Rain or shine: Relative importance of abiotic factors on species distributions

Novel approach to determining the relative importance of abiotic factors on species distributions shows a clear dependance on geographical scope

GBIF-mediated data resources used : 1,045,514 species occurrences
Alosa sapidissima
American shad (Alosa sapidissima) adults staging for spawning. Photo by Justin Garwood via iNaturalist–licensed under CC BY-NC 4.0.

The distribution of a species is controlled by a number of biotic and abiotic factors–but also access to suitable areas for dispersal and/or evolutionary ability to adapt to new conditions. The relative contribution of these vary by species, but their importance may be related to geography.

To be able to assess the spatial variability of abiotic factors, researchers studied the distribution of the world's freshwater fishes, using a novel approach–an instability index–to examine and visualize the varying importance of different predictors. Using GBIF-mediated occurrences combined with several bioclimatic and topograhic variables, the authors modelled the distribution of each species in three progressively widening extents.

In their results, they find temperature and altitude to be the most important predictors at the river basin level. Expanding to the regional level, altitude is replaced by precipitation, which finally becomes the single most important predictor at the global level.

Suggesting that predictors depend on geographical scope, this study presents an important implication to be considered in species distribution modelling.

Link to original article

Manjarrés-Hernández AM, Guisande C, García-Roselló E, Pelayo-Villamil P, González-Dacosta J, Heine J, González Vilas L, Granado-Lorencio C, Duque SR and Lobo JM (2017) A procedure to assess the spatial variability in the importance of abiotic factors affecting distributions: the case of world freshwater fishes. Current Zoology. Oxford University Press (OUP). Available at: https://doi.org/10.1093/cz/zox063.