Aphid and Water flea have a High Rate of Gene Duplications Compared to Other Arthropods 2009

Abstract

Comparison of gene orthology and paralogy groups among thirteen arthropod genomes (insects.eugenes.org/arthropods/) finds the pea aphid Acyrthosiphon pisum and the water flea Daphnia pulex, both cyclical asexuals, have four times the gene duplications of other arthropods. These duplicates are not from whole genome duplication, and artifacts do not account for this. Gene models for these 13 arthropod genomes are summarized in Fig 2 in categories of orthologs or species unique, duplicate paralogs or singleton genes. This indicates the large difference in gene counts from 16,000 in dipterans to over 30,000 in Aphid and Daphnia. The main effects for high versus low gene count appear to be paralogs. Aphid has 2,475 genes in 625 groups compared to 621 average insect genes, a rate of 3.8 to 1. Daphnia has 2,621 duplicated genes in 589 groups, compared to 610 average insect genes, a rate of 4.4 to 1. These two species are also abundant in genes in many groups that lack homology (Fig. 2B).