Data from: Defense traits of larval Drosophila melanogaster exhibit genetically based tradeoffs against different species of parasitoids

Populations of Drosophila melanogaster face significant mortality risks from parasitoid wasps that use species-specific strategies to locate and survive in hosts. We tested the hypothesis that parasitoids with different strategies select for alternative host defense characteristics and in doing so contribute to the maintenance of fitness variation and produce trade-offs among traits. We characterized defense traits of Drosophila when exposed to parasitoids with different host searching behaviors (Aphaereta sp. and Leptopilina boulardi). We used host larvae with different natural alleles of the gene Dopa decarboxylase (Ddc), a gene controlling the production of dopamine and known to influence the immune response against parasitoids. Previous population genetic analyses indicate that our focal alleles are maintained by balancing selection. Genotypes exhibited a trade-off between the immune response against Aphaereta sp. and the ability to avoid parasitism by L. boulardi. We also identified a trade off between the ability to avoid parasitism by L. boulardi and larval competitive ability as indicated by differences in foraging and feeding behavior. Genotypes differed in dopamine levels potentially explaining variation in these traits. Our results highlight the potential role of parasitoid biodiversity on host fitness variation and implicate Ddc as an antagonistic pleiotropic locus influencing larval fitness traits.黑腹果蝇（Drosophila melanogaster）种群面临寄生蜂带来的严重致死风险，此类寄生蜂可借助物种特异性策略定位宿主并在宿主体内存活。本研究验证了如下假说：采用不同生存策略的寄生蜂会对宿主的差异化防御特征施加选择压力，进而维持宿主的适合度变异，并引发性状间的权衡效应。研究针对两种具有不同宿主搜寻行为的寄生蜂——阿氏茧蜂属物种（Aphaereta sp.）与布氏潜蝇茧蜂（Leptopilina boulardi）——系统表征了黑腹果蝇的防御性状。本研究使用携带多巴脱羧酶（Dopa decarboxylase, Ddc）基因不同天然等位基因的宿主幼虫；该基因负责调控多巴胺的合成，且已被证实可影响宿主对抗寄生蜂的免疫应答。既往种群遗传学研究表明，本研究所关注的这些等位基因通过平衡选择得以维持。不同果蝇基因型在对抗阿氏茧蜂属物种的免疫应答与规避布氏潜蝇茧蜂寄生的能力之间呈现出显著权衡关系。研究还发现，规避布氏潜蝇茧蜂寄生的能力与幼虫竞争能力之间存在权衡，这一结论可通过果蝇的觅食与取食行为差异得到印证。不同果蝇基因型的多巴胺水平存在显著差异，这或许可以解释上述性状的变异模式。本研究结果凸显了寄生蜂生物多样性对宿主适合度变异的潜在调控作用，并表明多巴脱羧酶基因（Ddc）是一个调控幼虫适合度相关性状的拮抗多效性基因座。