Post-bottleneck inbreeding accumulation reduces fitness and adaptive potential in populations of Tribolium castaneum under environmental stress

The present study used a model organism, Tribolium castaneum, to evaluate the effect of inbreeding accumulation on additive genetic variance and fitness related traits, owing to population bottleneck events, under laboratory conditions and environmental stressors. Demographic bottlenecks were imposed on 21 populations of T. castaneum, varying in intensity and duration, for up to five generations. After recovering to original census numbers, later generations of the populations were subjected to stressful environmental conditions. A significant decrease in additive genetic variance and heritability of pupa weight was observed in all populations as a result of the bottleneck. Fitness was quantified using adult weight, total progeny, fecundity and survivorship. When the estimated inbreeding accumulation in the populations approached 40%, there was evidence for a decrease in the mean of fitness-related traits. This relationship became statistically significant when the populations were under environmental stress. Populations with increased inbreeding accumulation demonstrated decreased survival of progeny under stress. The observed decrease in heritable variation could result in reduced potential for adaptation.