Stress resistance and environmental dependency of inbreeding depression inDrosophila melanogaster

Both inbreeding and environmental stress can have adverse effects on fitnes s that affect the conservation of endangered species. Two important issues are whether stress and inbreeding effects are independent as opposed to syn ergistic, and whether inbreeding effects are general across stresses as opp osed to stress-specific. We found that inbreeding reduced resistance to ace tone and desiccation in adult Drosophila melanogaster, whereas resistance t o knockdown heat stress was not affected. Inbred flies, however, experience d a greater proportional decrease in productivity than outbreds following h eat stress. Correlations using line means indicated that all resistance tra its were uncorrelated in the inbred as well as in the outbred flies. Recess ive, deleterious alleles therefore did not appear to have any general delet erious effects on stress resistance. Inbreeding within a specific environme nt and selection for resistant genotypes may therefore purge a population o f deleterious genes specific to only one environmental stress.