The South American plains vizcacha, Lagostomus maximus inhabits primarily the Pampean and adjoining Espinal, Monte and Chaquenean regions of Argentina. In order to study the population genetic ...structure of L. maximus, a fragment of 560 bp of the mitochondrial DNA hypervariable region 1from 90 individuals collected from the 3 subspecies and 8 groups along Argentina was amplified and analyzed. We found 9 haplotypes. The haplotype network did not show an apparent phylogeographical signal. Although low levels of genetic variation were found in all the subspecies and groups analyzed, a radiation of L. maximus would have occurred from the North and Center of the Pampean region toward the rest of its geographic range in Argentina. Low levels of genetic diversity, the existence of a single genetically distinct population in Argentina and changes of its effective size indicate that metapopulation processes and changes in human population dynamics during the late-Holocene were important factors shaping the population genetic structure of L. maximus in Argentina.
European starlings (Sturnus vulgaris) were introduced ca. 40 years ago to South America, where they naturalized to central and northern Argentina, now reaching some neighboring countries. While ...Patagonia (southern Argentina and Chile) has remained free of European starlings (ES) in the past, they are now present along its northern boundary. Our objectives were to 1) investigate the factors explaining this recent invasion, and 2) predict how starlings might expand across southernmost America based on niche modeling using landform, land cover, and climatic variables representing conditions that may limit ES. Based on records from community science, informants, and our own observations, we conclude that two parallel processes generated new population nodes in northern Patagonia: 1) a southwards expansion from their core areas near the Atlantic coast (generating an incipient population node in NE Patagonia), and 2) birds released or escaped from captivity (generating an isolated population node in north-central Patagonia). Community science data was most useful from 2018 onwards, while data from informants was key to understand previous events (e.g., first ES confiscated from illegal trade in 2008; first free ranging ES seen in 2014). The most parsimonious model confirmed our prediction that human transformed lands in several portions within the target area are suitable for ES establishment, both in Chile and Argentina. Null suitability was modeled for the lands in southernmost Patagonia (all cover types). Desert lands (Patagonian steppe, Monte Desert, High Andes) that skirt the Andean temperate forests on the north, and most of the Andean forests, turned out to be unsuitable (especially with increasing latitude). Conversely, most of coastal Argentine Patagonia and the human-transformed lands of south-central Chile emerged as moderately suitable habitat for ES. Because the riverine areas under current ES colonization in northern Patagonia are fovourable for ES (i.e., agricultural and urban lands with abundant nesting sites), without control actions, this species might soon spread over ca. 5000 km2 around the Colorado and Negro rivers, affecting their agricultural industry. These rivers, which run west-east through desert lands unsuitable for ES, now represent corridors into south-Andean ecosystems, as they are surrounded by treed land (willows and poplars introduced from Europe) not originally available, connecting formerly separate ecoregions. In case ES manage to reach the eastern slopes of the Andes, they might cross to Chile through low elevation passes (<1000 masl) available south of ca. 38°S. The valleys of south-central Chile are both suitable habitat for ES and valuable productive lands that may be threatened by the invasion. We present management suggestions, and advocate for the development of a bi-national strategy to retard, prevent and alleviate the far-reaching impacts ES may exert on America’s southernmost ecosystems and resources.
Due to anthropogenic factors, the franciscana dolphin, Pontoporia blainvillei, is the most threatened small cetacean on the Atlantic coast of South America. Four Franciscana Management Areas have ...been proposed: Espiritu Santo to Rio de Janeiro (FMA I), São Paulo to Santa Catarina (FMA II), Rio Grande do Sul to Uruguay (FMA III), and Argentina (FMA IV). Further genetic studies distinguished additional populations within these FMAs. We analyzed the population structure, phylogeography, and demographic history in the southernmost portion of the species range. From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range. The haplotype network did not show an apparent phylogeographical signal for the southern FMAs. Two populations were identified: Monte Hermoso (MH) and Necochea (NC)+Claromecó (CL)+Río Negro (RN). The low levels of genetic variability, the relative constant size over time, and the low levels of gene flow may indicate that MH has been colonized by a few maternal lineages and became isolated from geographically close populations. The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations. Additionally, RN may have experienced a recent split from CL and NC; current high levels of gene flow may be occurring between the latter ones. FMA IV would comprise four franciscana dolphin populations: Samborombón West+Samborombón South, Cabo San Antonio+Buenos Aires East, NC+CL+Buenos Aires Southwest+RN and MH. Results achieved in this study need to be taken into account in order to ensure the long-term survival of the species.
