Joly Nicolas, Chiaradia Andre, Georges Jean-Yves, Saraux Claire
Université de Strasbourg, CNRS, Institut Pluridisciplinaire Hubert Curien (IPHC), UMR 7178, Strasbourg, France.
Conservation Department, Phillip Island Nature Parks, Cowes, Victoria, Australia.
Evolution. 2023 Sep 1;77(9):2056-2067. doi: 10.1093/evolut/qpad126.
While the heterogeneity among individuals of a population is more and more documented, questions on the paths through which it arises, particularly whether it is linked to fixed heterogeneity or chance alone, are still widely debated. Here, we tested how individual quality, energy allocation trade-offs, and environmental stochasticity define individual fitness. To do so, we simultaneously investigated the contribution of 18 life-history traits to the fitness of breeding little penguins (Eudyptula minor), using a structural equation model. Fitness was highly variable amongst the 162 birds monitored over their entire lifespan. It increased with the individual penguin's ability to increase (a) the number of breeding events (i.e., living longer, breeding younger, breeding more often, and producing more second clutches) and (b) the breeding success per event through increased foraging performances (i.e., mass gained at sea). While all three processes (stochasticity, individual quality, and allocation trade-offs) affected fitness, interindividual variability in fitness was mainly driven by individual quality, birds consistently breeding earlier in the season and displaying higher foraging efficiency exhibiting higher fitness. Why some birds consistently can perform better at sea and breed earlier remains a question to investigate to understand how selection applies to these traits.
尽管越来越多的文献记录了种群中个体间的异质性，但关于其产生途径的问题，尤其是它是否仅与固定的异质性或偶然性相关，仍存在广泛争议。在这里，我们测试了个体质量、能量分配权衡和环境随机性如何定义个体适应性。为此，我们使用结构方程模型，同时研究了18种生活史特征对繁殖小企鹅（小企鹅属）适应性的贡献。在监测的162只小企鹅的整个生命周期中，适应性变化很大。它随着个体企鹅增加（a）繁殖事件数量（即寿命更长、繁殖年龄更小、繁殖更频繁以及产更多第二窝蛋）和（b）通过提高觅食能力（即在海上获得的体重）来提高每次繁殖成功率的能力而增加。虽然所有三个过程（随机性、个体质量和分配权衡）都影响适应性，但适应性的个体间差异主要由个体质量驱动，在季节中始终较早繁殖且表现出较高觅食效率的鸟类具有更高的适应性。为什么有些鸟类在海上始终能表现得更好且繁殖更早，这仍是一个有待研究的问题，以了解选择如何作用于这些特征。
