Fishes of Southern South America: a story driven by temperature

The latitudinal extension of southern South America imposes a thermal gradient that affects the structure of marine and freshwater fish assemblages and the biology of the species throughdirect exposure to the temperature gradients or by means of a web of historical and ecological relationships. We have reviewed biological and ecological data of marine and freshwater fishes from the southern Neotropics, including Patagonia, and report several examples of dependence on temperature, from glacial times to today?s climate change. We were able to identify historic and present effects on the diversity of fish assemblages, isolation, southernlimits for the distribution of species, and morphological variation among populations. There is a wide range of characteristics that exemplify an adaptation to low temperatures, including biochemical peculiarities, physiological adjustments, and alternative life history patterns, and these appear in both freshwater and marine, and native and exotic fishes. The consequences of stable temperature regimes in both the ocean and thermal streams deserve special mention as these shape specialists under conditions of low selective pressure. At present, habitat use and interactions among species are being subject to changes as consequences of watertemperature, and some of these are already evident in the northern and southern hemispheres.

Fil: Cussac, Victor Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina

Fil: Fernandez, Daniel Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina

Fil: Gomez, Sergio Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina

Fil: Lopez, Hugo Luis. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina