Abstracts (first author)
Outbreeding depression and heterosis are predicted by demography, environmental and cytogenetic contexts in natural populations
When individuals from separate populations mate, the resulting hybrid offspring can experience fitness benefits (heterosis) or costs (outbreeding depression) relative to their parents. Understanding the distribution and extent of these genetic benefits and costs is essential for guiding conservation plans that seek to mix wildlife populations. We use meta-analysis to test the hypothesis that phenotypic responses to intraspecific outbreeding can be predicted by combining information on population demography, environmental and cytogenetic contexts. Our dataset comprised 510 effect sizes describing intrinsic outbreeding responses, from 98 studies on animals and plants (79 species). Our results indicate that information on population context can be used to predict both observed outbreeding depression and heterosis. Studies for which we predicted a risk of outbreeding depression showed a cost to fitness (viability, survival, reproduction) in the F2 generation, relative to mid-parent performance. In cases predicted to exhibit heterosis we observed a corresponding fitness benefit relative to the mid-parent. We discuss whether and how these results, and our approach to predicting outbreeding responses, might be useful in conservation practice.