A Study of Biodiversity of Russian Local Sheep Breeds Based on Pattern of Runs of Homozygosity ^†

A rapid spreading of cosmopolite breeds leads to decrease of population sizes of Russian local sheep that consequently might result in their biodiversity loss. Estimation of the runs of homozygosity (ROH) in local sheep genomes is an informative tool to address their current genetic state. In this work, we aimed to address the distribution of the ROH and to estimate genome inbreeding in Russian local sheep breeds based on SNP-genotyping. Medium-density SNP-genotypes of twenty-three local sheep breeds (n = 332) were obtained in our previous study. We used a consecutive runs method implemented in the R package “detectRUNS” to calculate ROH which were estimated for each animal and then categorized in the ROH length classes (1–2 Mb, 2–4 Mb, 4–8 Mb, 8–16 Mb, >16 Mb). The frequency of short ROH segments (≤2 Mb) were the highest in all studied breeds (63.15–93.10%). The longest segments (>16 Mb) were the least frequent and were missing in four breeds. The genomic coefficients based on ROH estimation varied from medium (0.114) to low (0.035). Thus, we found that Russian local sheep breeds are characterized by a low level of genomic inbreeding.