title: Quantitative trait loci (QTL) mapping of resistance to strongyles and coccidia in the free-living Soay sheep (Ovis aries).
abstract: A genome-wide scan was performed to detect quantitative trait loci (QTL) for resistance to gastrointestinal parasites and ectoparasitic keds segregating in the free-living Soay sheep population on St. Kilda (UK). The mapping panel consisted of a single pedigree of 882 individuals of which 588 were genotyped. The Soay linkage map used for the scans comprised 251 markers covering the whole genome at average spacing of 15cM. The traits here investigated were the strongyle faecal egg count (FEC), the coccidia faecal oocyst count (FOC) and a count of keds (Melophagus ovinus). QTL mapping was performed by means of variance component analysis so that the genetic parameters of the study traits were also estimated and compared with previous studies in Soay and domestic sheep. Strongyle FEC and coccidia FOC showed moderate heritability (h(2)=0.26 and 0.22, respectively) in lambs but low heritability in adults (h(2)<0.10). Ked count appeared to have very low h(2) in both lambs and adults. Genome scans were performed for the traits with moderate heritability and two genomic regions reached the level of suggestive linkage for coccidia FOC in lambs (logarithm of the odds=2.68 and 2.21 on chromosomes 3 and X, respectively). We believe this is the first study to report a QTL search for parasite resistance in a free-living animal population and therefore may represent a useful reference for similar studies aimed at understanding the genetics of host-parasite co-evolution in the wild.
authors.affiliation: Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, UK. dario.beraldi@ed.ac.uk
authors.forename: Dario
authors.initials: D
authors.lastname: Beraldi
authors.forename: Allan F
authors.initials: AF
authors.lastname: McRae
authors.forename: Jacob
authors.initials: J
authors.lastname: Gratten
authors.forename: Jill G
authors.initials: JG
authors.lastname: Pilkington
authors.forename: Jon
authors.initials: J
authors.lastname: Slate
authors.forename: Peter M
authors.initials: PM
authors.lastname: Visscher
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Pemberton
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D003044:Coccidia / Q000235:genetics; D003048:Coccidiosis / Q000235:genetics / Q000662:veterinary*; D004478:Ectoparasitic Infestations / Q000235:genetics / Q000662:veterinary; D008040:Genetic Linkage / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D007411:Intestinal Diseases, Parasitic / Q000235:genetics / Q000662:veterinary; D010641:Phenotype; D011529:Protozoan Infections, Animal / Q000235:genetics*; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D012756:Sheep / Q000469:parasitology; D012757:Sheep Diseases / Q000235:genetics*; D034561:Sheep, Domestic / Q000469:parasitology; D017183:Strongylida / Q000235:genetics; D017206:Strongylida Infections / Q000235:genetics / Q000662:veterinary*; D013987:Ticks
chemical_list: D005819:Genetic Markers