Data from: Hybridization promotes color polymorphism in the aposematic harlequin poison frog, Oophaga histrionica

Whether hybridization can be a mechanism that drives phenotypic diversity is a widely debated topic in evolutionary biology. In poison frogs (Dendrobatidae), assortative mating has been invoked to explain how new color morphs persist despite the expected homogenizing effects of natural selection. Here, we tested the complementary hypothesis that new morphs arise through hybridization between different color morphs. Specifically, we (1) reconstructed the phylogenetic relationships among the studied populations of a dart-poison frog to provide an evolutionary framework, (2) tested whether microsatellite allele frequencies of one putative hybrid population of the polymorphic frog O. histrionica are intermediate between O. histrionica and O. lehmanni, and (3) conducted mate-choice experiments to test whether putatively intermediate females prefer homotypic males over males from the other two populations. Our findings are compatible with a hybrid origin for the new morph and emphasize the possibility of hybridization as a mechanism generating variation in polymorphic species. Moreover, because coloration in poison frogs is aposematic and should be heavily constrained, our findings suggest that hybridization can produce phenotypic novelty even in systems where phenotypes are subject to strong stabilizing selection.

杂交是否可作为驱动表型多样性的演化机制，是进化生物学领域广受热议的议题。在箭毒蛙科（Dendrobatidae）类群中，学界曾援引选型交配（assortative mating）假说，解释新型色型何以在自然选择预期的同质化效应下得以存续。本研究针对"新型色型起源于不同色型间的杂交"这一补充假说展开验证。具体而言，本研究开展了三项工作：(1) 对所研究的箭毒蛙种群重构系统发育关系，以构建演化框架；(2) 检验多态性箭毒蛙O. histrionica的一个疑似杂交种群的微卫星等位基因频率（microsatellite allele frequencies）是否介于O. histrionica与O. lehmanni之间；(3) 开展配偶选择实验（mate-choice experiments），以验证疑似中间型雌性是否更偏好同型雄性（homotypic males），而非另外两个种群的雄性。本研究结果支持新型色型的杂交起源假说，并凸显了杂交作为多态物种种内变异产生机制的可能性。此外，由于箭毒蛙的体色属于警戒色（aposematic），本应受到极强的约束，本研究结果表明，即便在表型受到强烈稳定选择（stabilizing selection）的类群中，杂交仍可产生表型创新。