Evolutionary dynamics in the aphid genome: Search for genes under positive selection and detection of gene family expansions

Abstract

Aphids have a high adaptative potential and their capacity to adapt to various environments could be linked with specific expansions in gene repertoires. A large scale acquisition of genomic data has been recently undertaken with the genome of Acyrthosiphon pisum (reference gene set) and EST data from three other species: Myzus persicae, Aphis gossypii and Toxoptera citricida. We identified paralogs through an intra-genomic Reciprocical Best Hit search in A. pisum and highlighted a high and steady level of duplications in A. pisum. We assembled, ESTs, predicted coding sequences and identified pairs of orthologs with A. pisum. We identified a fraction of fast-evolving sequences (high ratio of non-synonymous to synonymous rates) including genes shared by aphids but not identified in non-aphid species. Phylogenetic study of fast-evolving genes (Apo, C002, Spaetzel) shows that rate accelerations and duplication events are linked and could favour the emergence of specific biological functions. © 2010 Springer-Verlag Berlin Heidelberg.