Data from: Relative costs of offspring sex and offspring survival in a polygynous mammal

Costs of reproduction are expected to be ubiquitous in wild animal populations, and understanding the drivers of variation in these costs is an important aspect of life-history evolution theory. We use a 43-year dataset from a wild population of red deer to examine the relative importance of two factors that influence the costs of reproduction to mothers, and to test whether these costs vary with changing ecological conditions. Like previous studies, our analyses indicate fitness costs of lactation: mothers whose calves survived the summer subsequently showed lower survival and fecundity than those whose calves died soon after birth, accounting for 5% and 14% of the variation in mothers’ survival and fecundity, respectively. The production of a male calf depressed maternal survival and fecundity more than production of a female, but accounted for <1% of the variation in either fitness component. There was no evidence for any change in the effect of calf survival or sex with increasing population density.

繁殖代价普遍存在于野生动物种群之中，解析此类代价的变异驱动因素，是生活史进化理论（life-history evolution theory）的重要研究内容。我们采用一项基于野生马鹿种群的43年长期监测数据集，探究影响母体繁殖代价的两类因素的相对重要性，并检验此类代价是否会随生态环境变化而发生改变。与既往研究结果一致，本次分析显示泌乳存在适合度代价：幼鹿成功渡过夏季的母鹿，其后续存活率与繁殖力均显著低于幼鹿出生后不久即死亡的母鹿；该因素分别解释了母体存活率与繁殖力变异的5%与14%。产下雄性幼鹿对母体存活率与繁殖力的抑制作用强于产下雌性幼鹿，但该性别差异仅能解释两类适合度指标变异的不足1%。未发现幼鹿存活情况或幼崽性别对母体的影响随种群密度升高而发生变化的相关证据。