Institute of Natural and Mathematical Sciences, Massey University, Auckland, 0745, New Zealand.
Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, 80309, USA.
Mol Ecol. 2016 Aug;25(15):3521-4. doi: 10.1111/mec.13720.
Evolutionary biologists have long been fascinated by extravagant male traits that abound across the animal kingdom and yet convey no apparent benefits to survival. From isopods to elephants, from armaments to ornaments, researchers have spent decades studying male-male competition and female mate choice in an effort to understand the significance of these secondary sexual characteristics. Among socially monogamous species, a frequently proposed explanation for the existence of male ornaments is that they are indicators of male genetic quality subject to female extra-pair mate choice. However, despite over two decades of extensive research into extra-pair paternity (EPP), the evidence that females actually choose more ornamented extra-pair sires is surprisingly scant. Consequently, whether EPP and female choice have contributed to the evolution of male ornaments in socially monogamous species, and what fitness benefits (if any) they signal to females, remains unclear. Progress in this field has been hampered by the challenge of dissociating clear female choice for ornamentation from confounding factors. In this issue of Molecular Ecology, Whittingham & Dunn (2016) use an experimental approach in a bird species with very high rates of EPP to tease apart these correlative effects. In doing so, they demonstrate clearly that male ornamentation is subject to female extra-pair mate choice. Their findings further suggest that EPP can be adaptive for females, and represent an important step forward in validating the role of EPP as an evolutionary driver of ornamental elaboration in socially monogamous species.
进化生物学家长期以来一直对动物王国中普遍存在的华丽雄性特征着迷，这些特征对生存似乎没有明显的好处。从等足目动物到大象，从武器到装饰品，研究人员花了几十年的时间研究雄性之间的竞争和雌性的配偶选择，以试图理解这些次要性特征的意义。在社会一夫一妻制的物种中，一个经常被提出的解释是，雄性装饰物的存在是雄性遗传质量的指标，这些雄性遗传质量受到雌性的配偶选择。然而，尽管对婚外交配（EPP）进行了二十多年的广泛研究，但女性实际上选择更多装饰性的婚外亲代的证据却令人惊讶地稀少。因此，EPP 和雌性选择是否促进了社会一夫一妻制物种中雄性装饰物的进化，以及它们向雌性发出了什么适应度收益（如果有的话），仍然不清楚。在这个领域的进展受到了将雌性对装饰物的明显选择与混淆因素区分开来的挑战的阻碍。在本期《分子生态学》中，惠廷厄姆和邓恩（2016 年）使用了一种实验方法，在一种婚外交配率非常高的鸟类物种中，来梳理这些相关的影响。这样做，他们清楚地表明，雄性装饰物受到雌性的婚外配偶选择。他们的研究结果进一步表明，EPP 对女性是适应性的，并且代表着验证 EPP 作为社会一夫一妻制物种中装饰性精致进化驱动因素的重要一步。
