Ontogenetic niche shifts and flexible behavior in size-structured populations
Ontogenetic niche shifts and flexible behavior in size-structured populations
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DOI：
10.1890/0012-9615(2002)072
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发表时间：
2002-05-01
影响因子：
6.1
通讯作者：
Mittelbach, GG
中科院分区：
文献类型：
--
作者：
de Roos, AM;Leonardsson, K;Mittelbach, GG
柔性行为已被证明对非结构化模型中的种群动力学有实质性的影响。我们调查的影响灵活的行为的动态的大小结构的人口使用生理结构的建模方法。大小结构种群的个体可以选择生活在一个有风险但有利可图的栖息地，或者生活在一个更安全但利润较低的栖息地。两个栖息地中的每一个都有自己的资源种群，这些个体以其为食。两种类型的灵活的行为被认为是：离散的栖息地的变化，其中个人瞬间和不可逆地从生活在安全的栖息地转移到更危险/有利可图的栖息地，和连续的栖息地选择，其中个人可以不断地适应他们的栖息地选择，以当前的资源/死亡率条件。我们研究了该模型的动态作为一个功能的死亡率风险的风险/有利可图的栖息地。模型的制定和参数化来自欧亚鲈鱼（Perca fluviatilis）的数据，并描述为一个每年的事件，在夏季开始的繁殖，而所有其他过程是连续的时间。两个栖息地的存在本身。在所有消费者之间共享的唯一资源的情况下，与一个资源的情况相比，不改变模型动态。灵活的行为增加了种群可以持续生存的死亡率水平范围，因为它允许个体在危险的栖息地躲避高死亡率。相比之下，灵活的行为并没有显着改变动态的死亡率risks，消费者人口也坚持没有it. Discrete栖息地的变化导致模型的动态，在很大程度上类似于观察到的动态与连续的栖息地选择，只要个人强烈响应栖息地盈利能力的微小差异。在这些情况下，消费者在安全栖息地度过生命的第一年，而在危险栖息地的死亡风险增加。最终，消费者会因连续一年班级的群体间竞争而被驱逐到危险的栖息地。因此，主要的死亡率和快速增长发生在1岁的个体。年轻的个体表现出迟缓的增长，由于在安全的栖息地，这也可能会引起大幅度的波动时，死亡率的风险是高的风险栖息地的内竞争。随着不断的栖息地选择和栖息地盈利能力的低反应，消费者的持久性也增加了。但没有大幅度波动。在这种情况下，消费者总是在危险的栖息地度过他们生命的第一年的很大一部分，即使在高死亡率的风险。主要的死亡率和快速增长发生在年龄小于1岁的个体，而转移到危险的栖息地主要是由intracohort资源竞争引起的。高死亡率和年轻时的快速增长导致存活个体的最大尺寸和繁殖力增加，以及总种群生物量增加。我们认为，个人栖息地的使用模式主要是由人口对资源水平的反馈。
Flexible behavior has been shown to have substantial effects on population dynamics in unstructured models. We investigate the influence of flexible behavior on the dynamics of a size-structured population using a physiologically structured modeling approach. Individuals of the size-structured population have a choice between living in a risky but profitable habitat and living in a safer but less profitable habitat. Each of the two habitats houses its own resource population on which the individuals feed. Two types of flexible behavior are considered: discrete habitat shifts, in which individuals instantaneously and nonreversibly shift from living in the safe habitat to the more risky/profitable habitat, and continuous habitat choice, in which individuals can continuously adapt their habitat choice to current resource/mortality conditions. We study the dynamics of the model as a function of the mortality risk in the risky/profitable habitat. The model formulation and parameterization are derived using data on Eurasian perch (Perca fluviatilis) and describe reproduction as a yearly event at the beginning of summer, while all other processes are continuous in time. The presence of two habitats per se. with unique resources that are shared among all consumers, does not change model dynamics, when compared to the one-resource situation. Flexible behavior increases the range of mortality levels for which the population can persist, because it allows individuals to hide from high mortality in the risky habitat. In contrast, flexible behavior does not significantly change the dynamics for mortality risks, where the consumer population also persists without it. Discrete habitat shifts result in model dynamics that are largely similar to the dynamics observed with continuous habitat choice, as long as individuals strongly respond to small differences in habitat profitability. In these cases, consumers spend an increasing part of their first year of life in the safe habitat, when mortality risks in the risky habitat increase. Ultimately, consumers are driven out into the risky habitat by intercohort competition from their successive year class. Therefore, major mortality and rapid growth occur among 1-yr-old individuals. Younger individuals exhibit retarded growth due to intracohort competition in the safe habitat, which may also induce large-amplitude fluctuations when the mortality risk is high in the risky habitat. With continuous habitat choice and a low responsiveness to habitat profitability, consumer persistence is increased as well. but large-amplitude fluctuations are absent. In this case, consumers always spend a significant part of their first year of life in the risky habitat, even at high mortality risks. Major mortality and rapid growth occur among individuals younger than 1 yr, while the shift to the risky habitat is mainly induced by intracohort competition for resources. The high mortality and rapid growth at younger ages lead to an increase in maximum size and fecundity of surviving individuals, as well as to larger total population biomasses. We argue that the pattern of individual habitat use is mainly determined by population feedback on resource levels.