A pleiotropic interaction between vision loss and hypermelanism in Astyanax mexicanus cave x surface hybrids

Background Cave-dwelling animals evolve various traits as a consequence of life in darkness. Constructive traits (e.g., enhanced non-visual sensory systems) presumably arise under strong selective pressures. The mechanism(s) driving regression of features, however, are not well understood. Quantitative trait locus (QTL) analyses in Astyanax mexicanus Pachón cave x surface hybrids revealed phenotypic effects associated with vision and pigmentation loss. Vision QTL were uniformly associated with reductions in the homozygous cave condition, however pigmentation QTL demonstrated mixed phenotypic effects. This implied pigmentation might be lost through both selective and neutral forces. Alternatively, in this report, we examined if a pleiotropic interaction may exist between vision and pigmentation since vision loss has been shown to result in darker skin in other fish and amphibian model systems. Results We discovered that certain members of Pachón x surface pedigrees are significantly d...背景 穴居动物因长期栖息于黑暗环境，演化出多种适应性性状。诸如增强的非视觉感官系统这类建设性性状，推测是在强烈的选择压力下演化形成的。然而，驱动性状退化的具体机制尚未得到充分阐释。针对墨西哥丽脂鲤（Astyanax mexicanus）帕琼洞穴型与地表型的杂交后代开展的数量性状位点（Quantitative Trait Locus, QTL）分析，揭示了与视力丧失和色素丢失相关的表型效应。研究显示，所有与视力相关的QTL均在纯合洞穴型个体中表现出表型减弱效应，而与色素相关的QTL则呈现出混合的表型效应。这表明色素丢失可能通过选择压力和中性演化两种途径实现。此外，本研究还考察了视力与色素沉着之间是否存在多效性互作——因为已有研究证实，在其他鱼类和两栖类模式系统中，视力丧失会导致皮肤颜色加深。 结果 我们在帕琼型与地表型的杂交家系中发现，部分个体呈现出显著的……