Effects of Urbanization on the Ecology and Evolution of Arthropods

Abstract

The role of the ‘little things that run the world’ ( Wilson 1987 ) is challenged by the human enterprise in urban areas. High-density human habitation is associated with loss, fragmentation, isolation, and pollution of natural habitats, introduction and spread of exotic species, accumulation of waste products, and changes in climatic, edaphic, and hydrological processes ( Frankie & Ehler 1978 ; McIntyre et al . 2001 ). All of these impacts affect arthropod communities and their contributions to ecosystem function. On the other hand, this diversity of human actions also creates opportunities for arthropods to thrive in cities. Because they fi ll important functional roles in ecosystems, including decomposition, pollination, nutrient cycling, foodweb interactions, and biological control, arthropod communities refl ect urban environmental quality. Their short generation times and rapid responses to environmental change make arthropods especially well-suited for studying the biotic effects of urbanization. In addition, many arthropods have educational and aesthetic values to urban residents (Andersson et al . 2007) that increasingly balance negative perceptions of arthropods as pests in well-educated societies. Frankie and Ehler ( 1978 ) called for the establishment of ‘urban entomology’ as an independent discipline, but the fi eld has remained incompletely developed ( McIntyre 2000 ), although its importance is recognized, for example for urban pest management ( Robinson 1996 ). Nonetheless, urbanization reduces biodiversity ( Davis 1978 ; Connor et al . 2002 ) and thus has major implications for ecosystem function and the provision of ecological services, including a sense of human well-being. In hoping to stimulate research on non-pestiferous urban arthropods through this chapter, we review how urban arthropods are affected by: 1) habitat fragmentation, 2) habitat changes along the urban–rural gradient, 3) uniquely urban environments (such as domestic gardens, ruderal land, etc.), and 4) natural selection in urban environments. Based on this review, we consider major issues relevant to conservation of urban arthropods. Because of our collective experience with ground beetles, we draw extensively on that literature for examples, using studies of other arthropod species to amplify the generality of conclusions.