Life-history multistability caused by size-dependent mortality

Body size is a key determinant of mortality risk. In natural populations, a broad range of relationships are observed between body size and mortality, including positive and negative correlations. Previous evolutionary modelling has shown that negatively size-dependent mortality can result in life-history bistability, with early maturation at small size and late maturation at large size representing alternative fitness optima. Here we present a general analysis of conditions under which such life-history bistabilities can occur, reporting the following findings. First, alternative fitness optima can be found for any arbitrarily chosen forms of mortality functions, including functions according to which mortality smoothly declines with size. Second, while bistabilities occur more readily under negatively size-dependent mortality, our analysis reveals that they can also emerge under positively size-dependent mortality, a feature missed in earlier work. Third, any sharp drop of mortality w...

体型是决定死亡风险的核心影响因素。在自然种群中，体型与死亡率之间存在多样的关联模式，涵盖正相关与负相关两类情况。此前的进化建模研究表明，体型负依赖死亡率（negatively size-dependent mortality）可诱发生活史双稳态（life-history bistability），其中小型个体早熟、大型个体晚熟分别代表两种可替代的适合度最优解（fitness optima）。本研究针对此类生活史双稳态的发生条件开展了一般性分析，现将主要研究结果报告如下：其一，无论以任意形式设定死亡率函数——包括死亡率随体型平滑下降的函数类型——均能找到可替代的适合度最优解。其二，尽管体型负依赖死亡率条件下双稳态更易出现，但本研究分析显示，体型正依赖死亡率（positively size-dependent mortality）条件下同样可产生双稳态，这一特征在此前的研究中被遗漏。其三，死亡率的任何急剧下降……