BACKGROUND The theory of trade-off suggests that limited resources should lead to trade-off in resource intensive traits such as, immunity related and sexually selected traits in males. Alternatively, sexual exaggerations can also act as an honest indicator of underlying immunocompetence, leading to positive correlations between these traits. Evidences in support of either hypothesis in invertebrates are equivocal. Whereas several studies have addressed this question, few have used naturally occurring pathogens and realized post infection realized immunity (e.g., survivorship) to assay the fitness correlations between these two sets of traits. RESULTS Adopting an experimental evolution approach, we evolved replicate populations of Drosophila melanogaster under high and low sexual selection regimes for over a hundred generations and found the following in virgin and mated males in three separate assays: a.Post infection survivorship against two natural pathogens - Pseudomonas entomophila (Pe) and Staphylococcus succinus (Ss): Mated males survived better against Pe, but were no different than virgins against Ss.b.Bacterial clearance ability against a third natural pathogen Providencia rettgeri (Pr): Mated males had significantly lower CFUs than virgins. However, sexual selection history had no effect on realized immunity of either virgin or mated males. CONCLUSION We show that while mating can affect realized immunity in a pathogen specific way, sexual selection did not affect the same. The results highlight that complex polygenic traits such as immunity and reproductive traits not necessarily evolve following a binary trade-off model. We also stress the importance natural pathogens while studying sexual selection-immunity correlations.

中文翻译：

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在不同的性选择下进化的雄性果蝇的生殖-免疫权衡不存在。

背景技术权衡理论表明，有限的资源应导致资源密集型特征的权衡，例如男性的免疫相关性和性选择特征。另外，性的夸张也可以作为潜在免疫能力的诚实指标，从而导致这些特征之间的正相关。无脊椎动物支持这两种假设的证据都是模棱两可的。尽管有几项研究已经解决了这个问题，但是很少有研究使用天然存在的病原体并意识到感染后实现的免疫（例如生存）来分析这两组特征之间的适应性相关性。结果采用实验性进化方法，我们在高和低性别选择制度下进化了果蝇的复制种群一百余代，并通过三种独立的检测方法在原始和交配的雄性中发现了以下几项：a。针对两种天然病原体-假单胞菌（Pseudomonas entomophila）和葡萄球菌的感染后存活琥珀（Ss）：交配的雄性对Pe的存活更好，但与处女对Ss.b并无区别。b。对第三种自然病原体Providedcia rettgeri（Pr）的细菌清除能力：交配的雄性CFU明显低于处女。但是，性选择史对未婚男性或交配男性的已实现免疫没有影响。结论我们证明，虽然交配会以病原体特异性的方式影响已实现的免疫力，但性选择却不会对其产生影响。结果突出表明，复杂的多基因性状，例如免疫性和生殖性状，不一定按照二元权衡模型发展。在研究性选择-免疫相关性时，我们还强调了自然病原体的重要性。