Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA.
Department of Plant and Microbial Biology, University of Minnesota, St Paul, MN, 55108, USA.
New Phytol. 2021 Aug;231(4):1630-1643. doi: 10.1111/nph.17249. Epub 2021 Feb 27.
Self-incompatibility alleles (S-alleles), which prevent self-fertilisation in plants, have historically been expected to benefit from negative frequency-dependent selection and invade when introduced to a new population through gene flow. However, the most taxonomically widespread form of self-incompatibility, the ribonuclease-based system ancestral to the core eudicots, functions through collaborative non-self recognition, which can affect both short-term patterns of gene flow and the long-term process of S-allele diversification. We analysed a model of S-allele evolution in two populations connected by migration, focussing on comparisons among the fates of S-alleles initially unique to each population and those shared among populations. We found that both shared and unique S-alleles from the population with more unique S-alleles were usually fitter compared with S-alleles from the population with fewer S-alleles. Resident S-alleles often became extinct and were replaced by migrant S-alleles, although this outcome could be averted by pollen limitation or biased migration. Collaborative non-self recognition will usually either result in the whole-sale replacement of S-alleles from one population with those from another or else disfavour introgression of S-alleles altogether.
自交不亲和等位基因（S-alleles）可防止植物的自花授粉，从历史上看，它们有望受益于负频率依赖性选择，并通过基因流在引入新种群时入侵。然而，自交不亲和最具分类学广泛的形式，即核心真双子叶植物的核糖核酸酶为基础的系统，通过协作的非自我识别起作用，这会影响短期的基因流模式和 S-allele 多样化的长期过程。我们分析了通过迁移连接的两个种群中的 S-allele 进化模型，重点比较了最初每个种群特有的 S-alleles 和种群间共享的 S-alleles 的命运。我们发现，与来自 S-alleles 较少种群的 S-alleles 相比，来自 S-alleles 较多种群的共享和独特 S-alleles 通常更适合。尽管花粉限制或偏向性迁移可能会避免这种结果，但居留 S-alleles 通常会灭绝并被移民 S-alleles 取代。协作的非自我识别通常会导致一个种群的 S-alleles 被另一个种群的 S-alleles 全部取代，或者完全不利于 S-alleles 的渐渗。
