Patterns of variation in a caste-cluster of Dhangars of Maharashtra, India

We study patterns of variation among the 20 endogamous groups of Dhangars, a caste-cluster from Maharashtra State of India, who are semi-nomadic shepherds and cattle herders. To understand patterns of variation, we subjected the data on fourteen anthropometric measurements of about 2,500 adult males and data on 6 genetic markers, published among 13 of the 20 Dhangar castes, to R-matrix analysis, Harpending and Ward model of regression of heterozygosity on the distance from centroid of the populations, spatial autocorrelation analysis and Mantel statistics of matrix correspondence of the distances--geographic, anthropometric and genetic. Results of multiple regression analysis suggest a high degree of association between allele frequencies and the geographic longitude and latitude; R2 value suggests that about 70% of the variance in RH7 and ACP can be assigned to geographic distribution of groups. In case of anthropometry, this association with body size is found to be even stronger. Results of spatial autocorrelation analysis, as suggested by Moran's (I), are somewhat complementary to those based on multiple regression analysis. Mantel test indicates significant association between anthropometric distances and the geographic distances, not between geographic and genetic distances. The extent of differentiation of Dhangar sub-castes is much higher in anthropometric traits (F(ST) = 0.068) when compared to the genetic markers (F(ST) = 0.023). Yet, the F(ST) value obtained forgenetic markers is larger than the average for the Indian populations, based on similar class of markers. The positioning of the groups in the multivariate space reflects primarily geographic proximity of the groups with reference to anthropometric dimensions while no tangible pattern is evident forgenetic markers. The plot of average heterozygosity of the groups versus their distance from the gene frequency centroid seems to reflect population size variation, rather than group variation in external gene flow.