Department of Anthropology, Yale University, New Haven, CT 06520, USA.
Biol Lett. 2010 Dec 23;6(6):736-9. doi: 10.1098/rsbl.2010.0348. Epub 2010 May 12.
Life-history theory predicts that reduced extrinsic risk of mortality should increase species longevity over evolutionary time. Increasing group size should reduce an individual's risk of predation, and consequently reduce its extrinsic risk of mortality. Therefore, we should expect a relationship between group size and maximum longevity across species, while controlling for well-known correlates of longevity. We tested this hypothesis using a dataset of 253 mammal species and phylogenetic comparative methods. We found that group size was a poor predictor of maximum longevity across all mammals, as well as within primates and rodents. We found a weak but significant group-size effect on artiodactyl longevity, but in a negative direction. Body mass was consistently the best predictor of maximum longevity, which may be owing to lower predation risk and/or lower basal metabolic rates for large species. Artiodactyls living in large groups may exhibit higher rates of extrinsic mortality because of being more conspicuous to predators in open habitats, resulting in shorter lifespans.
生活史理论预测，随着进化时间的推移，降低外在死亡率风险应该会延长物种的寿命。增加群体大小应该会降低个体被捕食的风险，从而降低其外在死亡率风险。因此，我们应该期望在控制与寿命相关的已知因素的情况下，物种的群体大小与最大寿命之间存在关系。我们使用 253 种哺乳动物物种的数据集和系统发育比较方法来检验这一假设。我们发现，群体大小在所有哺乳动物中以及灵长类动物和啮齿动物中都不能很好地预测最大寿命。我们发现群体大小对偶蹄类动物的寿命有微弱但显著的影响，但方向是负面的。体重始终是最大寿命的最佳预测指标，这可能是由于大型物种的捕食风险较低和/或基础代谢率较低。生活在大群体中的偶蹄类动物由于在开阔栖息地中对捕食者更加明显，可能会表现出更高的外在死亡率，从而导致寿命缩短。
