CGC Bibliography Paper 5273

Levels of DNA polymorphism vary with mating system in the nematode genus Caenorhabditis.

Graustein A, Gaspar JM, Walters JR, Palopoli MF

Medline:

12019226

Citation:

Genetics 161: 99-107 2002

Type:

ARTICLE

Genes:

glp-1 spe-9 tra-2

Abstract:

Self-fertilizing species often harbor less genetic variation than cross-fertilizing species, and at least four different models have been proposed to explain this trend. To investigate further the relationship between mating system and genetic variation, levels of DNA sequence polymorphism were compared among three closely related species in the genus Caenorhabditis: two self-fertilizing species, Caenorhabditis elegans and C. briggsae, and one cross-fertilizing species, C. remanei. As expected, estimates of silent site nucleotide diversity were lower in the two self-fertilizing species. For the mitochondrial genome, diversity in the selling species averaged 42% of diversity in C. remanei. Interestingly, the reduction in genetic variation was much greater for the nuclear than for the mitochondrial genome. For two nuclear genes, diversity in the selfing species averaged 6 and 13% of diversity in C. remanei. We argue that either population bottlenecks or the repeated action of natural selection, coupled with high levels of selfing, are likely to explain the observed reductions in species-wide genetic diversity.