Generalists versus specialists in fluctuating environments: a bet-hedging perspective
Generalists versus specialists in fluctuating environments: a bet-hedging perspective
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DOI：
10.1111/oik.07109
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发表时间：
2020-06-01
期刊：
影响因子：
3.4
通讯作者：
Ratikainen, Irja Ida
中科院分区：
文献类型：
--
作者：
Haaland, Thomas Ray;Wright, Jonathan;Ratikainen, Irja Ida
下注对冲在波动的环境中进化，因为长期的基因型成功是由世代间的几何（而不是算术）平均适应度决定的。多样化的押注对冲产生不同的专家后代，而保守的押注对冲产生相似的通才后代。然而，许多领域，如行为生态学和热生理学，通常只从最大化个体的算术平均适应度利益的角度来考虑专家与通才策略。在这里，我们建立了环境可变性如何影响个体内部和个体之间表型变异的最佳数量，以最大化基因型适应度的模型，并通过比较长期算术和几何平均适应度来解耦个体水平优化和基因型水平下注对冲的影响。对于在一生中具有加性适应度效应的性状（例如，与觅食相关的性状），相似的通才或多样化的专才的基因型表现同样良好。然而，如果适应度效应在一生中是倍增的（例如，顺序生存概率），通才个体总是更受青睐。在这种情况下，几何平均适应度优化需要比算术平均适应度更多的个体内表型变异，导致个体更多面手，而不是简单地最大化自己的预期适应度。与之前下注对冲文献的结果相反，这种通才保守下注对冲效应总是比多样化下注对冲效应更受青睐。这些结果将行为和生态专业化的进化与早期的下注对冲模型联系起来，我们将我们的框架应用于从栖息地选择到寄主特异性的一系列自然现象。
Bet-hedging evolves in fluctuating environments because long-term genotype success is determined by geometric (rather than arithmetic) mean fitness across generations. Diversifying bet-hedging produces different specialist offspring, whereas conservative bet-hedging produces similar generalist offspring. However, many fields, such as behavioral ecology and thermal physiology, typically consider specialist versus generalist strategies only in terms of maximizing arithmetic mean fitness benefits to individuals. Here we model how environmental variability affects optimal amounts of phenotypic variation within and among individuals to maximise genotype fitness, and we disentangle the effects of individual-level optimization and genotype-level bet-hedging by comparing long-term arithmetic versus geometric mean fitness. For traits with additive fitness effects within lifetimes (e.g. foraging-related traits), genotypes of similar generalists or diversified specialists perform equally well. However, if fitness effects are multiplicative within lifetimes (e.g. sequential survival probabilities), generalist individuals are always favored. In this case, geometric mean fitness optimization requires even more within-individual phenotypic variation than does arithmetic mean fitness, causing individuals to be more generalist than required to simply maximize their own expected fitness. In contrast to previous results in the bet-hedging literature, this generalist conservative bet-hedging effect is always favored over diversifying bet-hedging. These results link the evolution of behavioral and ecological specialization with earlier models of bet-hedging, and we apply our framework to a range of natural phenomena from habitat choice to host specificity in parasites.