| We utilize 430 base pairs of D-Loop sequence data to characterize mitochondrial polymorphism and estimate the female evolutionary effective population size, Nef, of the Southern California Bight population of white seabass, (Atractoscion nobilis). The D Loop sequence data is highly polymorphic and reflects a population expansion signal according to both a coalescent-based and moment-based estimation procedures. The coalescent-based approach produces a Nef of 54,260, based on a mutation rate of 7.36 x 10-7 base-pairs/generation. In addition, the positive, exponential growth rate is 1.22 x 10-3. We also employ six nuclear microsatellites to characterize genetic diversity and detect recent demographic changes across six sampling locations. There are large amounts of heterozygosity deficiency and little geographic subdivision. The bottleneck signal agrees with demographic data, but juxtaposes a population expansion signal found in mitochondrial data in this species.; We also estimate Nb, the effective number of breeders for the progeny produced by each spawning event, for ten spawning events originating in the white seabass hatchery from numbers of offspring contributed per parent, as determined by genotypic assignment. From this data, we estimate N b for the entire 2001 release using an allele rarefaction procedure. We find that spawning events have very low effective number of breeders (2.0-8.1) and the 2001 Nb is 34.6. The impact of the hatchery releases on the wild population depends on the level of genetic diversity within the wild. We estimate the three parameters in the Ryman-Laikre model to examine the effect of supportive breeding on the wild effective population size. The effective population size, New, of the wild population is estimated using both a moment-based method and a pseudo-likelihood estimator of genetic drift based on temporally spaced changes in allele frequencies. The moment-based technique yields a mean of 5,679, and a 95% confidence interval of 3,977-7,678. The pseudo-likelihood method provides a mean of 6,087 and a 95% confidence interval of 2,384-57,310. All combinations of estimated Nˆeh, and Nˆew coupled with a proportional contribution from the hatchery to the total reproduction of 0.069 from tag-recapture studies result in negative effects on the genetic diversity of the wild population ranging from 1.5-92.9%. |
