Lisovski Simeon, Fröhlich Anne, von Tersch Matthew, Klaassen Marcel, Peter Hans-Ulrich, Ritz Markus S
Am Nat. 2016 Apr;187(4):532-9. doi: 10.1086/685282. Epub 2016 Feb 22.
In migratory animals, protandry (earlier arrival of males on the breeding grounds) prevails over protogyny (females preceding males). In theory, sex differences in timing of arrival should be driven by the operational sex ratio, shifting toward protogyny in female-biased populations. However, empirical support for this hypothesis is, to date, lacking. To test this hypothesis, we analyzed arrival data from three populations of the long-distance migratory south polar skua (Catharacta maccormicki). These populations differed in their operational sex ratio caused by the unidirectional hybridization of male south polar skuas with female brown skuas (Catharacta antarctica lonnbergi). We found that arrival times were protandrous in allopatry, shifting toward protogyny in female-biased populations when breeding in sympatry. This unique observation is consistent with theoretical predictions that sex-specific arrival times should be influenced by sex ratio and that protogyny should be observed in populations with female-biased operational sex ratio.
在迁徙动物中，雄性先熟（雄性比雌性更早到达繁殖地）比雌性先熟（雌性比雄性先到达）更为普遍。理论上，到达时间的性别差异应由实际性比驱动，在雌性偏多的种群中应向雌性先熟转变。然而，迄今为止，这一假设缺乏实证支持。为了验证这一假设，我们分析了三个远距离迁徙的南极贼鸥（Catharacta maccormicki）种群的到达数据。这些种群的实际性比因南极贼鸥雄性与棕贼鸥（Catharacta antarctica lonnbergi）雌性的单向杂交而有所不同。我们发现，在异域分布时到达时间是雄性先熟，而在同域繁殖时，在雌性偏多的种群中则向雌性先熟转变。这一独特的观察结果与理论预测一致，即特定性别的到达时间应受性比影响，并且在实际性比雌性偏多的种群中应观察到雌性先熟。
