Genomic Characterization of the Istrian Shorthaired Hound

SIMPLE SUMMARY: Istrian shorthaired hound is an old indigenous Croatian dog breed. However, there is no data available about its genetic diversity, population structure, and inbreeding level, which would be needed for advanced management and conservation of this breed. We studied the population structure using 220K SNP array and compared the genomic data with the genealogical records. This allowed us to place Istrian shorthaired hound on the map of the world dog populations. The Istrian shorthaired hound has a relatively high effective population size and low level of inbreeding. Its genome contains a higher number of short runs of homozygosity compared to other analysed breeds, thus confirming the old origin of the breed and balanced use of breeding animals. The breed was placed in the same clade with Italian hunting breeds suggesting that the Istrian shorthaired hound was probably used for the development of some of these breeds. The genomic analysis importantly contributes to the development of future breeding strategies and supports the conservation of the Istrian shorthaired hound. ABSTRACT: Istrian shorthaired hound is an old indigenous Croatian dog breed with historical traces of its origin, which date back to the 14th century. Due to its intelligence and great hunting abilities, it is considered an excellent hunting dog. Despite its ancient origin, there is no data on genetic diversity, population structure, and degree of inbreeding that could be used for advanced management and conservation of this breed. Our study aimed to provide a high-resolution population structure of the Istrian shorthaired hound using a 220K HD SNP array, to compare the obtained data with the genealogical records and to place the breed in a broader context of world dog populations. Relatively high population size and low inbreeding coefficient estimated from genealogical data indicate a preserved genetic diversity in this breed. The principle component analysis, the NeighborNet network, and TreeMix were used to determine the genetic relationship between the Istrian shorthaired hound and other breeds. The Istrian shorthaired hound was found to be genetically related to Italian hunting dogs sharing the same branch with the Segugio Italiano a Pelo Raso and Segugio Italiano a Pelo Forte. The ADMIXTURE analysis indicated that the Istrian shorthaired hound could be involved in the development of some other hunting dog breeds. The estimated effective population size (Ne) based on SNP data was similar to Ne calculated from genealogical data indicating the absence of bottlenecks and well-balanced use of breeding animals. The low genomic inbreeding coefficient, together with the higher number of short runs of homozygosity, observed in the Istrian shorthaired hound, confirms the ancient origin of the breed based on historical documents. The analysis of selective sweeps identified genomic regions with the strongest selection signals in the vicinity of the genes associated with cognitive performance and behavior. Genome analysis proved to be a useful tool for estimating population parameters and can be implemented in the conservation plan for this indigenous breed.