How Have Self-Incompatibility Haplotypes Diversified? Generation of New Haplotypes during the Evolution of Self-Incompatibility from Self-Compatibility
How Have Self-Incompatibility Haplotypes Diversified? Generation of New Haplotypes during the Evolution of Self-Incompatibility from Self-Compatibility
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DOI：
10.1086/687110
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发表时间：
2016-06
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影响因子：
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通讯作者：
S. Sakai
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文献类型：
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作者：
S. Sakai
我开发了一个配子体自交不亲和(SI)模型来研究导致SI单倍型多样化的条件。在该模型中，SI系统被认为是不完整的，并且表达给定专一性的花粉不会被表达相同专一性的雌蕊完全排斥。我还假设可以发生突变，增强具有相同单倍型变体的雌蕊对花粉的排斥，并减少具有相同单倍型变体的雌蕊对花粉的排斥。我发现，如果发生这样的突变，新的单倍型(突变变种)可以稳定地与产生突变的祖先单倍型共存。这是因为带有新单倍型的花粉在群体中的雌蕊中最强烈地被带有相同单倍型的雌蕊拒绝；因此，负频率依赖的选择阻止了它们的固定。我还进行了模拟，发现几乎完整的SI系统是从完全自交相容的种群进化而来的，SI单倍型可以在几千代内增加到大约40-50种。根据我的发现，我认为在SI从自交亲和的进化过程中，SI单倍型发生了多样化。
I developed a gametophytic self-incompatibility (SI) model to study the conditions leading to diversification in SI haplotypes. In the model, the SI system is assumed to be incomplete, and the pollen expressing a given specificity is not fully rejected by the pistils expressing the same specificity. I also assumed that mutations can occur that enhance the rejection of pollen by pistils with the same haplotype variant and reduce rejection by pistils with other variants in the same haplotype. I found that if such mutations occur, the new haplotypes (mutant variants) can stably coexist with the ancestral haplotype in which the mutant arose. This is because pollen bearing the new haplotype is most strongly rejected by pistils bearing the same new haplotype among the pistils in the population; hence, negative frequency-dependent selection prevents their fixation. I also performed simulations and found that the nearly complete SI system evolves from completely self-compatible populations and that SI haplotypes can increase to about 40–50 within a few thousand generations. On the basis of my findings, I propose that diversification of SI haplotypes occurred during the evolution of SI from self-compatibility.