Abstract
The origin of the insect odorant receptor (OR) gene family has been hypothesized to have coincided with the evolution of terrestriality in insects. Missbach et al. (2014) suggested that ORs instead evolved with an ancestral OR co-receptor (Orco) after the origin of terrestriality and the OR/Orco system is an adaptation to winged flight in insects. We investigated genomes of the Collembola, Diplura, Archaeognatha, Zygentoma, Odonata, and Ephemeroptera, and find ORs present in all insect genomes but absent from lineages predating the evolution of insects. Orco is absent only in the ancestrally wingless insect lineage Archaeognatha. Our new genome sequence of the zygentoman firebrat Thermobia domestica reveals a full OR/Orco system. We conclude that ORs evolved before winged flight, perhaps as an adaptation to terrestriality, representing a key evolutionary novelty in the ancestor of all insects, and hence a molecular synapomorphy for the Class Insecta.
Article and author information
Author details
Funding
National Science Foundation (IOS-1456678)
- Juan Luis Jurat-Fuentes
- Brian R Johnson
US Department of Agriculture Hatch (CA-D-ENM 2161-H)
- Brian R Johnson
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Richard Benton, University of Lausanne, Switzerland
Publication history
- Received: May 13, 2018
- Accepted: July 24, 2018
- Accepted Manuscript published: July 31, 2018 (version 1)
- Version of Record published: August 7, 2018 (version 2)
Copyright
© 2018, Brand et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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