A growing interest is devoted to global-scale approaches in ecology and evolution that examine patterns and determinants of species diversity and the threats resulting from global change. These analyses obviously require global datasets of species distribution. Freshwater systems house a disproportionately high fraction of the global fish diversity considering the small proportion of the earth’s surface that they occupy, and are one of the most threatened habitats on Earth. Here we provide complete species lists for 3119 drainage basins covering more than 80% of the Earth surface using 14953 fish species inhabiting permanently or occasionally freshwater systems. The database results from an extensive survey of native and non-native freshwater fish species distribution based on 1436 published papers, books, grey literature and web-based sources. Alone or in combination with further datasets on species biological and ecological characteristics and their evolutionary history, this database represents a highly valuable source of information for further studies on freshwater macroecology, macroevolution, biogeography and conservation.

The relative importance of contemporary and historical processes is central for understanding biodiversity patterns. While several studies show that past conditions can partly explain the current biodiversity patterns, the role of history remains elusive. We reconstructed palaeo-drainage basins under lower sea level conditions (Last Glacial Maximum) to test whether the historical connectivity between basins left an imprint on the global patterns of freshwater fish biodiversity. After controlling for contemporary and past environmental conditions, we found that palaeo-connected basins displayed greater species richness but lower levels of endemism and beta diversity than did palaeo-disconnected basins. Palaeo-connected basins exhibited shallower distance decay of compositional similarity, suggesting that palaeo-river connections favoured the exchange of fish species. Finally, we found that a longer period of palaeo-connection resulted in lower levels of beta diversity. These findings reveal the first unambiguous results of the role played by history in explaining the global contemporary patterns of biodiversity.

International audienceAimThree broad mechanisms have been proposed to explain geographic variation in species range size: habitat area/heterogeneity, climate seasonality and long-term climate variability. However, it has proved difficult to disentangle their relative role, particularly as temperature seasonality often covaries with the amplitude of long-term temperature oscillations. Here, we shed new light onto this debate by providing the first continental-scale analysis of range size and beta diversity in groundwater habitats, where taxa are not exposed to latitudinal variation in temperature seasonality.LocationEurope.MethodsWe compiled and mapped occurrence data for 1570 groundwater crustacean species. Generalized regression models were used to test for latitudinal variation in geographic range size and to assess the relative role of the three broad mechanisms in shaping present-day patterns of range size. We partitioned beta diversity into its spatial turnover and nestedness components and analysed their latitudinal variation across Europe.ResultsMedian range size increases with latitude above 43 degrees N and the range size of individual species is positively correlated to latitude, even after accounting for phylogenetic effects. Long-term temperature variability accounted for a substantially higher variation in median range size of groundwater crustaceans across Europe than precipitation seasonality and habitat heterogeneity, including aquifer area, elevation range, climatic rarity and productive energy. Spatial turnover contributes significantly more to beta diversity in southern regions characterized by stable historic climates than it does in northern Europe.Main conclusionsOur findings add support to the historic climate hypothesis which suggests that patterns of increasing range size and decreasing species turnover at higher latitudes in the Palaearctic region are primarily driven by long-term temperature oscillations rather than by climatic seasonality and the availability and heterogeneity of habitats

Summary 1.Whereas global patterns and predictors of species diversity are well known for numerous terrestrial taxa, our understanding of freshwater diversity patterns and their predictors is much more limited. 2. Here, we examine spatial concordance in global diversity patterns for five freshwater taxa (i.e. aquatic mammals, aquatic birds, fishes, crayfish and aquatic amphibians) and investigate the environmental factors driving these patterns at the river drainage basin grain. 3. We find that species richness and endemism patterns are significantly correlated among taxa. We also show that cross-taxon congruence patterns are often induced by common responses of taxa to their contemporary and historical environments (i.e. convergent patterns). Apart from some taxa distinctiveness (i.e. fishes), the 'climate/productivity' hypothesis is found to explain the greatest variance in species richness and endemism patterns, followed by factors related to the 'history/dispersion' and 'area/environmental heterogeneity' hypotheses. 4. As aquatic amphibians display the highest levels of congruency with other taxa, this taxon appears to be a good 'surrogate' candidate for developing global freshwater conservation planning at the river drainage basin grain.

Although habitat fragmentation fosters extinctions, it also increases the probability of speciation by promoting and maintaining divergence among isolated populations. Here we test for the effects of two isolation factors that may reduce population dispersal within river networks as potential drivers of freshwater fish speciation: 1) the position of subdrainages along the longitudinal river gradient, and 2) the level of fragmentation within subdrainages caused by natural waterfalls. The occurrence of native freshwater fish species from 26 subdrainages of the Orinoco drainage basin (South America) was used to identify those species that presumably arose from in-situ cladogenetic speciation (i.e. neo-endemic species; two or more endemic species from the same genus) within each subdrainage. We related subdrainages fish diversity (i.e. total, endemic and neo-endemic species richness) and an index of speciation to our two isolation factors while controlling for subdrainages size and energy availability. The longitudinal position of subdrainages was unrelated to any of our diversity measures, a result potentially explained by the spatial grain we used and/or the contemporary connection between Orinoco and Amazon basins via the upstream Casiquiare region. However, we found higher neo-endemic species richness and higher speciation index values in highly fragmented subdrainages. These results suggest that habitat fragmentation generated by natural waterfalls drives cladogenetic speciation in fragmented subdrainages. More generally, our results emphasize the role of history and natural waterfalls as biogeographic barriers promoting freshwater biodiversity in river drainage basins.

