Genetic monitoring reveals temporal stability over 30 years in a small, lake resident brown trout population

Knowledge of the degree of temporal stability of population genetic structure and composition is important for understanding microevolutionary processes and for addressing issues on human impact on natural populations. We know little about how representative single samples in time are to reflect population genetic constitution. We explore the temporal genetic variability patterns over a 30-year period of annual sampling of a lake resident brown trout (Salmo trutta) population, covering 37 consecutive cohorts and five generations. Levels of variation remain largely stable over this period with no indication of substructuring within the lake. We detect genetic drift, however, and the genetically effective population size (Ne) was assessed from allele frequency shifts between consecutive cohorts using an unbiased estimator that accounts for the effect of overlapping generation. The overall mean Ne is estimated as 74. We find indications that Ne varies over time, but th ere is no obvious te...