Credit: Brian Stauffer

“As a boy, I had two small aquaria in our backyard in which I watched, each spring, the nest building and other fascinating behaviours of sticklebacks.”


Threespined sticklebacks (Gasterosteus aculeatus) are small fish that have proven to be a powerful model system for identifying the genetic mechanisms that underlie adaptive morphological evolution.  But sticklebacks are also famous for their rich behavioral repertoire, which has attracted the attention of biologists since the days of the early ethologists, including Nobel Prize-winner Niko Tinbergen. For example, male sticklebacks aggressively defend nesting territories and are the sole providers of parental care that is necessary for offspring survival. Some individual sticklebacks are more willing to take risks than others, and the way an individual stickleback behaves toward competitors, predators, mates and offspring directly influences fitness and has a heritable component.

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Many of the axes of natural behavioral variation studied in sticklebacks have parallels with human behavioral variation, e.g. risk taking behavior, sensation seeking, extraversion and aggressiveness. Moreover, the system is tractable: sticklebacks can be readily drawn from the wild and measured in reliable behavioral assays, large sample sizes are feasible and they can be crossed and reared in the lab. In other words, sticklebacks have many of the advantages of traditional model organisms with the added advantage that we can study them in a wild state.

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Evidence that behavioral flexibility and boldness go hand in hand when animals disperse into and adapt to new environmentsAugust 1, 2022Miles 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. [...] Read more...