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Assessment of transboundary river basins for potential hydro-political tensions

Autores:

De Stefano, L., Petersen-Perlman, J., Sproles, E., Eynard, J., & Wolf, A.

Resumen:

This paper presents a systematic, global assessment of transboundary watersheds that identifies regions more likely to experience hydro-political tensions over the next decade and beyond based upon environmental, political, and economic indicators. The development of new water infrastructure in transboundary basins can strain relationships among fellow riparians as the impacts of new dams and diversions are felt across borders. Formal arrangements governing transboundary river basins, such as international water treaties and river basin organizations, provide a framework for dialogue and negotiation, thus contributing to assuaging potential disputes. Our study examines these two issues in tandem − the stresses inherent in development and the mitigating impact of institutions − and maps the risk of potential hydro-political tensions that exist where basins may be ill-equipped to deal with transboundary disputes triggered by the construction of new dams and diversions. We also consider several factors that could exacerbate those hydropolitical tensions in the near future, including changes in terrestrial water storage, projected changes in water variability, per capita gross national income, domestic and international armed conflicts, and recent history of disputes over transboundary waters. The study points to the vulnerability of several basins in Southeast Asia, South Asia, Central America, the northern part of the South American continent, the southern Balkans as well as in different parts of Africa, where new water infrastructure is being built or planned, but formal transboundary arrangements are absent. Moreover, in some of these regions there is a concomitance of several political, environmental and socioeconomic factors that could exacerbate hydropolitical tensions. This study contributes to the understanding of how the recent proliferation of development accompanied with unfavourable socio-economic and environmental indicators may influence global hydropolitical resilience.

Año: 2017

Palabras claves: Transboundary, Treaty, Assessment, Dispute, Cooperation, Conflict

Referencia APA: De Stefano, L., Petersen-Perlman, J., Sproles, E., Eynard, J., & Wolf, A. (2017). Assessment of transboundary river basins for potential hydro-political tensions. Global Environmental Change, 45, 35-46.

Different sensitivities of snowpacks to warming in Mediterranean climate mountain areas

Autores:

López-Moreno, J., Gascoin, S., Herrero, J., Sproles, E., Pons, M., Alonso-González, E., Hanich, L., Boudhar, A., Musselman, K.N., Molotch, N.P.

Resumen:

In this study we quantified the sensitivity of snow to climate warming in selected mountain sites having a Mediterranean climate, including the Pyrenees in Spain and Andorra, the Sierra Nevada in Spain and California (USA), the Atlas in Morocco, and the Andes in Chile. Meteorological observations from high elevations were used to simulate the snow energy and mass balance (SEMB) and calculate its sensitivity to climate. Very different climate sensitivities were evident amongst the various sites. For example, reductions of 9%–19% and 6–28 days in the mean snow water equivalent (SWE) and snow duration, respectively, were found per °C increase. Simulated changes in precipitation (±20%) did not affect the sensitivities. The Andes and Atlas Mountains have a shallow and cold snowpack, and net radiation dominates the SEMB; and explains their relatively low sensitivity to climate warming. The Pyrenees and USA Sierra Nevada have a deeper and warmer snowpack, and sensible heat flux is more important in the SEMB; this explains the much greater sensitivities of these regions. Differences in sensitivity help explain why, in regions where climate models project relatively greater temperature increases and drier conditions by 2050 (such as the Spanish Sierra Nevada and the Moroccan Atlas Mountains), the decline in snow accumulation and duration is similar to other sites (such as the Pyrenees and the USA Sierra Nevada), where models project stable precipitation and more attenuated warming. The snowpack in the Andes (Chile) exhibited the lowest sensitivity to warming, and is expected to undergo only moderate change (a decrease of <12% in mean SWE, and a reduction of < 7 days in snow duration under RCP 4.5). Snow accumulation and duration in the other regions are projected to decrease substantially (a minimum of 40% in mean SWE and 15 days in snow duration) by 2050.

