An emerging literature is documenting many examples of species adapting behaviorally, morphologically and genetically to urban life. Such an “evolution explosion” is hardly surprising given the extreme and rapid changes in urban habitats. Most of this literature focuses on the autoecological adaptations of individual organisms and species. However, these adaptive changes also have implications for the synecology of urban ecosystems. For example, the increasing number of species colonizing and adapting to urban habitats implies that the resulting novel urban ecosystems will have increasing complexity (more species present and more biotic interactions). This could also improve the ecological functions (and ecosystem services) of novel urban ecosystems, as evidence often indicates that such functions improve with increasing biodiversity and ecological complexity. One could thus argue that urban “niche construction” by humans and its effect on urban biota is producing the opposite process of the commonly-noted “invasional meltdown”. In this view, adaptations by introduced species promote the assembly of increasingly complex and higher functioning urban ecosystems through ecological and evolutionary time. This process could transform the debate about whether novel ecosystems are “good” or “bad” and whether they should be managed “for” (encouraged) or managed “against”. If urban novel ecosystems already provide some valuable functions and services that are not otherwise available in urban habitats, then they may provide even more biodiversity and ecological functions as their constituent species adapt to urban habitats and become more numerous and ecologically efficient. This represents a major paradigm shift in ecology away from viewing urban habitats as temporary aberrations from natural systems to the realization that these novel ecosystems are here for the foreseeable future. If true, ecology can help proactively inform the “ecological design” of novel urban communities for centuries.
Results/Conclusions
I review the rapidly growing literature on species adaptations to urban habitats showing that the number of plant and animal species adapting to urban conditions around the world is growing exponentially. In addition, I show an increase in the synecological associations of species in these novel ecosystems, which ostensibly increase the ecological function and services of these ecosystems. Examples include the documented increase through time in the number of insect species feeding on introduced plants. I also discuss the how patterns of colonization and adaptation in plants differ from those patterns in animals, with important consequences for novel ecosystem assembly and specific implications for green roofs, suburban landscaping, urban parks, and green infrastructure in general.