GENETIC-STUDY OF THE TRIBAL POPULATIONS OF ANDHRA-PRADESH, SOUTH-INDIA

Regional variation in the genetic constitution and genetic differentia tion of three tribal populations (Koya, Lambadi, and Chenchu) of Andhr a Pradesh, South India, was examined from the data of 27 poly morphic loci (9 blood groups, 13 red cell enzymes, and 5 serum proteins), Sign ificant heterogeneity was observed among the three tribal groups at se veral loci (ABO, RH, P, ADA, PGM, ACP, ESD, PGD, GPT, HP, C3, and BF). Pairwise comparisons also showed significant genetic differ ences bet ween the Koya and the Chenchu at seven loci, between the Koya and the Lambadi at nine loci, and between the Chenchu and the Lambadi at seven loci. Gene differentiation among the three tribes was sufficient to a llow an overall excess of heterozygosity. The F-lS estimates of each t ribe showed positive values, but a great number of alleles showed nega tive F-lS values, supporting varying degrees of gene flow and admixtur e with neighboring populations. The genetic differentiation and affini ty of 14 tribal populations of Andhra Pradesh were further examined us ing published and unpublished data on 11 polymorphic generic systems. Despite the genetic distinctions between two Chenchu samples and Koya and Koya-related tribes (Koya Dora and Konda Dora), geographic prox im ity seems to be an important determinant of affinity of the tribal pop ulations of Andhra Pradesh. The extent of genetic diversity is high co mpared with previous reports from this state. No evidence from the pre sent data indicates that selection had any appreciable effect on local differentiation, but the present analysis suggests that differences a re more likely to be maintained by genetic drift, admixture, and inbre eding.