Data from: Detecting genes for variation in parasite burden and immunological traits in a wild population: testing the candidate gene approach

Identifying the genes underlying phenotypic variation in natural
populations can provide novel insight into the evolutionary process. Here
we test the candidate gene approach to identifying loci involved in
variation in gastrointestinal parasite burden, in a wild population of
Soay sheep. A comprehensive literature review, Gene Ontology databases,
and comparative genomics resources were used to generate a list of
candidate genes. In a pilot study these candidates, along with 50 random
genes, were then sequenced in pools of Soay sheep with low and high
gastrointestinal nematode burden. Further candidates were identified from
SNPs that were highly differentiated between high and low resistance sheep
breeds. A panel of 192 candidate and control SNPs were then typed in 960
individual Soay sheep to examine whether they individually explained
variation in parasite burden, as measured as faecal egg count (FEC), as
well as two immune measures. The cumulative effect of the candidate and
control SNPs were estimated by fitting genetic relationship matrices
(GRMs) as random effects in animal models of the three traits. No more
significant SNPs were identified in the pilot sequencing experiment and
association study than expected by chance. Furthermore, no significant
difference was found between the proportions of candidate or control SNPs
that were found to be significantly associated with parasite burden/immune
measures. No significant effect of the candidate or control gene GRMs was
found. There is thus little support for the candidate gene approach to the
identification of loci explaining variation in parasitological and
immunological traits in this population.