Saccharomyces eubayanus is the close relative of the Lager-brewing yeast and was firstly found in North Patagonia associated with Nothofagus trees. In recent years additional strains were found in North America, Asia and New Zealand, and genomic analyses showed the existence of two main populations of this yeast, both of them present in Patagonia. Here, we performed the most comprehensive study of S. eubayanus in Patagonia natural environments (400 samples) and confirmed that this region has the highest isolation success rate for this species described worldwide (more than 10-fold). The genetic characterization of 200 isolates (COX2, DCR1, intFR) revealed five geographically structured subpopulations. We hypothesized that marine ingressions and glaciations, which shaped the Patagonian landscape, contributed on population differentiation. The first large screening of fermentation performance of 60 wild S. eubayanus strains indicated which subpopulations would be more suitable for beer production.

This article explores the potential role of UV radiation (UVR) as an influence on zooplankton communities. In the first section we provide a general overview of UVR effects on freshwater zooplankton, with an emphasis on Argentine and Chilean environments. In the second section we present the results of a survey involving 53 temperate lakes across a gradient of UVR exposure to determine patterns of species richness and specific diversity. These community characteristics decreased at high potential UVR exposure (i.e. high mean water column irradiance or low lake optical density). A threshold value of mean water column irradiance of approximately 10% of the surface level seems to limit both richness and diversity to minimum values. On the basis of the collected evidence it is not possible to definitely conclude that UVR rather than another covarying factor is responsible for the decrease in specific diversity observed at the lowest end of lake optical depth. However, lakes with values above the previous threshold are likely to exhibit highly depauperate zooplankton communities regardless of the mechanism. As a cautionary note we suggest that changes in the optical characteristics (i.e. changes due to atmospheric conditions, precipitation patterns or vertical displacement of the tree line) may result in sudden shifts in zooplankton community structure.

Abstract:The Torres del Paine National Park is located in the southern Chilean Patagonia. This park has numerous and heterogeneous lakes and ponds with different trophic status and zooplankton composition. The aim of this study was to analyze the influence of trophic status and conductivity on zooplankton assemblages in lakes and ponds within the Torres del Paine National Park. The water bodies described in the present study were previously classified in three groups. The first group consisted of large, deep and oligotrophic lakes with fish populations, low zooplankton species diversity and high predominance of calanoid copepods of small body size. The second group contained small mesotrophic lakes with fish populations and relatively high predominance of small sized daphnids. The third group consisted of fishless ponds of different trophic status, wide conductivity gradient and with zooplankton species of relatively large body size. The results show that Daphnids abundance was directly related to chlorophyll-a concentration and inversely associated with conductivity. Calanoids abundance was also directly associated with conductivity.

Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12-20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.

Urmia Lake, with a surface area between 4000 to 6000 km2, is a hypersaline lake located in northwest Iran. It is the saltiest large lake in the world that supports life. Urmia Lake National Park is the home of an almost endemic crustacean species known as the brine shrimp, Artemia urmiana. Other forms of life include several species of algae, bacteria, microfungi, plants, birds, reptiles, amphibians and mammals. As a consequence of this unique biodiversity, this lake has been selected as one of the 59 biosphere reserves by UNESCO. This paper provides a comprehensive species checklist that needs to be updated by additional research in the future.

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Chilean Patagonia has numerous unpolluted terrestrial and aquatic ecosystems, containing many unpolluted and pristine lakes and ponds. Published and unpublished information collected between 1989 and 1990 in lakes and ponds within Torres del Paine National Park, an unpolluted and pristine protected area in Southern Chile (51°S), was analysed in this study. A principal component analysis (PCA) was applied using mainly chemical parameters, zooplankton species richness and biomass. It was found that the cations (Ca, Na, Mg) chloride, seston and chlorophyll concentrations together with zooplankton biomass and zooplankton species richness were the main contributing variables to the derived model. According to this model, the following groups were observed: 1 st group-deep oligotrophic lakes with low zooplankton biomass and low species richness; 2 nd group -small mesotrophic lakes and ponds with moderate conductivity, zooplankton biomass and species richness. This latter group included small ponds with high nutrient and chlorophyll concentrations. A null model for species co-ocurrence was applied. The results in two of three simulations denoted that species associations are not random, which would agree with the PCA results. These results showed that oligotrophy and low ionic concentrations, and probably fish presence, are important regulatory factors in zooplankton community structure. These explain the similar patterns observed between Argentinean and Chilean Patagonian lakes.

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