Dingemanse NJ, Wright J, Kazem AJN, Thomas DK, Hickling R, Dawnay D. (2007) Behavioural syndromes differ predictably between 12 populations of three-spined sticklebacks. Journal of Animal Ecology 76: 1128-1138. doi: 10.1111/j.1365-2656.2007.01284.x
Brydges NM, Colegrave N, Heathcote RJP, Braithwaite VA. (2008) Habitat stability and predation pressure affect temperament behaviours in populations of three-spined sticklebacks. Journal of Animal Ecology 77: 229-235. doi: 10.1111/j.1365-2656.2008.01343.x
Existence of animal personalities or behavioural syndromes – i.e. correlated behavioural traits, either between different traits like aggression and boldness, or between the same trait measured in different contexts like aggression towards competitors, mate, offspring or predator – has been proven for several animal taxa. However, the cause behind the phenomenon remained controversial. Two general hypotheses exist: (i) the genetic constraint and (ii) the adaptive hypotheses.
In an earlier study, Bell (2005 JEB 18:464-473) showed that different behaviours were correlated in a threespine stickleback (Gasterosteus aculeatus) population where predation pressure was high, but not in another without predatory fish. Based on this, Bell rejected the genetic constraint and supported the adaptive hypothesis. However, even though the two-population comparison was enough to say that the syndrome did not exist everywhere, and thus reject the genetic constraint hypothesis; a deeper insight into the patterns requires a larger set of tested populations.
Recently, two studies had been published directly related to this issue by Dingemanse et al. (2007) and Brydges et al. (2008). Both used wild caught fish from populations varying in predatory risk. Dingemanse et al. (2007) found a perfect support for Bell’s (2005) suggestions: they could detect the syndrome in six predatory populations, but not in six populations with negligible predation. Results from Brydges et al (2008) are less straightforward: even though they found the predicted differences in boldness in their eight study populations, i.e. fish from low predation sites were bolder, they only detected behavioural correlations from one population.
In sum, both results are supporting Bell’s (2005) view; genetic constraints are not a plausible explanation for the existence of behavioural syndromes in threespine stickleback. It is noteworthy though that both studies used fish collected in the wild, so potential environmental effects could bias their results.