an order of magnitude less than our estimate of historical N e . To explain the large discrepancy between these estimates, we tested several alternative evolutionary scenarios that might explain the observed pattern of genetic diversity. Our results indicated that the observed genetic data were indeed best explained (i.e., 0.998 posterior probability of the data given the hypothesis) by overexploitation during the last half of the 20th century.