Beyond range size: drivers of species' observed and predicted geographic range structure in European plants
Different processes may affect the size and spatial structure of species' geographic ranges. Yet, biogeographic studies often exclusively focus on determinants of range size only. In a comparative analysis of 813 European vascular plants, we found that range structure was mostly decoupled from species' range size. We found large differences in range metrics between observed ranges and predictions from species distribution models (SDMs) for species with intermediate observed range size, and for species with low and high observed range division and patch shape complexity. Elevation heterogeneity, proximity to continental coasts and Southerly or Easterly range positions as well as narrow ecological niche breadth constrained species' observed and predicted range metrics to different extents. As range structure can have important ecological and evolutionary consequences, predictive models of species distributions will need to accommodate discrepancies between observed and modelled spatial range structures in different sets of species.
Distance to native niche margins explains establishment success of alien mammals
The environmental niche is a key concept in ecology that describes the conditions necessary for an organism to survive. It is widely used to predict species distributions and spatial community patterns. Accordingly, theory predicts that climatic conditions found at sites where alien species establish successfully should match the conditions of the native climatic niche (NCN). Yet , this hypothesis has surprisingly remained mostly untested, and was never assessed for mammals. Here, using a new index that provides a measure of how distant a site is inside or outside the NCN, we show that NCN-matching is a stronger predictor of establishment success of mammals worldwide than most previously tested life history attributes and historical factors.