Southeastern South America Research Articles

Cross–Time Scale Interactions and Rainfall Extreme Events in Southeastern South America for the Austral Summer. Part II: Predictive Skill

Abstract Potential and real predictive skill of the frequency of extreme rainfall in southeastern South America for the December–February season are evaluated in this paper, finding evidence indicating that mechanisms of climate variability at one time scale contribute to the predictability at another scale; that is, taking into account the interference of different potential sources of predictability at different time scales increases the predictive skill. Part I of this study suggested that a set of daily atmospheric circulation regimes, or weather types, was sensitive to these cross–time scale interferences, conducive to the occurrence of extreme rainfall events in the region, and could be used as a potential predictor. At seasonal scale, a combination of those weather types indeed tends to outperform all the other candidate predictors explored (i.e., sea surface temperature patterns, phases of the Madden–Julian oscillation, and combinations of both). Spatially averaged Kendall’s τ improvements of 43% for the potential predictability and 23% for real-time predictions are attained with respect to standard models considering sea surface temperature fields alone. A new subseasonal-to-seasonal predictive methodology for extreme rainfall events is proposed based on probability forecasts of seasonal sequences of these weather types. The cross-validated real-time skill of the new probabilistic approach, as measured by the hit score and the Heidke skill score, is on the order of twice that associated with climatological values. The approach is designed to offer useful subseasonal-to-seasonal climate information to decision-makers interested not only in how many extreme events will happen in the season but also in how, when, and where those events will probably occur.

Phylogenetic analysis ofAttalea(Arecaceae): insights into the historical biogeography of a recently diversified Neotropical plant group

We present a dated phylogenetic tree for the Neotropical genus Attalea (Arecaceae). We used six orthologues from the nuclear WRKY gene family across 98 accessions to address relationships among species and biogeographical hypotheses. We found that the formerly recognized groups within Attalea are not monophyletic and therefore there is no support for multiple genera as previously thought. Species of Attalea-like palms from the Atlantic forest form a well-supported clade sister to the Attalea species from Amazonia, the Andean valleys and Mesoamerica. Dates for the main divergence events suggest a relationship with the development of the dry forests that now span eastern South America and the now-lost Pebas Lake region in the western Amazon. Attalea crassispatha possibly colonized Hispaniola by a long-distance dispersal event, not via the land bridge Great Antilles Avian Ridge (GAAR), before the Panama channel closed. The common ancestor of Attalea appears to have been an Atlantic forest clade c. 30 Mya. The early split between the Atlantic-forest clade and the two Amazonian-northern Andean clades was probably the result of climatic changes that caused an increase in aridity in South America.

Generation of typical meteorological years for the Argentine Littoral Region

This work describes the generation of the typical meteorological year (TMY) for 15 locations all around the Littoral Region in northeastern Argentina, southeastern South America. The originally available weather data at each location contain, among others, dry-bulb and dew-point temperatures, wind velocity, and total sky cover, hourly measured during the period 1994–2014 by the National Meteorological Service (SMN) of Argentina. From other sources, two of these locations have hourly measured solar radiation during a few years. These radiation measurements were used to calibrate an existing Zhang–Huang solar radiation model that was then used to calculate the hourly solar radiation for the entire weather data base.Once we complete the long-term weather database at a given location, we define the typical meteorological year (TMY) at this location as the concatenation of 12 typical meteorological months (TMM). The typicality of a month is measured using Finkelstein–Schafer statistics based on nine daily indices (maximum, minimum and mean dry-bulb and dew-point temperatures, maximum and mean wind velocity, and global solar radiation).We finally show an example of application of the current TMYs for building energy simulation in a location deep inside Littoral. Subsequently we show the importance of the newly developed local TMY above using original TMY from neighbouring locations.

