@article {6047, title = {The global geography of fish diadromy modes}, journal = {Global Ecology and Biogeography}, year = {2019}, abstract = {

Aim: Geographical gradients in resource production are likely to translate into macroecological patterns in the biodiversity of migratory organisms, but few studies have addressed this question at a global scale. Here, we tested a hypothesis based on uncoupled latitudinal gradients in marine and freshwater primary productivities aimed at explaining where (e.g., at which latitude) and at which stage of the life cycle (larvae, amphidromy; juvenile, catadromy; or adult, anadromy) migration from ocean to freshwater occurs (diadromy).

Location: Global.

Time period: Current.

Major taxa studied: Fishes.

Methods: We modelled, using multinomial regressions, the proportion of catadromous, anadromous and amphidromous species in 994 river basins as a function of freshwater and marine net primary productivities (NPP; in milligrams of carbon per square metre per day) and additional biotic and abiotic variables. Using data extracted from the Global Biodiversity Information Facility (GBIF) database, we tested whether diadromous, catadromous and amphidromous species differed with respect to the NPP of their marine and freshwater occurrences.

Results: Among diadromous species, anadromous species are present in higher proportions when conditions for growth are more favourable in the sea (higher productivity, higher temperature and lower number of competitors) than in freshwaters. The model reconstructs the latitudinal pattern observed in the proportion of anadromous species, including an asymmetry between the Northern and Southern Hemispheres. According to GBIF occurrences, the ratio of marine over freshwater productivity is higher for anadromous species compared with catadromous and amphidromous species.

Main conclusions: Our results support the hypothesis stating that migration between ocean and freshwater occurs by choosing the biome that optimizes pre-reproductive growth and is one more example of the importance of primary productivity in shaping large-scale community patterns. This result suggests that some diadromous fish populations and species may suffer from anticipated climate change if interbiome productivity gradients are affected.

}, keywords = {amphidromy, anadromy, Biogeography, catadromy, dispersal, GBIF database, Last Glacial Maximum, latitudinal gradient, Migration, Species richness}, doi = {DOI: 10.1111/geb.12931}, author = {Chalant, Ana{\"\i}s and J{\'e}z{\'e}quel, C{\'e}line and Philippe Keith and Bernard Hugueny} } @article {3451, title = {Estimating how many undescribed species have gone extinct.}, journal = {Conserv Biol}, volume = {28}, year = {2014}, month = {2014 Oct}, pages = {1360-70}, abstract = {

Because both descriptions of species and modern human-driven extinctions started around the same time (i.e., eighteenth century), a logical expectation is that a large proportion of species may have gone extinct without ever having been recorded. Despite this evident and widely recognized assumption, the loss of undescribed species has never been estimated. We quantified this loss for several taxonomic groups and regions for which undescribed species extinctions are likely to have occurred. Across a wide range of taxonomic groups, we applied known extinction rates computed from recorded species losses to assumed exponential decay in the proportion of species remaining undiscovered. Because all previous modeling attempts to project total species richness implicitly assumed that undescribed species extinctions could be neglected, we also evaluated the effect of neglecting them. Finally, because we assumed constant description and extinction probabilities, we applied our model to simulated data that did not conform to this assumption. Actual species losses were severely underestimated by considering only known species extinctions. According to our estimates, the proportion of undiscovered extinct species over all extinctions ranged from 0.15 to 0.59, depending on the taxonomic group and the region considered. This means that recent extinctions may be up to twice as large as the number recorded. When species differed in their extinction or description probabilities, our model underestimated extinctions of undescribed species by up to 20\%.

}, issn = {1523-1739}, doi = {10.1111/cobi.12285}, author = {Pablo Tedesco and R{\'e}my Bigorne and Bogan, Arthur and Giam, Xingli and J{\'e}z{\'e}quel, C{\'e}line and Bernard Hugueny} } @article {3252, title = {Global imprint of historical connectivity on freshwater fish biodiversity.}, journal = {Ecol Lett}, volume = {17}, year = {2014}, month = {2014 Sep}, pages = {1130-40}, abstract = {

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.

}, keywords = {Animals, Biodiversity, Environment, Fishes, Fresh Water, Models, Biological}, issn = {1461-0248}, doi = {10.1111/ele.12319}, author = {Dias, Murilo S and Thierry Oberdorff and Bernard Hugueny and Leprieur, Fabien and J{\'e}z{\'e}quel, C{\'e}line and Cornu, Jean-Fran{\c c}ois and Brosse, S{\'e}bastien and Grenouillet, Gael and Pablo Tedesco} }