Año: 2017

Palabras claves: Snow, Mediterranean mountains, climate warming, snow simulations

Referencia APA: López-Moreno, J., Gascoin, S., Herrero, J., Sproles, E., Pons, M., Alonso-González, E., Hanich, L., Boudhar, A., Musselman, K.N., Molotch, N.P. (2017). Different sensitivities of snowpacks to warming in Mediterranean climate mountain areas. Environmental Research Letters, 12(7), 074006.

First circumglobal assessment of Southern Hemisphere humpback whale mitochondrial genetic variation and implications for management

Autores:

Rosenbaum H.C., Kershaw F., Mendez M., Pomilla C., Leslie M.S., Findlay K.P., Best P.B., Collins T., Vely M., Engel M.H., Baldwin R., Minton G., Meÿer M., Flórez-González L., Poole M.M., Hauser N., Garrigue C., Brasseur M., Bannister J., Anderson M., Olavarría C., Baker C.S.

Resumen:

The description of genetic population structure over a species’ geographic range can provide insights into its evolutionary history and also support effective management efforts. Assessments for globally distributed species are rare, however, requiring significant international coordination and collaboration. The global distribution of demographically discrete populations for the humpback whale Megaptera novaeangliae is not fully known, hampering the definition of appropriate management units. Here, we present the first circumglobal assessment of mitochondrial genetic population structure across the species’ range in the Southern Hemisphere and Arabian Sea. We combine new and existing data from the mitochondrial (mt)DNA control region that resulted in a 311 bp consensus sequence of the mtDNA control region for 3009 individuals sampled across 14 breeding stocks and subpopulations currently recognized by the International Whaling Commission. We assess genetic diversity and test for genetic differentiation and also estimate the magnitude and directionality of historic matrilineal gene flow between putative populations. Our results indicate that maternally directed site fidelity drives significant genetic population structure between breeding stocks within ocean basins. However, patterns of connectivity differ across the circumpolar range, possibly as a result of differences in the extent of longitudinal movements on feeding areas. The number of population comparisons observed to be significantly differentiated were found to diminish at the subpopulation scale when nucleotide differences were examined, indicating that more complex processes underlie genetic structure at this scale. It is crucial that these complexities and uncertainties are afforded greater consideration in management and regulatory efforts.

Año: 2017

Palabras claves: Humpback whale, International Whaling Commission, Management unit, Population structure, Southern Hemisphere, Arabian Sea

Referencia APA: Rosenbaum H.C., Kershaw F., Mendez M., Pomilla C., Leslie M.S., Findlay K.P., Best P.B., Collins T., Vely M., Engel M.H., Baldwin R., Minton G., Meÿer M., Flórez-González L., Poole M.M., Hauser N., Garrigue C., Brasseur M., Bannister J., Anderson M., Olavarría C., Baker C.S. (2017). First circumglobal assessment of Southern Hemisphere humpback whale mitochondrial genetic variation and implications for management. Endangered Species Research 32: 551–567.

Ancient female philopatry, asymmetric male gene flow, and synchronous population expansion support the influence of climatic oscillations on the evolution of South American sea lion (Otaria flavescens)

Autores:

Oliveira L.Rd., Gehara M.C.M., Fraga L.D, Lopes F., Túnez J.I., Cassini M.H., Majluf P., Cárdenas-Alayza S., Pavés H.J., Crespo E.A., García N., Loizaga de Castro R., Hoelzel A.R., Sepúlveda M., Olavarría C., Valiati V.H., Quiñones R., Pérez-Alvarez M.J., Ott P.H., Bonatto S.L.

