Natural selection among coastal populations of India: Trend and extent

Abstract

Background: Coastal populations have always been exposed to socio-cultural and natural vulnerability. The correlates between these coastal populations and their selection potentials have not been previously described.Aim: To describe selection potentials, their trend and extent among coastal and non-coastal populations of the Indian continent.Subjects and methods: Data on fertility and mortality differentials among five coastal populations were collected from 448 women of Orissa and Goa. Selection potential was computed. In addition, 48 studies among 100 different populations of India were reviewed for similar parameters, for comparison.Results: Total index of selection (It) varied from 0.221–0.417 in the population of Orissa; whereas the population of Goa showed a moderate index of selection. Regression analysis showed that among the coastal population the contribution of index of mortality (Im) is higher (92.5%) in total selection index (It) as compared to non-coastal populations (56.4%). After 1991, there was a radical shift in the role of mortality in the entire region. Simultaneously, the selection intensity (It) has gradually declined.Conclusion: There is a significant difference in the extent and process of natural selection among coastal and non-coastal populations. Mortality is playing a greater role in the total selection intensity of coastal populations, although the trend is declining in the entire region and reversal in the roles of Im and index of fertility (If) is witnessed.