Density and P‐wave velocity structure beneath the Paraná Magmatic Province: Refertilization of an ancient lithospheric mantle

AbstractWe estimate density and P‐wave velocity perturbations in the mantle beneath the southeastern South America plate from geoid anomalies and P‐wave traveltime residuals to constrain the structure of the lithosphere underneath the Paraná Magmatic Province (PMP) and conterminous geological provinces. Our analysis shows a consistent correlation between density and velocity anomalies. The P‐wave speed and density are 1% and 15 kg/m3 lower, respectively, in the upper mantle under the Late Cretaceous to Cenozoic alkaline provinces, except beneath the Goiás Alkaline Province (GAP), where density (+20 kg/m3) and velocity (+0.5%) are relatively high. Underneath the PMP, the density is higher by about 50 kg/m3 in the north and 25 kg/m3 in the south, to a depth of 250 − 300 km. These values correlate with high‐velocity perturbations of +0.5% and +0.3%, respectively. Profiles of density perturbation versus depth in the upper mantle are different for the PMP and the adjacent Archean São Francisco (SFC) and Amazonian (AC) cratons. The Paleoproterozoic PMP basement has a high‐density root. The density is relatively low in the SFC and AC lithospheres. A reduction of density is a typical characteristic of chemically depleted Archean cratons. A more fertile Proterozoic and Phanerozoic subcontinental lithospheric mantle has a higher density, as deduced from density estimates of mantle xenoliths of different ages and composition. In conjunction with Re‐Os isotopic studies of the PMP basalts, chemical and isotopic analyses of peridodite xenoliths from the GAP in the northern PMP, and electromagnetic induction experiments of the PMP lithosphere, our density and P‐wave speed models suggest that the densification of the PMP lithosphere and flood basalt generation are related to mantle refertilization. Metasomatic refertilization resulted from the introduction of asthenospheric components from the mantle wedge above Proterozoic subduction zones, which surrounded the Paraná lithosphere. The high‐density PMP lithosphere is presently gravitationally unstable and prone to delamination.

Horticulturists and oxygen ecozones in the tropical and subtropical forests of Southeast South America

We analyse the isotopic values (δ13C, δ15N) of the diet of pre-Columbian horticulturalist populations from tropical and subtropical areas of southeastern South America, belonging to the Guarani and Taquara archaeological units. The data indicate different trends in each one (T = 4.21; P = 0.0004), showing a mixed diet with maize consumption in the Guarani samples (δ13Cco = −15.5 ± 1.8‰; δ13Cap −10.4 ± 0.8‰) and a depleted one in the Taquara ones (δ13Cco −18.2 ± 1.7‰; δ13Cap −11.9 ± 0.9‰), with a significant internal dispersion in both populations. The first population has higher nitrogen values (δ15N 11.1 ± 0.6‰) compared to the Taquara samples (δ15N 9.3 ± 1‰), suggesting a more carnivorous diet. The recognition of these pre-Columbian mixed diets involves the identification of maize cultivation on the Atlantic side of the southernmost area of South America (Parana Delta, 34° SL). Through the analysis of δ18O we have identified two isotopic ecozones, the first along the Paraná River Valley, with an average value of δ18O −3.7 ± 0.5‰ (CV = 13.5%; CI = −3.83 / −3.16), and the second one, located in the Planalto of southern Brazil (Araucaria Forest), with a mean value of δ18O −1.5 ± 0.3‰ (CV = 16.5%; CI = −1.69 / −1.29). The isotopic data (δ13C, δ15N and δ18O) suggest human movements between these two ecozones.

Independent time markers validate 210 Pb chronologies for two shallow Argentine lakes in Southern Pampas

Abstract We report here the results of detailed 210Pb analysis from two lake sediment cores collected from Lagunas Encadenadas del Oeste (LEO), located in the southern Argentinean Pampas (37°S, 62°W). Non-exponential and non-monotonic 210Pbuns depth-profiles in the sedimentary record of these shallow lacustrine systems indicate the interaction of complex processes behind radionuclide fluxes and lake sedimentation. The chronologies and sediment accumulation rates (SAR) for the lake sediment sequences were modeled using different 210Pb-based mathematical models. Since modeled 210Pb ages must be validated against independent stratigraphic markers of known age, two chrono-stratigraphic markers were selected to control the upper and lowermost parts of the 210Pb dated sediments. The younger stratigraphic marker of AD 1980 ± 2 corresponds to an uppermost organic carbon-rich mud accumulated by 1977–78 matching the most noticeable lake highstand occurred during the 20th century, registered on instrumental and paleolimnological records across the Pampean Plains. The oldest stratigraphic marker corresponds to AD 1878 ± 10 matching with a high lake productivity and wet phase related to anomalously intense rainfall and flooding events in southeastern South America for AD 1877–1878. When comparing the resulting ages to the stratigraphic markers, our results show that CRS-model (constant rate of supply) performs better than the other models. Thus, these independent chronostratigraphic markers used along the sedimentary records were critical to validate 210Pb-derived ages and therefore to select the most appropriate model to establish the chronological framework of the recent sediments of the LEO system. The CRS-model appears to be an adequate technique for deriving ages and SAR in the LEO sedimentary record and other Pampean lacustrine systems under strong hydrological variability.

