The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Spatial analysis of fine-scale Y chromosome variation in Swahili and Yemeni males clarifies the expected distribution of genetic variation in societies with different post-marriage residence norms


Anthropology, Lehman College, CUNY, NYCEP, The New York Consortium in Evolutionary Primatology

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Different post-marital residence patterns are expected to produce clearly distinguishable distributions of genetic variation within and between populations. However, studies of genetic diversity at scales from the local to the global have recovered conflicting patterns. Most of these studies have been based on summary measures of genetic diversity that are better suited to equilibrium conditions. Here, I directly examine the spatial distribution of Y chromosome microsatellite variation in individuals carrying a Y chromosome in the same haplogroup in two different samples: Yemeni and Swahili males. Ethnographies of both societies report a normative patrilineality, but they differ in post-marriage residence patterns. Post-marriage residence is typically patrilocal in Yemen, while post-marriage residence in Swahili communities does not perfectly fit any of the standard patterns. The results of this analysis show how the non-equilibrium conditions and deviations from normative residence patterns that generally prevail in human populations lead to deviations from the expected distributions of genetic diversity within and between populations. In particular, the fine-scale spatial distribution of Y chromosome variation in Yemeni populations fits a normative patrilocality, but there is also clear evidence of male migration – on the order of 1-2 males per generation – which leads to misleading results when the data are analyzed using summary diversity statistics. Similarly, the spatial distribution of Y chromosome lineages on the Swahili coast reflects the greater diversity of post-marriage residence patterns, but summary measures fail to recover patterns of connections among communities.

This work was supported by NSF grant BCS-0518530 to Connie J Mulligan, NSF grant BCS-1029506 to RLR, and a PSC-CUNY Award to RLR, jointly funded by The Professional Staff Congress and The City University of New York.

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