Human activities have a strong impact on the distribution and abundance of other living organisms. This obviously is a key topic for conservation biology. However, this diverse and strong human impact also allows studying evolutionary responses (or the lack of response in some systems). We address this issue with grasshoppers in urban areas and with woodland butterflies in agricultural landscapes.
1. Grasshoppers and the city: diversity and adaptation
The proportion of land turned into urban area is growing rapidly worldwide. Urban areas have been shown to offer particular climates (i.e. warm and dry) that may be interesting for thermophilous insects like grasshoppers. However, the quality, quantity and configuration of ecological resources in urban areas may significantly affect their way of living. Buildings may, for example, facilitate or inhibit movements across urban areas. We study the distribution and life-history traits of grasshoppers (and some other taxonomic groups as well) in cities (e.g. Brussels). With laboratory experiments, we test to what extent the behaviour, morphology and life-history traits of individuals from urban populations differ from rural populations. We use the grasshopper Chorthippus brunneus as a study case.
2. From woodland specialist to landscape generalist? The speckled wood case
In NW-Europe (including Belgium), butterfly species have declined severely. This is also true for many widespread species. Loss and fragmentation of habitats are most often mentioned as key factors. We have chosen to study the evolutionary ecology of a winner. The speckled wood butterfly (Pararge aegeria) is one of the most successful butterfly species that increased significantly in distribution and abundance over recent time. The species used to be confined to woodlands (as it is still the case in N-Europe), but has expanded into other landscape types with some ‘woodland aspect’ (like gardens and agricultural landscapes with some hedges or woodlots). We study to what extent speckled woods from woodland landscape differ in behaviour, morphology, life history and genetics from conspecifics of agricultural landscape. Both types of landscapes are also from a thermal point of view two different worlds for a flying heliotherm like P. aegeria.