Whitlock Michael C
Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
Genetics. 2002 Mar;160(3):1191-202. doi: 10.1093/genetics/160.3.1191.
The subdivision of a species into local populations causes its response to selection to change, even if selection is uniform across space. Population structure increases the frequency of homozygotes and therefore makes selection on homozygous effects more effective. However, population subdivision can increase the probability of competition among relatives, which may reduce the efficacy of selection. As a result, the response to selection can be either increased or decreased in a subdivided population relative to an undivided one, depending on the dominance coefficient F(ST) and whether selection is hard or soft. Realistic levels of population structure tend to reduce the mean frequency of deleterious alleles. The mutation load tends to be decreased in a subdivided population for recessive alleles, as does the expected inbreeding depression. The magnitude of the effects of population subdivision tends to be greatest in species with hard selection rather than soft selection. Population structure can play an important role in determining the mean fitness of populations at equilibrium between mutation and selection.
一个物种细分为多个局部种群会导致其对选择的响应发生变化，即便选择在空间上是均匀的。种群结构会增加纯合子的频率，从而使对纯合效应的选择更加有效。然而，种群细分会增加亲属间竞争的可能性，这可能会降低选择的效力。因此，相对于未细分的种群，细分种群对选择的响应可能增加也可能减少，这取决于显性系数F(ST)以及选择是强选择还是弱选择。实际的种群结构水平往往会降低有害等位基因的平均频率。对于隐性等位基因，细分种群中的突变负荷往往会降低，预期的近亲繁殖衰退也是如此。在强选择而非弱选择的物种中，种群细分的影响程度往往最大。种群结构在决定处于突变与选择平衡状态的种群的平均适合度方面可能起着重要作用。
