Adaptive evolution of the FADS gene cluster within Africa.

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Mathias, Rasika A; Fu, Wenqing; Akey, Joshua M; Ainsworth, Hannah C; Torgerson, Dara G; Ruczinski, Ingo; Sergeant, Susan; Barnes, Kathleen C; Chilton, Floyd H
Year of Publication: 2012
Journal: PLoS One
Volume: 7
Issue: 9
Pagination: e44926
Date Published: 2012
Publication Language: eng
ISSN: 1932-6203
Keywords: Adaptation, Physiological, Africa, African Continental Ancestry Group, European Continental Ancestry Group, Evolution, Molecular, Fatty Acid Desaturases, Fatty Acids, Unsaturated, Gene Frequency, Humans, Multigene Family

Long chain polyunsaturated fatty acids (LC-PUFAs) are essential for brain structure, development, and function, and adequate dietary quantities of LC-PUFAs are thought to have been necessary for both brain expansion and the increase in brain complexity observed during modern human evolution. Previous studies conducted in largely European populations suggest that humans have limited capacity to synthesize brain LC-PUFAs such as docosahexaenoic acid (DHA) from plant-based medium chain (MC) PUFAs due to limited desaturase activity. Population-based differences in LC-PUFA levels and their product-to-substrate ratios can, in part, be explained by polymorphisms in the fatty acid desaturase (FADS) gene cluster, which have been associated with increased conversion of MC-PUFAs to LC-PUFAs. Here, we show evidence that these high efficiency converter alleles in the FADS gene cluster were likely driven to near fixation in African populations by positive selection ∼85 kya. We hypothesize that selection at FADS variants, which increase LC-PUFA synthesis from plant-based MC-PUFAs, played an important role in allowing African populations obligatorily tethered to marine sources for LC-PUFAs in isolated geographic regions, to rapidly expand throughout the African continent 60-80 kya.

DOI: 10.1371/journal.pone.0044926
Alternate Journal: PLoS ONE