Data from: Determination of the genetic architecture underlying short wavelength sensitivity in Lake Malawi cichlids

African cichlids are an exemplary system to study organismal diversity and rapid speciation. Species differ in external morphology including jaw shape and body coloration, but also differ in sensory systems including vision. All cichlids have seven cone opsin genes with species differing broadly in which opsins are expressed. The differential opsin expression results in closely related species with substantial differences in spectral sensitivity of their photoreceptors. In this work, we take a first step in determining the genetic basis of opsin expression in cichlids. Using a second generation cross between two species with different opsin expression patterns, we make a conservative estimate that short wavelength opsin expression is regulated by a few loci. Genetic mapping in 96 F2 hybrids provides clear evidence of a cis-regulatory region for (SWS1) opsin that explains 34% of the variation in expression between the two species. Additionally, in-situ hybridization has shown that (SWS1) and (SWS2B) opsins are coexpressed in individual single cones in the retinas of F2 progeny. Results from this work will contribute to a better understanding of the genetic architecture underlying opsin expression. This knowledge will help answer long-standing questions about the evolutionary processes fundamental to opsin expression variation and how this contributes to adaptive cichlid divergence.

非洲慈鲷（African cichlids）是研究生物多样性与快速物种形成的典范研究系统。该类群物种不仅在颌骨形态、体色等外部形态上存在差异，其视觉系统等感知系统亦各不相同。所有慈鲷均拥有7个视锥视蛋白基因，不同物种所表达的视蛋白类型存在显著差异。这种视蛋白表达差异，使得亲缘关系较近的物种间光感受器的光谱敏感性存在显著区别。本研究为解析慈鲷视蛋白表达的遗传基础迈出了第一步。我们以两种视蛋白表达模式存在差异的物种构建二代杂交群体，经保守估算可知，短波长视蛋白的表达受少数基因座调控。对96株F2杂交后代开展的遗传定位分析，为（SWS1）视蛋白的顺式调控区域提供了确凿证据，该区域可解释两个物种间34%的表达变异。此外，原位杂交（in-situ hybridization）实验结果显示，（SWS1）与（SWS2B）视蛋白在F2子代视网膜的单个单锥细胞中存在共表达现象。本研究结果将有助于更深入地理解视蛋白表达背后的遗传架构，该研究成果也将为解答长期存在的核心科学问题提供支撑：包括视蛋白表达差异背后的基础性进化过程，以及此类差异如何推动慈鲷的适应性分化。