The East African cichlid radiations are characterized by repeated and rapid diversification into many distinct species with different ecological specializations and by a history of hybridization events between nonsister species. Such hybridization might provide important fuel for adaptive radiation. Interspecific hybrids can have extreme trait values or novel trait combinations and such transgressive phenotypes may allow some hybrids to explore ecological niches neither of the parental species could tap into. Here, we investigate the potential of second‐generation (F2) hybrids between two generalist cichlid species from Lake Malawi to exploit a resource neither parental species is specialized on: feeding by sifting sand. Some of the F2 hybrids phenotypically resembled fish of species that are specialized on sand sifting. We combined experimental behavioral and morphometric approaches to test whether the F2 hybrids are transgressive in both morphology and behavior related to sand sifting. We then performed a quantitative trait loci (QTL) analysis using RADseq markers to investigate the genetic architecture of morphological and behavioral traits. We show that transgression is present in several morphological traits, that novel trait combinations occur, and we observe transgressive trait values in sand sifting behavior in some of the F2 hybrids. Moreover, we find QTLs for morphology and for sand sifting behavior, suggesting the existence of some loci with moderate to large effects. We demonstrate that hybridization has the potential to rapidly generate novel and ecologically relevant phenotypes that may be suited to a niche neither of the parental species occupies. Interspecific hybridization may thereby contribute to the rapid generation of ecological diversity in cichlid radiations.

中文翻译：

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在实验性丽鱼科鱼杂种中快速产生与生态相关的行为新颖性。

东非慈鲷的辐射特征是反复快速地多样化成具有不同生态专长的许多不同物种，并具有非姐妹物种之间发生杂交事件的历史。这种杂交可能为适应性辐射提供重要的燃料。种间杂种可能具有极端的性状价值或新的性状组合，而这种侵略性表型可能使某些杂种能够探索任何亲本物种都无法利用的生态位。在这里，我们研究了来自马拉维湖的两个普通慈鲷科动物之间的第二代（F2）杂种开发潜在资源的可能性，而这两种亲本物种都不擅长：通过筛沙喂养。一些F2杂种在表型上类似于专门筛沙的鱼类。我们结合了实验行为学和形态计量学方法，以测试F2杂种在形态和与沙滤相关的行为上是否都越过了。然后，我们使用RADseq标记物进行了数量性状基因座（QTL）分析，以研究形态和行为特征的遗传结构。我们表明海侵存在于几种形态特征中，出现了新的特征组合，并且我们观察到某些F2杂种的沙筛行为中海侵特征值。此外，我们发现了用于形态学和筛沙行为的QTL，表明存在一些具有中等到较大影响的基因座。我们证明杂交有潜力迅速产生新的和生态学相关的表型，可能适合任何一个亲本物种都不占据的利基。