Weak effect of urbanization on bdelloid rotifers living in lichens.

Human activities have an overwhelming impact on the natural environment, leading to a deep biodiversity crisis whose effects range from genes to ecosystems. Here, we analysed the effect of such anthropogenic impacts on bdelloid rotifers (Rotifera Bdelloidea), for whom these effects are poorly understood. We targeted bdelloid rotifers living in lichen patches across urbanization gradients in Flanders and Brussels (Belgium). Urbanization was measured as the percentage of built-up area (BU) across different spatial scales, at circles from 50 to 3200 m of radius around the lichen. Urbanization effects on biodiversity were assessed on abundance, species richness and community-weighted mean body size of bdelloid rotifers, as well as on genetic diversity of a mitochondrial marker (cytochrome c oxidase subunit I) of one of the most common and widespread bdelloid species, Adineta vaga. Overall, no negative effect of urbanization was found at any diversity level and any spatial scale. Counterintuitively, the BU area quantified at the largest spatial scale had a positive effect on abundance. These results leave open the question of whether negative effects of urbanization are present for bdelloid rotifers, if they are mediated by other unexplored drivers, or if such effects are only visible at even larger spatial scales.

Urbanization-driven changes in web building and body size in an orb web spider.

In animals, behavioural responses may play an important role in determining population persistence in the face of environmental changes. Body size is a key trait central to many life-history traits and behaviours. Correlations with body size may constrain behavioural variation in response to environmental changes, especially when size itself is influenced by environmental conditions. Urbanization is an important human-induced rapid environmental change that imposes multiple selection pressures on both body size and (size-constrained) behaviour. How these combine to shape behavioural responses of urban-dwelling species is unclear. Using web building, an easily quantifiable behaviour linked to body size and the garden spider Araneus diadematus as a model, we evaluated direct behavioural responses to urbanization and body size constraints across a network of 63 selected populations differing in urbanization intensity. We additionally studied urbanization at two spatial scales to account for some environmental pressures varying across scales and to obtain first qualitative insights about the role of plasticity and genetic selection. Spiders were smaller in highly urbanized sites (local scale only), in line with expectations based on reduced prey biomass availability and the Urban Heat Island effect. Web surface and mesh width decreased with urbanization at the local scale, while web surface also increased with urbanization at the landscape scale. The latter two responses are expected to compensate, at least in part, for reduced prey biomass availability in cities. The use of multivariate mixed modelling reveals that although web traits and body size are correlated within populations, behavioural responses to urbanization do not appear to be constrained by size: there is no evidence of size-web correlations among populations or among landscapes, and web traits appear independent from each other. Our results demonstrate that responses in size-dependent behaviours may be decoupled from size changes, thereby allowing fitness maximization in novel environments. The spatial scale at which traits respond suggests contributions of both genetic adaptation (for web investment) and plasticity (for mesh width). Although fecundity decreased with local-scale urbanization, A. diadematus abundances were similar across urbanization gradients; behavioural responses thus appear overall successful at the population level.

A database on the distribution of butterflies (Lepidoptera) in northern Belgium (Flanders and the Brussels Capital Region).

In this data paper, we describe two datasets derived from two sources, which collectively represent the most complete overview of butterflies in Flanders and the Brussels Capital Region (northern Belgium). The first dataset (further referred to as the INBO dataset - http://doi.org/10.15468/njgbmh) contains 761,660 records of 70 species and is compiled by the Research Institute for Nature and Forest (INBO) in cooperation with the Butterfly working group of Natuurpunt (Vlinderwerkgroep). It is derived from the database Vlinderdatabank at the INBO, which consists of (historical) collection and literature data (1830-2001), for which all butterfly specimens in institutional and available personal collections were digitized and all entomological and other relevant publications were checked for butterfly distribution data. It also contains observations and monitoring data for the period 1991-2014. The latter type were collected by a (small) butterfly monitoring network where butterflies were recorded using a standardized protocol. The second dataset (further referred to as the Natuurpunt dataset - http://doi.org/10.15468/ezfbee) contains 612,934 records of 63 species and is derived from the database http://waarnemingen.be, hosted at the nature conservation NGO Natuurpunt in collaboration with Stichting Natuurinformatie. This dataset contains butterfly observations by volunteers (citizen scientists), mainly since 2008. Together, these datasets currently contain a total of 1,374,594 records, which are georeferenced using the centroid of their respective 5 × 5 km² Universal Transverse Mercator (UTM) grid cell. Both datasets are published as open data and are available through the Global Biodiversity Information Facility (GBIF).