We can describe cognition as the mental processes involved when processing signals and information from our surroundings. Despite being vital for our actions, these processes can be biased by emotions, which results in a judgement bias of ambiguous information. Depressed individuals tend to be pessimistic about such ambiguous information, while individuals under normal or good condition, tend to be optimistic. This is true also for animals. Based on this, cognitive judgement bias tests are developed to measure the affective state of individuals. However, cognitive judgement bias tests require extensive pre-test training for animals to learn positive and negative reference cues. An alternative to using responses to pre-learnt cues could be to use naturally aversive stimuli instead. Eyespot patterns on lepidopterans can be aversive to birds. However, it is scarcely investigated if eyespot patterns can be used to measure affective state. The aim of my study was therefore to investigate if eyespots patterns can replace classic cues in cognitive judgment bias tests measuring affective state. I did so by comparing behavioural responses of red junglefowl chicks (Gallus gallus) to both eyespot patterns and classical cues in a cognitive judgement bias test. Responses correlated between some cues in the two tests, suggesting that eyespot patterns may work as a replacement of pre-learnt cues. However, no differences in responses to the eyespot patterns was found, and so further work is needed to improve the design of eyespot cues to obtain a clearer correlation between responses to eyespot patterns and classical pre-learnt cues in cognitive judgement bias tests. As less training is needed, such improved tests could have positive implications, and be a simpler and more user-friendly way to measure affective state in animals.

The Red Junglefowl is a species of bird that was domesticated by humans around 8 000 years ago. Over time, domestication has led to changes in behavior and morphology, made possible by reduced fear of humans. Fear has been shown to affect cognitive processes, such as the way ambiguous stimuli are perceived by the individual. In this study, I observed the behavior of Red Junglefowl hens that had been selected for either high or low fear of humans to see how the early stages of domestication would affect their tendency to make pessimistic or optimistic judgements. The hens were put in a test arena where they were exposed to positive, negative, and ambiguous stimulus cues, and the time taken to approach each was measured. Hens that had been selected for low fear of humans had overall, albeit not significantly, shorter latencies to approach ambiguous cues. In other words, they were more likely to make optimistic judgements. The results were also affected by the order each stimulus cue was presented. I conclude that domestication may influence the way Red Junglefowl perceive ambiguous stimuli by reducing pessimism.

The effects of domestication on animals’ behaviors and morphology are well known and documented. Changes due to domestication include higher sociability, decreased fearfulness, and increased boldness. These changes have been documented in the chicken breed known as White Leghorn (Gallus gallus domesticus), which is a domesticated relative to the Red Junglefowl (Gallus gallus). Though domestication have altered the chicken’s behavior, its effect on the cognitive learning capabilities of the chicken is still unclear, which is the focus of the study. Two tests were conducted in this study: associative learning and spatial learning. The fowls natural desire to remain close to other fowl was used as the main motivation for completing the tests. The associative learning test was performed by testing the two breeds of associating an item with finding their way to their flock. The spatial learning test was performed by measuring the time needed for an individual to return to their flock from behind an obstacle. For the associative learning test, a significant difference between the cognitive learning capability of the two breeds could be found for part 2 (tests 11-20), as well between part 1 and part 2 within the breed White Leghorn. Between the sexes no significant difference could be seen, but within the females, a significant difference was detected between part 1 and part 2. For the spatial learning test, no significant difference could be found between the two breeds nor the sexes. No correlation could be found between associative- and spatial learning test on an individual level. Due to few significant results, further studies should be conducted to confirm the effects of domestication on learning.

Environmental stress has shown to affect both the exposed individuals and the development of their offspring. Generally, it is thought that the stressed organism responds to stress by trying to adapt to it. This thesis investigates possible evolutionary consequences of cross-generational transmissions of stress, where the parent has been stressed but the offspring has not. In two studies we have exposed chicken parents of different breeds to an unpredictable circadian light rhythm, to investigate the influence of genetic background on the transmission of behaviour and patterns of genome-wide gene expression across generations. In Paper I, we can show that the domesticated chicken, by means of epigenetic factors, transmit their behaviours as well as their gene expression profiles to their offspring to a higher extent than their wild ancestor, the red junglefowl. Furthermore, in Paper II, even though the offspring never experienced the stress or had any contact with their stressed parents, they seemed to have adapted to it, which suggests that the parents might have prepared (or pre-adapted) them for living in the unpredictable environment. Additionally, eggs of stressed hens showed increased levels of estradiol that might have affected gene expression of specific immune genes, which were up-regulated in the offspring of stressed parents. It is possible that the traditional distinction between stress responses and evolutionary adaptation may be reevaluated, since our results indicate that they could be parts of the same evolutionary event.

<p>Environmental stress has shown to affect both the exposed individuals and the development of their offspring. Generally, it is thought that the stressed organism responds to stress by trying to adapt to it. This thesis investigates possible evolutionary consequences of cross-generational transmissions of stress, where the parent has been stressed but the offspring has not. In two studies we have exposed chicken parents of different breeds to an unpredictable circadian light rhythm, to investigate the influence of genetic background on the transmission of behaviour and patterns of genome-wide gene expression across generations. In Paper I, we can show that the domesticated chicken, by means of epigenetic factors, transmit their behaviours as well as their gene expression profiles to their offspring to a higher extent than their wild ancestor, the red junglefowl. Furthermore, in Paper II, even though the offspring never experienced the stress or had any contact with their stressed parents, they seemed to have adapted to it, which suggests that the parents might have prepared (or pre-adapted) them for living in the unpredictable environment. Additionally, eggs of stressed hens showed increased levels of estradiol that might have affected gene expression of specific immune genes, which were up-regulated in the offspring of stressed parents. It is possible that the traditional distinction between stress responses and evolutionary adaptation may be reevaluated, since our results indicate that they could be parts of the same evolutionary event.</p>