A NULL MODEL FOR EXPLAIN CRUSTACEAN ZOOPLANKTON SPECIES ASSOCIATIONS IN CENTRAL AND SOUTHERN PATAGONIAN INLAND WATERS.

The zooplankton assemblages in water bodies of central and southern Chilean Patagonia, is characterized by high endemism and a relative low species richness, the main regulator factor would be the conductivity and trophic status of their habitats. The aim of the present study was analyze published and unpublished information about crustacean zooplankton in central and southern Chilean Patagonian lakes and ponds (44- 53º S). To these data was applied the species / genera ratio, and also, a null mo-del analysis for species co-occurrence, based in a presence-absence species matrix, for determine the existence of random factors as regulator factors of species associations. Finally, it was applied a Jaccard Index for determine potential similarities in species associations for site. The results revealed low species number in large and deep lakes, whereas in small shallow permanent and ephemeral ponds had high species number, and low values in the species genera / ratio. The results of null model revealed the ab-sence of random factors as regulators of species associations for two of three simulations, and the results of Jaccard Index denoted the existence of three main groups based in the species associations of sites. These results agree with ecological information for southern Patagonia. Ecological and biogeographical topics are discussed