Inventory of the freshwater fishes from a densely collected area in South America-a case study of the current knowledge of Neotropical fish diversity.

We herein analyse the history of the description of the freshwater fish fauna from three drainages in one of the most densely collected areas of Brazil, and possibly of South America, the Rio Grande do Sul State, southern Brazil. An updated inventory of the freshwater fish species from rio Uruguay (partial) in Brazil, Laguna dos Patos (complete) and rio Tramandaí basins (complete) is presented. We found the number of new species described in these drainages increased nearly 56% since 1981, reaching a total of 422 species, but even now 10% of this number still corresponds to undescribed species. This rate of species description suggests that previous estimates of the Neotropical fish fauna are low, and we predict a final number of Neotropical fishes larger than the largest prediction estimate (8,000 species), after other regions of South and Central Americas become densely sampled. We discuss and attempt to demonstrate that species diversity knowledge is historically and strictly related to collecting efforts. We also demonstrate that the ecoregions in eastern South America with the highest density of species per area correspond to the areas more densely sampled in collections, and this may represent a bias in such kinds of analyses. This uneven sampling in Brazilian regions is apparently associated with the uneven distribution of Zoological research centers in different regions of the country. Small-sized species represents an important source of new species, along with little explored regions or little explored habitats, sometimes associated with restricted range species, and species complexes that need revisionary work. In contrast to other Neotropical regions, Atheriniformes are relatively diverse, sharing the fifth place in species richness with Gymnotiformes, and there is a remarkably high number of species of Rivulidae. Eight species are endemic to the rio Tramandaí drainage, 68 to the Laguna dos Patos system, and 78 to the rio Uruguay drainage. Almost 10% of the freshwater fish species are "Critically Endangered", "Endangered" or "Vulnerable" according to the IUCN criteria, with Rivulidae as the family with the largest number of threatened species.

Carbonate sediment production in the equatorial continental shelf of South America: Quantifying Halimeda incrassata (Chlorophyta) contributions

The middle and outer continental shelves of eastern equatorial South America (ESA) are characterized by intense production of carbonate sediments. Qualitative analyses of sediment deposits suggest that the calcareous green alga Halimeda incrassata is among the top CaCO3 producers. Nevertheless, no study so far has quantified its real contributions. To better understand the sediment dynamic in this area, we measured biomass, growth rates and calcium carbonate production by this alga. The species exhibited high growth rates (3.38 segments.individual−1.day−1), coverage (174 individuals.m−2) and biomass (214.02 g.m−2). Substitution of segments may allow a sedimentation rate of 1.53 mm.yr−1 and a complete turnover of the population every 60.2 days. The rapid growth indicates that this alga can produce as much CaCO3 (1.19 kg CaCO3.m−2.year−1) as other tropical organisms, such as corals and rhodoliths. In a conservative estimate, 773.500 tonnes of CaCO3 are produced per year in a 5000 km2 area off the northern coast of Brazil. Sedimentation rate seems to be higher than that promoted by continental inputs in middle and outer continental shelf. On the other hand, population turnover is twice as slow as in other H. incrassata assemblages, suggesting that South American populations are sensible to physical disturbances. New studies are necessary to accurately estimate H. incrassata coverage along the Brazilian coast and to integrate data on other CaCO3 producers, such as foraminifera and coralline algae. This would allow a better understanding of the role of South American continental shelf on the global carbon budget. Furthermore, analysis on the health of these organisms is urgent, since a decline in their populations could negatively affect ecosystems functioning and services.

