Balancing selection on immunity genes: review of the current literature and new analysis in Drosophila melanogaster.
Balancing selection has been widely assumed to be an important evolutionary force, yet even today little is known about its abundance and its impact on the patterns of genetic diversity. Several studies have shown examples of balancing selection in humans, plants or parasites, and many genes under balancing selection are involved in immunity. It has been proposed that host-parasite coevolution is one of the main forces driving immune genes to evolve under balancing selection. In this paper, we review the literature on balancing selection on immunity genes in several organisms, including Drosophila. Furthermore, we performed a genome scan for balancing selection in an African population of Drosophila melanogaster using coalescent simulations of a demographic model with and without selection. We find very few genes under balancing selection and only one novel candidate gene related to immunity. Finally, we discuss the possible causes of the low number of genes under balancing selection.
Department of Biology II, Ludwig Maximilian University Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany. Electronic address: croze@bio.lmu.de.
Myriam
M
Croze
Department of Biology II, Ludwig Maximilian University Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany.
Daniel
D
Živković
Department of Biology II, Ludwig Maximilian University Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany.
Wolfgang
W
Stephan
Department of Biology II, Ludwig Maximilian University Munich, Großhaderner Str. 2, D-82152 Planegg-Martinsried, Germany.
Stephan
S
Hutter
D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology*; D000071184:Pharmacogenomic Variants; D012641:Selection, Genetic
D029721:Drosophila Proteins
Balancing selection; Drosophila melanogaster; Host–parasite coevolution; Population genetics