Searching for Signals of Selection in Sled Dogs

Racing sled-dogs are a good illustration of how working dogs are selected and breeds are created.  In this study, signals of selection were analyzed within sled dogs, focusing on variation in performance between dogs classified as “sprinters” versus “distance” runners. Sprinters have been optimized for speed, traversing courses of up to 30 miles. Distance runners have undergone selection for extreme endurance, running races traversing over 1000 miles. Multiple breeds have been introduced into the sled-dog population in an attempt to enhance performance; using several genome analysis tests we were able to identify the impact of these introductions on breed development. A principle component analysis (PCA), marker based Fst, and identification of runs of homozygosity were used to provide insight regarding genetic differentiation of these two classifications of dogs and how they vary from pure-breeds.  The outputs of the PCA verified that significant genetic differentiation existed between sprint and distance dogs. Following PCA, runs of homozygosity (ROH) were identified and grouped by size.  When comparing the two classifications, distance dogs exhibited a higher number of average runs (168) than sprinters (130) and also had a larger percentage of longer runs suggesting increased inbreeding.  A homozygosity association test identified ROH correlated to either performance classification within sled dog or as compared to ancestral breeds. Biological significance of genomic variants was investigated using PANTHER gene pathway analysis.