< Back to previous page

Project

Effects of urbanisation on the ecology and evolution of a damselfly

The rate of urbanisation is increasing on a global scale. Compared to rural areas, cities are warmer, more polluted by chemicals, and more fragmented. Although biodiversity is clearly impacted by this anthropogenic activity, there are large gaps in our understanding on the effects of urbanisation at the population and individual levels. In this thesis, I tested whether urban and rural populations of the damselfly Coenagrion puella differed in their responses to higher temperatures, increased contamination, and more intense habitat fragmentation. For this, I mostly applied a common garden experimental approach, either in the laboratory or in semi-natural outdoor conditions, allowing the identification of genetic adaptation. To also test the outstanding question whether urbanisation influences sexual selection regimes, I additionally did an experiment with field-collected adult damselflies. All study populations were situated in Flanders, Belgium.

I found strong divergence between urban and rural populations in responses to each of the three studied urbanisation-related stressors, suggesting evolutionary responses to urbanisation. The higher temperatures in urban areas influenced the life history of urban damselflies by altering growing season length, yet did not affect behavioural traits. With regard to contamination, damselfly larvae from urban habitats showed different behavioural responses to pesticides when compared to rural larvae. Furthermore, pesticide exposure differently affected behavioural correlations in urban and in rural larvae. Interestingly, several responses to urban-related stressors strongly depended on the sex of the damselfly, as well as the life stage at which they were exposed to the stressor. Finally, the more fragmentated habitats in urban areas seem to have selected for better flyers by influencing the dispersal ecology of damselflies, which was further strengthened by sexual selection for a higher flight performance in urban populations.

In conclusion, I found clear effects of urbanisation on the evolution and ecology of a damselfly. My findings suggest that differential selection was imposed by the here tested urbanisation-related stressors. Importantly, these stressors were acting in different life stages, highlighting the need for a full life cycle approach when studying the effects of urbanisation.

Date:1 May 2014 →  23 May 2018
Keywords:evolutionary ecology, urbanisation
Disciplines:Evolutionary biology, General biology, Social medical sciences, Animal biology, Fisheries sciences
Project type:PhD project