Hastiness, brain size and predation regime affect the performance of wild guppies in a spatial memory task

The ability to return to, or avoid, specific locations is often critical to fitness-related activities. We tested for differences in spatial memory of guppies, Poecilia reticulata, from low- and high-predation populations in a maze task. We also measured the time each fish took to make a decision in the maze, because individuals can show a trade-off between the speed and the accuracy of their decisions during this kind of task. Because brain size can affect cognitive performance, we also measured brain size. There were no differences in the number of errors made or time to find the reward between predation regimes. However, high-predation guppies tended to take longer to make the decision about which maze chamber to enter than low- predation guppies; thus, low- predation guppies were more willing to make quick and potentially inaccurate decisions, a strategy we have termed 'hastiness'. Individuals within populations also varied in hastiness and we found that hasty guppies tended to have smaller telencephalons, the brain region most responsible for spatial memory. There was no difference in brain size in relation to predation regime, although lab-reared fish had smaller brains than wild-caught fish. This study shows that the careful observation of an animal's strategy for solving spatial problems may reveal subtle differences that are associated with ecology and brain size. (C) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.