ABSTRACT In Argentina there have been few evaluations of Andean pseudocereal plantings. This study explored the response of Amaranthus cruentus cv Mexicano to different plant densities under furrow ...irrigation in the lower valley of the river Negro, Patagonia, Argentina. The experimental design consisted of 3 blocks with randomized treatments (subplots), each one corresponding to different plant density. The treatments were sown in rows with spacing of 0.70 m (one row per ridge) and others with a spacing of 0.35 m (two rows per ridge). The plant densities evaluated were: 70,800 - 84,200 - 97,700 - 116,000 - 114,000 - 225,300 and 394,000 plants ha-1. Different biometric variables and their components were measured: plant height, number of leaves, biomass and economic yield. The results suggest that the optimum plant density was 116,000 plants ha-1 with a row spacing of 0.70 m. This density produces an adequate plant stand from which to harvest optimal biological and economical yields. The contributions of this study demonstrated the potential of the A. cruentus crop in the lower valley of the river Negro, representing the southernmost study of plant density made for this pseudocereal in the world.
Introduction. The production potential of grain amaranth has recently been demonstrated in northeastern Patagonia, Argentina. This crop under irrigation and in a temperate semi-arid climate showed an ...adequate development of the plants in their different phenological stages with high economic performance.Objectives. This study explored the response of Amaranthus cruentus cv Mexicano to different irrigation frequencies in the lower valley of Río Negro river, Patagonia, Argentina. Method. The experimental design was of three blocks with randomized treatments (subplots), each one corresponding to a different irrigation frequency. The first six irrigations were performed every 7 days for all the treatments, to ensure the establishment of the crop. Then the following treatments were applied: irrigation every 7 days (FI), every 14 days (FII), and every 21 days (FIII). The following biometric variables and their components were measured: height of plant, number of leaves, biomass and economic yield. Results. The results suggest that the optimum irrigation frequency was FII (14 days), resulting in an adequate plant stand at panicle initiation and allows a proper development of plant with optimal biological and economical yields and the highest efficiency of water use (4.02 kg·m-3). Conclusions. The contributions of this study demonstrated the production potential of A. cruentus crop in the lower valley of the Río Negro river under irrigation, representing the southernmost study on irrigation frequency made for this grain crop in the world. A management of irrigation water of 7 days for the establishment of the crop and then with a frequency of 14 days showed the highest yield and the best water use efficiency.
Fréquence d'irrigation de l'amarante dans le nord-est de la Patagonie, ArgentineIntroduction. Récemment, il a été démontré le potentiel de la culture d’amarante en Patagonie du Nord, en Argentine. Cette culture sous irrigation et en climat tempéré semi-aride a montré un développement adéquat des plantes dans leurs différents stades phénologiques avec des performances économiques élevéesObjectifs. Cette étude a exploré la réponse de Amaranthus cruentus cv Mexicano à une fréquence différente d’irrigation dans la basse vallée de la rivière Río Negro, en Patagonie, en Argentine.Méthode. Un modèle expérimental de trois blocs avec des traitements randomisés (sous-parcelles), chacun correspondant à différentes fréquences d'irrigation, a été appliqué. Les six premières irrigations pour tous les traitements effectués tous les 7 jours eurent pour but d'assurer l'implantation de la culture. Ensuite, la FI a maintenu cette fréquence, la FII tous les 14 jours et FIII tous les 21 jours. Les variables biométriques suivantes et leurs composants ont été mésurés : hauteur de la plante, nombre de feuilles, biomasse et rendement économique. Résultats. Les résultats suggèrent que FII est la fréquence d'irrigation optimale. Cette fréquence d'irrigation génère un peuplement adéquat à l'initiation des panicules et permet un développement correct de la plante avec des rendements biologiques et économiques optimaux et la meilleure efficacité d'utilisation de l'eau (4,02 kg·m-3).Conclusions. Cette étude a démontré le potentiel de culture de A. cruentus dans la basse vallée de la rivière Río Negro, représentant l'étude de la densité d’installation réalisée pour cette culture de céréales la plus australe au monde. Une gestion de l'eau d'irrigation de 7 jours pour la mise en place de la culture puis avec une fréquence de 14 jours a montré le rendement le plus élevé et la meilleure efficacité d'utilisation de l'eau.