Resumen:

The South American sea lion (Otaria flavescens) is widely distributed along the southern Atlantic and Pacific coasts of South America with a history of significant commercial exploitation. We aimed to evaluate the population genetic structure and the evolutionary history of South American sea lion along its distribution by analyses of mitochondrial DNA (mtDNA) and 10 nuclear microsatellites loci. We analyzed 147 sequences of mtDNA control region and genotyped 111 individuals of South American sea lion for 10 microsatellite loci, representing six populations (Peru, Northern Chile, Southern Chile, Uruguay (Brazil), Argentina and Falkland (Malvinas) Islands) and covering the entire distribution of the species. The mtDNA phylogeny shows that haplotypes from the two oceans comprise two very divergent clades as observed in previous studies, suggesting a long period (>1 million years) of low inter-oceanic female gene flow. Bayesian analysis of bi-parental genetic diversity supports significant (but less pronounced than mitochondrial) genetic structure between Pacific and Atlantic populations, although also suggested some inter-oceanic gene flow mediated by males. Higher male migration rates were found in the intra-oceanic population comparisons, supporting very high female philopatry in the species. Demographic analyses showed that populations from both oceans went through a large population expansion ~10,000 years ago, suggesting a very similar influence of historical environmental factors, such as the last glacial cycle, on both regions. Our results support the proposition that the Pacific and Atlantic populations of the South American sea lion should be considered distinct evolutionarily significant units, with at least two managements units in each ocean.

Año: 2017

Palabras claves: Sea lions, Mitochondrial DNA, Chile (country), Population genetics, Haplotypes, Peru, Argentina, Oceans

Referencia APA: Oliveira L.Rd., Gehara M.C.M., Fraga L.D, Lopes F., Túnez J.I., Cassini M.H., Majluf P., Cárdenas-Alayza S., Pavés H.J., Crespo E.A., García N., Loizaga de Castro R., Hoelzel A.R., Sepúlveda M., Olavarría C., Valiati V.H., Quiñones R., Pérez-Alvarez M.J., Ott P.H., Bonatto S.L. (2017). Ancient female philopatry, asymmetric male gene flow, and synchronous population expansion support the influence of climatic oscillations on the evolution of South American sea lion (Otaria flavescens). PLoS ONE 12(6): e0179442.

Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom

Autores:

Häussermann, V., Gutstein, C., Beddington, M., Cassis, D., Olavarria, C., & Dale, A., Valenzuela-Toro, A.M., Valenzuela-Toro, M.J., Sepúlveda, H.H., McConnell, K.M., Horwitz, F.E., Försterra, G.

Resumen:


While large mass mortality events (MMEs) are well known for toothed whales, they have been rare in baleen whales due to their less gregarious behavior. Although in most cases the cause of mortality has not been conclusively identified, some baleen whale mortality events have been linked to bio-oceanographic conditions, such as harmful algal blooms (HABs). In Southern Chile, HABs can be triggered by the ocean–atmosphere phenomenon El Niño. The frequency of the strongest El Niño events is increasing due to climate change. In March 2015, by far the largest reported mass mortality of baleen whales took place in a gulf in Southern Chile. Here, we show that the synchronous death of at least 343, primarily sei whales can be attributed to HABs during a building El Niño. Although considered an oceanic species, the sei whales died while feeding near to shore in previously unknown large aggregations. This provides evidence of new feeding grounds for the species. The combination of older and newer remains of whales in the same area indicate that MMEs have occurred more than once in recent years. Large HABs and reports of marine mammal MMEs along the Northeast Pacific coast may indicate similar processes in both hemispheres. Increasing MMEs through HABs may become a serious concern in the conservation of endangered whale species.

Año: 2017

Palabras claves: Chilean Patagonia, Red tide, El Niño, Sei whales, Drift models, Balaenoptera borealis, Paralytic shellfish poison, Balaenopteridae, Taphonomy, Climate Change

Referencia APA: Häussermann, V., Gutstein, C., Beddington, M., Cassis, D., Olavarria, C., & Dale, A., Valenzuela-Toro, A.M., Valenzuela-Toro, M.J., Sepúlveda, H.H., McConnell, K.M., Horwitz, F.E., Försterra, G. (2017). Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom. Peerj, 5, e3123.

