Seidel Hannah S, Rockman Matthew V, Kruglyak Leonid
Lewis-Sigler Institute for Integrative Genomics and Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
Science. 2008 Feb 1;319(5863):589-94. doi: 10.1126/science.1151107. Epub 2008 Jan 10.
Natural selection is expected to eliminate genetic incompatibilities from interbreeding populations. We have discovered a globally distributed incompatibility in the primarily selfing species Caenorhabditis elegans that has been maintained despite its negative consequences for fitness. Embryos homozygous for a naturally occurring deletion of the zygotically acting gene zeel-1 arrest if their sperm parent carries an incompatible allele of a second, paternal-effect locus, peel-1. The two interacting loci are tightly linked, with incompatible alleles occurring in linkage disequilibrium in two common haplotypes. These haplotypes exhibit elevated sequence divergence, and population genetic analyses of this region indicate that natural selection is preserving both haplotypes in the population. Our data suggest that long-term maintenance of a balanced polymorphism has permitted the incompatibility to persist despite gene flow across the rest of the genome.
自然选择预期会从杂交种群中消除遗传不相容性。我们在主要进行自体受精的秀丽隐杆线虫物种中发现了一种全球分布的不相容性，尽管它对适应性有负面影响，但仍得以维持。对于合子作用基因zeel-1自然发生缺失的纯合胚胎，如果其精子亲本携带第二个父本效应位点peel-1的不相容等位基因，就会停止发育。这两个相互作用的位点紧密连锁，不相容等位基因在两种常见单倍型中处于连锁不平衡状态。这些单倍型表现出较高的序列差异，对该区域的群体遗传学分析表明，自然选择在种群中保留了这两种单倍型。我们的数据表明，尽管整个基因组存在基因流动，但平衡多态性的长期维持使得这种不相容性得以持续存在。
