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Title
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Early bird or late night owl? Individual variation in activity timing in wild great tits
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Author
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Abstract
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| Many behavioural and physiological processes fluctuate throughout the day. Such circadian rhythms are predominantly regulated internally by the molecular clock, a negative feedback loop that controls gene expression roughly in a 24 hour schedule. Circadian rhythms are in addition modulated by external factors such as light and temperature (i.e. Zeitgebers) and activity rhythms can be strongly affected by masking factors, which directly affect the timing of behaviour without interacting with the circadian clock. Differences between individuals in the precise duration of the feedback loop or differences in sensitivity to Zeitgebers and masking factors can cause individuals to exhibit differences in activity rhythms, with some individuals tending to be generally active earlier in the day than others. An individual's temporal phenotype is also referred to as its chronotype and individual differences in chronotype are increasingly being reported in free-living species in a variety of taxa. Although the evolutionary history of the development of these differences in chronotype occurred mainly in natural conditions, many habitats today are disturbed by anthropogenic stressors, such as light, noise and chemical pollution, that can affect the timing of activity. In order to understand the possible effects of such stressors on wildlife, it is therefore of utmost importance to first increase our understanding of the functional consequences of differences in chronotypes as well as how and why variation in this trait occurs, as this has remained a mystery to date. Next, it is necessary to investigate how individual activity rhythms are affected by anthropogenic disturbances and what the possible consequences of such disturbances might be. To this end, I studied individual activity rhythms of great tits (Parus major) in a suburban population, by determining their timing of activity onset in the morning and activity offset in the evening. Altogether, this thesis has provided data that are needed to understand how selection can act on the timing of activities, i.e. chronotypes. It not only highlights the functional consequences of differences between individuals in the timing of behaviour, but it also emphasizes how anthropogenic stressors could impinge on urban birds. This knowledge could be of great importance for a better understanding of the key processes of the impact of urbanization on wildlife and to develop sustainable urban planning frameworks. |
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Language
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English
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Publication
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Antwerp
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University of Antwerp, Faculty of Science, Department of Biology
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2024
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DOI
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10.63028/10067/2079470151162165141
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Volume/pages
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252 p.
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Note
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Müller, Wendt [Supervisor]
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Eens, Marcel [Supervisor]
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Full text (open access)
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