Department of Animal Ecology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, Uppsala, Sweden.
Bull Math Biol. 2011 Jul;73(7):1666-81. doi: 10.1007/s11538-010-9587-3. Epub 2010 Oct 7.
The probability of, and time to, fixation of a mutation in a population has traditionally been studied by the classic Wright-Fisher model where population size is constant. Recent theoretical expansions have covered fluctuating populations in various ways but have not incorporated models of how the environment fluctuates in combination with different levels of density-compensation affecting fecundity. We tested the hypothesis that the probability of, and time to, fixation of neutral, advantageous and deleterious mutations is dependent on how the environment fluctuates over time, and on the level of density-compensation. We found that fixation probabilities and times were dependent on the pattern of autocorrelation of carrying capacity over time and interacted with density-compensation. The pattern found was most pronounced at small population sizes. The patterns differed greatly depending on whether the mutation was neutral, advantageous, or disadvantageous. The results indicate that the degree of mismatch between carrying capacity and population size is a key factor, rather than population size per se, and that effective population sizes can be very low also when the census population size is far above the carrying capacity. This study highlights the need for explicit population dynamic models and models for environmental fluctuations for the understanding of the dynamics of genes in populations.
传统上，通过经典的 Wright-Fisher 模型研究了群体中突变固定的概率和时间，其中种群大小是恒定的。最近的理论扩展以各种方式涵盖了波动的种群，但没有将环境波动的模型与影响生育力的不同程度的密度补偿结合起来。我们检验了这样一个假设，即中性、有利和有害突变的固定概率和时间取决于环境随时间波动的方式，以及密度补偿的水平。我们发现固定概率和时间取决于时间上承载能力的自相关模式，并与密度补偿相互作用。在小种群中发现的模式最为明显。这种模式因突变是中性的、有利的还是有害的而有很大差异。结果表明，承载能力与种群大小之间的不匹配程度是一个关键因素，而不是种群大小本身，即使在种群数量远远超过承载能力时，有效种群数量也可能非常低。这项研究强调了需要明确的种群动态模型和环境波动模型来理解种群中基因的动态。
