Abstract

The role of sexual selection in mediating levels of sexual conflict has been demonstrated in many experimental evolution studies on Drosophila spp. where competition among males for mating was the target of selection. Sexual selection has also been shown to affect the evolution of life-histories. However, the influence of divergent life-histories on reproductive strategies and, therefore, sexual selection and possibly sexual conflict has been less well studied. We examined D. melanogaster populations selected for a short development time and early age at reproduction for changes in reproductive behavior and traits that are proxies of sexual selection. We report a large reduction in reproductive competition experienced by the males of these populations, compared to ancestral populations that are not consciously selected for rapid development or early reproduction, potentially leading to reduced sexual selection. We show that rapidly developing and early reproducing populations have very low levels of mating in their lifetime (females are more or less monandrous), low courtship levels, shorter copulation duration, and longer time from eclosion to first mating, compared to the controls. These results are discussed in the context of the previously demonstrated reduction of inter-locus sexual conflict in these populations. We show that life-history strategies might have a large and significant impact on sexual selection, with each influencing the other and contributing to the complexities of adaptation.

Significance statement

Sexual conflict, often manifested as an arms-race between males and females trying to enhance their own reproductive success at some cost to the other, is of great evolutionary interest because it can maintain genetic variation in populations, prevent the independent optimization of male and female traits, and also promote speciation. Sexual selection, or variation in mating success, is well known to affect levels of sexual conflict. However, it is not so clear whether, and how, the regular evolution of life-histories also affects sexual selection. Here, we show that life-history evolution in fruit fly populations selected for traits not directly related to sexual conflict might, nevertheless, mediate the possible evolution of altered sexual conflict levels through effects on sexual selection. Populations that evolved to develop to adulthood fast, and reproduce relatively early in life, are shown to potentially experience less sexual selection, which can explain the low sexual conflict levels earlier observed in them.

中文翻译：

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黑腹果蝇实验室种群的有效寿命较短可能会减少性选择

摘要

在果蝇属的许多实验进化研究中已经证明了性选择在调节性冲突水平中的作用。雄性之间的交配竞争是选择的目标。性选择也被证明会影响生活史的演变。然而，不同的生活史对生殖策略以及性选择和可能的性冲突的影响尚未得到很好的研究。我们检查了黑腹果蝇选择在较短发育时间和较早繁殖年龄的种群，以改变作为性选择代表的繁殖行为和特征。我们报告了这些种群的雄性所经历的生殖竞争大大减少，与没有有意识地选择快速发育或早期繁殖的祖先种群相比，这可能导致性选择减少。我们表明，与对照组相比，快速发育和早期繁殖的种群在其一生中的交配水平非常低（雌性或多或少是单调的）、低求爱水平、更短的交配时间以及从羽化到第一次交配的时间更长。这些结果是在先前证明的减少这些人群中的位点间性冲突的背景下讨论的。

意义陈述

性冲突，通常表现为雄性和雌性之间的军备竞赛，试图以某种代价提高自己的繁殖成功率，具有重大的进化意义，因为它可以维持种群的遗传变异，阻止雄性和雌性的独立优化性状，也促进物种形成。众所周知，性选择或交配成功率的变化会影响性冲突的程度。然而，尚不清楚生活史的规律性进化是否以及如何影响性选择。在这里，我们表明，选择与性冲突不直接相关的性状的果蝇种群的生活史进化可能通过对性选择的影响来调节性冲突水平改变的可能进化。进化为快速发展到成年的种群，