Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, USA
Department of Environmental Sciences, University of Toledo, Toledo, OH, USA.
Biol Lett. 2018 Nov 7;14(11):20180557. doi: 10.1098/rsbl.2018.0557.
Hybridization between divergent taxa can provide insight into the breakdown of characters used in mate choice, as well as reproductive compatibility across deep evolutionary timescales. Hybridization can also occur more frequently in declining populations, as there is a smaller pool of conspecific mates from which to choose. Here, we report an unusual combination of factors that has resulted in a rare, three-species hybridization event among two genera of warblers, one of which is experiencing significant population declines. We use bioacoustic, morphometric and genetic data, to demonstrate that an early generation female hybrid between a golden-winged warbler () and a blue-winged warbler () went on to mate and successfully reproduce with a chestnut-sided warbler () We studied the product of this event-a putative × × hybrid-and show that this male offspring sang songs like , but had morphometric traits similar to warblers. The hybrid's maternal parent had mitochondrial DNA and with six plumage-associated loci, we predicted the maternal parent's phenotype to show that it was likely an early generation hybrid That this hybridization event occurred within a population of warblers in significant decline suggests that females may be making the best of a bad situation, and that wood-warblers in general have remained genetically compatible long after they evolved major phenotypic differences.
种间杂交可以深入了解用于配偶选择的特征的解体，以及跨越深远进化时间尺度的生殖兼容性。杂交也可能在衰退的种群中更频繁地发生，因为可供选择的同种配偶数量较少。在这里，我们报告了一个不寻常的组合因素，导致了两种莺属之间罕见的三物种杂交事件，其中一种莺属的种群数量正在显著下降。我们使用生物声学、形态计量学和遗传数据，证明了一只金翅莺（）和一只蓝翅莺（）之间的早期雌性杂种与一只栗胁林莺（）交配并成功繁殖。我们研究了这一事件的产物——一个假定的××杂种，并表明这只雄性后代唱出了像金翅莺一样的歌曲，但形态特征与莺属相似。杂种的母本有 线粒体 DNA，并且有六个与羽毛相关的基因座，我们预测母本的表型表明它可能是早期世代的杂种。这种杂交事件发生在数量显著下降的 莺种群中，这表明雌性可能在糟糕的情况下尽力而为，而且一般来说，在它们进化出主要表型差异很久之后，林莺属在遗传上仍然保持兼容。
