Male guppies exposed to predators in the wild or in captivity have heavier brains than those living in relatively predator-free conditions, according to new research published in the journal Functional Ecology.
Male guppies exposed to predators in the wild or in captivity have heavier brains than those living in relatively predator-free conditions, according to new research published in the journal Functional Ecology.
Behavioural ecologists at McGill University in Montreal sampled guppies from two rivers in northern Trinidad. In each river, guppies live both above a waterfall, a location that only guppies and a few other small species of fish have managed to colonize, and below the fall, where many predators including pike cichlids live.
“Guppies offer an excellent model for evolutionary research because they have colonized multiple independent rivers in Trinidad where they are exposed to a variety of different conditions,” says lead author Adam Reddon. “We were particularly interested in finding out how the brains of these widely-distributed fish have evolved for dealing with the challenges of living under predation threat.” Reddon, who is now at Liverpool John Moores University in the UK, worked on the project as a postdoctoral fellow in the lab of McGill Biology professor Simon Reader.
The researchers looked at whether there are differences in relative brain mass between wild guppies collected from high and low predation populations and found that, for their body size, males collected from high predation sites had on average 17% heavier brains compared to males from low predation sites in the same river. Female guppies, by contrast, did not show this pattern.
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Image via McGill University.
