A procedure to assess the spatial variability in the importance of abiotic factors affecting distributions: the case of world freshwater fishes

Abstract

Understanding the factors shaping species’ distributions is a key longstanding topic in ecology with unresolved issues. The aims were to test whether the relative contribution of abiotic factors that set the geographical range of freshwater fish species may vary spatially and/or may depend on the geographical extent that is being considered. The relative contribution of factors, to discriminate between the conditions prevailing in the area where the species is present and those existing in the considered extent, was estimated with the instability index included in the R package SPEDInstabR. We used 3 different extent sizes: 1) each river basin where the species is present (local); 2) all river basins where the species is present (regional); and 3) the whole Earth (global). We used a data set of 16,543 freshwater fish species with a total of 845,764 geographical records, together with bioclimatic and topographic variables. Factors associated with temperature and altitude show the highest relative contribution to explain the distribution of freshwater fishes at the smaller considered extent. Altitude and a mix of factors associated with temperature and precipitation were more important when using the regional extent. Factors associated with precipitation show the highest contribution when using the global extent. There was also spatial variability in the importance of factors, both between species and within species and from region to region. Factors associated with precipitation show a clear latitudinal trend of decreasing in importance toward the equator.

Predicting the effects of climate change on future freshwater fish diversity at global scale

“…Note that, when notches do not overlap, medians may be seen to differ significantly (Krzywinski and Altman 2014) and that the difference between "Actual.2000" and "Compared.2000" scenarios is due to the predicted disappearance of species in the future. the proportional abundance of species (Magurran 2004). Evenness, however, increased in 2050 and 2070, as compared to the present (Fig.…”

“…The DER function from the R package EcoIndR (Guisande et al 2017b; Guisande 2018a) is used for this purpose, which allows the calculation of 31 different indices for each river basin belonging to five categories: rarity (two indices), heterogeneity (14 indices), evenness (seven indices), taxonomic diversity (two indices) and functional diversity (six indices; see table 1 in Guisande et al 2017b). Since there is no index universally applicable to all ecological assemblages (Magurran 2004), the DER algorithm was also employed for the selection of the diversity indices that best showed the differences between river basins. Therefore, from all of the estimated indices, only one of each of category was chosen.…”

Diversity Dimensions of Freshwater Fish Species around the World

“…The second level of C. Granado-Lorencio et al Journal of Geographic Information System each river basin [46] as used as the spatial unit for estimating diversity measurements (n = 440). This is because the second level was the geographical extent that best illustrated the effects of environmental parameters on the distribution of freshwater fish species [47].…”

Modelling the potential distribution of two tropical freshwater fish species under climate change scenarios

“…Climate variables such as environmental temperature and precipitation influence the abundance, distribution, and dispersal of freshwater fish at regional and large scales (Knouft & Anthony, 2016; Manjarrés‐Hernández et al, 2018; Rolls et al, 2018). The effect of climate change on freshwater fish depends, among other factors, on the tolerance limits to environmental and climatic variables such as temperature and precipitation.…”