Universidad de Magallanes
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Population structure and microscale morphological differentiation in a freshwater snail from the Chilean Altiplano
No full textBackgroundThe diversity and population genetic structure of many species have been shaped by historical and contemporary climatic changes. For the species of the South American Altiplano, the historical climatic changes are mainly related to the wet events of great magnitude and regional influence that occurred during the Pleistocene climatic oscillations (PCOs). In contrast, contemporary climate changes are associated with events of lesser magnitude and local influence related to intensifications of the South American Summer Monsoon (SASM). Although multiple studies have analyzed the effect of PCOs on the genetic patterns of highland aquatic species, little is known about the impact of contemporary climate changes in recent evolutionary history. Therefore, in this study, we investigated the change in population structure and connectivity using nuclear and mitochondrial markers throughout the distribution range of Heleobia ascotanensis, a freshwater Cochliopidae endemic to the Ascotan Saltpan. In addition, using geometric morphometric analyses, we evaluated the concomitance of genetic divergence and morphological differentiation.ResultsThe mitochondrial sequence analysis results revealed the presence of highly divergent co-distributed and geographically nested haplotypes. This pattern reflects an extension in the distribution of groups that previously would have differentiated allopatrically. These changes in distribution would have covered the entire saltpan and would be associated with the large-scale wet events of the PCOs. On the other hand, the microsatellite results defined five spatially isolated populations, separated primarily by geographic barriers. Contemporary gene flow analyses suggest that post-PCO, climatic events that would have connected all populations did not occur. The morphometric analyses results indicate that there is significant morphological differentiation in the populations that are more isolated and that present the greatest genetic divergence.ConclusionsThe contemporary population structure and morphological variation of H. ascotanensis mainly reflect the post-PCO climatic influence. Although both markers exhibit high genetic structuring, the microsatellite and morphology results show the preponderant influence of fragmentation in recent evolutionary history. The contemporary genetic pattern shows that in species that have limited dispersal capabilities, genetic discontinuities can appear rapidly, erasing signs of historical connectivity
Which microbiome are we talking about? Contrasted diversity patterns and eco-evolutionary processes between gill and intestinal microbiomes of Antarctic fairy shrimps
No full textMetazoans comprise multiple physical niches ("microenvironments"), each colonized by unique microbiomes that contribute to their hosts' evolutionary dynamics, influencing their health, physiology, and adaptation to changing environments. Most wildlife microbiome studies focus on higher metazoans and multiple host microenvironments, while studies of lower species often concentrate on a single microenvironment, sometimes pooling whole bodies or specimens. This is particularly evident in small-sized animals, such as freshwater meiofaunal invertebrates, thus impeding a holistic understanding of microbiome assembly across host microenvironments and its relation with host population genetics. Leveraging the anostracan fairy shrimp Branchinecta, which has easily discernible organs and expected high levels of intraspecific genetic divergence, we aimed to investigate the microbiome assembly processes and test the phylosymbiosis signal in two microenvironments (gill and intestine) across four host populations of Branchinecta gaini within Maritime Antarctica, using 16S rRNA metabarcoding. Our results showed that the gill and intestine harbor strikingly different microbiomes resulting from the B. gaini ecological filtering of the surrounding environment microbial community. Both microenvironments exhibit their respective core microbiomes, yet the gill's core microbiome is narrower and constitutes a smaller proportion of the overall bacterial community compared to that of the intestine. Within each host population (i.e. each sampling site), the microbiome assembles through distinct eco-evolutionary processes in both microenvironments, mostly stochastically (ecological drift) in the gill and deterministically (variable selection) in the intestine. Across different B. gaini populations, variable selection dominates in driving compositional divergence of both microenvironment microbiomes, although to a lesser extent in the gill. Lastly, our study reveals robust correlation between host intraspecific genetic structure and intestine microbiome composition, providing evidence of phylosymbiosis in anostracans. Contrastingly, phylosymbiosis was less pronounced in the gill microbiome. We discuss the potential differences in ecological filtering between each host microenvironment that may underlie the difference in the strength of phylosymbiosis. Our study highlights the relevance of considering host microenvironment and intraspecific levels in testing the phylosymbiosis hypothesis to better understand the intricate eco-evolutionary relationships between hosts and their microbiomes
Effects of glacial melting on physiological performance of Macrocystis pyrifera in the Fjord of the Mountains, Magellanic Sub-Antarctic ecoregion, Chile
