Evolutionary replacement of obligate symbionts in an ancient and diverse insect lineage. (9th April 2013)

• Record Type: Journal Article
• Authors: Koga, Ryuichi; Bennett, Gordon M.; Cryan, Jason R.; Moran, Nancy A.
• Is Part Of: Environmental microbiology. Volume 15:Number 7(2013:Jul.)
• Page Start: 2073
• Page End: 2081
• Publication Date: 2013-04-09
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12121
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Many insect groups depend on ancient obligate symbioses with bacteria that undergo long‐term genomic degradation due to inactivation and loss of ancestral genes. Sap‐feeding insects in the hemipteran suborder Auchenorrhyncha show complex symbioses with at least two obligate bacterial symbionts, inhabiting specialized host cells (bacteriocytes). We explored the symbiotic relationships of the spittlebugs (Auchenorrhyncha: Cercopoidea) using phylogenetic and microscopy methods. Results show that most spittlebugs contain the symbionts <italic>Sulcia muelleri</italic> (<italic>Bacteroidetes</italic>) and <italic>Zinderia insecticola</italic> (<italic>Betaproteobacteria</italic>) with each restricted to its own bacteriocyte type. However, the ancestral <italic>Zinderia</italic> symbiont has been replaced with a novel symbiont closely related to <italic>Sodalis glossinidius</italic> (<italic>Enterobacteriaceae</italic>) in members of the ecologically successful spittlebug tribe Philaenini. At least one spittlebug species retains <italic>Sulcia</italic> and <italic>Zinderia</italic>, but also has acquired a <italic>Sodalis</italic>‐like symbiont, possibly representing a transitional stage in the evolutionary succession of symbioses. Phylogenetic analyses including symbionts of other Auchenorrhyncha lineages suggest that <italic>Zinderia</italic>, like <italic>Sulcia</italic>, descends from an ancestral symbiont present in the common ancestor of Auchenorrhyncha. This betaproteobacterial symbiont has been repeatedly replaced by other symbionts, such as the <italic>Sodalis</italic>‐like symbiont of spittlebugs. Symbiont replacement may offer a route for hosts to escape dependence on an ancient, degraded and potentially inefficient symbiont.</p> </abstract>