The effect of population size on effective population size: an empirical study in the red flour beetleTribolium castaneum

Summary Despite the increasing number of studies on the magnitude ofNe/Nratios, much remains unknown about the effects of demographic and environmental variables onNe/N. We determinedNe/Nfor seven population size treatments, ranging fromN= 2 toN= 960, in the red flour beetle Tribolium castaneum.Ne/Ndecreased with increasingN, as evidenced by a significant negative relationship between logNandNe/N. Our results are consistent with other published data on the relationship betweenNe/NandN. Effective population sizes in large populations may be much smaller than previously recognized. These results have important implications for conservation and evolutionary biology.