There are several plausible explanations for the initial evolution of aposematism and warning signals but, since these all have support in the form of experimental evidence, it is unlikely that there is one single, simple evolutionary pathway. I investigated the influence of predator psychology on the design of aposematic signals and concentrated on the effects of (innate) colour preferences, learning and memory, using two species of avian predators: ('naYve') domestic chicks (Gallus domesticus) and wild (and therefore experienced) great tits (Paros major). I found that young chicks had innate preferences for some specific colours that were. more saturated and from the long-wavelength part of the spectrum. Furthermore, these preferences were not based on an effect of contrast with the viewing background. However, I did not observe any colour preferences in the great tits, perhaps because they are naturally a generalist species. Domestic chicks trained with two rewarded colours generalise between them to strongly prefer an intermediate colour. I used this phenomenon to further investigate the learning and memorability of colours in chicks. I found an interesting effect, where there is a delay between an encounter with novel prey and when this experience affects behaviour, which could potentially affect avoidance learning. I additionally investigated the relationship between attractiveness and memorability of coloured signals and found that these are potentially distinct features of warning patterns. Finally, observed how great tits learnt and remembered some typically-aposematic colours and compared this to my findings from the chicks. The great tits not only failed to show any colour preferences, but red, yellow and neutral grey stimuli were also equally well learnt in a discrimination task and remembered. The great tits did not show the same generalisation to an intermediate colour as the chicks, but generalised their learning to the novel colour more strongly when the trained colours were unpalatable than when they were palatable
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:288162 |
| Date | January 2003 |
| Creators | Ham, Abigail Doreen |
| Publisher | University of Sussex |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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