1] Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK [2].
Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
Nature. 2014 Jan 30;505(7485):672-5. doi: 10.1038/nature12949. Epub 2014 Jan 22.
To resolve the mechanisms that switch competition to cooperation is key to understanding biological organization. This is particularly relevant for intrasexual competition, which often leads to males harming females. Recent theory proposes that kin selection may modulate female harm by relaxing competition among male relatives. Here we experimentally manipulate the relatedness of groups of male Drosophila melanogaster competing over females to demonstrate that, as expected, within-group relatedness inhibits male competition and female harm. Females exposed to groups of three brothers unrelated to the female had higher lifetime reproductive success and slower reproductive ageing compared to females exposed to groups of three males unrelated to each other. Triplets of brothers also fought less with each other, courted females less intensively and lived longer than triplets of unrelated males. However, associations among brothers may be vulnerable to invasion by minorities of unrelated males: when two brothers were matched with an unrelated male, the unrelated male sired on average twice as many offspring as either brother. These results demonstrate that relatedness can profoundly affect fitness through its modulation of intrasexual competition, as flies plastically adjust sexual behaviour in a manner consistent with kin-selection theory.
要解决将竞争转变为合作的机制是理解生物组织的关键。这对于种内竞争尤其重要，因为种内竞争常常导致雄性伤害雌性。最近的理论提出，亲缘选择可以通过放松雄性亲属之间的竞争来调节雌性伤害。在这里，我们通过实验操纵竞争雌性的雄性果蝇群体之间的亲缘关系，证明了如预期的那样，群体内的亲缘关系抑制了雄性竞争和雌性伤害。与暴露于彼此不相关的三个雄性的雌性相比，暴露于与雌性不相关的三个雄性的雌性具有更高的终生繁殖成功率和更慢的繁殖衰老。然而，兄弟之间的联系可能容易受到无关雄性的少数群体的入侵：当两个兄弟与一个无关的雄性匹配时，无关的雄性平均比任何一个兄弟都要多生两倍的后代。这些结果表明，亲缘关系可以通过调节种内竞争深刻地影响适应性，因为苍蝇以与亲缘选择理论一致的方式灵活地调整性行为。
