Evaluation of diversity between different Spanish chicken breeds, a tester line, and a White Leghorn population based on microsatellite markers.

The present study was conducted to evaluate the genetic variability and the genetic divergence of 13 Spanish chicken breeds, a tester line, and a White Leghorn population, using 24 microsatellite markers. A total of 150 alleles were detected across all population. The number of alleles by locus ranged from 2 to 13, with the mean value being 6.25. The mean polymorphic information content was 0.591, ranging from 0.847 to 0.172. The combined parentage exclusion probability of excluding 1 parent or 2 parents was 99 and 100%, respectively. The observed heterozygosity was lower than the expected heterozygosity for all loci, the mean values being 0.461 and 0.637. The observed and expected heterozygosity ranged from 0.003 to 0.735 and 0.181 to 0.863, respectively. Mean deficit of heterozygotes within populations (F(IS)) was 0.056 and mean fixation index of each population (F(ST)) was 0.244. The mean global deficit of heterozygotes across populations (F(IT)) was 0.286. A total of 15 private alleles in 10 microsatellites were observed, and in some populations, fixed alleles were found for 7 microsatellites. A total of 300 birds (83%) were properly assigned to the source population. The average observed heterozygosity for each population was 0.461, ranging from 0.328 (Quail Castellana) to 0.538 (Red Villafranquina), and the average expected heterozygosity was 0.488, ranging from 0.320 (Quail Castellana) to 0.550 (White-Faced Spanish). All of the Spanish breeds except the Quail Castellana were more polymorphic than the White Leghorn population. The mean value of the deviation of heterozygote number was 0.052. Nei's genetic distance showed a range from 0.109 (between White-Faced Spanish and Black Menorca) to 0.437 (between Buff Prat and White Leghorn). A phylogenetic tree constructed by the neighbor-joining method, based on Nei's genetic distance, showed a clear separation between the White Leghorn and the remaining breeds. The results indicate that the panel of microsatellite markers was useful in studying the genetic diversity of chicken breeds.