Sexual selection and the origin of species: experimental insight into adaptation, the purging of deleterious mutations, and the evolution of sexual isolation

性选择和物种起源：对适应、有害突变的清除和性隔离进化的实验洞察

• 批准号: RGPIN-2016-05038
• 负责人: Rundle, Howard
• 金额: $ 3.79万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615459
• 关键词: Sexual; selection; origin; species; experimental

Darwin had famously wide ranging research interests but preeminent among these were the two branches of my research program: selection in relation to sex and the origin of species. With respect to the former, sexual selection occurs when individuals differ in reproductive success and it can result in the evolution of striking differences between males and females in size, appearance, and behaviour. Indeed, Darwin originally proposed his theory of sexual selection to account for the evolution of such differences, most notably traits like the peacock’s tail that are maladaptive in terms of survival. In the intervening years, we have come to understand well sexual selection’s role in the evolution of costly sexual traits. However, questions concerning other fundamental aspects of sexual selection remain unanswered and the first branch of my research program addresses two of these. First, does sexual selection promote or hinder adaptation, and second, does it help in removing the harmful mutations that arise every generation in populations? Limited attention has been given to these consequences of sexual selection for nonsexual fitness and the work that has been done tends to involve highly simplified lab environments that may be providing biased insight. My proposal describes a series of experiments that test the various population genetic consequences of sexual selection and whether and how these depend on environmental complexity. The second branch of my research concerns how new species arise and thus speaks to the origins of a major component of the world’s biological diversity. Species are defined by the presence of reproductive barriers that restrict genetic exchange between them. The evolution of sexual isolation, whereby individuals from different populations are less attracted to one another as potential mates, has long been suggested to be a key reproductive barrier that is important in both initiating and completing the speciation process. Although the existence of sexual isolation is straightforward to demonstrate, understanding its evolution requires identifying the underlying traits responsible so that we can determine how they have diverged. Surprisingly, even in the best studied groups of organisms the traits causing sexual isolation are seldom known. My proposal outlines an additional series of experiments that build a comprehensive understanding of the causes of sexual isolation in a pair of N. America mushroom-feeding flies, and in doing so addresses several understudied topics in speciation research. Both branches on my research program rely heavily on a powerful technique called experimental evolution in which we compare how the evolutionary process unfolds in populations under different conditions. The results of this work will have broad implications for our basic understanding of evolution including how adaptation occurs and the diversity of life arises.

达尔文的研究兴趣是出了名的广泛，但其中最突出的是我研究计划的两个分支：与性别有关的选择和物种起源。就前者而言，当个体在繁殖成功方面存在差异时，就会发生性选择，这可能导致雄性和雌性在体型、外貌和行为方面的显著差异的进化。事实上，达尔文最初提出了他的性选择理论来解释这些差异的进化，尤其是像孔雀尾巴这样的特征，这些特征在生存方面是不适应的。在这中间的几年里，我们已经很好地理解了性选择在昂贵的性特征进化中的作用。然而，关于性选择的其他基本方面的问题仍然没有答案，我的研究计划的第一个分支解决了其中的两个问题。首先，性选择是促进还是阻碍适应，其次，它是否有助于消除种群中每一代出现的有害突变？人们对性选择对非性适应性的影响的关注有限，而且所做的工作往往涉及高度简化的实验室环境，这可能会提供有偏见的见解。我的提案描述了一系列实验，这些实验测试了性选择的各种种群遗传结果，以及这些结果是否以及如何取决于环境的复杂性。