the environmental dependence of inbreeding depression in a wild bird population近交衰退的环境依赖野生鸟类种群.pdf

The Environmental Dependence of Inbreeding Depression in a Wild Bird Population Marta Szulkin*, Ben C. Sheldon Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, United Kingdom Background. Inbreeding depression occurs when the offspring produced as a result of matings between relatives show reduced fitness, and is generally understood as a consequence of the elevated expression of deleterious recessive alleles. How inbreeding depression varies across environments is of importance for the evolution of inbreeding avoidance behaviour, and for understanding extinction risks in small populations. However, inbreeding-by-environment (I 6E) interactions have rarely been investigated in wild populations. Methodology/Principal Findings. We analysed 41 years of breeding events from a wild great tit (Parus major) population and used 11 measures of the environment to categorise environments as relatively good or poor, testing whether these measures influenced inbreeding depression. Although inbreeding always, and environmental quality often, significantly affected reproductive success, there was little evidence for statistically significant I 6E interactions at the level of individual analyses. However, point estimates of the effect of the environment on inbreeding depression were sometimes considerable, and we show that variation in the magnitude of the I 6E interaction across environments is consistent with the expectation that this interaction is more marked across environmental axes with a closer link to overall fitness, with the environmental dependence of inbreeding depression being elevated under such conditions. Hence, our analyses provide evidence for an environmental dependence of the inbreeding 6environment interaction: effectively an I 6E