INFLUENCE OF ENVIRONMENTAL FACTORS ON FRESHWATER DECAPOD DISTRIBUTIONS IN SOUTHERN SOUTH AMERICA

GIRI FEDERICO; WILLINER VERONICA; TUMINI GEORGINA; COLLINS PABLO AGUSTIN

FRESHWATER BIOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 61 p. 715 - 728

0046-5070

1. An intensively debated issue in macroecology is whether the distribution of organisms is related to biogeographic history or current environmental features. The distribution of freshwater decapods in southern South America has been attributed largely to historical factors. Here we offer a macro-scale level analysis to test the hypothesis that their current distribution in Argentina is strongly influenced by selected environmental variables. 2. Occurrence data of five freshwater decapod families (Sergestidae, Palaemonidae, Parastacidae, Aeglidae and Trichodactylidae) were analysed at a biogeographical scale to identify associations with selected environmental variables, i.e. altitude, stability of the water body, Annual Temperature Range (ATR), pH and water conductivity while adjusting for the effect of latitude and longitude. Generalized linear models (GLM) with a binomial response were constructed separately for each family in the case of palaemonidae, Aeglidae and Trichodactylidae, and for the species Acetes paraguayensis (only member of the Family Sergestidae), Parastacus pilimanus and Samastacus spinifrons (Parastacidae). 3. The occurrence of freshwater decapods in Argentina was strongly associated with interacting spatial and environmental factors. Latitudinal and/or longitudinal gradients o occurrence were found in Acetes paraguayensis, Palaemonidae, Aeglidae an Trichodactylidae, but two of them (longitudinal patterns in Palaemonidae an Trichodactylidae) were either changed drastically or sufficiently explained when environmental variables were considered. Altitude and water stability were consistent found associated with the occurrence of all families examined, and ATR, pH an conductivity were significantly associated with at least two families. In most cases, theffect of one of the studied variables depended on the interaction with one or more of thremaining, especially with latitude.4. Contradicting the extant literature, our results show that the macro-distribution of freshwater decapods is not exclusively a consequence of historical processes. Most environmental variables evaluated were consistently found to be strongly associated with freshwater decapod occurrence, suggesting a limited plasticity and strong adaptation to the habitats they colonised. Our study highlights that environmental factors should not be neglected in studies of crustacean biogeography and macroecology.