Submitted on September 28, 2007
Accepted on December 17, 2007
Widespread Genetic Incompatibility in C. Elegans Maintained by Balancing Selection
Hannah S. Seidel 1
*, Matthew V. Rockman 1*, Leonid Kruglyak 1*
1 Lewis-Sigler Institute for Integrative Genomics and Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
* To whom correspondence should be addressed.
Hannah S. Seidel , E-mail: hseidel{at}princeton.edu
Matthew V. Rockman , E-mail: mrockman{at}princeton.edu
Leonid Kruglyak , E-mail: leonid{at}genomics.princeton.edu
These authors contributed equally to this work.
Natural selection is expected to eliminate genetic incompatibilities from interbreeding populations. We have identified 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.
