Hierarchical filters determine community assembly of urban species pools

Abstract

Abstract. The majority of humanity now lives in cities or towns, with this proportion expected to continue increasing for the foreseeable future. As novel ecosystems, urban areas offer an ideal opportunity to examine multi-scalar processes involved in community assembly as well as the role of human activities in modulating environmental drivers of biodiversity. Although ecologists have made great strides in recent decades at documenting ecological relationships in urban areas, much remains unknown, and we still need to identify the major ecological factors, aside from habitat loss, behind the persistence or extinction of species and guilds of species in cities. Given this paucity of knowledge, there is an immediate need to facilitate collaborative, interdisciplinary research on the patterns and drivers of biodiversity in cities at multiple spatial scales. In this review, we introduce a new conceptual framework for understanding the filtering processes that mold diversity of urban floras and faunas. We hypothesize that the following hierarchical series of filters influence species distributions in cities: (1) regional climatic and biogeographical factors; (2) human facilitation; (3) urban form and development history; (4) socioeconomic and cultural factors; and (5) species interactions. In addition to these filters, life history and functional traits of species are important in determining community assembly and act at multiple spatial scales. Using these filters as a conceptual framework can help frame future research needed to elucidate processes of community assembly in urban areas. Understanding how humans influence community structure and processes will aid in the management, design, and planning of our cities to best support biodiversity.

Magnitude and correlates of bird collisions at glass bus shelters in an urban landscape

“…Such an approach would both lead to a greater understanding of the anthropogenic forces which shape urban biota across cities [34, 35] and allow for a more nuanced assessment of the effect of varying land cover types and landscape patterns on collision rates. This approach would also result in a broader variety of bus shelter designs being captured, including those of varying sizes, heights, and orientations relative to surrounding vegetation and roadways, and with different types of glass.…”

Context Matters: Contrasting Ladybird Beetle Responses to Urban Environments across Two US Regions

“…In disturbed urban landscapes, more abundant species are habitat generalists and/or non-native to a region [2,75]. These species have ecological traits that allow them to exploit resources and persist [76], and environmental filters have been used to explain taxonomic differences between urban habitats [12,77]. Most (though not all) of the ladybird species that we observed in Michigan sites are native species from the greater Northeast and Midwest region (Table 1).…”

“…Indeed, the strongest pattern from our study is the response of unique species to both the percent impervious surface and to the rate of urbanization, with abundance of unique beetles significantly increasing in California but decreasing in Michigan. This suggests that there are environmental filters at regional as well as local scales for species' traits that allow them to thrive in more urban areas and habitats [12,65] in California, and that in Michigan, those species are not present. Only species with traits that allow them to persist in urban environments should similarly increase with increasing rates of urbanization across regions.…”

“…Some species are able to persist and thrive in altered urban environments, while environmental filters and competition can cause other species to decline [12]. The species that thrive, what some consider "urban exploiters", are often habitat generalists that are able to live, exploit resources and reproduce in diverse, resource poor environmental conditions [2].…”

Unifying functional trait approaches to understand the assemblage of ecological communities: synthesizing taxonomic divides

“…Throughout its history (Laureto et al 2015), trait-based perspectives have advanced our understanding of major ecological processes, including niche differentiation (McGill et al 2006, Blonder 2017, response to environmental disturbance (Flynn et al 2009, Mouillot et al 2013, Kimball et al 2016, Fountain-Jones et al 2017, and community assembly via environmental filtering (Lebrija-Trejos et al 2010, Aronson et al 2016. Throughout its history (Laureto et al 2015), trait-based perspectives have advanced our understanding of major ecological processes, including niche differentiation (McGill et al 2006, Blonder 2017, response to environmental disturbance (Flynn et al 2009, Mouillot et al 2013, Kimball et al 2016, Fountain-Jones et al 2017, and community assembly via environmental filtering (Lebrija-Trejos et al 2010, Aronson et al 2016.…”