Many animal species across different taxa change their habitat during their development. An ontogenetic habitat shift enables the development of early vulnerable‐to‐predation stages in a safe “nursery” habitat with reduced predation mortality, whereas less vulnerable stages can exploit a more risky, rich feeding habitat. Therefore, the timing of the habitat shift is crucial for individual fitness. We investigate the effect that size selectivity in mortality in the rich feeding habitat has on the optimal body size at which to shift between habitats using a population model that incorporates density dependence. We show that when mortality risk is more size dependent, it is optimal to switch to the risky habitat at a smaller rather than larger body size, despite that individuals can avoid mortality by staying longer in the nursery habitat and growing to safety in size. When size selectivity in mortality is high, large reproducing individuals are abundant and produce numerous offspring that strongly compete in the nursery habitat. A smaller body size at habitat shift is therefore favored because strong competition reduces growth potential. Our results reveal the interdependence among population structure, density dependence, and life history traits, and highlight the need for integrating ecological feedbacks in the study of life history evolution.

中文翻译：

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死亡率对转移栖息地的最佳体型的密度依赖性影响：为什么尽管死亡风险增加，但体型越小越好


不同类群的许多动物物种在发育过程中改变了它们的栖息地。个体发生栖息地的转变使得早期易受捕食阶段的发展能够在安全的“育苗”栖息地中发展，降低捕食死亡率，而较不脆弱的阶段可以利用风险更大、丰富的摄食栖息地。因此，栖息地转移的时间对于个体的健康至关重要。我们使用包含密度依赖性的种群模型研究了丰富的摄食栖息地中死亡率的体型选择性对在栖息地之间转移的最佳体型的影响。我们表明，当死亡风险更多地依赖于体型时，最好是切换到体型较小而不是体型较大的危险栖息地，尽管个体可以通过在保育栖息地停留更长时间并长到安全的体型来避免死亡。当死亡率的大小选择性很高时，大型繁殖个体就会大量繁殖，并产生大量在苗圃栖息地中激烈竞争的后代。因此，栖息地转移时较小的体型受到青睐，因为激烈的竞争会降低生长潜力。我们的结果揭示了种群结构、密度依赖性和生活史特征之间的相互依赖性，并强调了在生活史进化研究中整合生态反馈的必要性。