Fasel N, Saladin V, Richner H
Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
J Evol Biol. 2016 Nov;29(11):2242-2255. doi: 10.1111/jeb.12949. Epub 2016 Sep 9.
The use of alternative reproductive tactics (ARTs) is widespread in animals. Males of some species may change tactics depending on age, body condition and social environment. Many bat species are polygynous where a fraction of males only have access to fertile females. For polygynous bats, knowledge of the reproductive success of males using different ARTs is scarce, and it remains unclear how age of males is related to switching decisions between social statuses. We studied a large captive population of Carollia perspicillata, where males are either harem holders, bachelors or peripheral males. Using a multistate procedure, we modelled the age-related switches in reproductive tactics and in survival probability. From the model, we calculated the reproductive success and the frequencies of males displaying different reproductive tactics. As in mammals, the switch between social statuses is often related to age, we predicted that the transition probability of bachelor and peripheral males to harem status would increase with age. We show, however, that social status transition towards a harem holding position was not related to age. Reproductive success changed with age and social status. Harem males had a significantly higher reproductive success than bachelor males except between a short period from 3.8 to 4.4 years of age where success was similar, and a significantly higher reproductive success than peripheral males between 2.6 and 4.4 years of age. Harem males showed a clear decrease in the probability of maintaining social status with age, which suggests that senescence reduces resource holding potential.
替代生殖策略（ARTs）在动物中广泛存在。一些物种的雄性可能会根据年龄、身体状况和社会环境改变策略。许多蝙蝠物种是一夫多妻制的，其中一部分雄性只能接触到可育雌性。对于一夫多妻制的蝙蝠，关于使用不同替代生殖策略的雄性的繁殖成功率的了解很少，而且雄性年龄与社会地位转换决策之间的关系仍不清楚。我们研究了一大群圈养的秘鲁叶鼻蝠，其中雄性要么是妻妾成群的首领、单身汉，要么是边缘雄性。我们使用多状态程序，对与年龄相关的生殖策略转换和生存概率进行了建模。从模型中，我们计算了繁殖成功率以及表现出不同生殖策略的雄性的频率。由于在哺乳动物中，社会地位的转换通常与年龄有关，我们预测单身汉和边缘雄性转变为妻妾成群地位的转换概率会随着年龄的增长而增加。然而，我们发现，向妻妾成群地位的社会地位转变与年龄无关。繁殖成功率随年龄和社会地位而变化。妻妾成群的雄性比单身汉雄性有显著更高的繁殖成功率，除了在3.8至4.4岁的短时间内成功率相似，以及在2.6至4.4岁之间比边缘雄性有显著更高的繁殖成功率。妻妾成群的雄性随着年龄的增长保持社会地位的概率明显下降，这表明衰老会降低资源占有潜力。
