Transcriptome analyses of primitively eusocial wasps reveal novel insights into the evolution of sociality and the origin of alternative phenotypes
© 2013 Ferreira et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
BACKGROUND: Understanding how alternative phenotypes arise from the same genome is a major challenge in modern biology. Eusociality in insects requires the evolution of two alternative phenotypes - workers, who sacrifice personal reproduction, and queens, who realize that reproduction. Extensive work on honeybees and ants has revealed the molecular basis of derived queen and worker phenotypes in highly eusocial lineages, but we lack equivalent deep-level analyses of wasps and of primitively eusocial species, the latter of which can reveal how phenotypic decoupling first occurs in the early stages of eusocial evolution. RESULTS: We sequenced 20 Gbp of transcriptomes derived from brains of different behavioral castes of the primitively eusocial tropical paper wasp Polistes canadensis. Surprisingly, 75% of the 2,442 genes differentially expressed between phenotypes were novel, having no significant homology with described sequences. Moreover, 90% of these novel genes were significantly upregulated in workers relative to queens. Differential expression of novel genes in the early stages of sociality may be important in facilitating the evolution of worker behavioral complexity in eusocial evolution. We also found surprisingly low correlation in the identity and direction of expression of differentially expressed genes across similar phenotypes in different social lineages, supporting the idea that social evolution in different lineages requires substantial de novo rewiring of molecular pathways. CONCLUSIONS: These genomic resources for aculeate wasps and first transcriptome-wide insights into the origin of castes bring us closer to a more general understanding of eusocial evolution and how phenotypic diversity arises from the same genome.
We thank Centre for Genomic Regulation (CRG) (Heinz Himmelbauer and Francisco Câmara), GenePool and the Babraham Institute (Wolf Reik and Simon Andrews) for support and access to their sequencing facilities. We thank RCUK, CONSOLIDER (CSD2007-0005), the Spanish Ministry of Science (BIO2006-03380, BFU2009-09168), GTEX (NIH Project 1RO1MH090941-01), and a Wellcome Trust Senior Investigator Award to Wolf Reik. SS was supported by a UK Research Council (RCUK) fellowship, and PGF by a FCT postdoctoral grant (SFRH/BPD/42003/2007) from the Portuguese Ministry of Science and Technology. We thank the Smithsonian Tropical Research Institute (particularly William Wcislo, Mary Jane West-Eberhard, Jorge Morales and staff at the Galeta Field Station) for hosting the fieldwork, and Stephanie Dreier and Thibault Lengronne for assistance in the field. The fieldwork was conducted under ANAM Permit No. SE/A-33-09
This is the final version of the article. Available from the publisher via the DOI in this record.
Vol. 14: R20
PubMed Central ID
Place of publication