Uranium irradiation history of carbonado diamond; implications for Paleoarchean oxidation in the São Francisco craton

Abstract Carbonado is a porous polycrystalline diamond rock found in central African and Brazilian placer deposits. It contains unsupported radiogenic isotopes of He, Ne, Kr, Xe, and Pb. Here we show that these, and the radiation-related defects introduced to the diamond structure, are a result of uranium precipitation, with no isotopic or spectroscopic evidence of Th enrichment. The daughter products are unsupported due to Proterozoic U remobilization. Combining existing carbonado Pb isotope data with recent studies of the geochronology of the tectonic evolution of the São Francisco craton (eastern South America) reveals that the most likely scenario is Paleoarchean uranium enrichment of carbonado, followed by Mesoproterozoic uranium dissolution. Under all possible scenarios, the carbonado radiation damage history requires U mobilization in the Mesoarchean or late Paleoarchean. This is consistent with recent studies of South Africa and India Mesoarchean paleosols, which also show evidence for local oxygen activity greater than that of the Archean atmosphere and ocean. While those studies rely on whole-rock trace element and transition metal stable isotope measurements, this combination of crystallographic defects, sedimentary geochronology, and radiogenic isotopes supports the same conclusions of nonmarine, near-surface Archean oxygen enhancement.

Molecular phylogeny and global diversity of the remarkable genus Bondarzewia (Basidiomycota, Russulales)

Bondarzewia is a remarkable polypore genus due to its relatively large poroid basidiocarps and belongs to order Russulales according to recent phylogenetic analyses. Two species, B. berkeleyi and B. mesenterica, are commonly reported in North America and Europe but the genus is poorly known elsewhere. We explored the phylogeny and species diversity of Bondarzewia based on a larger number of samples covering a wider geographic range, including eastern Asia, Europe, North America, Oceania and South America. Sequences were generated from the nuc rDNA region encompassing the internal transcribed spacers 1 and 2, along with the 5.8S rDNA (ITS) and nuc 28S rDNA D1-D2 domains (28S), and the final dataset included 28 samples of which 21 ITS and 28S sequences were newly generated. As a result of phylogenetic analyses and comparison of morphological features we propose a new classification of the genus recognizing 10 species. Most of the novel taxonomic concepts are geographically restricted in contrast to the past broad species concepts, especially of B. berkeleyi. In addition, a degree of host specificity is observed with B. mesenterica, B. occidentalis, B. podocarpi, B. propria and B. submesenterica apparently restricted to gymnosperms and all others on angiosperm hosts where known. Three new species, B. kirkii, B. occidentalis and B. submesenterica, are described and illustrated. Three new combinations (B. dickinsii, B. propria, B. retipora) are revived from synonymy under B. berkeleyi. A key to known species of Bondarzewia is provided.

Cytogenetic Analysis of the South American Fruit Fly Anastrepha fraterculus (Diptera:Tephritidae) Species Complex: Construction of Detailed Photographic Polytene Chromosome Maps of the Argentinian Af. sp.1 Member.

Genetic and cytogenetic studies constitute a significant basis for understanding the biology of insect pests and the design and the construction of genetic tools for biological control strategies. Anastrepha fraterculus is an important pest of the Tephritidae family. It is distributed from southern Texas through eastern Mexico, Central America and South America causing significant crop damage and economic losses. Currently it is considered as a species complex; until now seven members have been described based on multidisciplinary approaches. Here we report the cytogenetic analysis of an Argentinian population characterized as Af. sp.1 member of the Anastrepha fraterculus species complex. The mitotic karyotype and the first detailed photographic maps of the salivary gland polytene chromosomes are presented. The mitotic metaphase complement consists of six (6) pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement shows a total number of five long chromosomes that correspond to the five autosomes of the mitotic karyotype and a heterochromatic network corresponding to the sex chromosomes. Comparison of the polytene chromosome maps between this species and Anastrepha ludens shows significant similarity. The polytene maps presented here are suitable for cytogenetic studies that could shed light on the species limits within this species complex and support the development of genetic tools for sterile insect technique (SIT) applications.

Lectotypification of two names in the genus Rubus L. (Rosaceae)

