Drivers of diversification in individual life courses

Heterogeneity in life courses among individuals of a population influences the speed of adaptive evolutionary processes, but it is less clear how biotic and abiotic environmental fluctuations influence such heterogeneity. We investigate principal drivers of variability in sequence of stages during an individual's life in a stage-structured population. We quantify heterogeneity by measuring population entropy of a Markov chain, which computes the rate of diversification of individual life courses. Using individual data of a primate population, we show that density regulates the stage composition of the population, but its entropy and the generating moments of heterogeneity are independent of density. This lack of influence of density on heterogeneity is neither due to low year-to-year variation in entropy nor due to differences in survival among stages, but due to differences in stage transitions. Our analysis thus shows that well-known classical ecological selective forces, such as dens...

种群内个体间的生命历程异质性会影响适应性进化过程的速率，但目前尚不清楚生物与非生物环境波动如何对该类异质性产生调控作用。本研究针对阶段结构化种群中个体生命阶段序列的变异核心驱动因素展开探究。我们通过计算马尔可夫链（Markov chain）的种群熵来量化异质性，该指标可用于衡量个体生命历程的分化速率。借助某灵长类种群的个体观测数据，我们证实种群密度可调控种群的阶段组成，但其熵值与异质性的生成矩均与密度无关。密度对异质性并无影响的现象，既非源于熵值的年际波动幅度较低，亦非缘于不同阶段间的存活差异，而是由阶段转换的差异所导致。据此，本研究表明，诸如种群密度这类经典生态学选择力，如密...