Risk-taking by threespine stickleback (Gasterosteus aculeatus) pelvic phenotypes: Does morphology predict behaviour?

The relationship between risk-taking behaviour and anti-predator morphology was studied in benthic threespine sticklebach fish (Gasterosteus aculeatus ) from Paxton and Priest Lakes on Texada Island, British Columbia, Canada. in general, Priest Lake benthies possess complete pelvic girdles and numero us lateral plates. In contrast, Paxton Lake benthies exhibit an apparent po lymorphism in anti-predator morphology; some individuals possess complete p elvic girdles while other lack them entirely. Although phenotypes tended to differ in their willingness to risk exposure to a trout predator while for aging, the predicted positive relationship between risk-taking behaviour an d anti-predator morphology was not observed. While 'girdled' Paxton individ uals were more willing to forage in the vicinity of the predator than 'gird leless' Paxton individuals, the more heavily armoured Priest fish were inte rmediate in their risk-taking behaviour. These results suggest that the rel ationship between risk-taking behaviour and anti-predator morphology may be influenced by differences between phenotypes in predation regime and life history.