Rubus Linnaeus (1753: 492) is one of the largest genera in the family Rosaceae, represented by more than 700 species (Lu & Boufford 2003) and numerous apomictic taxa distributed worldwide but mainly in temperate regions (Mabberly 2008). The greatest species diversity of the genus is found in Southeastern Asia, East Asia and South America (Kalkman 1993, Gupta & Dash 2015a). The genus is recognized as one of the unsolved complexes for species delimitation due to hybridization, polyploidy and the large number of apomictic taxa (Weber 1996). The genus is characterized by woody or rarely herbaceous habit with simple to pinnate or compound leaves, terminal solitary to racemose and cymose inflorescence subtended by a foliar bract, pentamerous (rarely more petals) flowers with numerous stamens and pistils; drupaceous fruits with a distinct torus. A current estimate shows that, in India, about 75 species occur (Gupta & Dash 2015b) with the largest concentration in eastern Himalayan states. Hooker (1878) reported 41 species of Rubus from the then British India out of which 39 species and 15 varieties are found within the present political boundary of India. Long (1987) reported 35 species and 1 variety from Sikkim while dealing with Flora of Bhutan. Very limited information is available on the genus in India except some sketchy enumerations in the state floras (Kanjilal et al. 1922, Sharma & Kachroo 1981, Chowdhery & Wadhwa 1984, Chowdhery et al. 1996). Therefore, taxonomic treatment of less known Indian species of Rubus has not been worked out; as a result these names are only being referred as unresolved names in contemporary databases (e.g. The Plant List 2013).The majority were collected during the colonial era but without any designation of types. Therefore, to maintain the current taxonomic status, detailed studies are needed for all these species. We (first two authors) currently are revising the taxonomy of Rubus in India and this is part of the PhD thesis of the first author. During our research, we traced specimens of Rubus collected from western Himalaya (India) referable to less known and untypified R. chambicus Rolfe (1920: 132) and R. almorensis Dunn (1921: 310).

Modelling the effects of climate change on the risk of invasion by alien squirrels

Assessing invasion risk by alien organisms implies evaluating the likelihood of successful establishment and spread once they are accidentally or deliberately introduced. The importance of implementing accurate risk–assessment procedures is further stressed by the evidence that ongoing climate change can promote invasion processes, from initial introduction through establishment and spread. Although squirrels are considered powerful invaders with well–documented negative impacts on biodiversity and human activities, there is a noticeable gap of comprehensive investigations specifically focused on this group, especially as far as the effect of climate change on worldwide invasion risk is concerned. In this study we predicted current and 2070 potential distributions of eight squirrel species with a SDM–based framework, also detecting current potential hotspots of invasion and evaluating how these could be modified by climate change in 2070. SDM predicted the eight species to potentially occur in large areas worldwide (12.12% to 39.23% of the mainland), with 70 to 129 countries vulnerable to a potential invasion. Model projections over the 2070 climate change scenarios predicted five to seven squirrel species undergoing an increase in their future potential distribution in non–native ranges. Current hotspots of potential invasion were predicted to occur in southeastern Asia, northeastern Australia, tropical Africa and South America, as well as Central and North America. Projections to 2070 showed most of the hotspots of invasion to remain substantially stable in terms of number of potential invasive species, regardless of the scenario. The most relevant increase/reduction in extent of species distribution and in the number of potential invasive species in invasiveness hotspots were predicted for 2070 under the most severe scenarios. We emphasize a strong species–specific response to climate change, which could also affect invasive species by making them less competitive, therefore potentially leading to a retreat from the invaded ranges.

SECULAR CHANGES IN RELATIONSHIPS BETWEEN PLATE-TECTONIC AND MANTLE-PLUME ENGENDERED PROCESSES DURING PRECAMBRIAN TIME

Paradoxically, the lists of “proxies” of both plate- and plume-related settings are devoid of even a mention of the high-grade metamorphic rocks (granulite, amphibolite and high-temperature eclogite facies). However, the granulite-gneiss belts and areas which contain these rocks, have a regional distribution in both the Precambrian and the Phanerozoic records. The origin and evolution of the granulite-gneiss belts correspond to the activity of plumes expressed in vigorous heating of the continental crust; intraplate magmatism; formation of rift depressions filled with sediments, juvenile lavas, and pyroclastic flow deposits; and metamorphism of lower and middle crustal complexes under conditions of granulite and high-temperature amphibolite facies that spreads over the fill of rift depressions also. Granulite-gneiss complexes of the East European Craton form one of the main components of the large oval intracontinental tectonic terranes of regional or continental rank. Inclusion of the granulite-gneiss complexes from Eastern Europe, North and South America, Africa, India, China and Australia in discussion of the problem indicated in the title to this paper, suggests consideration of a significant change in existing views on the relations between the plate- and plume-tectonic processes in geological history, as well as in supercontinent assembly and decay. The East European and North American cratons are fragments of the long-lived supercontinent Lauroscandia. After its appearance at ~2.8 Ga, the crust of this supercontinent evolved under the influence of the sequence of powerful mantle plumes (superplumes) up to ~0.85 Ga. During this time Lauroscandia was subjected to rifting, partial breakup and the following reconstruction of the continent. The processes of plate-tectonic type (rifting with the transition to spreading and closing of the short-lived ocean with subduction) within Lauroscandia were controlled by the superplumes. Revision of the nature of the granulite-gneiss complexes has led to a fundamental new understanding of: a more important role than envisaged previously for mantle-plume processes in the juvenile additions to the continental crust, especially during the Neoarchaean-Proterozoic; the existence of the supercontinent Lauroscandia from ~2.80 to 0.85 Ga; the leading role of mantle plumes in the interaction of plate- and plume-tectonics in the Neoarchaean-Proterozoic history of Lauroscandia and perhaps of the continental crust as a whole. We propose that the evolution of the geodynamic settings of the Earth’s crust origin can be represented as a spiral sequence: the interaction of mantle-plume processes and embryonic microplate tectonics during the Palaeo-Mezoarchaean (~3.8–2.8 Ga) → plume-tectonics and local plume-driven plate-tectonics (~2.80–0.55 Ga) → Phanerozoic plate tectonics along with a reduced role of mantle plumes.

