Dipartimento di Biologia, Università degli Studi di Milano, Milano, Italy.
ISPRA, Via Cà Fornacetta 9, Ozzano dell'Emilia (BO), Italy.
J Evol Biol. 2010 Oct;23(10):2054-2065. doi: 10.1111/j.1420-9101.2010.02068.x. Epub 2010 Aug 17.
Timing of arrival/emergence to the breeding grounds is under contrasting natural and sexual selection pressures. Because of differences in sex roles and physiology, the balance between these pressures on either sex may differ, leading to earlier male (protandry) or female (protogyny) arrival. We test several competing hypotheses for the evolution of protandry using migration data for 22 bird species, including for the first time several monochromatic ones where sexual selection is supposedly less intense. Across species, protandry positively covaried with sexual size dimorphism but not with dichromatism. Within species, there was weak evidence that males migrate earlier because, being larger, they are less susceptible to adverse conditions. Our results do not support the 'rank advantage' and the 'differential susceptibility' hypotheses, nor the 'mate opportunity' hypothesis, which predicts covariation of protandry with dichromatism. Conversely, they are compatible with 'mate choice' arguments, whereby females use condition-dependent arrival date to assess mate quality.
到达/出现繁殖地的时间受到自然选择和性选择压力的影响。由于性别角色和生理的差异，这些压力在两性之间的平衡可能不同，导致雄性（雄性先熟）或雌性（雌性先熟）更早到达。我们使用 22 种鸟类的迁徙数据来测试雄性先熟进化的几个竞争假说，其中首次包括一些据称性选择不那么强烈的单色鸟类。在物种间，雄性先熟与性二态性呈正相关，但与二色性无关。在物种内，有微弱的证据表明雄性更早迁徙，因为它们体型较大，不易受到不利条件的影响。我们的结果不支持“等级优势”和“差异易感性”假说，也不支持“配偶机会”假说，该假说预测雄性先熟与二色性的协同进化。相反，它们与“配偶选择”论点相兼容，即雌性根据条件依赖的到达日期来评估配偶的质量。
