Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
J Evol Biol. 2010 Jul;23(7):1399-411. doi: 10.1111/j.1420-9101.2010.02000.x. Epub 2010 Apr 23.
Understanding the patterns of diversification in sexual traits and the selection underlying such diversification represents a major unresolved question in evolutionary biology. We examined the phylogenetic diversification for courtship and external genitalic characters across ten species of Timema walking-sticks, to infer the tempos and modes of character change in these sexual traits and to draw inferences regarding the selective pressures underlying speciation and diversification in this clade. Rates of inferred change in male courtship behaviours were proportional to speciation events, but male external genitalic structures showed a pattern of continuous change across evolutionary time, with divergence proportional to branch lengths. These findings suggest that diversification of courtship behaviour is mediated by processes that occur in association with speciation, whereas diversification of genitalia occurs more or less continuously, most likely driven by forces of sexual selection.
理解性特征多样化的模式以及这种多样化背后的选择是进化生物学中一个尚未解决的主要问题。我们研究了十种种 Timema 步行棒的求偶和外部生殖器特征的系统发育多样化，以推断这些性特征中特征变化的速度和模式，并推断出这个类群中物种形成和多样化的选择压力。推断出的雄性求偶行为变化率与物种形成事件成正比，但雄性外部生殖器结构在进化时间上表现出连续变化的模式，与分支长度成正比的分歧。这些发现表明，求偶行为的多样化是由与物种形成相关的过程介导的，而生殖器的多样化则或多或少是连续的，很可能是由性选择的力量驱动的。
