• One strategy doesn’t fit all: determinants of urban adaptation in mammals

      Santini, Luca; González‐Suárez, Manuela; Russo, Danilo; Gonzalez‐Voyer, Alejandro; von Hardenberg, Achaz; Ancillotto, Leonardo; Radboud University; University of Reading; University of Napoli; Universidad Nacional Autónoma de México; University of Chester (Wiley, 2018-12-20)
      Urbanisation exposes wildlife to new challenging conditions and environmental pressures. Somemammalian species have adapted to these novel environments, but it remains unclear which char-acteristics allow them to persist. To address this question, we identified 190 mammals regularlyrecorded in urban settlements worldwide, and used phylogenetic path analysis to test hypothesesregarding which behavioural, ecological and life history traits favour adaptation to urban environ-ments for different mammalian groups. Our results show that all urban mammals produce largerlitters; whereas other traits such as body size, behavioural plasticity and diet diversity were impor-tant for some but not all taxonomic groups. This variation highlights the idiosyncrasies of theurban adaptation process and likely reflects the diversity of ecological niches and roles mammalscan play. Our study contributes towards a better understanding of mammal association tohumans, which will ultimately allow the design of wildlife-friendly urban environments and con-tribute to mitigate human-wildlife conflicts.
    • The role of brain size on mammalian population densities

      González-Suárez, Manuela; Gonzalez-Voyer, Alejandro; von Hardenberg, Achaz; Santini, Luca; University of Reading; Universidad Autonoma de Mexico; University of Chester; Italian National Research Council (Wiley, 2020-12-22)
      1. The local abundance or population density of different organisms often varies widely. Understanding what determines this variation is an important, but not yet fully resolved question in ecology. Differences in population density are partly driven by variation in body size and diet among organisms. Here we propose that the size of an organism’ brain could be an additional, overlooked, driver of mammalian population densities. 2. We explore two possible contrasting mechanisms by which brain size, measured by its mass, could affect population density. First, because of the energetic demands of larger brains and their influence on life history, we predict mammals with larger relative brain masses would occur at lower population densities. Alternatively, larger brains are generally associated with a greater ability to exploit new resources, which would provide a competitive advantage leading to higher population densities among large‐brained mammals. 3. We tested these predictions using phylogenetic path analysis, modelling hypothesized direct and indirect relationships between diet, body mass, brain mass and population density for 656 non‐volant terrestrial mammalian species. We analysed all data together and separately for marsupials and the four taxonomic orders with most species in the dataset (Carnivora, Cetartiodactyla, Primates, Rodentia). 4. For all species combined, a single model was supported showing lower population density associated with larger brains, larger bodies and more specialized diets. The negative effect of brain mass was also supported for separate analyses in Primates and Carnivora. In other groups (Rodentia, Cetartiodactyla and marsupials) the relationship was less clear: supported models included a direct link from brain mass to population density but 95% confidence intervals of the path coefficients overlapped zero. 5. Results support our hypothesis that brain mass can explain variation in species’ average population density, with large‐brained species having greater area requirements, although the relationship may vary across taxonomic groups. Future research is needed to clarify whether the role of brain mass on population density varies as a function of environmental (e.g. environmental stability) and biotic conditions (e.g. level of competition).