Estimating Genetic Composition in Introgressed Largemouth Bass Populations: Does Age Matter?

Abstract In estimating population-level introgression for largemouth bass Micropterus salmoides populations, it is unclear which age-class, if any, is most appropriate to sample and what biases may be introduced by the sampling of specific age-classes. Estimates of introgression between Florida largemouth bass M. salmoides floridanus and northern largemouth bass M. salmoides salmoides in six populations were made based on seven microsatellite loci from different age-classes and combinations of age-classes. Levels of introgression were not significantly different for 40 of 42 pairwise age-class comparisons within reservoirs or for five of six comparisons between age-0 fish and adults. In addition, measures of precision based on each estimate were similar within reservoirs. These results suggest that age-0 largemouth bass samples can be used to make accurate and precise estimates of introgression at the population level. However, these results also suggest that alternate year-classes or combinations of year...