Department of Zoology, University of British Columbia, Vancouver, Canada.
Evolution. 2012 Apr;66(4):957-72. doi: 10.1111/j.1558-5646.2011.01513.x. Epub 2012 Feb 14.
Mutations that alter the morphology of floral displays (e.g., flower size) or plant development can change multiple functions simultaneously, such as pollen export and selfing rate. Given the effect of these various traits on fitness, pleiotropy may alter the evolution of both mating systems and floral displays, two characters with high diversity among angiosperms. The influence of viability selection on mating system evolution has not been studied theoretically. We model plant mating system evolution when a single locus simultaneously affects the selfing rate, pollen export, and viability. We assume frequency-independent mating, so our model characterizes prior selfing. Pleiotropy between increased viability and selfing rate reduces opportunities for the evolution of pure outcrossing, can favor complete selfing despite high inbreeding depression, and notably, can cause the evolution of mixed mating despite very high inbreeding depression. These results highlight the importance of pleiotropy for mating system evolution and suggest that selection by nonpollinating agents may help explain mixed mating, particularly in species with very high inbreeding depression.
改变花部形态（如花大小）或植物发育的突变可以同时改变多个功能，例如花粉输出和自交率。鉴于这些不同特征对适应性的影响，多效性可能会改变有性生殖系统和花部形态的进化，这两个特征在被子植物中具有很高的多样性。关于适合度选择对有性生殖系统进化的影响，还没有从理论上进行研究。当单个基因座同时影响自交率、花粉输出和活力时，我们对植物有性生殖系统的进化进行了建模。我们假设频率独立交配，因此我们的模型描述了先验自交。增加活力和自交率之间的多效性减少了纯异交进化的机会，尽管自交衰退很高，也可以有利于完全自交，而且值得注意的是，尽管自交衰退非常高，也可以导致混合交配的进化。这些结果强调了多效性对有性生殖系统进化的重要性，并表明非传粉者的选择可能有助于解释混合交配，特别是在自交衰退很高的物种中。
