Generalists versus specialists in fluctuating environments: a bet-hedging perspective
Generalists versus specialists in fluctuating environments: a bet-hedging perspective
复制标题
波动环境中的通才与专家：对冲视角
DOI：
10.1101/581371
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
I. Ratikainen
中科院分区：
文献类型：
--
作者：
T. R. Haaland;Jonathan Wright;I. Ratikainen
套期保值是在波动的环境中演变的，因为长期的基因型成功取决于世代之间的几何平均适合度。然而，专家和多面手的策略通常是根据个体的算术平均健康益处来考虑的，比如在栖息地或觅食偏好方面。我们对环境变化如何影响个体内部和个体之间的表型差异进行建模，以最大化长期算术适应度与几何平均适应度。对于在一生中具有加性适合度效应的性状(例如与觅食相关的性状)，相似多面手或多样化专家的基因类型表现同样好。然而，如果适应度效应在寿命内是乘性的(例如，序贯生存概率)，则多面手总是受到青睐，因为几何平均适应度比算术平均适应度更有利于个体内的表型差异。有趣的是，这种保守的押注对冲效应胜过了多样化的押注对冲。这些结果将行为和生态的专门化和早期的下注对冲模型联系起来，因此适用于从寄生虫的栖息地选择到宿主专一性的一系列自然现象。影响总结哪些因素决定了成为专家还是多面手更好？由于人类引起的快速环境变化，全球范围内的环境波动正变得更大、更不可预测。因此，进化生物学的一个关键挑战是了解生物体如何适应世代内和世代之间的这种变化，目前这是进化理论中的一个知识鸿沟。在这里，我们关注的是当(不断变化的)环境决定了一个性状的最佳值时，性状是如何演变的，从而使最佳性状值随着时间的推移发生了不可预测的变化。我们的数学模型调查了一个性状的最佳变异程度。我们预计在稳定的环境中，专家(低个体内性状变异)会受到青睐，而多面手(高特质变异)会在更多变的环境中受到青睐。我们表明，答案取决于我们是从个人的角度看，还是从相同基因的所有个人的角度看。如果一个个体在短期内表现良好，但他的后代都经历了不同的环境，因此表现不佳，那么这个基因作为一个整体就有麻烦了，从长远来看，将不会受到青睐。解决这一问题的一种方法可能是培育出具有不同特征价值的后代，以确保至少一些后代无论成长在什么环境条件下都能做得很好。这种“不要把所有鸡蛋放在一个篮子里”的多样化策略在一些生物体中是众所周知的，但如果也有一些个体内部(即多面手)的特征变异，这有多大帮助？通过在不同的环境情景下回答这些问题，我们将进化生态学和动物行为中的许多不同概念联系在一起，增加了我们对生物如何应对当前世界各地环境条件变化的理解。
Bet-hedging evolves in fluctuating environments because long-term genotype success is determined by geometric mean fitness across generations. However, specialist versus generalist strategies are usually considered in terms of arithmetic mean fitness benefits to individuals, as in habitat or foraging preferences. We model how environmental variability affects phenotypic variation within and among individuals to maximize either 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, since geometric mean fitness favors greater within-individual phenotypic variation than arithmetic mean fitness does. Interestingly, this conservative bet-hedging effect outcompetes diversifying bet-hedging. These results link behavioral and ecological specialization and earlier models of bet-hedging, and thus apply to a range of natural phenomena from habitat choice to host specificity in parasites. Impact summary Which factors determine whether it is better to be a specialist or a generalist? Environmental fluctuations are becoming larger and more unpredictable across the globe as a result of human-induced rapid environmental change. A key challenge of evolutionary biology is therefore to understand how organisms adapt to such variation within and among generations, and currently represents a knowledge gap in evolutionary theory. Here we focus on how traits evolve when the (changing) environment determines the optimal value of a trait, so that the optimal trait value changes unpredictably over time. Our mathematical model investigates how much variation is optimal in a trait. We expect specialists (low within-individual trait variation) to be favored in stable environments, with generalists (high trait variation) favored in more variable environments. We show that the answer depends on whether we look from the point of view of the individual or all individuals of the same genotype. If an individual does well in the short term, but its offspring all experience a different environment and therefore do badly, the genotype as a whole is in trouble, and will not be favored in the long term. One solution to this problem could be to produce offspring with different trait values, to ensure that at least some of the offspring do well no matter the environmental conditions they grow up in. This “don’t put all your eggs in one basket” diversification strategy is well-known in some organisms, but how helpful is it if there is also some within-individual (i.e. generalist) trait variation? By answering these questions under various environmental scenarios, we link together many different concepts in evolutionary ecology and animal behavior, increasing our understanding about how organisms may cope with the current changes in environmental conditions around the world.
影响因子：
8.8
作者：
Dall SR;Bell AM;Bolnick DI;Ratnieks FL
通讯作者：
Ratnieks FL