Urbanization drives community shifts towards thermophilic and dispersive species at local and landscape scales

Abstract

The increasing conversion of agricultural and natural areas to human-dominated urban landscapes is predicted to lead to a major decline in biodiversity worldwide. Two conditions that typically differ between urban environments and the surrounding landscape are increased temperature, and high patch isolation and habitat turnover rates. However, the extent and spatial scale at which these altered conditions shape biotic communities through selection and/or filtering on species traits are currently poorly understood. We sampled carabid beetles at 81 sites in Belgium using a hierarchically nested sampling design wherein three local-scale (200 × 200 m) urbanization levels were repeatedly sampled across three landscape-scale (3 × 3 km) urbanization levels. First, we showed that communities sampled in the most urbanized locations and landscapes displayed a distinct species composition at both local and landscape scale. Second, we related community means of species-specific thermal preferences and dispersal capacity (based on European distribution and wing morphology, respectively) to the urbanization gradients. We showed that urban communities consisted on average of species with a preference for higher temperatures and with better dispersal capacities compared to rural communities. These shifts were caused by an increased number of species tolerating higher temperatures, a decreased richness of species with low thermal preference, and an almost complete depletion of species with very low-dispersal capacity in the most urbanized localities. Effects of urbanization were most clearly detected at the local scale, although more subtle effects could also be found at the scale of entire landscapes. Our results demonstrate that urbanization may fundamentally and consistently alter species composition by exerting a strong filtering effect on species dispersal characteristics and favouring replacement by warm-dwelling species.

The origin of urban communities: From the regional species pool to community assemblages in city

“…Our results are consistent with previous studies on carabid beetles (e.g. Piano et al, ), bees (e.g. Deguines et al, ), birds (e.g.…”

Increased body size along urbanization gradients at both community and intraspecific level in macro‐moths

“…Here, contrastingly, we show that the community‐level body size shifts fully align with the population‐level (i.e., intraspecific) shifts (see also Peters et al., ). While the wide array of drivers associated with urbanization (e.g., pollution, fragmentation) was already known to cause biotic homogenization by filtering communities for specific traits, such as mobility (McKinney, ; Niemelä & Kotze, ; Concepción et al., ; Piano et al., ), the shift alignment means that urbanization not only results in macro‐moth communities consisting of on average larger, more mobile species, but that it causes the remaining species also to consist of on average larger and more mobile individuals than in less urbanized settings. This finding cannot simply be extrapolated to other taxa.…”

“…In order to test whether urbanization results in a decrease of small species and/or an increase in large species (i.e., filtering), species were assigned to one of three wingspan classes so that each class contains a similar amount of species (sensu Piano et al., ). This approach was done separately for light‐trapped and bait‐trapped samples, and it resulted in 70 small (17–30 mm) and 70 large (40–80 mm) species for the light‐trap sample, and in 22 small (20–33 mm) and 22 large (40–80 mm) species for the bait‐trap sample.…”

Intraspecific variation shapes community‐level behavioral responses to urbanization in spiders

“…, Piano et al. ). We used available data on land use (the Large‐scale Reference Database, an object‐oriented reference map of Flanders) to select sites using the percentage of built‐up surfaces as a proxy of urbanization (map available online) .…”