Male size predicts extrapair paternity in a socially monogamous bird with extreme sexual size dimorphism
Male size predicts extrapair paternity in a socially monogamous bird with extreme sexual size dimorphism
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雄性体型预测具有极端性别体型二态性的社会一夫一妻制鸟类的额外父子关系
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发表时间：
2015
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影响因子：
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通讯作者：
D. Gleeson
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文献类型：
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作者：
S. Wells;W. Ji;J. Dale;Beatrix Jones;D. Gleeson
对外父系（Extrapair paternity，EPP）被认为是羽毛二型性进化的重要贡献者，但相对较少的研究表明，EPP对雄性性状产生选择压力。相反，性别大小二态性（SSD）通常被认为是与一夫多妻制而不是EPP相关的进化。然而，新西兰的tui，Prossthemadera novaeseelanalus，是一个社会一夫一妻制的雀形目动物，表现出极端的SSD和性羽毛二型性。在这里，我们研究EPP是否有助于SSD的发展，在身体尺寸和装饰尺寸的推。我们发现了目前已知的最高的EPP率之一，在72%的育雏中发生了额外的幼仔，占所有后代的57%。雄性个体的体型和装饰物的大小与EPP都有很强的相关性，配对内亲子鉴定成功率与这两个性状都呈正相关。男性饰品的大小，而不是身体的大小，是一个显着的预测男性的成功在siring extrapair后代。虽然这些模式可能是通过雄性-雄性竞争或雌性选择产生的，但这两种机制在tui中可能并不相互排斥。这项研究提供的证据表明，EPP既可以创造选择压力的男性性状，并有助于SSD的进化。
Extrapair paternity (EPP) is purported to be an important contributor to the evolution of plumage dimorphism, and yet relatively few studies have demonstrated that EPP creates selection pressures on male traits. Sexual size dimorphism (SSD) is instead typically assumed to have evolved in association with polygyny rather than EPP. Yet, the New Zealand tui, Prosthemadera novaeseelandiae, is a socially monogamous passerine exhibiting extreme SSD and sexual plumage dimorphism. Here, we examine whether EPP has contributed to the evolution of SSD in body size and ornament size in the tui. We discovered one of the highest rates of EPP currently known, with extrapair young occurring in 72% of broods and accounting for 57% of all offspring. Both male body size and ornament size were strongly correlated to EPP, with within-pair paternity success positively related to both traits. Male ornament size, but not body size, was a significant predictor of a male’s success at siring extrapair offspring. Although these patterns may have arisen through either male–male competition or female choice, it is likely that these 2 mechanisms are not mutually exclusive in tui. This study provides evidence that EPP can both create selection pressures on male traits, and contribute to the evolution of SSD.