Schierup Mikkel H, Bechsgaard Jesper S, Christiansen Freddy B
Department of Ecology and Genetics, Institute of Biology, University of Aarhus, 8000 Aarhus C, Denmark.
Genetics. 2008 Oct;180(2):1051-9. doi: 10.1534/genetics.108.088799. Epub 2008 Sep 9.
We survey the distribution of haplotypes at the self-incompatibility (SI) locus of Arabidopsis lyrata (Brassicaceae) at 12 locations spread over the species' natural distribution in Iceland. Previous investigations of the system have identified 34 functionally different S haplotypes maintained by frequency-dependent selection and arranged them into four classes of dominance in their phenotypic expression. On the basis of this model of dominance and the island model of population subdivision, we compare the distribution of S haplotypes with that expected from population genetic theory. We observe 18 different S haplotypes, recessive haplotypes being more common than dominant ones, and dominant ones being shared by fewer populations. As expected, differentiation, although significant, is very low at the S locus even over distances of up to 300 km. The frequency of the most recessive haplotype is slightly larger than expected for a panmictic population, but consistent with a subdivided population with the observed differentiation. Frequencies in nature reflect effects of segregation distortion previously observed in controlled crosses. The dynamics of the S-locus variation are, however, well represented by a 12-island model and our simplified model of dominance interactions.
我们调查了冰岛拟南芥（十字花科）自交不亲和（SI）位点单倍型在该物种自然分布范围内12个地点的分布情况。此前对该系统的研究已鉴定出34种由频率依赖选择维持的功能不同的S单倍型，并根据其表型表达将它们分为四类显性。基于这种显性模型和种群细分的岛屿模型，我们将S单倍型的分布与种群遗传理论预期的分布进行了比较。我们观察到18种不同的S单倍型，隐性单倍型比显性单倍型更常见，且显性单倍型在较少的种群中共享。正如预期的那样，即使在长达300公里的距离上，S位点的分化虽然显著，但非常低。最隐性单倍型的频率略高于随机交配种群的预期频率，但与具有观察到的分化的细分种群一致。自然中的频率反映了先前在控制杂交中观察到的分离畸变效应。然而，S位点变异的动态很好地由一个12岛模型和我们简化的显性相互作用模型表示。
