Testing the usefulness of the molecular coancestry information to assess genetic relationships in livestock using a set of Spanish sheep breeds.

Recent studies have proposed the use of molecular coancestry coefficients as a measure of genetic variability and as a useful tool for conservation purposes. Using simulated data, molecular coancestry has been shown to become constant very quickly after separation of populations, leading to population diversity remaining constant. However, the use of molecular coancestry information to study the genetic relationships between breeds has not yet been widely explored. Here we analyze the polymorphism of 14 microsatellites in 222 unrelated individuals belonging to seven native Spanish breeds to ascertain the usefulness of molecular coancestry-based methodologies in providing information on their genetic relationships. Average kinship distance (D(k)) and average molecular coancestry coefficients (f(ij)) were compared with well-known genetic distances, such as between-breed Reynolds' distance (D(R)), Nei's standard distance (D(s)), and shared allele distance (D(AS)). Kinship distance and f(ij) have moderate to low correlations with the other genetic distances, showing that they provide different information: both D(k) and f(ij) account for the allele frequencies in the founder population, whereas D(R), D(s), and D(AS) characterize the short-term evolution of the populations. Furthermore, D(k) and f(ij) were only moderately correlated (-0.500). The present study used field data to confirm previous research pointing out the ability of molecular coancestry coefficients to assess genetic differentiation of an ancestral origin. In this respect, molecular coancestry-based parameters may be used with classical genetic parameters to obtain information on population dynamics in livestock breeds. This study additionally presents reliable evidence on the history of these sheep breeds.