Data from: Courting disaster: how diversification rate affects fitness under risk

Life is full of risk. To deal with this uncertainty, many organisms have evolved bet-hedging strategies that spread risk through phenotypic diversification. These rates of diversification can vary by orders of magnitude in different species. Here we examine how key characteristics of risk and organismal ecology affect the fitness consequences of variation in diversification rate. We find that rapid diversification is strongly favored when the risk faced has a wide spatial extent, with a single disaster affecting a large fraction of the population. This advantage is especially great in small populations subject to frequent disaster. In contrast, when risk is correlated through time, slow diversification is favored because it allows adaptive tracking of disasters that tend to occur in series. Naturally-evolved diversification mechanisms in diverse organisms facing a broad array of environmental risks largely support these results. The theory presented in this paper provides a testable ecological hypothesis to explain the prevalence of slow stochastic switching among microbes and rapid, within-clutch diversification strategies among plants and animals.

生命处处潜藏风险。为应对这种不确定性，诸多生物演化出风险对冲（bet-hedging）策略，通过表型多样化分散风险。不同物种的表型多样化速率可相差数个数量级。本研究探讨了风险核心特征与生物生态学特性如何影响多样化速率差异带来的适合度后果。研究结果表明：当所面临的风险具有广泛空间波及范围——即单次灾害可影响种群的大部分个体时，快速多样化会受到强烈的正向选择；在频繁遭遇灾害的小型种群中，这一优势尤为显著。反之，当风险随时间呈现相关性（即灾害倾向于连续发生）时，缓慢的多样化则更受青睐，因为该策略可使种群适应性追踪连续发生的灾害事件。针对各类环境风险的多样生物中，其自然演化形成的多样化机制大体与本研究结论相符。本文提出的理论可提供一个可检验的生态学假说，用以解释微生物中普遍存在的缓慢随机切换策略，以及动植物常见的同窝（clutch）内快速多样化策略。