Urban land-use is linked to higher fitness in a key pollinator
Ash E. Samuelson, Ash E. Samuelson , Richard J. Gill , Mark J. F. Brown , Elouise Leadbeater
Royal Holloway, University of London; Royal Holloway, University of London ; Imperial College London ; Royal Holloway, University of London ; Royal Holloway, University of London
Urbanisation represents a major expanding driver of global land-use change, and has been shown to impact negatively upon species abundance and diversity for many taxa. Some groups successfully exploit the anthropogenic habitat, and there is evidence to place wild bees among this number. However, the question of whether land-use directly affects fitness – the ultimate driver of ecological success and evolutionary change – remains a largely neglected missing link in the correlations between urbanisation and species abundance. Here we show that urban land-use is linked to colony reproductive success in a key pollinator by monitoring bumblebee (Bombus terrestris) colonies across an urbanization gradient from inner city to rural farmland. Our land-use cluster analysis identified three site categories, and this categorization was a strong predictor of colony performance. Crucially, colonies in the two clusters characterized by urban development produced more sexual offspring than those in the cluster dominated by agricultural land, most likely because they reached higher peak size, had more food stores, encountered fewer parasite invasions and survived for longer. Our results show a link between urbanisation and bumblebee colony fitness, supporting the theory that urban areas provide a refuge for pollinator populations in an otherwise barren agricultural landscape.