Sexual selection, viability and sexual differences

许多动物物种的雄性炫耀着精心制作的武器或炫耀，用于竞争和吸引配偶。尽管达尔文解释说，这些特征是通过性选择进化而来的，但我们仍然缺乏对为什么这种类型的选择通常对雄性比对雌性更大的充分理解。为了解决这个问题，我们研究了特殊的物种，显示“反向”性选择，即女性之间的性竞争。因此，我们可以理解一般的性选择模式。拟议的研究重点是性别特异性的第二性结构，如装饰，一个主要的问题是为什么性别特异性的装饰在女性中是罕见的，即使在“角色颠倒”的物种。 这些预测来自于关于这些特征如何在女性身上进化的理论的新发展。我们将使用选择的统计分析来测试预测-不仅是性选择，而且是通过对被捕食个体的生存能力选择。 研究将在几个季节进行，以检查选择的变化。我们的生物体是几种直翅目（蟋蟀和盟友）和双翅目（苍蝇），它们的雌性在确保雄性提供的交配食物（礼物）方面表现出性竞争。项目将使用配偶选择实验，并将检查对女性特征的多变量性选择的强度和形式，（i）在某些情况下使用DNA标记（正在另一个实验室开发）估计女性交配成功（交配次数，因此收到礼物），以及（ii）检查具有不同大小装饰品的女性的可行性选择（通过蜘蛛网捕食）。对于我们的一个研究小组，一个有许多物种的属，在不同程度的女性装饰，分子遗传进化树（从合作者）将被用来测试有关装饰进化的假设。 我们的物种与女性的性选择将与男性性选择的相关物种进行比较，研究性选择和男性特有的特征，如武器和吸引配偶的歌曲的可行性选择的项目。实验室的工作将证实这样一个事实，即在我们的研究物种的交配礼物是显着的价值，以女性。

Males of many animal species sport elaborate weaponry or ornamentation used in competing for and attracting mates. Although such traits were explained by Darwin to have evolved via sexual selection, we still lack a full understanding of why this type of selection is usually greater on males than on females. To address this we study exceptional species that show 'reversed' sexual selection, i.e. sexual competition among females. Thus we can understand patterns of sexual selection in general. The proposed research focuses on sex-specific secondary sexual structures, such as ornaments, with a main question being why sex-specific ornamentation is rare in females even in 'role-reversed' species. Predictions come from new developments in theory of how these traits evolve in females. We will test predictions using statistical analyses of selection - not only sexual selection but also viability selection through predation on ornamented individuals. Studies will be conducted over several seasons in order to examine variation in selection. Our organisms are several orthopterans (crickets and allies) and dipterans (flies) with ornamented females that show sexual competition in securing mating meals (gifts) provided by males. Projects will use mate choice experiments and will examine the intensity and form of multivariate sexual selection on the female traits both (i) estimating female mating success (number of copulations thus gifts received) in some cases using DNA markers (being developed in another lab) and (ii) examining viability selection (via spider web predation) on females with different sized ornaments. For one of our study groups, a genus with many species that vary in degree of female ornamentation, molecular-genetic evolutionary trees (from collaborators) will be used to test hypotheses about ornament evolution. Our species with sexual selection on females will be compared to related species with male sexual selection in projects examining sexual selection and viability selection on male-specific traits such as weaponry and mate-attracting songs. Lab work will confirm the fact that mating gifts in our study species are of significant value to females.