Pollination Ecology of Polylepis tomentella (Rosaceae), an Andean Anemophilous Tree Presenting a Potential Floral Fungal Infection

Autores:

Domic, A., Bernhardt, P., Edens-Meier, R., Camilo, G., & Capriles, J.

Resumen:

Premise of research. Anemophily is considered to be a mechanism that evolved to promote pollination success. However, reproductive output can decrease if pollen loads are scarce due to low abundance of compatible mates or floral infections. Here we analyze the effects of breeding system, pollen limitation, and a potential floral fungal infection on the reproductive output of the Andean tree Polylepis tomentella (Rosaceae).

Methodology. We performed pollen supplementation experiments in the field to assess the extent of the effect of pollen limitation on fruit and seed set and to identify any pre- or postzygotic self-incompatibility responses within receptive pistils. Supplementary scanning electron microscopy and epifluorescence microscopy were used to observe the possible effects of a potential floral fungal infection on sexual reproduction.

Pivotal results. Pollen supplementation did not increase fruit and seed set, suggesting weak evidence of pollen limitation. Most stigmas from self- and cross-pollinated flowers showed germinated pollen grains and pollen tubes in the style, indicating that the species exhibits prezygotic self-compatibility. The presence of three Ascomycota genera in stigmas and styles appears to have negatively affected the germination of pollen grains by inhibiting pollen tube growth, but we did not find evidence suggesting that hyphae are able to penetrate the ovary.

Conclusions. This study showed that P. tomentella possesses a prezygotic self-compatible system and that fruit and seed set are not affected by pollen limitation. Therefore, reproductive assurance is achieved through pollen transfer between plants by wind and the role played by self-compatibility that allows selfing in the species. However, it is possible that the potential fungal infection could reduce the fecundity of its tree host, as hyphae are able to penetrate pollen grains.

Año: 2017

Palabras claves: Pollen limitation, potential floral fungal infection, prezygotic self-incompatibility, treeline, wind pollination.

Referencia APA: Domic, A., Bernhardt, P., Edens-Meier, R., Camilo, G., & Capriles, J. (2017). Pollination Ecology of Polylepis tomentella (Rosaceae), an Andean Anemophilous Tree Presenting a Potential Floral Fungal Infection. International Journal Of Plant Sciences, 178(7), 512-521.

Patterns of composition, richness and phylogenetic diversity of woody plant communities of Quillaja saponaria Molina (Quillajaceae) in the Chilean sclerophyllous forest

Autores:

Letelier, L., Valderrama, A., Stoll, A., García-Gonzáles, R., & González-Rodríguez, A.

Resumen:

Sclerophyllous forest is among the most representative types of woody plant communities in central Chile where Quillaja saponaria is considered to be one of the most important species. In this study, we analysed the main factors that explain the geographical patterns of variation in composition, richness and phylogenetic diversity of woody plant communities in the Chilean sclerophyllous forest where Quillaja saponaria is present. Vegetation surveys were performed for trees and shrubs in thirty-nine sites from 30° to 38° of latitude South in the Mediterranean biome of Chile. Composition, richness, alfa diversity and phylogenetic diversity metrics of the communities were calculated and associated with spatial (latitude, longitude and altitude), climate (annual mean temperature, annual precipitation, aridity), and disturbance variables (type of adjacent vegetation matrix) using multiple regression models. Sixty taxa were identified, distributed in 29 families, including 23 trees and 37 shrubs. A significant effect of the type of adjacent vegetation matrix (i.e. agricultural land, commercial forestry plantation or natural forest) on diversity and composition of the sampled communities was found. Significant effects of latitude on diversity, and altitude, latitude and annual mean temperature on composition were also found. Metrics of phylogenetic diversity and structure were only associated with altitude and latitude. In conclusion, diversity, composition and phylogenetic structure patterns of sclerophyllous forest communities are associated with spatial and climate variables, and anthropogenic disturbance has also caused important changes in these communities.

