What Do Lake Malawi Cichlid Fishes See?

东非五大湖的慈鲷是快速适应辐射的典型例子。在过去的一百万年里，这些鱼类中有数百种是从一个共同的祖先进化而来的。它们的快速形成被认为部分是由于性选择，在这种选择中，雌性的配偶偏好驱动了雄性颜色模式的进化。当雄性的颜色模式改变以更好地匹配雌性的偏好时，具有这些新颜色模式的鱼成为新的物种，不再与具有旧颜色模式的鱼杂交。为了理解这是如何发生的，我们需要知道稚鱼是如何选择配偶的。这需要了解这些鱼的视觉敏感性，以及不同物种的视觉敏感性是否不同。本项目将研究非洲马拉维湖慈鲷的视觉交流的几个方面。首先，我们将通过对五种视锥蛋白基因进行测序并测量它们在视网膜中的相对表达水平，来量化各种慈鲷物种的视觉敏感性多样性。我们已经知道，一些马拉维慈鲷对紫外线波长敏感，而另一些则不敏感。这项调查将确定紫外线敏感性是否在这一群体中普遍存在，以及它是如何进化的。其次，我们将测量与自然环境相比较的慈鲷颜色图案的色调。这将决定颜色模式是否也包含在光谱的紫外部分的显著贡献。第三，我们将把视觉系统和颜色模式联系起来，以确定“通过鲷鱼的眼睛”看到的颜色模式的显著性。这些研究将与生态或行为因素有关，以确定颜色的使用是否在不同的地方或不同的社会环境下被改变。我们还将研究水质和光传输对视觉通信的重要性。马拉维湖历来是世界上最清澈的湖泊之一。保持清澈可能是保护这些鱼类惊人多样性的一个重要因素。所提出的努力将为我们理解物种多样性如何产生和维持提供重要的科学贡献。此外，这项工作将整合生物学和物理学的方法来理解视觉传达。它还将支持一名少数民族研究生的科学培训，该研究生将由该项目全额资助。

The cichlid fishes of the Great Lakes of East Africa are a classic example of rapid adaptive radiation. Hundreds of species of these fishes have evolved from a common ancester in the past one million years. Their rapid speciation is thought to result in part from sexual selection, in which female mate preferences drive the evolution of male color patterns. As male color patterns change to better match the preferences of females, fish with these new color patterns become new species which no longer interbreed with fish having the old color patterns. In order to understand how this happens, we need to know how cichlids choose mates. This requires an understanding of t he visual sensitivities of these fish and whether visual sensitivities differ among species. This project will examine several aspects of visual communication in the cichlid fishes of Lake Malawi, Africa. First, we will quantify the diversity of visual sensitivities in a broad range of cichlid species by sequencing the five cone opsin genes and measuring their relative expression levels in the retina. We already know that some Malawi cichlids are sensitive to ultraviolet wavelengths while others are not. This survey will determine whether ultraviolet sensitivity is widespread in this group and how it evolved. Second, we will measure the hues of cichlid color patterns as compared to their natural environment. This will determine whether color patterns also contain significant contributions in the ultraviolet part of the spectrum. Third, we will relate the visual system and color patterns in order to determine the conspicuousness of the color patterns as seen"through cichlid eyes." These studies will be related to ecological or behavioral factors to determine whether color usage is modified in different localities or under different social situations. We will also examine the importance of water quality and optical transmission for visual communication. Lake Malawi has historically been one of the clearest lakes in the world. Maintaining its clarity may be an important factor in preserving the spectacular diversity of these fishes.The proposed effort will provide important scientific contributions to our understanding of how species diversity arises and is maintained. In addition, this work will integrate biological and physical approaches to understanding visual communication. It will also support the scientific training of a minority graduate student who will be fully funded by this project.