Why does freshwater fish species richness differ between Pacific and Atlantic drainages of the Americas?

David Griffiths

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)


    Aim: To identify the contributions of geomorphological and hydrological/climaticfactors to differences in total and endemic freshwater fish species richness betweenAtlantic and Pacific drainages.Location: Glaciated and unglaciated catchments draining to the Atlantic and PacificOceans in North (NA) and South America (SA).Taxon: Fish.Methods: A database of native freshwater fish species richnesses in drainage basinswas compiled from published information, and the contributions of temperature,rainfall, catchment area, river length, channel gradient, discharge and geographiclocation in accounting for variation in total and endemic species richness wereassessed using boosted regression trees.Results: Atlantic drainages have larger catchments, with longer rivers, lower channelgradients, greater discharges and lower flow variability than Pacific ones of thesame size. Unglaciated Atlantic drainages in both NA and SA have more speciesthan Pacific drainages, but glaciated Pacific NA had significantly more species thanthe other Pacific areas. Geographic location had the greatest influence on total richness,but catchment area, river length and temperature were more important forendemic species. Pacific drainages had proportionally more endemics than Atlanticdrainages.Main conclusions: Tectonically driven topographic change, by altering relief, affectscatchment size, slopes and connectivity, with the latter also affected by climaticchanges in ice cover and aridity. These geomorphic and long-term climatic changes,by influencing speciation, extinction and dispersal, govern freshwater fish speciesrichness in Atlantic and Pacific catchments.
    Original languageEnglish
    Pages (from-to)784-792
    JournalJournal of Biogeography
    Publication statusPublished (in print/issue) - Apr 2018


    • America
    • catchment area
    • channel gradient
    • climate
    • endemism
    • freshwater fish
    • geomorphology
    • glaciation
    • river length
    • species richness


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