Evolution of Coloration and Mate Preferences Along Resource Availability Gradients

色彩和择偶偏好在资源可用性梯度上的进化一些近亲物种之间繁殖的唯一障碍是雌性对雄性第二性征的择偶偏好。导致雌性配偶偏好进化的因素（即，世代变化）可能导致新物种的形成。科学家们刚刚开始了解环境在这一过程中的作用。孔雀鱼是一种原产于特立尼达的小型溪流鱼类，雌性更喜欢有更大、更亮的橙色斑点的雄性。橙色的斑点含有两种色素，一种是雄性可以合成的（果蝇素），另一种是它们必须摄取的（类胡萝卜素）。孔雀鱼从生长在河床岩石上的藻类中获取类胡萝卜素。孔雀鱼的藻类供应受到森林冠层覆盖的强烈影响，因此受到溪流宽度的影响（更宽的溪流在森林中造成更大的间隙）。拟议的项目将扩大和加强努力，以了解森林冠层覆盖的溪流之间的变化如何影响雄性颜色的进化和雌性配偶偏好。此外，将进行新的实验来确定(1)类胡萝卜素的摄入是否会影响寄生虫的抵抗力，(2)类胡萝卜素从母体传递给后代是否会影响后代的生存能力，以及(3)雄性是否也表达基于类胡萝卜素的配偶偏好。方法包括田间实验、实验室育种实验、颜色测量和生化分析。更广泛的目标是更深入地了解环境是如何影响择偶偏好及其偏好特征的进化的。这项研究将有助于我们对生物多样性的认识。

Evolution of coloration and mate preferences along resource availability gradientsGregory Frank Grether (PI)Gita Raman Kolluru (co-P)The only barriers to reproduction between some closely related species are female mate preferences for male secondary sexual characters. Factors that cause female mate preferences to evolve (i.e., change over generations) can lead to the formation of new species. Scientists are just beginning to understand the role of the environment in this process. In guppies, a small stream-dwelling fish native to Trinidad, females prefer males with larger and "brighter" orange spots. The orange spots contain two types of pigments, one which males can synthesize (drosopterins) and another which they must ingest (carotenoids). Guppies acquire carotenoids from algae, which grow on rocks in the streambed. Algae availability for guppies is strongly influenced by forest canopy cover and therefore by stream width (wider streams create larger gaps in the forest). The proposed project will expand and strengthen efforts to understand how variation among streams in forest canopy cover affects the evolution of male coloration and female mate preferences. In addition, new experiments will be carried out to determine (1) whether carotenoid consumption influences parasite resistance, (2) whether transfer of carotenoids from mothers to offspring affects offspring viability, and (3) whether males also express carotenoid-based mate preferences. The methods will include field experiments, laboratory breeding experiments, color measurements and biochemical analyses. The broader goal is to develop a deeper understanding of how the environment affects the evolution of mate preferences and the traits they favor. This study will contribute to our knowledge of biological diversity.