Working towards a better understanding of Helicobacter pylori-related gastric cancer’s biology

<p>Gastric cancer is a significant cause of cancer-related mortality and morbidity. In terms of disease etiology, it ranks as the fourth and fifth most common contributor of male and female cancer-related death, respectively [1]. A marked geographical variability has been observed for gastric cancer incidence, with the majority of cases reported in Eastern Europe, South America, and Asia [2]. This has been ascribed to environmental (<em>e.g.</em>, <em>H. pylori</em> infection), dietary, as well as genetic factors [3]. <em>H. pylori</em> is considered as a definite carcinogen by the International Agency for Research on Cancer, and intes-tinal metaplasia has been suggested as the intermediate event in the development of <em>H. pylori</em>-related gastric cancer [4]. However, the molecular mechanism of this event needs to be further elucidated. In this issue of <em>AMOR</em>, a report from Ukraine’s Vinnitsa National Pigorov Memorial Medical University by Sergii Vernygorodskyi attempts to improve our current understanding of the molecular mechanism associated with <em>H. pylori</em>-related gastric carcinogenesis [5]. The investigator found that the activation of CDX2, along with the simultaneous inactivation and a decreased number of genes (<em>e.g.</em>, <em>SHH</em>, <em>SOX2</em>, and <em>RUNX3</em>) responsible for gastric differentiation, is a probable cause that leads to the ap-pearance of intestinal metaplasia. Therefore, this study serves as an important catalyst to promote further research on the molecular mechanism and programming of gastric cancer cells, in hope of gaining new knowledge in the prevention and treatment of gastric cancer.</p>

Interannual variability of the frontal activity in the Southern Hemisphere: relationship with atmospheric circulation and precipitation over southern South America

The interannual variability of the frontal activity over the western Southern Hemisphere and its linkage with the variability of the atmospheric circulation and precipitation over southern South America is studied. The analysis is focused on the austral winter and spring seasons. The frontal activity is represented by an index defined as the product between the horizontal gradient of temperature and the relative vorticity at 850 hPa (FI) and is computed from the ERA Interim and NCEP2 reanalysis. For the two seasons the main mode of variability of FI, as depicted by the first Empirical Orthogonal Function, presents centres of action located in the southern part of the western Southern Hemisphere. This pattern is present in the two reanalysis datasets. The correlation coefficients between the principal component of the leading mode of FI and the two main modes of the 500 hPa geopotential height indicate that both the ENSO-mode and the SAM modulate the leading pattern of FI in winter while during the spring season the ENSO-mode controls the FI variability. The variability of the FI has a robust influence on the interannual variability of precipitation over southern South America and adjacent oceans. Over the continent, it was found that the pattern of precipitation anomalies associated with the variability of the FI depicts significant signals over southeastern South America (SESA), centre and south of Chile for winter and over SESA and southeastern Brazil for spring and agrees with the pattern of the leading mode of precipitation variability over southern South America.

Genetic guidelines for captive breeding and reintroductions of the endangered Black-fronted Piping Guan, Aburria jacutinga (galliformes, cracidae), an Atlantic Forest endemic.

