Dispersal as a source of variation in age-specific reproductive strategies in a wild population of lizards

Dispersal syndromes describe patterns of covariation of morphological, behavioral and life history traits associated with dispersal. Studying dispersal syndromes is critical to understanding the demographic and genetic consequences of movements. Among studies describing the association of life history traits with dispersal, there is anecdotal evidence suggesting that dispersal syndromes can vary with age. Recent theory also suggests that dispersive and philopatric individuals might have different age-specific reproductive efforts. In a wild population of the common lizard (Zootoca vivipara), we investigated whether dispersive and philopatric individuals have different age-specific reproductive effort, survival, offspring body condition and offspring sex ratio. Consistent with theoretical predictions, we found that young dispersive females have a higher reproductive effort than young philopatric females. Our results also suggest that the early high investment in reproduction of dispersive females trades-off with an earlier onset of senescence than in philopatric females. We further found that young dispersive females produce smaller offspring in lower body condition than do young philopatric females. Overall, our results provide empirical evidence that dispersive and philopatric individuals have different age-specific life history traits.

扩散综合征（dispersal syndromes）用于描述与扩散行为相关的形态、行为及生活史性状的协同变异模式。对扩散综合征的研究，是解析扩散行为所带来的种群动态与遗传效应的关键所在。在探讨生活史性状与扩散行为关联的现有研究中，已有轶事性证据表明，扩散综合征会随年龄发生变化。近期的理论研究同样提出，扩散个体与定居个体（philopatric）的年龄特异性繁殖投入可能存在差异。本研究以胎生蜥蜴（Zootoca vivipara）的野生种群为研究对象，探究了扩散个体与定居个体在年龄特异性繁殖投入、存活率、后代身体状况以及后代性比方面是否存在差异。与理论预测一致，本研究发现年轻的扩散性雌性个体的繁殖投入高于年轻的定居性雌性个体。本研究结果还显示，相较于定居个体，扩散性雌性个体早期的高繁殖投入会与更早的衰老起始存在生存权衡关系。此外，本研究进一步发现，年轻的扩散性雌性个体所产的后代体型更小，身体状况也差于年轻定居性雌性个体的后代。综上，本研究结果为扩散个体与定居个体存在年龄特异性生活史性状差异提供了实证依据。