Geospatial data of freshwater habitats for macroecological studies: an example with freshwater fishes

Abstract

Global data sets are essential in macroecological studies. File formats of the few available data sets of freshwater ecosystems, however, are either incompatible with most macroecological software packages, incomplete, or of coarse spatial resolutions. We integrated more than 460 million geographical coordinates for freshwater habitats in the FRWater data set, partitioned into seven different habitats (lentic, wetlands, reservoirs, small rivers, large rivers, small ditches, large ditches, small channels, large channels, small drains and large drains) in ModestR (http://www.ipez.es/ModestR). A comprehensive collection of geospatial rasters was assembled, one for each of the seven freshwater habitats, with the area in km 2 occupied by each habitat presented in cells of 5 arc-minute resolution. The utility of FRWater was evaluated using hierarchical partitioning via the identification of the contribution of the seven different freshwater habitats to both species richness and rarity. To this end, we used a data set of 836,123 geographical records of the 16,216 species of freshwater fishes recognized as valid by systematists at the end of 2014. Areas in North America and Europe are the most detailed in the FRWater data set, evidencing the higher quality of data sources in those regions. The number of geographical coordinates is much lower for Africa, Asia, Australia, and South America where many water bodies remain unmapped. In light of the variation in information quality at continental levels, we performed and present comparative analyses for Europe versus South America at local (5ʹ × 5ʹ grid cells) and regional (5°× 5°grid cells) scales. The relative contribution of small rivers to both species richness and rarity was highest under almost all analyses, followed by lentic habitats and large rivers. The areas of different habitats moreover explained a relatively high proportion of the observed variance in geographic rarity. Our findings corroborate previous findings that the greater contribution of small rivers to species richness is probably due to these habitats promoting geographical rarity. Hence, species richness is favored by the isolation resultant from, and the refuges associated with, small river basins and via the diversification processes promoted by such isolation.

Effects of temperature and water turbulence on vertebral number and body shape in Astyanax mexicanus (Teleostei: Characidae)

“…There was a greater range of variation in the number of caudal vertebrae [14–19] than in the number of precaudal vertebrae [12–14], although it was the number of precaudal vertebrae that differed significantly among temperature treatments. Greater variation in the number of caudal vertebrae has been documented frequently in fishes [16,27,80,81].…”

“…Environmental conditions can change quickly in some freshwater ecosystems, leading to strong variation of environmental conditions over small geographic distances. Combined with other factors like reduced rates of gene flow, this environmental heterogeneity has contributed to the high rates of fish diversity in freshwater ecosystems throughout the world [12]. For example, in Neotropical streams with great fish diversity, environmental variables like nutrient concentration, water velocity, and water temperature can vary considerably along elevational gradients [13].…”

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

“…Due to the importance of the selected geographical extent both in the results and in the discrimination capacity of SDMs ( Barve et al 2011 ; Acevedo et al 2012 ; Niamir et al 2016 ), 3 progressively widening extents were used to determine the comparative importance of environmental predictors. The more restricted used extent (E1) is delimited as each one of the river basins of level 2 ( González-Vilas et al 2016 ), where there are observations of each species. Thus, if a species has presence data in 3 different basins of level 2, the contribution of predictors is individually estimated for each basin.…”

Diversity Dimensions of Freshwater Fish Species around the World

“…Each sub-basin was assigned a unique Pfafstetter code, (i.e., a six-digit code with information regarding the interconnectedness of the basins). 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].…”