Summary1. We tested how habitat structure and fragmentation affect the spatial distribution of common murine rodents inhabiting human-dominated landscapes in South-East Asia. The spatial distribution patterns observed for each rodent species were then used to assess how changes in habitat structure may potentially affect the risk of several major rodent-borne diseases. 2. For this analysis, we used an extensive geo-referenced data base containing details of rodents trapped from seven sites in Thailand, Cambodia and Lao PDR. We also developed land-cover layers for each site. Results from published studies that screened for five major rodent-borne pathogens in rodents were used to estimate how these pathogens would likely be impacted by these alterations in habitat structure and composition. 3. Our results confirmed the specialist and/or synanthropic status of several rodent species, although the majority of species studied demonstrated some degree of low level of habitat specialization. 4. Habitat diversity and its alteration (decreasing forest cover, increasing fragmentation, increasing urbanization) were found to favour the presence of synanthropic rodent species such as Rattus tanezumi, known to damage crops and host important rodent-borne diseases. 5. Synthesis and applications. The five major rodent-borne pathogens were linked to ongoing changes in habitat structure. In particular, the presence of Bartonella spp. and hantaviruses seemed to be favoured in wooded landscapes affected by ongoing fragmentation and human encroachments. Rodents also pose significant problems for crop production in South-East Asia. Our results showed that the structure of the landscape affects the likely presence of rodent species considered as agricultural pests. The patchy structure of a landscape can either enhance, such as B. indica, or decrease, such as B. savilei, the presence of rodents that may cause serious damage to crops.

Summary1. Current models estimating impact of habitat loss on biodiversity in the face of global climate change usually project only percentages of species 'committed to extinction' on an uncertain timescale. Here, we show that this limitation can be overcome using an empirically derived 'background extinction rate-area' curve to estimate natural rates and project future rates of freshwater fish extinction following variations in river drainage area resulting from global climate change. 2. Based on future climatic projections, we quantify future active drainage basin area losses and combine them with the extinction rate-area curve to estimate the future change in extinction rate for each river basin. We then project the number of extinct species in each river basin using a global data base of freshwater fish species richness. 3. The median projected extinction rate owing to climate change conditions is c. 7% higher than the median background extinction rate. A closer look at the pattern reveals great geographical variations highlighting an amplification of aridity by 2090 and subsequent increase in extinction rates in presently semi-arid and Mediterranean regions. Among the 10% mostimpacted drainage basins, water availability loss will increase background extinction rates by 18Á2 times (median value). 4. Projected numbers of extinct species by 2090 show that only 20 river basins among the 1010 analysed would experience fish species extinctions attributable to water availability loss from climate change. Predicted numbers of extinct species for these rivers range from 1 to 5. 5. Synthesis and applications. Our results strongly contrast with previous alarming predictions of huge surface-dependent climate change-driven extinctions for riverine fishes and other taxonomic groups. Furthermore, based on well-documented fish extinctions from Central and North American drainages over the last century, we also show that recent extinction rates are, on average, 130 times greater than our projected extinction rates from climate change. This last result implies that current anthropogenic threats generate extinction rates in rivers far greater than the ones expected from future water availability loss. We thus argue that conservation actions should be preferentially focused on reducing the impacts of present-day anthropogenic drivers of riverine fish extinctions.

In this paper two geomorphologic maps (landform level and landscape level) are presented covering the French Guianan rainforest (84,000 km 2 ) using full-resolution Shuttle Radar Topography Mission (SRTM) data. The entire country was segmented into 224,000 landform units on the basis of an original object-oriented approach using a modified counting box algorithm. A Principal Components Analysis (PCA) followed by k-means clustering (Ward's method) identified 12 different landform types corresponding to theoretical elementary landforms. The landscape map was generated by analyzing the spatial distribution of the different landform types. The different maps and models were compared with topographic field data collected on 92 transects totaling 260 km in length. The object-focused approach is a very efficient method that preserves geomorphologic consistency and discriminates between landforms using simple descriptors that are easily understood by non-geomorphologists. Despite major noise in the data, the landform map proved to be reliable and provided a strong spatial structure for the definition of landscape units. We recommend using the landform map at scales 1: 100,000-1: 250,000. Landscape map, used on a 1:1,000,000-1:2,000,000 scale, enabled us to draw bio-geographical limits in this region and provides exhaustive relief information that usefully supplements the geological map.