No full textThe Magellanic Sub-Antarctic ecoregion (MSE) was covered by ice during the Last Glacial Maximum (21,000 years ago), with the ice masses advancing and retreating throughout the Quaternary. Currently, this ecoregion supports a significant number of endemic species and a high diversity of macroalgae. However, anthropogenic climate change has accelerated global warming, exacerbating glacier melt over the last decade. In this study, we evaluated the effect of glacial melting on the ecophysiology of Macrocystis pyrifera, a brown macroalga that forms underwater forests and is considered a foundation species susceptible to environmental change. Tissue samples were collected from apical and basal fronds of young individuals from three M. pyrifera populations located in the Fjord of the Mountains (51 degrees 10'53 '' S-73 degrees 17'08 '' W). We found significant differences in maximum relative electron transport rate (rETR(max)), electron transport efficiency (Alpha), and light saturation point (E-k) between apical and basal fronds, as well as between sites influenced by glacial-melt (high turbidity, low temperature, and low salinity) versus those with minimal or no glacial influence (low turbidity, high temperature, and high salinity). Pigment concentrations (chlorophyll-a, chlorophyll-c, and fucoxanthin) did not show significant variation between fronds and sites, except under extreme conditions. Our results indicate that photosynthetic response differs between sites affected by glacial melt and those unaffected. Apical fronds demonstrated higher photosynthetic efficiency in response to environmental fluctuations. This study offers valuable insights into how M. pyrifera adjusts its photosynthetic performance in response to varying conditions driven by glacial-melt, thereby enhancing our understanding of how kelp forests might locally respond to climate change
Una mirada socioambiental de la historia de la explotación de mamíferos marinos y aves en el paisaje malvinero y atlántico patagónico, 1800-1914
No full textReseña bibliográfica Balleneros, loberos y guaneros en Patagonia y Malvinas. Una historia socioambiental del mar (1800-1914) El libro Balleneros, loberos y guaneros en Patagonia y Malvinas trata sobre la historia de la apropiación y transformación del paisaje atlántico patagónico y malvinero en el transcurso de una de las olas expansivas y extractivas del capitalismo global que a contar de fines del siglo XVIII tuvo como escenario el extremo austral americano
The Roles of Alpha, Beta, and Functional Diversity Indices in the Ecological Connectivity between Two Sub-Antarctic Macrobenthic Assemblages
No full textThe study of ecological connectivity is a global priority due to the important role it plays in the conservation of diversity. However, few studies in this context have focused on marine benthic ecosystems. To address this issue, the present work determines the ecological connectivity between two sub-Antarctic macrobenthic assemblages through assessment of the alpha-, beta-, and functional diversity indices. Samples were collected using a van Veen grab at stations located in Bahia Inútil and Seno Almirantazgo. The ecological analysis was based on a total of 113 invertebrate taxa. The mean abundance values were lower in Bahia Inútil (888.9 +/- 26.8 ind m-2) than in Seno Almirantazgo (1358.6 +/- 43.4 ind m-2). While the mean alpha-diversity values showed significant differences between assemblages, beta- and functional diversity indices presented no significant differences. These results indicate that, despite the distance (56 km) separating the two basins from each other, there is a high degree of connectivity at the functional level between the assemblages due to the high number of shared species and their functional traits. The species most responsible for this observation were the polychaetes Capitela capitata and Aricidia (Acmira) finitima, as well as the bivalves Nucula pisum and Yoldiella sp. 1. In terms of functional biodiversity, species characterized as omnivorous and with lecithotrophic larval development were mostly responsible for connectivity between assemblages. These results suggest the importance of including beta- and functional diversity indices as criteria in the future planning of marine protected areas for the maintenance of marine ecosystem integrity
Entrenamiento de fuerza para prevención de caídas en personas mayores: Una revisión sistemática
No full textRESUMEN Introducción: El entrenamiento de fuerza está asociado con cambios positivos hacia un envejecimiento saludable y con calidad de vida, dado que previenen las lesiones, fragilidad, así como las caídas. Objetivo: El objetivo de este estudio fue evaluar la evidencia científica disponible sobre los efectos del entrenamiento de fuerza en la prevención de caídas en personas mayores. Metodología: Se realizó una búsqueda de artículos científicos en las bases de datos Medline vía PubMed, Web of Science (WOS) y Literatura Latinoamericana y del Caribe en Ciencias de la Salud (LILACS) vía Biblioteca Virtual de Salud (BVS) que cumplieran con los criterios de elegibilidad; el análisis se realizó entre el 8 de mayo de 2022 hasta el 11 de octubre de 2022. Resultados: Se seleccionaron 10 artículos; el promedio de edad fue de 75,3 años; en el 90 % de los artículos predominó el sexo femenino. Con respecto a los programas, el 70 % duró 60 minutos y en el 50% predominó ejercicios principalmente de miembros inferiores, y el 60 % de los artículos usó el Timed Up and Go para evaluar sus programas. La totalidad de los artículos demuestran que el entrenamiento de fuerza redujo el riesgo de caídas a corto plazo. Conclusión: Las principales conclusiones apuntan a un cambio favorable en la prevención de caídas a través del análisis de la fuerza, el equilibrio, la tasa de caídas, la aptitud física y/o el miedo a caer tras realizar entrenamiento de fuerza
