期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2017
卷号：114
期号：44
页码：11582-11590
DOI：10.1073/pnas.1710679114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We analyze the stochastic demography and evolution of a density-dependent age- (or stage-) structured population in a fluctuating environment. A positive linear combination of age classes (e.g., weighted by body mass) is assumed to act as the single variable of population size, N , exerting density dependence on age-specific vital rates through an increasing function of population size. The environment fluctuates in a stationary distribution with no autocorrelation. We show by analysis and simulation of age structure, under assumptions often met by vertebrate populations, that the stochastic dynamics of population size can be accurately approximated by a univariate model governed by three key demographic parameters: the intrinsic rate of increase and carrying capacity in the average environment, r 0 and K , and the environmental variance in population growth rate, σ e 2 . Allowing these parameters to be genetically variable and to evolve, but assuming that a fourth parameter, θ , measuring the nonlinearity of density dependence, remains constant, the expected evolution maximizes E [ N θ ] = [ 1 − σ e 2 / ( 2 r 0 ) ] K θ . This shows that the magnitude of environmental stochasticity governs the classical trade-off between selection for higher r 0 versus higher K . However, selection also acts to decrease σ e 2 , so the simple life-history trade-off between r - and K -selection may be obscured by additional trade-offs between them and σ e 2 . Under the classical logistic model of population growth with linear density dependence ( θ = 1 ), life-history evolution in a fluctuating environment tends to maximize the average population size.
关键词：age distribution ; environmental variance ; evolutionary maximization ; r -selection ; K -selection
