Vitalis Renaud, Glémin Sylvain, Olivieri Isabelle
Laboratoire Genetique et Environnement, C C 065, Institut des Sciences de l'Evolution de Montpellier, Universite Montpellier II, 34095 Montpellier Cedex 05, France.
Am Nat. 2004 Feb;163(2):295-311. doi: 10.1086/381041. Epub 2004 Feb 13.
In many annual plant populations, seeds may be dormant for several seasons before they germinate. Here, we investigate the consequences of both conditional (dispersed seeds cannot enter a dormant stage) and unconditional seed dormancy on the amount and the distribution of neutral genetic diversity within and among populations. We present joint demographic and population genetics models for single and subdivided populations and derive the effective size and population differentiation at both local and metapopulation scales. We suggest that a Wahlund effect is unlikely to result from age structure alone. Furthermore, the differentiation among populations is decreased by the presence of seed banks. We also extend these models to describe monocarpic (semelparous) perennial life cycle, where the nonreproductive stages are vegetative rosettes instead of dormant seeds. The main difference between the models relies in the way the density-dependent regulation is acting. The effective size of monocarpic perennial species may be less than the census number of individuals, and among-population differentiation is always larger than in annual species. We discuss our results in the light of recent population genetics surveys of annual plants with seed banks.
在许多一年生植物种群中，种子在萌发前可能会休眠几个季节。在此，我们研究了条件性（散布的种子无法进入休眠阶段）和无条件种子休眠对种群内部和种群间中性遗传多样性的数量和分布的影响。我们提出了针对单一和细分种群的联合种群统计学和种群遗传学模型，并推导了局部和集合种群尺度下的有效种群大小和种群分化。我们认为，仅年龄结构不太可能导致瓦伦德效应。此外，种子库的存在会降低种群间的分化。我们还扩展了这些模型以描述单次结果实（一年生）多年生生命周期，其中非生殖阶段是营养莲座叶而不是休眠种子。模型之间的主要差异在于密度依赖调节的作用方式。单次结果实多年生物种的有效种群大小可能小于个体普查数量，并且种群间分化始终大于一年生物种。我们根据最近对具有种子库的一年生植物进行的种群遗传学调查来讨论我们的结果。
