Section for Climate and Environmental Modelling, Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, N-0349 Oslo, Norway.
Biol Rev Camb Philos Soc. 2012 Aug;87(3):742-55. doi: 10.1111/j.1469-185X.2012.00225.x. Epub 2012 Mar 10.
In unpredictably varying environments, strategies that have a reduced variance in fitness can invade a population consisting of individuals that on average do better. Such strategies 'hedge their evolutionary bets' against the variability of the environment. The idea of bet-hedging arises from the fact that appropriate measure of long-term fitness is sensitive to variance, leading to the potential for strategies with a reduced mean fitness to invade and increase in frequency. Our aim is to review the conceptual foundation of bet-hedging as a mechanism that influences short- and long-term evolutionary processes. We do so by presenting a general model showing how evolutionary changes are affected by variance in fitness and how genotypic variance in fitness can be separated into variance in fitness at the level of the individuals and correlations in fitness among them. By breaking down genotypic fitness variance in this way the traditional divisions between conservative and diversified strategies are more easily intuited, and it is also shown that this division can be considered a false dichotomy, and is better viewed as two extreme points on a continuum. The model also sheds light on the ideas of within- and between-generation bet-hedging, which can also be generalized to be seen as two ends of a different continuum. We use a simple example to illustrate the virtues of our general model, as well as discuss the implications for systems where bet-hedging has been invoked as an explanation.
在不可预测的变化环境中，适应度方差降低的策略可以入侵由平均表现更好的个体组成的种群。这些策略“对冲”了环境变化的风险。赌注对冲的想法源于这样一个事实，即适当的长期适应度衡量标准对方差敏感，这使得平均适应度降低的策略有了入侵和增加频率的潜力。我们的目的是回顾赌注对冲作为一种影响短期和长期进化过程的机制的概念基础。为此，我们提出了一个通用模型，展示了适应度方差如何影响进化变化，以及适应度的基因型方差如何分为个体水平的适应度方差和它们之间的适应度相关性。通过以这种方式分解基因型适应度方差，可以更容易地理解传统的保守策略和多样化策略之间的区别，并且还表明这种划分可以被视为一个错误的二分法，而更好地被视为一个连续体上的两个极端点。该模型还阐明了代内和代间赌注对冲的思想，也可以将其推广为不同连续体的两个端点。我们使用一个简单的例子来说明我们的通用模型的优点，并讨论赌注对冲作为解释被引用的系统的含义。
