Data from: Nonadditive indirect effects of group genetic diversity on larval viability in Drosophila melanogaster imply key role of maternal decision-making

Genetic variation can have important consequences for populations: high population genetic diversity is typically associated with ecological success. Some mechanisms that account for these benefits assume that local social groups with high genetic diversity are more successful than low-diversity groups. At the same time, active decision-making by individuals can influence group genetic diversity, a behavioral process not generally incorporated into discussions of population-level diversity effects. Here, we examine how maternal decisions that determine group genetic diversity influence the viability of Drosophila melanogaster larvae. Our groups contained wildtype larvae, whose genetic diversity we manipulated; and genetically-marked “tester” larvae, whose genotype and frequency were identical in all trials. We measured wildtype and tester viability for each group. Surprisingly, the viability of wildtype larvae did not depend on group genetic diversity. However, the viability of the tester genotype was substantially depressed in large, high-diversity groups. Further, not all high-diversity groups produced this effect: certain combinations of wildtype genotypes were deleterious to tester viability, while other groups of the same diversity—but containing different wildtype genotypes—were not deleterious. These deleterious combinations of wildtype genotypes could not be predicted by observing the performance of the same tester and wildtype genotypes in low-diversity groups. Taken together, these results suggest that non-additive interactions among genotypes, rather than genetic diversity per se, account for between-group differences in viability in D. melanogaster; and that predicting the consequences of genetic diversity at the population level may not be straightforward.遗传变异对种群具有重要影响：种群层面的高遗传多样性通常与生态成功息息相关。用以阐释此类益处的部分机制提出假定，遗传多样性较高的局域群体，其适合度表现要优于低多样性群体。与此同时，个体的主动决策会影响群体遗传多样性，但这类行为过程通常未被纳入种群层面多样性效应的相关讨论范畴。 本研究旨在探究决定群体遗传多样性的母体决策，如何影响黑腹果蝇（Drosophila melanogaster）幼虫的生活力。我们的实验群体包含两类幼虫：一类是可调控遗传多样性的野生型（wildtype）幼虫，另一类是遗传标记"测试"幼虫（tester larvae），所有实验中该类幼虫的基因型与出现频率均保持一致。我们对每个实验群体中的野生型幼虫与测试幼虫的生活力进行了测定。 令人意外的是，野生型幼虫的生活力并未受群体遗传多样性的影响。但在大型高多样性群体中，测试基因型幼虫的生活力出现了显著下降。此外，并非所有高多样性群体都会出现该效应：部分野生型基因型的组合会对测试幼虫的生活力产生有害影响，而其他遗传多样性水平相同但野生型基因型组合不同的群体则无此危害。通过观察低多样性群体中同一测试基因型与野生型基因型的表现，无法预测这类有害的野生型基因型组合。 综合来看，这些结果表明，黑腹果蝇群体间生活力的差异，并非由遗传多样性本身所致，而是源于基因型间的非加性互作；同时，在种群层面预测遗传多样性带来的影响或许并非易事。