Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, UK.
J Evol Biol. 2012 Nov;25(11):2232-41. doi: 10.1111/j.1420-9101.2012.02603.x. Epub 2012 Sep 17.
Our expectations for the evolution of chemical signals in response to sexual selection are uncertain. How are chemical signals elaborated? Does sexual selection result in complexity of the composition or in altered quantities of expression? We addressed this in Drosophila pseudoobscura by examining male and female cuticular hydrocarbons (CHs) after 82 generations of elevated (E) sexual selection or relaxed sexual selection through monogamy (M). The CH profile consisted of 18 different components. We extracted three eigenvectors using principal component analysis that explained 72% of the variation. principal component (PC)1 described the amount of CHs produced, PC2 the trade-off between short- and long-chain CHs and PC3 the trade-off between apparently arbitrary CHs. In both sexes, the amount of CHs produced was greater in flies from the E treatment. PC3 was also higher, indicating that sexual selection also influenced the evolution of CH composition. The sexes differed in all three PCs, indicating substantial sexual dimorphism in this species, although the magnitude of this dimorphism was not increased as a result of our experimental evolution. Collectively, our work provides direct evidence that sexual selection plays an important role in the evolution of CHs in D. pseudoobscura and that both increased quantity and overall composition are targeted.
我们对于化学信号在性选择下进化的预期是不确定的。化学信号是如何产生的？性选择是否导致组成的复杂性或表达量的改变？我们通过检查经过 82 代的升高的（E）性选择或通过一夫一妻制（M）放松的性选择后的黑腹果蝇的表皮碳氢化合物（CH），来解决这个问题。CH 图谱由 18 种不同的成分组成。我们使用主成分分析提取了三个特征向量，它们解释了 72%的变化。主成分（PC）1 描述了 CHs 的产生量，PC2 描述了短链和长链 CHs 之间的权衡，PC3 描述了明显任意的 CHs 之间的权衡。在雌雄两性中，来自 E 处理的果蝇产生的 CHs 数量更多。PC3 也更高，表明性选择也影响了 CH 组成的进化。这三个 PC 在两性中都存在差异，表明该物种存在显著的性二型性，尽管这种二型性的程度没有因我们的实验进化而增加。总的来说，我们的工作提供了直接的证据，表明性选择在黑腹果蝇 CHs 的进化中起着重要作用，并且数量和整体组成都成为了选择的目标。
