Miles Bensky took advantage of a series of replicated populations of sticklebacks in Alaska that vary in time since establishment to show evidence that boldness is important for getting into new habitats, and behavioral flexibility is favored when adapting to them. The paper was just published in the American Naturalist – check it out!
This video shows a fish during the barrier task, which was used to measure behavioral flexibility. The fish has been trained to find food (bloodworm) in the Petri dish outside the shelter, but a transparent barrier has now been added between the shelter and the food. Sticklebacks from well established freshwater populations spend less time persisting at the apex of the barrier trying to reach the food (i.e. they are more flexible), relative to sticklebacks from new freshwater populations or from ancestral marine populations.
This video shows a fish emerging from a shelter. Some individuals consistently emerge faster than others, and we interpret quick emergence as relatively “bolder” behavior. Sticklebacks from ancestral marine populations emerge faster than sticklebacks from derived freshwater populations, and these differences are maintained in a common garden environment, suggesting that they have a heritable basis.
Moreover, individuals that were more bold were less flexible, and this behavioral syndrome was also apparent at both the family and population levels.