Soudijn Floor H, de Roos André M
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
Theor Ecol. 2017;10(1):73-90. doi: 10.1007/s12080-016-0309-9. Epub 2016 Sep 1.
Seasonal reproduction causes, due to the periodic inflow of young small individuals in the population, seasonal fluctuations in population size distributions. Seasonal reproduction furthermore implies that the energetic body condition of reproducing individuals varies over time. Through these mechanisms, seasonal reproduction likely affects population and community dynamics. While seasonal reproduction is often incorporated in population models using discrete time equations, these are not suitable for size-structured populations in which individuals grow continuously between reproductive events. Size-structured population models that consider seasonal reproduction, an explicit growing season and individual-level energetic processes exist in the form of physiologically structured population models. However, modeling large species ensembles with these models is virtually impossible. In this study, we therefore develop a simpler model framework by approximating a cohort-based size-structured population model with seasonal reproduction to a stage-structured biomass model of four ODEs. The model translates individual-level assumptions about food ingestion, bioenergetics, growth, investment in reproduction, storage of reproductive energy, and seasonal reproduction in stage-based processes at the population level. Numerical analysis of the two models shows similar values for the average biomass of juveniles, adults, and resource unless large-amplitude cycles with a single cohort dominating the population occur. The model framework can be extended by adding species or multiple juvenile and/or adult stages. This opens up possibilities to investigate population dynamics of interacting species while incorporating ontogenetic development and complex life histories in combination with seasonal reproduction.
季节性繁殖会因种群中年轻小个体的周期性流入，导致种群大小分布出现季节性波动。此外，季节性繁殖意味着繁殖个体的能量体况会随时间变化。通过这些机制，季节性繁殖可能会影响种群和群落动态。虽然季节性繁殖通常在使用离散时间方程的种群模型中有所体现，但这些方程并不适用于大小结构种群，在这类种群中，个体在繁殖事件之间持续生长。考虑季节性繁殖、明确生长季节和个体水平能量过程的大小结构种群模型以生理结构种群模型的形式存在。然而，用这些模型对大量物种集合进行建模几乎是不可能的。因此，在本研究中，我们通过将具有季节性繁殖的基于队列的大小结构种群模型近似为一个由四个常微分方程组成的阶段结构生物量模型，开发了一个更简单的模型框架。该模型将关于食物摄取、生物能量学、生长、繁殖投资、繁殖能量储存和季节性繁殖的个体水平假设转化为种群水平基于阶段的过程。对这两个模型的数值分析表明，除非出现单个队列主导种群的大幅度周期，否则幼体、成体和资源的平均生物量值相似。通过添加物种或多个幼体和/或成体阶段，可以扩展该模型框架。这为研究相互作用物种的种群动态开辟了可能性，同时结合个体发育和复杂生活史以及季节性繁殖。
