Submitted on June 18, 2007
Accepted on September 19, 2007
Wasp Gene Expression Supports an Evolutionary Link Between Maternal Behavior and Eusociality
Amy L. Toth 1*, Kranthi Varala 2, Thomas C. Newman 1, Fernando E. Miguez 2, Stephen K. Hutchison 3, David A. Willoughby 3, Jan Fredrik Simons 3, Michael Egholm 3, James H. Hunt 4, Matthew E. Hudson 2, Gene E. Robinson 5
1 Department of Entomology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, IL 61801, USA.
2 Department of Crop Sciences, University of Illinois at Urbana-Champaign, IL 61801, USA.
3 454 Life Sciences, Branford, CT 06405, USA.
4 Department of Biology, University of Missouri at St. Louis, MO 63121, USA.
5 Department of Entomology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, IL 61801, USA. ; Neuroscience Program, University of Illinois at Urbana-Champaign, IL 61801, USA.
* To whom correspondence should be addressed.
Amy L. Toth , E-mail: amytoth{at}uiuc.edu
The presence of workers that forgo reproduction and care for their siblings is a defining feature of eusociality and a major challenge for evolutionary theory. It has been proposed that worker behavior evolved from maternal care behavior. We explored this idea by studying gene expression in the primitively eusocial wasp Polistes metricus. Because little genomic information existed for this species, we used 454 sequencing to generate 391,157 brain cDNA reads, resulting in robust hits to 3,017 genes from the honey bee genome, from which we identified and assayed orthologs of 32 honey bee behaviorally-related genes. Wasp brain gene expression in workers was more similar to foundresses, which show maternal care, than to queens and gynes, which do not. Insulin-related genes were among the differentially regulated genes, suggesting that the evolution of eusociality involved major nutritional and reproductive pathways.
