Mitochondrial DNA and Y-chromosome variation in five eastern Aleut communities: evidence for genetic substructure in...

Since Russian contact in 1741, the Aleut communities of southwestern Alaska have undergone a series of demographic upheavals stemming from forced relocations, disease epidemics, population bottlenecks, and pervasive admixture with European populations. This study investigates the impact of key historical events on the genetic structure of the Aleut population through analysis of mitochondrial and Y-chromosome DNA variation in five eastern Aleut communities. Results from HVS-I sequencing and Y-chromosome typing reveal patterns of variability that exhibit east-west geographic differentiation for the major Aleut haplogroups. This finding is underscored by SAMOVA and Monmonier analyses that identify genetic discontinuities between eastern and western Aleut populations. The majority of Aleut Y-chromosomes were characterized to haplogroups of mostly Russian, Scandinavian and Western European origin (approximately 85%), which is in stark contrast to the 3.6% of Aleut mtDNA lineages identified as non-Native American, and thus indicating a large degree of asymmetrical gene flow between European men and Aleut women. Overall, this study identifies a significant relationship between geography and genetic variation in the Aleut population, with a distinct substructure along an east-west axis that reflects the combined effects of founder events in aggregate island communities, male-biased gene flow from European populations, and the original peopling of the Aleutian Archipelago.