Abstract: | China is rich in chicken genetic resources, and many indigenous breeds can be found throughout the country. Due to poor productive
ability, some of them are threatened by the commercial varieties from domestic and foreign breeding companies. In a large-scale
investigation into the current status of Chinese poultry genetic resources, 78 indigenous chicken breeds were surveyed and
their blood samples collected. The genomes of these chickens were screened using microsatellite analysis. A total of 2740
individuals were genotyped for 27 microsatellite markers on 13 chromosomes. The number of alleles of the 27 markers ranged
from 6 to 51 per locus with a mean of 18.74. Heterozygosity (H) values of the 78 chicken breeds were all more than 0.5. The average H value (0.622) and polymorphism information content (PIC, 0.573) of these breeds suggested that the Chinese indigenous chickens
possessed more genetic diversity than that reported in many other countries. The fixation coefficients of subpopulations within
the total population (F
ST) for the 27 loci varied from 0.065 (LEI0166) to 0.209 (MCW0078), with a mean of 0.106. For all detected microsatellite loci,
only one (LEI0194) deviated from Hardy-Weinberg equilibrium (HWE) across all the populations. As genetic drift or non-random
mating can occur in small populations, breeds kept on conservation farms such as Langshan chicken generally had lower H values,
while those kept on large populations within conservation regions possessed higher polymorphisms. The high genetic diversity
in Chinese indigenous breeds is in agreement with great phenotypic variation of these breeds. Using Nei’s genetic distance
and the Neighbor-Joining method, the indigenous Chinese chickens were classified into six categories that were generally consistent
with their geographic distributions. The molecular information of genetic diversity will play an important role in conservation,
supervision, and utilization of the chicken resources. |