Migration and genetic diversity in an island population: Karkar, Papua New Guinea

Abstract

This paper examines genetic diversity on Karkar Island, Papna New Guinea, and its relation to patterns of migration within and between the two linguistic groups (Waskia and Takia) on the island. Exchange between linguistic groups is found to be small: less than 3 % of married individuals living in one linguistic group were born in the other. There is evidence of a secular trend in movement with significantly greater proportions of younger married individuals living outside their village group of birth. The migration patterns are examined by principal coordinate analysis of kinship coefficients derived from three sets of migration probabilities: ages 15—29, 30—44, 45 and over. For all three age groups the linguistic division is preserved and there is broad agreement between relatedness and the geographical arrangement of the village groups. The 22 polymorphic genetic systems examined show considerable diversity, most of which is within or between village groups in the same linguistic division. The greater level of diversity between Takia groups is consistent with their greater isolation from one another. Genetic distances between village groups show good agreement with geographical distances and there is no overlap between Waskia and Takia. The present-day genetic structure of Karkar Island can be interpreted as being largely the result of the interplay of migration and drift processes. The paper considers the use of analyses of this kind in establishing the magnitude and role of evolutionary forces operating on the genetic structure of human populations and the problems of unravelling rigorously and in detail the historical development of this structure.