Identity by Descent Analysis Reveals Fine-Scale Population Structure in Crete

• Activity Number: 248
• Type: Contributed
• Date/Time: Monday, August 10, 2015 : 2:00 PM to 3:50 PM
• Sponsor: Section on Statistics in Epidemiology
• Author(s): Anna Plantinga* and Fotis Tsetsos and Peristera Paschou and Petros Drineas and Brian Browning and George Stamatoyannopoulos
• Companies: University of Washington and Democritus University of Thrace and Democritus University of Thrace and Rensselaer Polytechnic Institute and University of Washington and University of Washington
• Keywords: IBD ; identity by descent ; Crete ; population structure

Abstract

The island of Crete is 160 miles long and 37 miles at its widest point. Despite its small area, Crete contains populations that historically have been relatively isolated due to Crete's mountainous topography. We hypothesized that this isolation would create detectable fine-scale population structure across Crete. To study this structure, SNP array data was collected for 129 subjects sampled from 17 regions of Crete. All individuals were at least 70 years old at the time of sampling and reported having maternal and paternal grandparents from the same region as the subject. We show that identity by descent (IBD) analysis, which compares the amount of genetic material shared between individuals due to inheritance from recent common ancestors, reveals fine-scale regional relationships that are consistent with the geography and history of Crete. For instance, the amount of genetic material shared IBD between two populations decreases both with increasing east-west distance and with separation by mountains or other natural barriers. Possible origins of the division between East and West Crete, including differential migration from Peloponnese and Dodecanese, are under investigation.