Español

El Bosque Esclerófilo es uno de los tipos más representativos de las comunidades de plantas leñosas en el centro de Chile, donde Quillaja saponaria es considerada una de las especies más importantes. En este trabajo se analizaron los principales factores que explican la distribución geográfica de la variación en la composición, riqueza y diversidad filogenética de las comunidades de plantas leñosas del Bosque Esclerófilo de Chile, donde Q. saponaria está presente. Se llevaron a cabo censos de vegetación de árboles y arbustos en treinta y nueve sitios desde los 30° a los 38° de latitud sur en el bioma mediterráneo de Chile. Se calcularon la composición, riqueza, diversidad alfa y la diversidad filogenética de las comunidades y se asociaron con variables espaciales (latitud, longitud y altitud), climáticas (temperatura media anual, precipitación anual, aridez), y variables de perturbación (tipo de matriz de la vegetación adyacente) usando modelos de regresión múltiple. Se identificaron sesenta taxones, distribuidos en 29 familias, incluyendo 23 árboles y 37 arbustos. Se encontró un efecto significativo del tipo de matriz de vegetación adyacente (es decir, tierras agrícolas, plantaciones forestales comerciales o bosques naturales) en la diversidad y composición de las comunidades estudiadas. También se encontraron efectos significativos de la latitud sobre la diversidad; y de la altitud, latitud y temperatura media anual sobre la composición de las comunidades, la diversidad filogenética sólo se asoció con la altitud y la latitud. En conclusión, la diversidad, composición y patrones de estructura filogenética se asocian con variables espaciales y climáticas; y las perturbaciones antropogénicas también han provocado cambios importantes en estas comunidades.

Año: 2017

Palabras claves: Diversity; forest fragmentation; Mediterranean flora; phylogenetic diversity; vegetation matrix

Referencia APA: Letelier, L., Valderrama, A., Stoll, A., García-Gonzáles, R., & González-Rodríguez, A. (2017). Patterns of composition, richness and phylogenetic diversity of woody plant communities of Quillaja saponaria Molina (Quillajaceae) in the Chilean sclerophyllous forest. Gayana. Botánica, (ahead), 0-0.

Development of microsatellite markers and assembly of the plastid genome in Cistanthe longiscapa (Montiaceae) based on low-coverage whole genome sequencing

Autores:

Stoll, A., Harpke, D., Schütte, C., Stefanczyk, N., Brandt, R., Blattner, F., & Quandt, D.

Resumen:

Cistanthe longiscapa is an endemic annual herb and characteristic element of the Chilean Atacama Desert. Principal threats are the destruction of its seed deposits by human activities and reduced germination rates due to the decreasing occurrence of precipitation events. To enable population genetic and phylogeographic analyses in this species we performed paired-end shotgun sequencing (2x100 bp) of genomic DNA on the Illumina HiSeq platform and identified microsatellite (SSR) loci in the resulting sequences. From 29 million quality-filtered read pairs we obtained 549,174 contigs (average length 614 bp; N50 = 904). Searching for SSRs revealed 10,336 loci with microsatellite motifs. Initially, we designed primers for 96 loci, which were tested for PCR amplification on three C. longiscapa individuals. Successfully amplifying loci were further tested on eight individuals to screen for length variation in the resulting amplicons, and the alleles were exemplarily sequenced to infer the basis for the observed length variation. Finally we arrived at 26 validated SSR loci for population studies in C. longiscapa, which resulted in 146 bi-allelic SSR markers in our test sample of eight individuals. The genomic sequences were also used to assemble the plastid genome of C. longiscapa, which provides an additional set of maternally inherited genetic markers.

