Does side matter? The evolution of asymmetric genitalia in livebearing fish

形态不对称在其他两侧对称的生物体中普遍存在。简单的左右不对称性便于在不同生物体之间进行比较，因此具有增加我们对进化过程的理解的巨大潜力。特别有希望的是动物生殖器中不对称多态的进化，因为它与适应能力有很强的相关性。现在很清楚，性选择在动物生殖器的进化中起着基础性的作用；然而，具体的机制仍然不清楚。目前，最合理的解释是神秘的雌性选择、男性和男性精子竞争，以及性对抗的共同进化。区分它们很有挑战性，因为它们并不是相互排斥的。另一个限制是对单一或少数物种的关注。我建议使用系统发育控制的比较方法来研究一组有生命的鱼类生殖器不对称的进化。斑翅目的大多数物种表现出内部受精，许多物种表现出生殖器不对称。然而，这种不对称性的进化影响在很大程度上仍未得到研究。我建议进行一系列实验，以加深我们对Anablepae生殖器不对称的原因和后果的了解。首先，我将在全基因组标记的基础上建立一个良好的系统发育图，并将不对称性映射到这个系统发育图中，以推断斑翅目生殖器不对称性的进化史。然后，我将在自然种群中进行种群遗传分析，以确定不对称对随机交配和种群分化的影响。最后，我将进行特定的杂交和系谱分析，以确定AnablEpidae生殖器不对称的适合性后果和遗传基础。

Morphological asymmetries are ubiquitous among otherwise bilaterally symmetric organisms. The simple left-right nature of asymmetry facilitates comparisons across organisms, thus holding great potential to increase our understanding of evolutionary processes. Particularly promising is the evolution of asymmetric polymorphisms in animal genitalia, because of its strong correlation with fitness. It is now clear that sexual selection plays a fundamental role in the evolution of animal genitalia; however, the specific mechanisms are still unclear. Currently, the most plausible explanations are cryptic female choice, male-male sperm competition, and sexually antagonistic coevolution. Distinguishing among them is challenging because these are not mutually exclusive. Another limitation has been the focus on a single or few species. I propose to study the evolution of genital asymmetry in a group of livebearing fishes using phylogenetically controlled comparative methods. Most species in Anablepidae show internal fertilization, and many species exhibit genital asymmetry. Yet, the evolutionary implications of this asymmetry remain largely unstudied. I propose to conduct a series of experiments aimed to further our understanding of the causes and consequences of genital asymmetry in Anablepidae. First, I will produce a well-resolved phylogeny based on genome-wide markers, and map asymmetry into this phylogeny to make inference on the evolutionary history of genital asymmetry in Anablepidae. Then, I will conduct population genetic analyses in natural populations to determine the consequences of asymmetry for random mating and population differentiation. Finally, I will conduct specific crosses and pedigree analyses to determine the fitness consequences and genetic bases of genital asymmetry in Anablepidae.