Data from: Environmental fluctuations promote intraspecific diversity and population persistence via inflationary effects

The impact of temporal variation in the environment, specifically the amount of temporal autocorrelation, on population processes is of growing interest in ecology and evolutionary biology. It was recently discovered that temporal autocorrelation in the environment can significantly increase the abundance of populations that would otherwise have low, or even negative long-term growth rates (via so-called ‘inflationary effects’), provided that immigration from another source prevents extinction. Here we use a mathematical model to ask whether inflationary effects can also increase population persistence without immigration if different phenotypes within that population partition growth over time and buffer each other from extinction via mutation. Using a combination of analytical and numerical methods, we find that environmental autocorrelation can inflate the abundance of phenotypes that would otherwise be excluded from the population, provided that phenotypes are sufficiently different in their use of the environment. This inflation of abundance at the phenotypic level also generates an inflation of abundance at the population level. Remarkably, intraspecific inflationary effects can increase both phenotypic and whole population abundance even if one or all phenotypes are maladapted to the environment, as long as mutations prevent phenotypic extinction during periods of poor environmental conditions. Given the prevalence of temporally autocorrelated environmental variables in nature, intraspecific inflationary effects have the potential to be of widespread importance for population persistence as well as the maintenance of intraspecific diversity.

环境的时间变异，尤其是时间自相关（temporal autocorrelation）程度对种群过程的影响，正日益受到生态学与进化生物学领域的关注。近期研究发现，环境中的时间自相关可通过所谓的"通胀效应（inflationary effects）"显著提升原本长期增长率较低甚至为负的种群丰度，前提是外源迁入能够阻止种群灭绝。本文采用数学模型，探究在无外源迁入的情境下，若种群内不同表型（phenotype）在时间维度上分配增长机会，并通过突变相互缓冲以避免灭绝，那么通胀效应是否同样能够提升种群存续能力。结合解析法与数值模拟方法，我们发现：当表型对环境的利用方式存在足够显著的差异时，环境自相关可使原本会被种群排除的表型丰度得到提升。这种表型层面的丰度提升，同样会带动种群整体丰度的增长。值得注意的是，即便一种或所有表型均不适应环境，只要突变能够在环境条件恶劣的时期阻止表型灭绝，种内通胀效应仍可同时提升表型与种群整体的丰度。鉴于自然界中存在大量具有时间自相关特性的环境变量，种内通胀效应有望对种群存续以及种内多样性维持产生广泛的重要意义。