Presentation Detail

Molecular Evolution

Duncan, Rebecca P. [1], Van Leuven, James T. [4], Filip, Husnik [2], Davalos, Liliana M [3], McCutcheon, John P. [4], Wilson, Alex C.C. [1].

A role for gene duplication in the evolution of novel, nutritional interactions between sap-feeding insects and their symbionts.

Sap-feeding insects like aphids, white flies, and mealybugs rely on intracellular bacterial symbionts to supplement their diet with essential amino acids. Bacterial symbionts reside within membrane-bound compartments inside specialized insect cells called bacteriocytes. Thus, host/symbiont amino acid exchange critically requires membrane-bound amino acid transporters. Previously, we discovered that aphid amino acid transporters have undergone extensive gene duplication followed by some paralogs evolving expression in bacteriocytes, leading us to hypothesize that gene duplication plays a role in recruiting amino acid transporters to operate at the host/symbiont interface. To test this hypothesis, we identified amino acid transporters in transcriptomes from other sap-feeding and non sap-feeding insects with obligate symbiotic relationships with bacteria, reconstructed gene phylogenies, and quantified relative expression in mealybug bacteriocytes to compare with previous expression data available for aphid bacteriocytes. Phylogenies revealed that amino acid transporters underwent extensive gene duplication independently in sap-feeding insects compared with non sap-feeding insects, and gene expression data demonstrated that some mealybug paralogs have enriched expression in bacteriocytes, similar to what we previously observed for aphids. Further, the distribution of expression data strongly suggests that bacteriocyte enrichment is derived in both aphids and mealybugs, consistent with our hypothesis that recruitment to operate in bacteriocytes evolved after gene duplication. Our results that amino acid transporter paralogs have been recruited to the host/symbiont interface in sap-feeding insects suggests that gene duplication may be an important general mechanism enabling the evolution of novel, intimate interactions in symbiotic systems.

1 - University of Miami, Department of Biology, 1301 Memorial Dr., Coral Gables, FL, 33146, USA
2 - University of South Bohemia & Institute of Parasitology, Faculty of Science, Branisovska 31, Czech Academy of Sciences, Ceske Budejovice , 37005, Czech Republic
3 - Stony Brook University, Ecology and Evolution, 650 Life Sciences, Stony Brook, NY, 11794, USA
4 - University of Montana, Division of Biological Sciences, 32 Campus Drive, HS104, Missoula, MT, 59812, USA

Keywords:
Gene duplication
Neofunctionalization
symbiosis
Intracellular bacterial symbiont
Aphid
Mealybug
Sap-feeding insect.

Presentation Type: Regular Oral Presentation
Session: 135
Location: Alpine A and B/Snowbird Center
Date: Tuesday, June 25th, 2013
Time: 11:00 AM
Number: 135003
Abstract ID:92
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation