Evolution of gene expression in response to sexual selection

我们对两性形态上的差异着迷。达尔文用他的性选择理论解释了男性和女性在形态上的巨大差异。随后对两性二态特征的研究表明，具有夸张特征的男性更容易获得交配成功。因此，预计性选择强度的增加会增加性状的夸张，因此性选择被认为是生物多样性的主要力量。然而，要使这些性状发生变化，控制它们的基因也必须发生变化。这一事实引发了一种观点，即性选择也是导致分子进化的强大力量。然而，性选择也引起基因组变化的证据是间接的，主要基于与生殖有关的基因差异（例如，两性二态表达或生殖组织中的表达）与性选择的存在之间的相关性。最近的技术进步使我们能够超越相关研究，直接检查基因变化对性选择的反应。在这里，我们建议通过一种结合的方法来测试性选择在分子进化中的作用，在果蝇的实验进化中，性选择被操纵为存在或不存在，而下一代测序中，由于性选择的变化而产生的遗传变化被直接识别。我们已经发现，与没有性选择的种群相比，存在性选择的种群在形态和行为上进化出更大的性别差异。因此，我们可以将这些表型生物多样性的变化与与这些性状相关的潜在遗传变化联系起来，这些变化被预测为性选择的结果。这项工作将为性选择如何导致遗传分化提供决定性的证据，反过来，它又如何产生与交配系统变异相关的表型特征的惊人多样性。因此，我们将提高我们对生物多样性的主要驱动因素之一的理解。

We are fascinated with morphological differences between the sexes. Darwin explained the observation that males and females can differ dramatically in morphology with his theory of sexual selection, or the competition for mates. Subsequent interest in sexually dimorphic traits showed that males who bear exaggerated features enjoyed greater mating success. Thus, increased intensity of sexual selection is predicted to increase trait exaggeration and therefore sexual selection is considered to be a major force responsible for biodiversity. For these trait changes to occur, however, the genes that control them must also change. This fact gave rise to the idea that sexual selection is also a strong force responsible for molecular evolution. However, evidence that sexual selection also causes changes in the genome is indirect, largely based on correlations between differences in genes associated with reproduction (e.g., sexually dimorphic expression or expression in reproductive tissues) and the presence of sexual selection. Recent technological advances allow us to move beyond correlative studies and directly examine genomic changes in response to sexual selection. Here we propose to test the role of sexual selection in molecular evolution by a combined approach of experimental evolution of fruit flies, in which sexual selection is manipulated to be either present or absent, and next generation sequencing, in which genetic changes due to variation in sexual selection are identified directly. We already have found that populations in which sexual selection is present have evolved greater sex differences in morphology and behaviour compared to populations in which sexual selection is absent. We can thus connect these phenotypic biodiversity changes that were predicted as a consequence of sexual selection with the underlying genetic changes associated with these traits. This work will provide decisive evidence for how sexual selection causes genetic divergence, and in turn how it may generate the spectacular diversity of phenotypic traits associated with variation in mating systems. Thus, we will improve our understanding of one of the major drivers of biological diversity.