Barrière Antoine, Félix Marie-Anne
Institut Jacques Monod, CNRS-Universities of Paris 6 and 7, 75251 Paris Cedex 05, France.
Genetics. 2007 Jun;176(2):999-1011. doi: 10.1534/genetics.106.067223. Epub 2007 Apr 3.
Caenorhabditis elegans is a major laboratory model system yet a newcomer to the field of population genetics, and relatively little is known of its biology in the wild. Recent studies of natural populations at a single time point revealed strong spatial population structure and suggested that these populations may be very dynamic. We have therefore studied several natural C. elegans populations over time and genotyped them at polymorphic microsatellite loci. While some populations appear to be genetically stable over the course of observation, others seem to go extinct, with full replacement of multilocus genotypes upon regrowth. The frequency of heterozygotes indicates that outcrossing occurs at a mean frequency of 1.7% and is variable between populations. However, in genetically stable populations, linkage disequilibrium between different chromosomes can be maintained over several years at a level much higher than expected from the heterozygote frequency. C. elegans seems to follow metapopulation dynamics, and the maintenance of linkage disequilibrium despite a low yet significant level of outcrossing suggests that selection may act against the progeny of outcrossings.
秀丽隐杆线虫是一种主要的实验室模型系统，但在群体遗传学领域却是一个新成员，人们对其在自然环境中的生物学特性了解相对较少。近期对自然种群在单一时间点的研究揭示了强烈的空间种群结构，并表明这些种群可能非常动态。因此，我们长期研究了几个秀丽隐杆线虫自然种群，并在多态微卫星位点对它们进行了基因分型。虽然在观察过程中一些种群似乎基因稳定，但其他种群似乎灭绝了，重新生长时多位点基因型被完全取代。杂合子频率表明异交发生的平均频率为1.7%，且在不同种群间存在差异。然而，在基因稳定的种群中，不同染色体之间的连锁不平衡可以在几年内维持在一个比根据杂合子频率预期的水平高得多的水平。秀丽隐杆线虫似乎遵循集合种群动态，尽管异交水平较低但显著，连锁不平衡的维持表明选择可能作用于异交后代。
