Alleaume-Benharira M, Pen I R, Ronce O
Laboratoire Génétique et Environnement, Université de Montpellier II, Institut des Sciences de l'Evolution, Montpellier Cedex, France.
J Evol Biol. 2006 Jan;19(1):203-15. doi: 10.1111/j.1420-9101.2005.00976.x.
We use individual-based stochastic simulations and analytical deterministic predictions to investigate the interaction between drift, natural selection and gene flow on the patterns of local adaptation across a fragmented species' range under clinally varying selection. Migration between populations follows a stepping-stone pattern and density decreases from the centre to the periphery of the range. Increased migration worsens gene swamping in small marginal populations but mitigates the effect of drift by replenishing genetic variance and helping purge deleterious mutations. Contrary to the deterministic prediction that increased connectivity within the range always inhibits local adaptation, simulations show that low intermediate migration rates improve fitness in marginal populations and attenuate fitness heterogeneity across the range. Such migration rates are optimal in that they maximize the total mean fitness at the scale of the range. Optimal migration rates increase with shallower environmental gradients, smaller marginal populations and higher mutation rates affecting fitness.
我们使用基于个体的随机模拟和解析确定性预测，来研究在渐变选择下，漂变、自然选择和基因流之间的相互作用对一个分布破碎的物种在其分布范围内局部适应模式的影响。种群间的迁移遵循踏脚石模式，密度从分布范围的中心向边缘递减。迁移增加会加剧边缘小种群中的基因淹没现象，但通过补充遗传变异和帮助清除有害突变来减轻漂变的影响。与分布范围内连通性增加总是抑制局部适应的确定性预测相反，模拟表明，中等偏低的迁移率会提高边缘种群的适合度，并减弱整个分布范围内的适合度异质性。这样的迁移率是最优的，因为它们在分布范围尺度上使总平均适合度最大化。最优迁移率随着环境梯度变浅、边缘种群变小以及影响适合度的突变率升高而增加。
