The evolution of city life

Abstract

Urbanization represents a dominant and growing form of disturbance to Earth's natural ecosystems, affecting biodiversity and ecosystem services on a global scale. While decades of research have illuminated the effects of urban environmental change on the structure and function of ecological communities in cities, only recently have researchers begun exploring the effects of urbanization on the evolution of urban populations. The 15 articles in this special feature represent the leading edge of urban evolutionary biology and address existing gaps in our knowledge. These gaps include: (i) the absence of theoretical models examining how multiple evolutionary mechanisms interact to affect evolution in urban environments; (ii) a lack of data on how urbanization affects natural selection and local adaptation; (iii) poor understanding of whether urban areas consistently affect non-adaptive and adaptive evolution in similar ways across multiple cities; (iv) insufficient data on the genetic and especially genomic signatures of urban evolutionary change; and (v) limited understanding of the evolutionary processes underlying the origin of new human commensals. Using theory, observations from natural populations, common gardens, genomic data and cutting-edge population genomic and landscape genetic tools, the papers in this special feature address these gaps and highlight the power of urban evolutionary biology as a globally replicated 'experiment' that provides a powerful approach for understanding how human altered environments affect evolution.

Urban colonization through multiple genetic lenses: The city‐fox phenomenon revisited

“…We additionally identified outlier loci with putative gene functions related to urban‐associated processes, such as energy metabolism, behavior, and immunity. In addition to system‐specific information gained, this study contributes toward our overall understanding of the genetics of urban evolution, an exciting frontier within urban evolutionary biology (Johnson & Munshi‐South, ; Santangelo et al, ). It further emphasizes the value of combining datasets to parse the roles of stochastic and adaptive processes underlying evolutionary change in an increasingly urban world.…”

“…Impacts of urbanization include homogenizing habitat and reducing species diversity (McKinney, 2006), reducing phylogenetic richness (Knapp et al, 2017), and increasing human-wildlife conflict (Soulsbury & White, 2015). Although urbanization can homogenize a multispecies wildlife community, urban gradients can lead to population subdivision within a species due to reduced gene flow across urban barriers and divergent selection pressures between rural and urban conspecifics (Johnson & Munshi-South, 2017;Santangelo, Ruth Rivkin, & Johnson, 2018). Urban barriers include buildings, freeways, and densely populated areas (such as city centers), with divergent selection pressures including varied noise and light pollution, diet, and disease and toxicant exposure between urban and rural environments (Brans, Stoks, & De Meester, 2018;Harris & Munshi-South, 2017;Isaksson, 2015;Ouyang et al, 2017;Sih, Ferrari, & Harris, 2011).…”

“…Urban barriers include buildings, freeways, and densely populated areas (such as city centers), with divergent selection pressures including varied noise and light pollution, diet, and disease and toxicant exposure between urban and rural environments (Brans, Stoks, & De Meester, 2018;Harris & Munshi-South, 2017;Isaksson, 2015;Ouyang et al, 2017;Sih, Ferrari, & Harris, 2011). The possibility for urban-rural gradients facilitating divergence has created a need for more research dedicated to assessing the evolutionary changes associated with urbanization (Alberti, 2015;Donihue & Lambert, 2015;Santangelo et al, 2018). As such, there has recently been a surge of studies examining the genetic effects of urbanization across diverse taxa, with each system providing unique insights into the processes shaping wildlife in the Anthropocene (Combs, Byers et al, 2018;Johnson, Prashad, Lavoignat, & Saini, 2018;Miles, Dyer, & Verrelli, 2018;Mueller, Kuhl et al, 2018;Theodorou et al, 2018).…”

Metropolitan lizards? Urbanization gradient and the density of lagartixas (Tropidurus hispidus) in a tropical city

“…Basic ecological and evolutionary mechanisms in urban ecosystems remain poorly understood, and most studies are limited to temperate regions (Alberti et al, 2016;El-Sabaawi, 2018;Faeth, Bang, & Saari, 2011;Johnson & Munshi-South, 2017;McKinney, 2008;Santangelo, Rivkin, & Johnson, 2018). In this sense, lagartixas could be excellent models; they are extremely common in tropical cities, have a wide niche breadth, a short generation time (≤3 years: Flower, 1925;Wiederhecker, Pinto, Paiva, & Colli, 2003), and make extreme use of artificial substrates, which are associated with evolutionary change in Anolis (e.g., Marnocha et al, 2011;Winchell, Maayan, et al, 2018;Winchell et al, 2016).…”

Biodiversity in the Anthropocene

“…Other species are already adapting to city life through rapid evolution. Exotic and introduced species often become integral parts of the biodiversity (Santangelo et al 2018). We need to plan to protect this part of the Anthropocene biodiversity through collaborations among city engineers, construction companies, economists, sociologists, politicians, and biologists.…”