Post-copulatory sexual selection (PSS) is an important selective force that determines fitness in polyandrous species. PSS can be intense in some cases and can drive the evolution of remarkable ejaculate properties. In males, investment in ejaculate plays an important role in the outcome of PSS. Thus, males are expected to adaptively tailor their ejaculate according to the perceived competition in their vicinity. Plastic responses in ejaculate investment to variation in intra-sexual competition are disparate and widespread in males. We investigated the evolution of plasticity in reproductive traits using Drosophila melanogaster populations evolving for more than 150 generations under male- or female-biased sex ratios. When exposed to different numbers of competitors early in their life, males from these two regimes responded differently in terms of their copulation duration and sperm competitive ability. In addition, the effect of this early life experience wore off at different rates in males of male-biased and female-biased regimes with increasing time from the removal of competitive cues. Furthermore, our study finds that males change their reproductive strategies depending upon the identity of rival males. Together, our results provide evidence of the evolution of male reproductive investment that depends on socio-sexual cues experienced early in life. This article is protected by copyright. All rights reserved.

中文翻译：

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在改变的操作性别比率下进化的黑腹果蝇实验室种群对可变社会性环境的反应差异

交配后性选择 (PSS) 是一种重要的选择力，它决定了一妻多夫物种的适应性。在某些情况下，PSS 可能会很强烈，并且可以推动显着的射精特性的演变。在男性中，对射精的投入在 PSS 的结果中起着重要作用。因此，预计男性会根据他们附近感知到的竞争来适应性地调整他们的射精。射精投资对性内竞争变化的可塑性反应在男性中是不同且普遍的。我们使用黑腹果蝇种群在男性或女性偏见的性别比例下进化了 150 多代，研究了生殖性状可塑性的进化。当他们早年接触不同数量的竞争对手时，来自这两种制度的雄性在交配持续时间和精子竞争能力方面的反应不同。此外，这种早期生活经历的影响在男性偏见和女性偏见制度的男性中以不同的速度消退，随着竞争线索消除时间的增加。此外，我们的研究发现，雄性根据敌对雄性的身份改变其生殖策略。总之，我们的结果提供了男性生殖投资进化的证据，这取决于生命早期经历的社会性暗示。本文受版权保护。版权所有。随着消除竞争线索的时间越来越长，这种早期生活经历的影响在男性偏见和女性偏见制度的男性中以不同的速度消退。此外，我们的研究发现，雄性根据敌对雄性的身份改变其生殖策略。总之，我们的结果提供了男性生殖投资进化的证据，这取决于生命早期经历的社会性暗示。本文受版权保护。版权所有。随着消除竞争线索的时间越来越长，这种早期生活经历的影响在男性偏见和女性偏见制度的男性中以不同的速度消退。此外，我们的研究发现，雄性根据敌对雄性的身份改变其生殖策略。总之，我们的结果提供了男性生殖投资进化的证据，这取决于生命早期经历的社会性暗示。本文受版权保护。版权所有。