Chemoreceptor

Genome

Ecology

Arthropod

Glutamate receptor

Receptor

Gene family

Gene duplication

Evolutionary biology

Biology

Phylogenetics

Gene

Molecular evolution

Ionotropic effect

Phylogenetic tree

Functional divergence

Genetics

Annual Review of Entomology

The evolutionary origins of the three major families of chemoreceptors in arthropods-the odorant receptor (OR), gustatory receptor (GR), and ionotropic receptor (IR) families-occurred at the base of the Insecta, Animalia, and Protostomia, respectively. Comparison of receptor family sizes across arthropods reveals a generally positive correlation with their widely disparate complexity of chemical ecology. Closely related species reveal the ongoing processes of gene family evolution, including gene duplication, divergence, pseudogenization, and loss, that mediate these larger patterns. Sets of paralogous receptors within species reveal positive selection on amino acids in regions likely to contribute to ligand binding and specificity. Ligands of many ORs and some GRs and IRs have been identified; however, ligand identification for many more chemoreceptors is needed, as are structures for the OR/GR superfamily, to improve our understanding of the molecular evolution of these ecologically important receptors in arthropods.

Molecular Evolution of the Major Arthropod Chemoreceptor Gene Families