Functional traits drive the fate of Orthoptera in urban areas

Abstract

The replacement of natural areas due to urbanisation represents a major threat to wildlife. Wild species may be classified according to their response towards urban areas. Such responses lead to persistence (exploiters and tolerant) or local extinction (avoiders) of species within cities, which in turn contributes to shaping the assemblages found therein, usually according to specific sets of ecological and morphological traits. Here, we focus on Orthoptera as a model group to test hypotheses on the relationships between species' traits and persistence in urban environments, using the city of Rome, Italy, as study area. By compiling and comparing species checklists for two distinct time frames, we assessed assemblage variation across the last three decades and revealed that local extinction of Orthoptera in urban areas is trait‐biased. Species with low mobility and fertility, and narrower—more specialised—climatic niches showed higher probability of local extinction. Our results point at both climate and land use changes as potentially major drivers of orthopterans' local extinction in urban areas, suggesting that strategies to increase natural habitat preservation and connectivity, and mitigate climate‐change induced events, may both prove effective in sustaining richer insect communities within urban areas.

Urbanization reduces Orthoptera diversity and changes community structure towards mobile species

“…From an ecological perspective, the physiologically predetermined niche breadth width often plays a role in the selection of species in the city, and thus a decrease in habitat specialists-species with a narrow niche breadth-is predominantly assumed (Ancillotto & Labadessa, 2024;Bonier et al, 2007;Penone et al, 2013). We can only partially confirm this concept.…”

“…However, urbanization affects single grasshopper species differently, which could result in generalists and mobile species being present more and in higher numbers in urban ecosystems than sedentary species and specialists (Penone et al, 2013). For example, Ancillotto and Labadessa (2024) discovered that the local extinction of Orthoptera species in Rome over time is correlated with low mobility and more specialized climatic niches. Conflicting findings often result from the initial rarity of less mobile species in urban areas (Huchler et al, 2022;Melliger et al, 2017)…”

Insect ecology and conservation in urban areas: An overview of knowledge and needs

“…Urban density may also select for dispersal-enhancing morphologies within populations or species assemblages, which has been proposed for flight-related traits of aquatic beetles (Liao & Lin, 2024), as well as body size of wild bees (Brasil et al, 2023) and macro moths (Merckx, Kaiser, & Van Dyck, 2018). These patterns, which are also considered a form of ecological filtering, may reflect changes in the costs and benefits of dispersal in urban environments (Ancillotto & Rocco, 2024;Jones & Leather, 2012), although they may also reflect traits of founder individuals in low-dispersal systems, and conclusions are largely uncertain (see also genetics section below) (Federico et al, 2024).…”

“…Many works indicate a homogenisation and decrease in functional type, species diversity and/or insect abundance as urban density increases (in this SI see: Barao et al, 2024; Casanelles‐Abella et al, 2024; Federico et al, 2024; Rivest & Kharouba, 2024; Sanetra et al, 2024; Svenningsen et al, 2024). This picture is, however, nuanced (e.g., Ancillotto & Rocco, 2024; Federico et al, 2024; Ombugadu et al, 2024) and although urban areas can detrimentally impact some insect taxa through the predominance of artificial environments, constrained habitats and disturbances, other taxa can adapt and thrive in the mosaic of semi‐natural and novel environments, management variation and abundant resources (Curry et al, 2024; Hill et al, 2024; Nunes et al, 2024; Plummer et al, 2024; Xu et al, 2024). Lessons from metapopulation ecology and a better understanding of patch quality for specific taxa will be critical to raising urban insect diversity and conserving this as a stable ecosystem component (e.g., Azhar et al, 2024; Liao & Lin, 2024).…”