About the Project
In the last few decades, Tribolium castaneum has been developed into a powerful genetic model for studying the evolution of arthropod developmental mechanisms (‘EvoDevo’ studies), and with a view to identifying genetic strategies to combat Tribolium as a pest of stored grain products. The Tribolium castaneum genome has been sequenced (Tribolium Genome Sequencing Consortium, 2008), gene expression can be knocked down efficiently in individuals and their offspring using parental RNA interference (RNAi) and many transgenic techniques and resources have been established. Importantly, many T. castaneum strains and transgenic lines are available that allow easy identification of individuals from the same Tribolium species in competition experiments. T. confusum has not seen the same level of investment, but the first draft genome sequence has recently become available. Interestingly, the T. castaneum genome sequence reveals an evolutionary expansion in the number of odorant receptors relative to other insect classes. A high number of pseudogenes suggests rapid evolutionary turnover in these sensory receptors during the evolution of this, and potentially related, beetle species. The ecological significance of this large repertoire, and evolutionary turnover, of sensory receptors remains to be determined.
The interested applicant will be free to pursue a number of different avenues of investigation, some of which are summarized below. All involve modulating intrinsic variables (lowering gene expression using parental RNAi) and/or extrinsic variables (altering environmental conditions) and determining their effect on Tribolium population dynamics at both the intraspecific and interspecific level:
Foraging and migration – A few arthropod genes that encode receptors or enzymes exhibiting highly conserved roles in the control of foraging and/or migratory behaviour are known. Expression of these genes will be targeted by RNAi in an attempt to modify foraging and/or migratory behavior in T. castaneum and/or T. confusum populations, and monitor the effects on population ecology. Beetles will be assayed both individually and in the context of experimental metapopulations that vary in complexity and connectivity.
Benzoquinone production – The iBeetle whole genome RNAi screen has identified 65 genes that when knockdown lead to stink gland abnormalities consistent with a failure to produce benzoquinones. The results of this screen will be published shortly, allowing the production of laboratory T. castaneum and/or T. confusum populations with a reduced ability to produce and secrete these chemical cues. These experiments could be carried out in combination with those described below in (3).
Odor perception – It has been shown that Tribolium castaneum beetles loose the ability to respond to the Tribolium aggregation pheromone when a central part of odor reception (Tc-odr1) is knocked down. Targeting Tc-odr1 will allow the production of laboratory T. castaneum and/or T. confusum populations with a reduced ability to perceive chemical cues (probably including benzoquinones, although this needs to be tested) which can then be tested to evaluate the consequences for habitat preference, dispersal, and aggregation in both species.
Park T (1954) Experimental Studies of Interspecies Competition II. Temperature, Humidity, and Competition in Two Species of Tribolium. Physiological Zoology, 27, 177-238.
Park T (1957) Experimental Studies of Interspecies Competition. III Relation of Initial Species Proportion to Competitive Outcome in Populations of Tribolium. Physiological Zoology, 30, 22-40.
Park T, Marian Burton F (1948) The fecundity and development of the flour beetles, Tribolium confusum and Tribolium castaneum, at three constant temperatures. Ecology, 29, 368-374.
Park T, Mertz DB, Grodzinski W, Prus T (1965) Cannibalistic predation in populations of flour beetles. Physiological Zoology, 38, 289-321.
Tribolium Genome Sequencing Consortium (2008) The genome of the model beetle and pest Tribolium castaneum. Nature, 452, 949-955.
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