Unexpected patterns of plastic energy allocation in stochastic environments.
Unexpected patterns of plastic energy allocation in stochastic environments.
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DOI：
10.1086/596536
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发表时间：
2009-03
期刊：
影响因子：
--
通讯作者：
Dieckmann U
中科院分区：
文献类型：
--
作者：
Fischer B;Taborsky B;Dieckmann U
当环境条件随机变化时，个体通过表现出表型可塑性来获得健康益处。在这里，我们分析了一个通用的动态规划模型，该模型描述了随机环境中个体的最佳能量分配。成熟后，个体会反复决定如何在繁殖和维持之间分配传入的能量。我们根据环境的可变性和可预测性来分析投资于繁殖的最佳能量比例以及由此产生的可塑性程度。我们的分析揭示了意想不到的最佳能源分配模式。当能量可用性较低时，所有能量都会分配给繁殖，尽管这意味着个体在繁殖后将无法生存。在能源可用性超过一定阈值时，最佳生殖投资会降至最低，甚至在高度变化的环境中完全消失。随着能源供应的进一步提高，最优生殖投资再次逐渐增加。可塑性成本仅在数量上影响这种分配模式。我们的研究结果表明，最佳生殖投资不会随着能源可用性的增长而单调增加，并且能源可用性的微小变化可能会导致最佳能源分配的重大变化。我们的结果有助于统一生命史理论中两个明显相反的预测，即生物体应该在环境条件改善和条件恶化时增加生殖投资（“终端投资”）。
When environmental conditions vary stochastically, individuals accrue fitness benefits by exhibiting phenotypic plasticity. Here we analyze a general dynamic-programming model describing an individual’s optimal energy allocation in a stochastic environment. After maturation, individuals repeatedly decide how to allocate incoming energy between reproduction and maintenance. We analyze the optimal fraction of energy invested in reproduction and the resultant degree of plasticity in dependence on environmental variability and predictability. Our analyses reveal unexpected patterns of optimal energy allocation. When energy availability is low, all energy is allocated to reproduction, although this implies that individuals will not survive after reproduction. Above a certain threshold of energy availability, the optimal reproductive investment decreases to a minimum and even vanishes entirely in highly variable environments. With further improving energy availability, optimal reproductive investment gradually increases again. Costs of plasticity affect this allocation pattern only quantitatively. Our results show that optimal reproductive investment does not increase monotonically with growing energy availability and that small changes in energy availability can lead to major variations in optimal energy allocation. Our results help to unify two apparently opposing predictions from life-history theory, that organisms should increase reproductive investment both with improved environmental conditions and when conditions deteriorate (“terminal investment”).
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影响因子：
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