ENVIRONMENTAL DEPENDENCY OF INBREEDING DEPRESSION - IMPLICATIONS FOR CONSERVATION BIOLOGY

Inbreeding depression is environmentally dependent, such that a popula tion may suffer from inbreeding depression in one environment but not another. We examined the phenotypic responses of 35 inbred (F = 0.672) lineages of the red flour beetle Tribolium castaneum in two different climatic environments. We found a significant environmental effect on males but not females. More important, we found that the rank fitness order of lineages differs between environments, lineages of high fitn ess in one environment may have low fitness in another environment. Th is change in rank is evident in a significant genotype-by-environment interaction for inbreeding depression for both females and males. Thes e results suggest that even if we know the average environmental effec t of inbreeding depression in a population, for any particular lineage measurements of inbreeding depression in one environment may not pred ict the level of inbreeding depression in another environment. Conserv ation biologists need to be aware of the environmental dependency of i nbreeding depression when planning wildlife refuges or captive propaga tion programs for small populations. Ideally, captive propagation prog rams should maintain separate lineages for release efforts. Refuge des ign programs should consider maintaining a range of habitat types.