Effective size in density-dependent two-sex populations: the effect of mating systems

Density dependence in vital rates is a key feature affecting temporal fluctuations of natural populations. This has important implications for the rate of random genetic drift. Mating systems also greatly affect effective population sizes, but knowledge of how mating system and density regulation interact to affect random genetic drift is poor. Using theoretical models and simulations, we compare Ne in short-lived, density dependent animal populations with different mating systems. We study the impact of a fluctuating, density dependent sex ratio and consider both a stable and a fluctuating environment. We find a negative relationship between annual Ne/N and adult population size N due to density dependence, suggesting that loss of genetic variation is reduced at small densities. The magnitude of this decrease was affected by mating system and life history. A male-biased, density dependent sex ratio reduces the rate of genetic drift compared to an equal, density independent sex ratio, b...

生活史速率的密度依赖性是影响自然种群时间动态波动的核心特征，其对随机遗传漂变的发生速率具有重要意义。交配系统同样会显著影响有效种群大小（effective population size，简称Ne），但目前学界对交配系统与密度调控如何共同作用以影响随机遗传漂变的认知仍较为匮乏。本研究借助理论模型与模拟实验，对比了不同交配系统下的短寿命、具有密度依赖性的动物种群的Ne。我们探究了波动的密度依赖性性比所带来的影响，并同时考量了稳定环境与波动环境两种情境。研究发现，由于密度依赖性作用，年度Ne/N与成年种群大小N之间呈负相关关系，这表明在种群密度较低时，遗传变异的丢失会得到缓解。这种遗传变异丢失量的缩减幅度会受到交配系统与生活史特征的调控。相较于密度无关的均等性比，具有密度依赖性的偏雄性性比会降低遗传漂变的速率，然而……