Identifying the genetic architecture underlying complex phenotypes is a notoriously difficult problem that often impedes progress in understanding adaptive eco-evolutionary processes in natural populations. Host–parasite interactions are fundamentally important drivers of evolutionary processes, but a lack of understanding of the genes involved in the host's response to chronic parasite insult makes it particularly difficult to understand the mechanisms of host life history trade-offs and the adaptive dynamics involved. Here, we examine the genetic basis of gastrointestinal nematode (Trichostrongylus tenuis) burden in 695 red grouse (Lagopus lagopus scotica) individuals genotyped at 384 genome-wide SNPs. We first use genome-wide association to identify individual SNPs associated with nematode burden. We then partition genome-wide heritability to identify chromosomes with greater heritability than expected from gene content, due to harbouring a multitude of additive SNPs with individually undetectable effects. We identified five SNPs on five chromosomes that accounted for differences of up to 556 worms per bird, but together explained at best 4.9% of the phenotypic variance. These SNPs were closely linked to genes representing a range of physiological processes including the immune system, protein degradation and energy metabolism. Genome partitioning indicated genome-wide heritability of up to 29% and three chromosomes with excess heritability of up to 4.3% (total 8.9%). These results implicate SNPs and novel genomic regions underlying nematode burden in this system and suggest that this phenotype is somewhere between being based on few large-effect genes (oligogenic) and based on a large number of genes with small individual but large combined effects (polygenic).
PLINK MAP file for 271 genome-wide SNPs: PLINK MAP file containing chromosomal locations of 271 SNPs that passed quality control.
SNP genotypes of 695 red grouse individuals: Tab-delimited text file containing SNP genotypes for 695 samples, in truncated PLINK PED format.
Metadata (sampling-related and phenotype data) for 695 red grouse individuals:
Tab-delimited text file containing sampling-related and phenotype data for 695 individuals.
This work is licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license.
- Ecological Genetics
- Host Parasite Interactions
- Lagopus lagopus scotica
- Trichostrongylus tenuis