While the gene flow in some organisms is strongly affected by physical barriers and geographical distance, other highly mobile species are able to overcome such constraints. In southern South ...America, the Andes (here up to 6,900 m) may constitute a formidable barrier to dispersal. In addition, this region was affected by cycles of intercalating arid/moist periods during the Upper/Late Pleistocene and Holocene. These factors may have been crucial in driving the phylogeographic structure of the vertebrate fauna of the region. Here we test these hypotheses in the burrowing parrot Cyanoliseus patagonus (Aves, Psittaciformes) across its wide distributional range in Chile and Argentina.
Our data show a Chilean origin for this species, with a single migration event across the Andes during the Upper/Late Pleistocene, which gave rise to all extant Argentinean mitochondrial lineages. Analyses suggest a complex population structure for burrowing parrots in Argentina, which includes a hybrid zone that has remained stable for several thousand years. Within this zone, introgression by expanding haplotypes has resulted in the evolution of an intermediate phenotype. Multivariate regressions show that present day climatic variables have a strong influence on the distribution of genetic heterogeneity, accounting for almost half of the variation in the data.
Here we show how huge barriers like the Andes and the regional environmental conditions imposed constraints on the ability of a parrot species to colonise new habitats, affecting the way in which populations diverged and thus, genetic structure. When contact between divergent populations was re-established, a stable hybrid zone was formed, functioning as a channel for genetic exchange between populations.
El visón americano (Neovison vison) es el carnívoro exótico invasor de mayor distribución en Patagonia. Basados en relevamientos de campo y archivos históricos se presenta información detallada sobre ...su actual distribución en 180 km del Río Negro. Este foco representa la distribución más noreste, un nuevo ambiente invadido (Monte Oriental) y una nueva provincia con poblaciones silvestres (Buenos Aires). Documentamos la existencia de un criadero en las ciudades de Carmen de Patagones y Viedma (1965-1974), que podría ser el origen de este foco. Recomendamos diseñar e implementar planes de monitoreo y control de manera urgente.
The main ecosystem in northern Patagonia, Argentina, is the Monte, a semi-desert scrubland home to a high biodiversity. Monte is the most endangered ecosystem of southern South America, with an ...annual rate of clearance of the native vegetation estimated at 3.7%. Here we report the results of bird surveys carried out in the province of Río Negro, northern Patagonia. We surveyed four localities mostly dominated by the Monte ecosystem, between 1986 and 2010. Three localities are Important Bird Areas (IBAs): El Cóndor, San Antonio Oeste and Meseta de Somuncurá. The fourth locality is the Paso Córdoba nature reserve. We recorded a total of 263 bird species. The highest species richness was observed at San Antonio Oeste, followed by El Cóndor. Information regarding the period of occurrence and habitats are provided for all species and localities. Additionally, we indicated the cases in which breeding behavior was observed. This information is urgently needed for the evaluation of the consequences of habitat destruction and deterioration as well as for the success of intended remediation measures.
Abstract
The Pleistocene glacial period shaped the current genetic structure of numerous species. The last glacial dynamics has been proposed to have split the South American sea lion, Otaria ...flavescens, into two Evolutionarily Significant Units (ESUs), one on each side of the continent. However, previous studies have not provided genetic information on colonies found along 3000 km of coastline of the southernmost limit of the species distribution, where gene flow could occur. We conducted an exhaustive phylogeographical analysis of O. flavescens using a mtDNA marker, including, for the first time, data from colonies living south of latitude 45° S, in the Argentinian provinces of Santa Cruz and Tierra del Fuego. Our results indicated the presence of five Conservation Units across the distribution range of O. flavescens and suggest that the Patagonian population must have expanded about 150 000 BP. We found evidence for gene flow across the entire species range, supporting a scenario of secondary contact in Tierra del Fuego where representatives of the oldest lineages coexist. The presence of gene flow between oceans leads us to reject the assumption of complete reciprocal monophyly for mtDNA between the presumed ESUs, suggesting that the species constitutes a single Evolutionarily Significant Unit.
PDF
