Data from: Quantitative genetic analyses of male color pattern and female mate choice in a pair of cichlid fishes of Lake Malawi, East Africa

The traits involved in sexual selection, such as male secondary sexual characteristics and female mate choice, often co-evolve which can promote population differentiation. However, the genetic architecture of these phenotypes can influence their evolvability and thereby affect the divergence of species. The extraordinary diversity of East African cichlid fishes is often attributed to strong sexual selection and thus this system provides an excellent model to test predictions regarding the genetic architecture of sexually selected traits that contribute to reproductive isolation. In particular, theory predicts that rapid speciation is facilitated when male sexual traits and female mating preferences are controlled by a limited number of linked genes. However, few studies have examined the genetic basis of male secondary sexual traits and female mating preferences in cichlids and none have investigated the genetic architecture of both jointly. In this study, we artificially hybridized a pair of behaviorally isolated cichlid fishes from Lake Malawi and quantified both melanistic color pattern and female mate choice. We investigated the genetic architecture of both phenotypes using quantitative genetic analyses. Our results suggest that 1) many non-additively acting genetic factors influence melanistic color patterns, 2) female mate choice may be controlled by a minimum of 1–2 non-additive genetic factors, and 3) F2 female mate choice is not influenced by male courting effort. Furthermore, a joint analysis of color pattern and female mate choice indicates that the genes underlying these two traits are unlikely to be physically linked. These results suggest that reproductive isolation may evolve rapidly owing to the few genetic factors underlying female mate choice. Hence, female mate choice likely played an important role in the unparalleled speciation of East African cichlid fish.

参与性选择（sexual selection）的性状，如雄性第二性征（secondary sexual characteristics）与雌性配偶选择（mate choice），往往会发生协同进化，进而推动种群分化（population differentiation）。然而，这些表型的遗传结构（genetic architecture）会影响其演化能力（evolvability），进而影响物种分化（species divergence）进程。东非丽鱼科鱼类（East African cichlid fishes）拥有极为丰富的物种多样性，这一现象常被归因于强烈的性选择作用，因此该类群为检验与生殖隔离（reproductive isolation）相关的性选择性状的遗传结构相关预测提供了极佳的研究模型。具体而言，理论预测，当雄性性征与雌性择偶偏好由少数连锁基因调控时，物种快速成种过程将得到促进。不过，目前针对丽鱼科鱼类雄性第二性征与雌性配偶选择的遗传基础研究仍较为匮乏，且尚无研究同时对二者的遗传结构开展联合分析。本研究人工杂交了一对来自马拉维湖、存在行为生殖隔离的丽鱼科鱼类，并对其黑色素体色模式（melanistic color pattern）与雌性配偶选择进行了量化分析。我们通过数量遗传分析（quantitative genetic analyses）方法，探究了这两种表型的遗传结构。研究结果显示：1）诸多非加性遗传因子（non-additively acting genetic factors）会对黑色素体色模式产生影响；2）雌性配偶选择或许至少受1~2个非加性遗传因子调控；3）子二代（F2）雌性的配偶选择不受雄性求偶行为强度的影响。此外，针对体色模式与雌性配偶选择的联合分析表明，调控这两种性状的基因大概率不存在物理连锁关系。上述结果提示，由于雌性配偶选择仅受少数遗传因子调控，生殖隔离或可快速形成。由此可见，雌性配偶选择在东非丽鱼科鱼类无与伦比的物种成种过程中发挥了关键作用。