epistatic selection

Rohlfs RV, Swanson WJ & Weir BS 2010 Detecting coevolution through allelic association between physically unlinked loci. Am J Hum Genet 86:674-685.

• we propose using both composite linkage disequilibrium (CLD) and a measure of association between genotypes, which we call genotype association (GA)

• in abalone, physically unlinked gamete receptor genes were recently found to be in linkage disequilibrium

• even across chromosomes, functionally related genes have higher LD than do functionally unrelated genes in Drosophila¹² and between inbred mouse lines¹³
• however, see ¹⁴

• most cases of selective advantage for specific allele pairing would be resolved with fixation of the optimal allele pair
• for sustained selection-induced allele pairing, additional forces must maintain polymorphism

• we propose allelic association as an indicator of selection for allele pairing
• LD is typically thought of as a measure of recombination rate correlated with physical distance
• LD was originally devised to detect allelic association due to epistatic selection

• we are interested in association between paternal egg receptor (ZP3R) alleles and maternal sperm receptor (ZP3) alleles, which is quantified in a specific nongametic allelic association, rather than gametic LD
• we consider population-based data, in which there is no gametic phase information
• instead of haplotypic gametic or nongametic LD, we use genotypic association measures, which include the relevant nongametic allelic association along with other allelic associations