Beyond range size: drivers of species’ geographic range structure in European plants

Abstract

Beyond range size: drivers of species' geographic range structure in European plants 1 2 Running title: Geographic range structure of European plant species 3 4 Abstract 5 Aim: To assess if and how species' range size relates to range structure, if the observed 6 geographic range properties can be retrieved from predicted maps based on species distribution 7 modeling, and whether range properties are predictable from biogeophysical factors.8 Location: Europe 9 Time period: Current 10 Major taxa studied: 813 vascular plant species endemic to Europe 11Methods: We quantified the size and spatial structure of species' geographic ranges and 12 compared ranges currently occupied with those predicted by species distribution models (SDMs). 13SDMs were constructed using complete occurrence data from the Atlas Florae Europaeae and 14 climatic, soil and topographic predictors. We used landscape metrics to characterize range size, 15 range division and patch shape structure, and analysed the phylogenetic, geographic and 16 ecological drivers of species' range size and structure using phylogenetic generalized least 17 squares (pGLS). 18Results: Range structure metrics were mostly decoupled from species' range size. We found 19 large differences in range metrics between observed and predicted ranges, in particular for 20 species with intermediate observed range size and occupied area, and species with low and high 21 observed patch size distribution, geographic range filling, patch shape complexity and 22 geographic range fractality. Elevation heterogeneity, proximity to continental coasts, Southerly 23 or Easterly geographic range positions and narrow ecological niche breadth constrained species' 24 1 observed range size and range structure to different extents. The strength and direction of the 25 relationships differed between observed and predicted ranges.26Main conclusions: Several range structure metrics, in addition to range size, are needed to 27 adequately describe and understand species' ranges. Species' range structure can be well 28 explained by geophysical factors and species niche width, albeit not consistently for observed 29 and predicted ranges. As range structure can have important ecological and evolutionary 30 consequences, we highlight the need to develop better predictive models of range structure than 31 provided by current SDMs, and we identify the kinds of species for which this is most necessary. 32 33

Shadow distributions: Deconstructing the geography of human impacts on species' natural distribution

“…Exploring how internal range structure is environmentally determined is an emerging field. In general, the factors influencing internal structure of a geographical range are expected to differ from those affecting geographical range boundaries 57 . Recent research has revealed that climate change can modify internal range structure independently from range edges, which may arise if metapopulation viability differs between range interior and range edges 58 .…”

Applying landscape metrics to species distribution model predictions to characterize internal range structure and associated changes

“…Range shifts are therefore key to species persistence (Muir et al, 2020). Beyond range size and boundaries, internal range structure metrics are needed to adequately | 643 describe species' ranges and more accurately quantify how they will be affected in the future (Csergő et al, 2020), particularly for species with discontinuous distributions. Analysing which landscape-level processes scale up to structure species biogeographic ranges has however remained largely unexplored.…”

“…the external range structure), thus overlooking changes taking place within ranges (i.e. the internal range structure; Csergő et al, 2020).…”