Patterns of nucleotide polymorphism distinguish temperate and tropical wild isolates of Caenorhabditis briggsae

Asher D. Cutter, Marie-Anne Felix, Antoine Barriere, Deborah Charlesworth

Research output: Contribution to journalArticlepeer-review

Abstract

Caenorhabditis briggsae provides a natural comparison species for the model nematode C. elegans, given their similar morphology, life history, and hermaphroditic mode of reproduction. Despite C. briggsae boasting a published genome sequence and establishing Caenorhabditis as a model genus for genetics and development, little is known about genetic variation across the geographic range of this species. In this study, we greatly expand the collection of natural isolates and characterize patterns of nucleotide variation for six loci in 63 strains from three continents. The pattern of polymorphisms reveals differentiation between C. briggsae strains found in temperate localities in the northern hemisphere from those sampled near the Tropic of Cancer, with diversity within the tropical region comparable to what is found for C. elegans in Europe. As in C. elegans, linkage disequilibrium is pervasive, although recombination is evident among some variant sites, indicating that outcrossing has occurred at a low rate in the history of the sample. In contrast to C. elegans, temperate regions harbor extremely little variation, perhaps reflecting colonization and recent expansion of C. briggsae into northern latitudes. We discuss these findings in relation to their implications for selection, demographic history, and the persistence of self-fertilization.

Original languageEnglish
Pages (from-to)2021-2031
Number of pages11
JournalGenetics
Volume173
Issue number4
DOIs
Publication statusPublished - Aug 2006

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