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 7 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 2 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 2 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经典实验模型体系。该类群物种不仅在颌骨形态、体色等外部形态特征上存在显著分化，在视觉等感官系统层面亦表现出差异。所有慈鲷均携带7个视锥视蛋白基因（cone opsin genes），不同物种间所表达的视蛋白类型存在广泛差异。视蛋白表达模式的差异，使得亲缘关系相近的物种其光感受器的光谱敏感性产生显著分歧。本研究为解析慈鲷视蛋白表达的遗传机制迈出了开创性的一步。本研究利用两种视蛋白表达模式存在差异的慈鲷物种构建的二代杂交群体，经保守估算发现：短波长视蛋白的表达受少数基因座调控。通过对96株F2杂交个体开展遗传定位分析，本研究获得了明确证据：SWS1视蛋白（SWS1 opsin）存在一个顺式调控区域，该区域可解释两个物种间34%的表达变异量。此外，原位杂交实验证实，F2后代视网膜的单个单锥细胞中，SWS1视蛋白与SWS2B视蛋白（SWS2B opsins）存在共表达现象。本研究结果将有助于更全面地理解视蛋白表达背后的遗传调控架构。相关研究成果将助力解答长期困扰学界的科学问题：即视蛋白表达变异背后的核心进化过程，以及该变异如何推动慈鲷的适应性分化。