Dittrich Carolin, Rodríguez Ariel, Segev Ori, Drakulić Sanja, Feldhaar Heike, Vences Miguel, Rödel Mark-Oliver
Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Berlin, Germany.
TU Braunschweig, Zoologisches Institut, Evolutionsbiologie, Braunschweig, Germany.
Behav Ecol. 2018 Mar-Apr;29(2):418-428. doi: 10.1093/beheco/arx188. Epub 2018 Jan 10.
Assortative mating is a common pattern in sexually reproducing species, but the mechanisms leading to assortment remain poorly understood. By using the European common frog () as a model, we aim to understand the mechanisms leading to size-assortative mating in amphibians. With data from natural populations collected over several years, we first show a consistent pattern of size-assortative mating across our 2 study populations. We subsequently ask if assortative mating may be explained by mate availability due to temporal segregation of migrating individuals with specific sizes. With additional experiments, we finally assess whether size-assortative mating is adaptive, i.e. influenced by mating competition among males, or by reduced fertilization in size-mismatched pairs. We find that size-assortative mating is in accordance with differences in mate availability during migration, where larger individuals of both sexes reach breeding ponds earlier than smaller individuals. We observe an indiscriminate mate choice behavior of small males and an advantage of larger males pairing with females during scramble competition. The tactic of small males, to be faster and less discriminative than large males, may increase their chances to get access to females. Experimental tests indicate that the fertilization success is not affected by size assortment. However, since female fecundity is highly correlated with body size, males preferring larger females should maximize their number of offspring. Therefore, we conclude that in this frog species mate choice is more complex than formerly believed.
选型交配是有性繁殖物种中的一种常见模式，但导致选型的机制仍知之甚少。以欧洲普通青蛙（）为模型，我们旨在了解两栖动物中导致体型选型交配的机制。利用多年来从自然种群收集的数据，我们首先展示了在我们的两个研究种群中一致的体型选型交配模式。随后，我们询问选型交配是否可能由具有特定体型的迁徙个体的时间隔离导致的配偶可获得性来解释。通过额外的实验，我们最终评估体型选型交配是否具有适应性，即受雄性间的交配竞争影响，还是受体型不匹配的配对中受精率降低的影响。我们发现体型选型交配与迁徙期间配偶可获得性的差异一致，即两性中较大的个体比较小的个体更早到达繁殖池塘。我们观察到小雄蛙的无差别择偶行为以及在争夺竞争中大雄蛙与雌蛙配对的优势。小雄蛙比大雄蛙更快且更不挑剔的策略可能会增加它们接触雌蛙的机会。实验测试表明受精成功率不受体型选型的影响。然而，由于雌性繁殖力与体型高度相关，偏好较大雌蛙的雄蛙应能使后代数量最大化。因此，我们得出结论，在这种蛙类中，择偶比以前认为的更为复杂。
