Tribolium castaneum - the red flour beetle
Tribolium is a genus of small brown beetles that are thought to once have lived under the bark of trees, but now they are overwhelmingly found living alongside humans, in grain storage facilities, where they are pests - eating and spoiling food products and causing massive economic losses.
We don’t know how long that transition from a free-living to a more human-commensal lifestyle has taken, but there is evidence of their being in ancient Egyptian flour urns, which are roughly 5000 years old.
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It's easy to see, then, that studying these beetles could bring important benefits by improving food security - but Tribolium also have many features that make them a really useful model system for biologists. For example, as a member of the very largest order of animals (beetles make up ~25% of all species), Tribolium are well positioned to represent a great proportion of the tree of life. In a practical sense too, they can survive in the lab just in a pot of flour, and are not disturbed by handling, so individuals are easily sieved out, sexed or marked when necessary.
Tribolium castaneum males marked with blue dots during an experiment
Tribolium castaneum individuals viewed down a microscope
My PhD, supervised by Prof David Richardson at the University of East Anglia, is investigating the genetic and demographic factors underlying dispersal and colonisation of insects, using Tribolium as a model system.
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I am using artificial selection to breed lines that show high or low dispersal ability, in order to find the genetic basis of this behaviour, and investigate which other behavioural and/or morphological traits correlate with dispersal.
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Also, by conducting lab experiments that mimic population foundation events we hope to tease apart what attributes of some populations allow them to establish while others are driven to extinction.
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When we breed dispersers and non-dispersers together, we see a remarkably fast change in the behaviour of their offspring.
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This response to artificial selection shows that dispersal behaviour has a strong genetic component.
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Simulations we have done alongside these experiments suggest that there are not more than a few genes controlling dispersal. One of our next objectives is to find them!
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Figure taken from Pointer et al. 2023, Heredity
We have also shown that many other traits change in populations selected for high or low dispersal.
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Some of these traits are probably involved in actually achieving dispersal, such as levels of activity, straightness of movement direction and body size.
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But others are linked to dispersal through the complex web of interactions and trade-offs that result from living in a complex and variable environment. Examples of these are mating behaviour for males, egg laying for females, development time and lifespan.
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Life-history traits changing with dispersal. Figure taken from Pointer et al. 2024, Journal of Evolutionary Biology
Potentially dispersal-enabling traits changing with dispersal. Figure taken from an article in review at the Journal of Insect Behaviour