The survival of a number of birds rely on captive breeding and reintroduction into the wild, but captive populations are often small and can be exposed to the negative effects of inbreeding and genetic drift. Then, managers are concerned not only with producing as much offspring as possible, but also with the retention of the maximum genetic variability within and between populations. The Black-fronted Piping Guan, Aburria jacutinga, is an endangered cracid endemic to the Atlantic Forest of southeastern South America. Because of its conservation status and functional importance, a captive breeding program started independently, mainly in three aviaries, in the decade of 1980. Although they have supplied animals for reintroductions, genetic variability aspects have never been considered. Here we addressed levels of genetic variability within and between these aviaries. Bayesian clustering analyses revealed two lineages. Inbreeding was not detected, although we found evidences for a recent bottleneck in one of the aviaries. Then, our main management recommendations are: i) reintroducing the species in areas where it has been extinct is more prudent than supplementing natural populations, as it could involve risks of disrupting local adaptive complexes; ii) as far as inbreeding can be avoided, the captive groups should be managed separately to minimize adaptation to captivity; iii) crossbreedings in pre-release generations could improve reintroduction success; and iv) a studbook should be implemented. As populations of Black-fronted Piping Guan from conservation units are progressively declining, these captive genetic repositories may gain importance in a near future. Zoo Biol. 35:313-318, 2016. © 2016 Wiley Periodicals, Inc.

The influence of different El Niño types on the South American rainfall

ABSTRACTThe impacts of El Niño (EN) on the rainfall over South America are investigated considering three EN types differing in the locations of the maximum sea surface temperature (SST) anomalies in the equatorial Pacific: the Central‐Pacific (CP), Eastern‐Pacific (EP) and the Mixed (MIX) types. The largest positive (SST) anomalies for the EP and CP types occur, respectively, in the eastern and central sectors of the tropical Pacific during all seasons. The SST anomaly pattern for the MIX‐EN resembles that of the EP–EN during its onset stage, and of the CP–EN during its mature and demise stages. The different SST anomaly patterns affect the large‐scale (Walker circulation and the tropospheric Rossby‐wave trains) and local (South American low‐level jet – SALLJ) atmospheric circulation patterns in different ways and lead to distinct precipitation anomaly patterns over South America. Variations in the position and longitudinal extension of the downward motions of the EN‐related eastward‐displaced Walker circulation explain the differences in the dryness over equatorial South America. For the CP–EN, a double Walker cell defines a more zonal configuration of the equatorial dryness over South America during the first three analysed seasons. This feature is not noted for the other two EN types. The Rossby‐wave train pattern path depends on the EN types and seasons. In consequence, the associated local atmospheric circulation patterns depend also on the season and EN types. In all seasons, an intense SALLJ for the EP EN contrasts with weak or inexistence SALLJ for the other two EN types. Thus, a wetter condition over southeastern South America, southern and eastern Brazil occurs for the EP EN in relation to the other EN types. The results shown here, in particular considering the MIX EN type, have not been discussed before and might be useful mainly for climate monitoring purposes.

Characterization of Genetic Variability and Population Structure of the Tick Amblyomma aureolatum (Acari: Ixodidae).

The hard tick Amblyomma aureolatum (Pallas) is a vector of the bacterium Rickettsia rickettsii, the etiologic agent of Brazilian spotted fever (BSF) in parts of Brazil. Despite its wide distribution in southeastern South America and its public health importance, there is no information about genetic variation of this species that might help to understand the epidemiology of BSF. Using data from eight microsatellite markers and ticks from six localities, we used a population genetics approach to test the hypothesis that tick populations from areas with the presence of R. rickettsii are genetically different from ticks from areas without R. rickettsii Contrary to expectations, we found low genetic structure between studied regions. Thus, the presence of R. rickettsii in the specific area is more likely correlated with ecological and the environmental conditions or due to unknown gene coding regions of A. aureolatum genome that would be related to R. rickettsii infection resistance.

Silcrete as a valuable resource for stone tool manufacture and its use by Paleo-American hunter–gatherers in southeastern South America

In the mid-eastern part of the southern cone of South America, sources of silcrete extend from eastern Entre Ríos province in Argentina to mid-western Uruguay. As a material for stone tool manufacture this rock was used with different levels of intensity in the regional archaeological record. In areas currently covered by Buenos Aires province in Argentina and the Republic of Uruguay in particular, diverse Paleo-American artifacts were made with this material between ~13 and 12cal.ka BP. Due to this material's exploitation by early human occupiers, this paper addresses and discusses its distribution, source location, quality, use, and its probable preference by one of the earliest groups of foragers living during the late Pleistocene.