Evidence of balancing selection in multiple indigenous chicken populations

Microsatellite DNA markers, which are assumed to drift, have been widely used to assess genetic diversity in all major domestic animal species. These markers provide insight into the arrival and dispersion history of a species, with regard to their content or management history. However, no direct evidence supports current standard microsatellite markers falling under this assumption. Therefore, the objective of this study was to investigate the effect and divergence of microsatellites under different types of selection on genetic patterns and population diversity. A total of 192 birds (Gallus gallus) from eight different geographic locations were investigated using 20 microsatellites that are classified into different groups by their selective effect (neutral, positive selection, and balancing selection) by the FDIST2 outlier test. The results showed that most polymorphisms were in the balancing selection marker group, the expected heterozygosity was 0.70, the observed heterozygosity was 0.65, and the mean number of alleles was 6.91. AMOVA revealed that the balancing group contributed the lowest amount of variance among groups, which was -0.60%, the highest variance contributed within the population being 92.28% in comparison with that of other groups. A similar pattern of population genetics was revealed following Slatkin linearized FST, principal component factor analysis, and population structure by Bayesian clustering. In conclusion, balancing selective markers offer high polymorphism for estimating genetic diversity but reduced genetic divergence between populations.