Fig. 4.

Inbreeding and genetic load of predomesticated vs. modern breeds. (A) Genome-wide distribution of heterozygosity estimates for genomic tracks, calculated as the logarithm of the Watterson estimators, averaged across the track and weighted by its length. Transitions were excluded when calculating the Watterson estimators. Genomics tracks are defined as continuous regions of similar Watterson estimator values. The bimodal distributions observed for the modern horses, but not for CGG10022 and CGG10023, are indicative of inbreeding in these individuals. Dashed lines indicate ancient individuals. (B) Additive deleterious mutation load estimated from coding sequences of modern breeds and the high-coverage predomesticated sample (CGG10022), excluding the Thoroughbred Twilight and CGG10023.