Early Holocene Archaeological Context and Assemblages of Baño Nuevo 1: A Key Site in Central West Patagonia
No full textThe Bano Nuevo 1 site, a cave with paleontological and archaeological deposits located in the eastern steppes of Central West Patagonia, provides a uniquely dry environment that allowed the survival of organic materials that are not common in excavated sites in the region. The remains include paleontological evidence from the late Pleistocene deposits and a series of discontinuous occupational events that spanned the Holocene. However, an assemblage containing the remains of at least 10 human individuals of early Holocene age stands out as a distinctive set of synchronic burials, among the earliest on the continent. This review presents updated information on the studies carried out at the site while discussing them in the frame of other relatable archaeological findings of the early Holocene in the broader region
Plantas Medicinales De Uso Tradicional
No full textLa presente edición entrega una visión general del estado actual de la química y farmacología de una selección de plantas medicinales autóctonas y extranjeras de uso frecuente y tradicional. Las plantas medicinales han constituido desde tiempos remotos un valioso recurso para cubrir las necesidades terapéuticas de la población. Hoy en día, su estudio se ha convertido en un hecho científico universal el que trasciende no sólo en beneficio de la salud sino del sistema productivo y económico de los países. Este libro incluye una descripción actualizada de la fitoquímica de los compuestos químicos, elucidación de la estructura detectados, aislados y caracterización de la actividad biológica de diversas sustancias producidas por los vegetales, sobre los cuales se les ha practicado variados tipos de ensayos biológicos. Obra principalmente dirigida a fitoquímicos, farmacólogos, farmacéuticos, bioquímicos, profesionales del área de la salud y público en general que busca información relacionada con el uso de las plantas y beneficios de ellas en la salud
Extended ozone depletion and reduced snow and ice cover-Consequences for Antarctic biota
No full textStratospheric ozone, which has been depleted in recent decades by the release of anthropogenic gases, is critical for shielding the biosphere against ultraviolet-B (UV-B) radiation. Although the ozone layer is expected to recover before the end of the 21st century, a hole over Antarctica continues to appear each year. Ozone depletion usually peaks between September and October, when fortunately, most Antarctic terrestrial vegetation and soil biota is frozen, dormant and protected under snow cover. Similarly, much marine life is protected by sea ice cover. The ozone hole used to close before the onset of Antarctic summer, meaning that most biota were not exposed to severe springtime UV-B fluxes. However, in recent years, ozone depletion has persisted into December, which marks the beginning of austral summer. Early summertime ozone depletion is concerning: high incident UV-B radiation coincident with snowmelt and emergence of vegetation will mean biota is more exposed. The start of summer is also peak breeding season for many animals, thus extreme UV-B exposure (UV index up to 14) may come at a vulnerable time in their life cycle. Climate change, including changing wind patterns and strength, and particularly declining sea ice, are likely to compound UV-B exposure of Antarctic organisms, through earlier ice and snowmelt, heatwaves and droughts. Antarctic field research conducted decades ago tended to study UV impacts in isolation and more research that considers multiple climate impacts, and the true magnitude and timing of current UV increases is needed. The last 4 years have seen unusually long-lived ozone holes over Antarctica, persisting into early summer-the crucial period of new plant growth and peak animal breeding season. Less ozone means the UV index has doubled, reaching extreme levels of 14. Ice and snow reflect light, and long-lasting ozone holes mean that emperor penguin chicks and seal pups born in late spring are potentially impacted by this enhanced UV radiation. Less sea ice, driven by climate change, means more sunlight penetrates the ocean. Increasing UV impacts survival of phytoplankton and krill, with cascading effects higher up the food chain.imag
Effects of heavy metals on bacterial growth parameters in degradation of phenol by an Antarctic bacterial consortium
No full textAntarctica has often been perceived as a pristine continent until the recent few decades as pollutants have been observed accruing in the Antarctic environment. Irresponsible human activities such as accidental oil spills, waste incineration and sewage disposal are among the primary anthropogenic sources of heavy metal contaminants in Antarctica. Natural sources including animal excrement, volcanism and geological weathering also contribute to the increase of heavy metals in the ecosystem. A microbial growth model is presented for the growth of a bacterial cell consortium used in the biodegradation of phenol in media containing different metal ions, namely arsenic (As), cadmium (Cd), aluminium (Al), nickel (Ni), silver (Ag), lead (Pb) and cobalt (Co). Bacterial growth was inhibited by these ions in the rank order of Al < As < Co < Pb < Ni < Cd < Ag. Greatest bacterial growth occurred in 1 ppm Al achieving an OD600 of 0.985 and lowest in 1 ppm Ag with an OD600 of 0.090. At a concentration of 1.0 ppm, Ag had a considerable effect on the bacterial consortium, inhibiting the degradation of phenol, whereas this concentration of the other metal ions tested had no effect on degradation. The biokinetic growth model developed supports the suitability of the bacterial consortium for use in phenol degradation