Descamps Sébastien, Boutin Stan, Berteaux Dominique, Gaillard Jean-Michel
Chaire de Recherche du Canada en Conservation des Ecosystèmes Nordiques et Centre d'Etudes Nordiques, Université du Québec à Rimouski, Rimouski, Québec, Canada.
Proc Biol Sci. 2006 Sep 22;273(1599):2369-74. doi: 10.1098/rspb.2006.3588.
Age at primiparity plays a crucial role in population dynamics and life-history evolution. Long-term data on female North American red squirrels were analysed to study the fitness consequences of delaying first reproduction. Early breeders were born earlier, had a higher breeding success and achieved a higher lifetime reproductive success than females who delayed their first reproduction, which suggests a higher quality of early breeders. However, early breeders had similar mass when tagged, and similar number of food caches available at one year of age as late breeders. Nevertheless, we found evidence of survival costs of early primiparity. Early breeders had a lower survival between one and two years of age than late breeders and a lower lifespan. Our study points out that two reproductive tactics co-occurred in this population: a tactic based on early maturity at the cost of a lower survival versus a tactic based on delayed maturity and long lifespan. High quality individuals express the most profitable tactic by breeding early whereas low quality individuals do the best of a bad job by delaying their first reproduction.
初产年龄在种群动态和生活史进化中起着至关重要的作用。对北美雌性红松鼠的长期数据进行了分析，以研究推迟首次繁殖对适合度的影响。与推迟首次繁殖的雌性相比，早期繁殖者出生更早，繁殖成功率更高，终生繁殖成功率也更高，这表明早期繁殖者的质量更高。然而，早期繁殖者在被标记时体重相似，一岁时可用的食物储存数量与晚期繁殖者也相似。尽管如此，我们发现了早期初产存在生存成本的证据。早期繁殖者在一到两岁之间的存活率低于晚期繁殖者，寿命也较短。我们的研究指出，该种群中同时存在两种繁殖策略：一种是以较低的存活率为代价的早熟策略，另一种是以延迟成熟和长寿为基础的策略。高质量个体通过早期繁殖表现出最有利可图的策略，而低质量个体则通过推迟首次繁殖在不利情况下尽力而为。
