Yanchukov Alexey, Proulx Stephen R
Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, California, United States of America.
PLoS One. 2014 Feb 14;9(2):e88651. doi: 10.1371/journal.pone.0088651. eCollection 2014.
A steady influx of a single deleterious multilocus genotype will impose genetic load on the resident population and leave multiple descendants carrying various numbers of the foreign alleles. Provided that the foreign types are rare at equilibrium, and all immigrant genes are eventually eliminated by selection, the population structure can be inferred explicitly from the branching process taking place within a single immigrant lineage. Unless the migration and recombination rates were high, this novel method gives a close approximation to the simulation with all possible multilocus genotypes considered. Once the load and the foreign genotypes frequencies are known, it becomes possible to estimate selection acting on the invading modifiers of (i) dominance and (ii) recombination rate on the foreign gene block. We found that the modifiers of the (i) type are able to invade faster than the type (ii) modifier, however, this result only applies in the strong selection/low migration/low recombination scenario. Varying the number of genes in the immigrant genotype can have a non-monotonic effect on the migration load and the modifier's invasion rate: although blocks carrying more genes can give rise to longer lineages, they also experience stronger selection pressure. The heaviest load is therefore imposed by the genotypes carrying moderate numbers of genes.
单一有害多位点基因型的持续涌入会给本地种群带来遗传负荷，并留下携带不同数量外来等位基因的多个后代。假设外来类型在平衡状态下很罕见，且所有移民基因最终都会被选择淘汰，那么种群结构可以从单个移民谱系内发生的分支过程中明确推断出来。除非迁移率和重组率很高，这种新方法能非常接近地模拟考虑所有可能多位点基因型的情况。一旦知道了负荷和外来基因型频率，就有可能估计作用于外来基因块上（i）显性和（ii）重组率的入侵修饰因子的选择作用。我们发现，（i）类修饰因子比（ii）类修饰因子能更快地入侵，然而，这一结果仅适用于强选择/低迁移/低重组的情况。改变移民基因型中的基因数量会对迁移负荷和修饰因子的入侵率产生非单调影响：尽管携带更多基因的基因块可以产生更长的谱系，但它们也会经历更强的选择压力。因此，携带中等数量基因的基因型会带来最重的负荷。
