Coupled Relationships between Humans and other Organisms in Urban Areas

Abstract

Today’s urban landscapes, from cities and suburbs to sparse rural and exurban settlements, are the stages for an incredible evolutionary play. Humans are the lead actors, affecting the genetic and cultural inheritance of other species. But non-human organisms are also important players, infl uencing our culture and genetic legacy. Humans, other species, and abiotic elements and processes are tightly coupled in urban ecosystems, perhaps more today than ever before. This coupling of human and natural systems ( Liu et al . 2007a , b ) has recently gained attention, with researchers expressing a need to investigate the mechanistic underpinnings and complexities of these interactions ( Grimm et al . 2000 ; Alberti et al . 2003 ; Liu et al . 2007a , b ). This need stems from both a purely theoretical point of view and an applied perspective. As the world becomes more urbanized, our increased well-being has come at a cost to nature, which in turn is now becoming costly to humans ( Tarsitano 2006 ; Lui et al . 2007a). Although we might appreciate the potential extent of human and natural system coupling as our urban footprint (Marzluff et al . 2008; Fig. 3.1.1 ), it is more diffi cult to imagine our ongoing evolution. It appears that we have distanced ourselves from the natural world, creating ‘artifi cial’ environments by altering nature in physical ways, with the removal of vegetation and building of man-made structures, and changing the way we obtain food (e.g. no longer hunting or gathering). However, as urban areas increase worldwide we are increasing both the number of our interactions with the natural world and the intensity of these interactions ( Liu et al . 2007a , b ), and these increases affect people and nature ( Marzluff & Angell 2005a ). The infl uence of humans on other organisms, from wild to domesticated, is profound (see also Adams and Lindsay, Chapter 2.4 ). Humans affect species survival, population structure, reproduction, behaviour, and evolution in urban areas (e.g. Marzluff 2001 , 2005 ; Chace & Walsh 2006 ; Ditchkoff et al . 2006 ; Brunzel et al . 2009 ). Changing landcover has had a major infl uence on wildlife populations and communities across the globe, and fragmentation, degradation, and pollution are also known to have negative and positive consequences for the survival of animal and plant populations ( Donnelly & Marzluff 2006 ). However, less is known about the extent to which human behaviour towards other organisms (intentional or unintentional) can affect urban plants and wildlife and subsequently affect their population viability and evolution. In this chapter we provide a brief background on the relationship between humans and natural systems and how complex feedback loops can emerge and form coupled systems. We will then focus on interactions between humans and other organisms, the selective forces they impose, and the potential outcomes of such relationships. We document interactions that began with early sedentary lifestyles up to present urban settings and discuss the potential for coevolution. We then describe in detail how a