Domestication effects on behaviour : foraging, parent-offspring interactions and antipredation in pigs and fowl

The aim of this thesis was to study domestication effects on behaviour from a functional perspective. I have used the domestic pig versus the wild boar (Sus scrofa) and the domestic fowl versus the red jungle fowl (Gallus gallus) as experimental model animals. The foraging behaviour of pigs and fowl was studied in two environments where there was a difference in the energy acquired to move between the food sources. Both pigs and fowl responded to some qualitative predictions from optimal foraging theory, moreover the differences between the genotypes were concluded to be a result from a shift of behaviour optimum towards less costly strategies. Maternal behaviour, including nestbuilding behaviour, nursing behaviour, post-massage behaviour and mother-offspring interactions of pigs was studied in a semi-natural environment. Despite many generations of domestication, most aspects of maternal behaviour seem to be unaffected. However, the differences between genotypes that were found suggest that the domestic pigs are adapted to a domestic life and thereby more likely to invest more in current offspring. Anti-predatory behaviour offowl was studied in two experiments. First the vigilance behaviour in two different group sizes and then the direct response to an airborne predator model. Results show that the anti-predatory behaviour is to a large extent unmodified during domestication. However, the differences between genotypes that were found are likely a result from the relaxation of natural selection factors, i.e. predator avoidance that follow with domestication. This thesis represents one ofthe first attempts to study functional effects of domestication. The results are mostly not conclusive but suggest that the approach can be very fruitful and helpful in providing a basis for future research.