On urbanisation and birds : Insights from a molecular and physiological perspective
Author
Summary, in English
Regarding telomere dynamics, the results show that urban environments inflict an early-life detrimental effect on telomere length, probably through a combination of being exposed to multiple urban stressors and poorer diet. This early-life effect on telomere length had implications for survival, with strong selection against short telomere length individuals in the first year, especially in the urban environment. However, if the bird survives their first year, the urban environment does not seem to affect the telomere shortening more than the rural environment. Possibly, some of the urban factors such as supplementary feeding, higher temperatures or lower predation risk, may outweigh the costs of being exposed to different stressors (e.g. air and noise pollution or artificial light at night).
With respect to oxidative stress physiology, we found that in four common urban passerine species, the plasma antioxidant capacity was positively correlated with increases in urbanisation and air pollution intensity (i.e., NOx exposure estimates). Although, their response to urbanisation/NOx was similar, there were significant differences between the four species in absolute levels, suggesting different reaction norms to urbanisation/NOx or different capacities in the up-regulation of the antioxidant physiology. Indeed, and despite the increase in the antioxidant capacity, one of the species, the tree sparrow (Passer montanus), had increased levels of protein carbonyls (oxidative damage biomarker), but only in relation to NOx exposure. This suggests that this species is more sensitive to pollution. Furthermore, the latter result highlights the importance to study markers of oxidative stress across species and in the same environments, in order to understand how urban environmental stress affects species differently.
Finally, our genomic analysis of multiple great tit urban populations reveals that despite the overall low genetic differentiation, some loci diverged in relation to urbanisation. This implies that parallel evolution of a few key genes may play an important role for adaption to the urban environment.
In summary, the results presented in this thesis shed light and offer new perspectives in the emerging field of urban ecology, particularly for bird urban ecology, but also regarding life-history variation and the potential mechanisms involved in shaping phenotypic traits to novel environmental stressors.
Department/s
Publishing year
2017-10
Language
English
Full text
Document type
Dissertation
Publisher
Lund University, Faculty of Science, Department of Biology
Topic
- Natural Sciences
Keywords
- Air Pollution
- Antioxidants
- Birds
- great tit Parus major
- Local adaptation
- Nitrogen oxides
- Oxidative stress
- Parallel evolution
- Survival
- Telomere dynamics
- Telomeres
- Urbanisation
Status
Published
Supervisor
ISBN/ISSN/Other
- ISBN: 978-91-7753-384-9
- ISBN: 978-91-7753-383-2
Defence date
20 October 2017
Defence time
09:00
Defence place
Lecture hall “Blå hallen”, Ecology building, Sölvegatan 37, Lund
Opponent
- Karl Evans (Dr.)