Patterns of positive selection in seven ant genomes.
The evolution of ants is marked by remarkable adaptations that allowed the development of very complex social systems. To identify how ant-specific adaptations are associated with patterns of molecular evolution, we searched for signs of positive selection on amino-acid changes in proteins. We identified 24 functional categories of genes which were enriched for positively selected genes in the ant lineage. We also reanalyzed genome-wide data sets in bees and flies with the same methodology to check whether positive selection was specific to ants or also present in other insects. Notably, genes implicated in immunity were enriched for positively selected genes in the three lineages, ruling out the hypothesis that the evolution of hygienic behaviors in social insects caused a major relaxation of selective pressure on immune genes. Our scan also indicated that genes implicated in neurogenesis and olfaction started to undergo increased positive selection before the evolution of sociality in Hymenoptera. Finally, the comparison between these three lineages allowed us to pinpoint molecular evolution patterns that were specific to the ant lineage. In particular, there was ant-specific recurrent positive selection on genes with mitochondrial functions, suggesting that mitochondrial activity was improved during the evolution of this lineage. This might have been an important step toward the evolution of extreme lifespan that is a hallmark of ants.
Department of Ecology and Evolution, University of Lausanne, Lausanne, SwitzerlandSIB Swiss Institute of Bioinformatics, Lausanne, Switzerland julien.roux@unil.ch.
Julien
J
Roux
Department of Ecology and Evolution, University of Lausanne, Lausanne, SwitzerlandSIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.
Eyal
E
Privman
Department of Ecology and Evolution, University of Lausanne, Lausanne, SwitzerlandSIB Swiss Institute of Bioinformatics, Lausanne, SwitzerlandVital-IT Group, SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.
Sébastien
S
Moretti
Department of Ecology and Evolution, University of Lausanne, Lausanne, SwitzerlandSIB Swiss Institute of Bioinformatics, Lausanne, SwitzerlandCMPG, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
Josephine T
JT
Daub
Department of Ecology and Evolution, University of Lausanne, Lausanne, SwitzerlandSIB Swiss Institute of Bioinformatics, Lausanne, Switzerland.
Marc
M
Robinson-Rechavi
Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
Laurent
L
Keller
D000818:Animals; D001000:Ants / Q000145:classification / Q000235:genetics*; D030541:Databases, Genetic; D019143:Evolution, Molecular; D050259:Genes, Mitochondrial; D049750:Genome, Insect; D019476:Insect Proteins / Q000235:genetics*; D005810:Multigene Family; D010802:Phylogeny; D012641:Selection, Genetic
D019476:Insect Proteins
Drosophila; Hymenoptera; aging; bees; comparative genomics; dN/dS; immunity; lifespan; metabolism; neurogenesis; olfactory receptors; sociality