Population structure and genetic differentiation among the substructured Vysya caste population in comparison to the other populations of Andhra Pradesh,India

Objectives : The present paper focuses on the study of the patterns of genetic microdifferentiation among one of the substructured caste populations of Andhra Pradesh, namely Vysya, with reference to 17 other Telugu speaking populations from the same region of India. Subjects and methods : A total of 302 individuals from the three Vysya subgroups (101 of Arya Vysya, 100 from Kalinga Vysya and 101 from Thrivarnika) were typed in 17 blood groups and protein polymorphisms. Nei's gene diversity analysis, as well as neighbour-joining tree and UPGMA cluster diagrams, derived from standard genetic distances, R-matrix analysis and a regression model for investigating the patterns of external gene flow and genetic drift due to isolation under the island model, were done at two levels: (1) considering only the three Vysya populations and (2) considering common loci among 20 populations of Andhra Pradesh. Results : Seven of the 17 systems investigated were found to be monomorphic among all the three Vysya groups. The UPGMA tree and bidimensional scaling of the D 2 distances derived from R-matrix analysis show a very distinct cluster of Vysya populations. Application of the model of regression of average heterozygosity versus the distance of populations from the centroid shows the three Vysya populations placed as clear outliers above the theoretical regression line. Conclusions : Different approaches employed in this study give support to the hypothesis of different origin and/or demographic story for the three Vysya groups compared with other populations of Andhra Pradesh.