Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544.
Proc Natl Acad Sci U S A. 2018 Nov 13;115(46):E10879-E10887. doi: 10.1073/pnas.1813662115. Epub 2018 Oct 22.
Global biodiversity is being degraded at an unprecedented rate, so it is important to preserve the potential for future speciation. Providing for the future requires understanding speciation as a contemporary ecological process. Phylogenetically young adaptive radiations are a good choice for detailed study because diversification is ongoing. A key question is how incipient species become reproductively isolated from each other. Barriers to gene exchange have been investigated experimentally in the laboratory and in the field, but little information exists from the quantitative study of mating patterns in nature. Although the degree to which genetic variation underlying mate-preference learning is unknown, we provide evidence that two species of Darwin's finches imprint on morphological cues of their parents and mate assortatively. Statistical evidence of presumed imprinting is stronger for sons than for daughters and is stronger for imprinting on fathers than on mothers. In combination, morphology and species-specific song learned from the father constitute a barrier to interbreeding. The barrier becomes stronger the more the species diverge morphologically and ecologically. It occasionally breaks down, and the species hybridize. Hybridization is most likely to happen when species are similar to each other in adaptive morphological traits, e.g., body size and beak size and shape. Hybridization can lead to the formation of a new species reproductively isolated from the parental species as a result of sexual imprinting. Conservation of sufficiently diverse natural habitat is needed to sustain a large sample of extant biota and preserve the potential for future speciation.
全球生物多样性正以前所未有的速度退化，因此保护未来物种形成的潜力非常重要。为未来提供保障需要将物种形成理解为当代生态过程。系统发育年轻的适应性辐射是详细研究的理想选择，因为多样化仍在继续。一个关键问题是初生物种如何彼此间产生生殖隔离。在实验室和野外已经对基因交流的障碍进行了实验研究，但在自然交配模式的定量研究中，信息很少。尽管我们尚不清楚配偶偏好学习所基于的遗传变异程度，但我们提供的证据表明，两种达尔文雀会根据父母的形态特征进行印记，并进行交配的选择性。对假定的印记的统计证据对于儿子来说比女儿要强，对于父亲的印记要强于母亲。形态和从父亲那里学到的物种特异性歌声结合起来，构成了杂交的障碍。物种在形态和生态上的差异越大，障碍就越强。这种障碍偶尔会被打破，物种会杂交。当物种在适应性形态特征（例如体型和喙的大小和形状）上彼此相似时，杂交最有可能发生。杂交可能导致形成一个与亲本物种生殖隔离的新物种，这是由于性印记的结果。需要保护足够多样化的自然栖息地，以维持大量现存生物群，并保护未来物种形成的潜力。
