Department of Biology and Burke Museum of Natural History and Culture, University of Washington , Seattle, WA , USA.
PeerJ. 2014 Jun 3;2:e409. doi: 10.7717/peerj.409. eCollection 2014.
Conspecific rape often increases male reproductive success. However, the haste and aggression of forced copulations suggests that males may sometimes rape heterospecific females, thus making rape a likely, but undocumented, source of hybrids between broadly sympatric species. We present evidence that heterospecific rape may be the source of hybrids between Black-footed and Laysan Albatrosses (Phoebastria nigripes, and P. immutabilis, respectively). Extensive field studies have shown that paired (but not unpaired) males of both of these albatross species use rape as a supplemental reproductive strategy. Between species differences in size, timing of laying, and aggressiveness suggest that Black-footed Albatrosses should be more successful than Laysan Albatrosses in heteropspecific rape attempts, and male Black-footed Albatrosses have been observed attempting to force copulations on female Laysan Albatrosses. Nuclear markers showed that the six hybrids we studied were F1s and mitochondrial markers showed that male Black-footed Albatrosses sired all six hybrids. Long-term gene exchange between these species has been from Black-footed Albatrosses into Laysan Albatrosses, suggesting that the siring asymmetry found in our hybrids has long persisted. If hybrids are sired in heterospecific rapes, they presumably would be raised and sexually imprinted on Laysan Albatrosses, and two unmated hybrids in a previous study courted only Laysan Albatrosses.
同种相残通常会增加雄性的繁殖成功率。然而，强迫交配的匆忙和攻击性表明，雄性有时可能会强奸异配种的雌性，从而使强奸成为广泛同域物种之间杂交的一个可能但未被记录的来源。我们提出的证据表明，异配种强奸可能是黑脚和莱桑信天翁（Phoebastria nigripes 和 P. immutabilis 分别）之间杂交的来源。广泛的实地研究表明，这两种信天翁的配对（而非未配对）雄性都将强奸作为一种补充生殖策略。物种间在体型、产卵时间和攻击性方面的差异表明，黑脚信天翁在异配种强奸尝试中应该比莱桑信天翁更成功，而且已经观察到雄性黑脚信天翁试图强迫雌性莱桑信天翁交配。核标记显示，我们研究的六个杂交种是 F1，线粒体标记显示，雄性黑脚信天翁是这六个杂交种的全部父本。这些物种之间的长期基因交流是从黑脚信天翁到莱桑信天翁，这表明我们在杂交种中发现的父本不对称性长期存在。如果杂种是在异配种强奸中产生的，它们可能会被抚养并在莱桑信天翁身上留下性印记，而在之前的一项研究中，两只未配对的杂种只向莱桑信天翁求爱。
