The Evolutionary Genetics of Sexual Size Dimorphism in a Seed-Feeding Beetle

这项研究将测试关于性状之间的遗传关系如何响应自然选择而变化的理论预测。更具体地说，它将研究如何在男性和女性不同的性状表达的遗传关系的变化，以应对不同的选择对男性和女性。利用一种几乎没有两性异形的昆虫物种，实验将对一次一种性别或一次两种性别的身体大小进行人工选择（模拟自然界中经常观察到的自然选择模式），并检查（a）交替性别中的相关进化反应，（B）其他非选择性状（例如，生殖性状），以及（c）遗传方差和协方差的进化。实验还将对雌性生殖力和雄性和雌性发育时间进行选择。 这将测试的假设，选择增加繁殖力和选择短的发展时间的影响，性别大小二型性的进化方式的理论预测，虽然许多研究已经研究了性状是如何在遗传上相互关联，很少有以前的研究探讨这些遗传关系如何改变时，性状受到自然选择。然而，自然选择在自然界中无处不在;在农业动植物育种计划中，在农业领域使用杀虫剂时，在使用抗生素时，以及每当操纵自然生物事件时，人类都会将自然选择强加于生物体。了解性状之间的遗传关系如何随着我们对这些性状施加自然选择而变化，对于理解种群对这种选择的长期进化反应至关重要。

This study will test theoretical predictions about how genetic relationships between traits change in response to natural selection. More specifically, it will examine how genetic relationships between traits expressed differently in males and females change in response to differing selection on males and females. Using an insect species that exhibits little sexual dimorphism, the experiments will impose artificial selection on the body size of either one sex at a time or both sexes at once (simulating patterns of natural selection often observed in nature) and examine (a) correlated evolutionary responses in the alternate (unselected) sex, (b) correlated responses of other non-selected traits (e.g., reproductive traits), and (c) the evolution of genetic variances and covariances. The experiments will also impose selection on female fecundity, and male and female development time. This will test the hypotheses that selection for increased fecundity and selection for short development time influence the evolution of sexual size dimorphism in a manner predicted by theory.Although many studies have examined how traits are genetically related to each other, few previous studies have examined how these genetic relationships change when traits are subject to natural selection. Yet natural selection is ubiquitous in nature; and human beings impose natural selection on organisms in agricultural animal and plant breeding programs, during application of pesticides to agricultural fields, in the use of antibiotics, and whenever natural biological events are manipulated. Understanding how genetic relationships among traits change as we impose natural selection on these traits is critical to understanding the long-term evolutionary responses of populations to this selection.