Organisms Diversity & Evolution 3 (2003)
Electronic Supplement 7

Claudio Baigún, Ricardo Ferriz:
Distribution patterns of native freshwater fishes in Patagonia (Argentina).

print version: Org. Divers. Evol. 3(2): 151-159. 2003 (full article)
electr. suppl.: Figures A-I and Tables A-V pdf-format, 489 KB

Abstract:

The Patagonian ichthyofauna comprises a total of 29 species. This low species richness contrasts with other cold-temperate regions of the southern hemisphere. The fauna includes only 15 species native to the Patagonian Province and seven to the Brazilian Province. Knowledge of native fish fauna diversity patterns is still fragmentary. Based on extensive sampling during the IBOY initiative and also reviewing seminal and review literature, we provide an updated perspective of native freshwater fishes in Patagonia by describing and analyzing their distribution and occurrence across basins.
The results show that species richness varies along latitude, with a maximum at the 38°-40° interval, principally due to the presence of Brazilian species inhabiting northern Patagonia. However, species numbers remained constant south of 48° latitude. We report extended distribution ranges for several species such as Diplomystes mesembrinus, Hatcheria macraei, Trichomycterus areolatus, and Odontesthes hatcheri, and also the new discovery of a Brazilian species (Corydoras paleatus) in the north of Patagonia. Cluster analysis based on presence-absence information revealed co-occurrence patterns at the level of basins, showing that only few species (Percichtys trucha, Odontesthes hatcheri, Hatcheria macraei, Galaxias platei, and G. maculates) are ubiquitous. Restricted distribution and even endemism for the remaining species could be attributed to river drainage systems which influence dispersion ability, to the influence of past glaciation events, and impact by introduced salmonids in the last century. Future research therefore should be focused on distribution patterns of introduced species since they are an important component of present Patagonian fish assemblages. Also, efforts should be devoted to understanding how diversity patterns of freshwater fish communities vary across scales and how community changes are relevant for native species conservation.

Key words: Native species, Patagonia, diversity, distribution, habitat, presence-absence

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