title: History shaped the geographic distribution of genomic admixture on the island of Puerto Rico.
abstract: Contemporary genetic variation among Latin Americans human groups reflects population migrations shaped by complex historical, social and economic factors. Consequently, admixture patterns may vary by geographic regions ranging from countries to neighborhoods. We examined the geographic variation of admixture across the island of Puerto Rico and the degree to which it could be explained by historic and social events. We analyzed a census-based sample of 642 Puerto Rican individuals that were genotyped for 93 ancestry informative markers (AIMs) to estimate African, European and Native American ancestry. Socioeconomic status (SES) data and geographic location were obtained for each individual. There was significant geographic variation of ancestry across the island. In particular, African ancestry demonstrated a decreasing East to West gradient that was partially explained by historical factors linked to the colonial sugar plantation system. SES also demonstrated a parallel decreasing cline from East to West. However, at a local level, SES and African ancestry were negatively correlated. European ancestry was strongly negatively correlated with African ancestry and therefore showed patterns complementary to African ancestry. By contrast, Native American ancestry showed little variation across the island and across individuals and appears to have played little social role historically. The observed geographic distributions of SES and genetic variation relate to historical social events and mating patterns, and have substantial implications for the design of studies in the recently admixed Puerto Rican population. More generally, our results demonstrate the importance of incorporating social and geographic data with genetics when studying contemporary admixed populations.
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, California, United States of America. mvia@ub.edu
authors.forename: Marc
authors.initials: M
authors.lastname: Via
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Gignoux
authors.forename: Lindsey A
authors.initials: LA
authors.lastname: Roth
authors.forename: Laura
authors.initials: L
authors.lastname: Fejerman
authors.forename: Joshua
authors.initials: J
authors.lastname: Galanter
authors.forename: Shweta
authors.initials: S
authors.lastname: Choudhry
authors.forename: Gladys
authors.initials: G
authors.lastname: Toro-Labrador
authors.forename: Jorge
authors.initials: J
authors.lastname: Viera-Vera
authors.forename: Taras K
authors.initials: TK
authors.lastname: Oleksyk
authors.forename: Kenneth
authors.initials: K
authors.lastname: Beckman
authors.forename: Elad
authors.initials: E
authors.lastname: Ziv
authors.forename: Neil
authors.initials: N
authors.lastname: Risch
authors.forename: Esteban González
authors.initials: EG
authors.lastname: Burchard
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Martínez-Cruzado
mesh_terms: D005828:Genetics, Population; D015894:Genome, Human / Q000235:genetics*; D005843:Geography; D006801:Humans; D011647:Puerto Rico / Q000208:ethnology; D044469:Racial Groups / Q000235:genetics*; D012919:Social Behavior