Faculty of Biological Sciences, University of Leeds, Leeds, West Yorkshire, United Kingdom.
PLoS One. 2013;8(1):e54194. doi: 10.1371/journal.pone.0054194. Epub 2013 Jan 24.
Social structure evolves from a trade-off between the costs and benefits of group-living, which are in turn dependent upon the distribution of key resources such as food and shelter. Males and females, or juveniles and adults, may have different priorities when selecting habitat due to differences in physiological or behavioural imperatives, leading to complex patterns in group composition. We studied social structure and mating behaviour in the insectivorous bat Myotis daubentonii along an altitudinal gradient, combining field studies with molecular genetics. With increasing altitude the proportion of males in summer roosts increased and only males were present in the highest roosts. With increasing altitude environmental temperature decreased, nightly variation in temperature increased, and bat foraging activity decreased, supporting the hypothesis that the harsher, high elevation sites cannot support breeding females. We found that offspring in female-dominated lowland roosts had a very high probability of being fathered by bats caught during autumn swarming at hibernation sites, in contrast to those in intermediate roosts, which had a high probability of being fathered by males sharing the nursery roost with the females. Whilst females normally appear to exclude males from nursery colonies, for those in marginal habitats, one explanation for the presence of males is that the thermoregulatory benefits to the females may outweigh disadvantages, such as competition for food, and give some males an opportunity to increase their breeding success. We suggest that the environment, and its effects on resource distribution, thus determine social structure, which in turn determines the mating pattern that has evolved.
社会结构是在群体生活的成本和收益之间权衡的结果，而这些又取决于食物和住所等关键资源的分布。由于生理或行为需求的差异，雄性和雌性，或幼体和成年个体在选择栖息地时可能有不同的优先事项，从而导致群体组成的复杂模式。我们结合野外研究和分子遗传学，研究了昆虫食蝙蝠 Myotis daubentonii 在海拔梯度上的社会结构和交配行为。随着海拔的升高，夏季栖息地中雄性的比例增加，而只有雄性存在于最高的栖息地中。随着海拔的升高，环境温度降低，夜间温度变化增加，蝙蝠觅食活动减少，这支持了这样的假设，即更恶劣的高海拔地区无法支持繁殖雌性。我们发现，在以雌性为主的低海拔栖息地中，后代成为在冬眠地秋群中捕获的蝙蝠的父亲的可能性非常高，而在中等海拔栖息地中，后代成为与雌性共享育儿地的雄性的父亲的可能性非常高。虽然雌性通常似乎将雄性排除在育儿群体之外，但对于那些处于边缘栖息地的雄性来说，雄性存在的一个解释是，雌性的体温调节益处可能超过竞争食物等劣势，并为一些雄性提供了增加繁殖成功的机会。我们认为，环境及其对资源分布的影响决定了社会结构，进而决定了进化出的交配模式。