Año: 2017

Palabras claves:

Referencia APA: Stoll, A., Harpke, D., Schütte, C., Stefanczyk, N., Brandt, R., Blattner, F., & Quandt, D. (2017). Development of microsatellite markers and assembly of the plastid genome in Cistanthe longiscapa (Montiaceae) based on low-coverage whole genome sequencing. PLOS ONE, 12(6), e0178402. http://dx.doi.org/10.1371/journal.pone.0178402

Paracas dust storms: Sources, trajectories and associated meteorological conditions

Autores:

Briceño-Zuluaga, F., Castagna, A., Rutllant, J.A., Flores-Aqueveque, V., Caquineau, S., Sifeddine, A., Velazco, F., Gutierrez, D., Cardich, J.

Resumen:

Dust storms that develop along the Pisco-Ica desert in Southern Peru, locally known as “Paracas” winds have ecological, health and economic repercussions. Here we identify dust sources through MODIS (Moderate Resolution Imaging Spectroradiometer) imagery and analyze HYSPLIT (Hybrid Single Particles Lagrangian Integrated Trajectory) model trajectories and dispersion patterns, along with concomitant synoptic-scale meteorological conditions from National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis (NCEP/NCAR). Additionally, surface pressure data from the hourly METeorological Aerodrome Report (METAR) at Arica (18.5°S, 70.3°W) and Pisco (13.7°S, 76.2°W) were used to calculate Alongshore (sea-level) Pressure Gradient (APG) anomalies during Paracas dust storms, their duration and associated wind-speeds and wind directions. This study provides a review on the occurrence and strength of the Paracas dust storms as reported in the Pisco airfield for five-year period and their correspondence with MODIS true-color imagery in terms of dust-emission source areas. Our results show that most of the particle fluxes moving into the Ica-Pisco desert area during Paracas wind events originate over the coastal zone, where strong winds forced by steep APGs develop as the axis of a deep mid-troposphere trough sets in along north-central Chile. Direct relationships between Paracas wind intensity, number of active dust-emission sources and APGs are also documented, although the scarcity of simultaneous METAR/MODIS data for clearly observed MODIS dust plumes prevents any significant statistical inference. Synoptic-scale meteorological composites from NCEP/NCAR reanalysis data show that Paracas wind events (steep APGs) are mostly associated with the strengthening of anticyclonic conditions in northern Chile, that can be attributed to cold air advection associated with the incoming trough. Compared to the MODIS images, HYSPLIT outputs were able to spatially reproduce trajectories and dust dispersion plumes during the Paracas wind storms. HYSPLIT trajectories revealed that part of the wind-eroded lithological material can be transported downwind several kilometers along the Peruvian coast and also deposited over the nearby coastal ocean, giving support to the presence of an aeolian signal in continental shelf sediments, of great importance for paleoenvironmental studies.

Año: 2017

Palabras claves: Aeolian transport, HYSPLIT trajectories, Dust storms, Southern, Peru, Synoptic-scale meteorological patterns

Referencia APA: Briceño-Zuluaga, F., Castagna, A., Rutllant, J.A., Flores-Aqueveque, V., Caquineau, S., Sifeddine, A., Velazco, F., Gutierrez, D., Cardich, J. (2017). Paracas dust storms: Sources, trajectories and associated meteorological conditions. In Atmospheric Environment. Volume 165, 2017. Pages 99-110.

Recent Deceleration of the Ice Elevation Change of Ecology Glacier (King George Island, Antarctica)

Autores:

Pętlicki, M., Sziło, J., MacDonell, S., Vivero, S. and Bialik, R.

Resumen:

Glacier change studies in the Antarctic Peninsula region, despite their importance for global sea level rise, are commonly restricted to the investigation of frontal position changes. Here we present a long term (37 years; 1979–2016) study of ice elevation changes of the Ecology Glacier, King George Island (62∘11′S, 58∘29′W). The glacier covers an area of 5.21 km2 and is located close to the H. Arctowski Polish Antarctic Station, and therefore has been an object of various multidisciplinary studies with subject ranging from glaciology, meteorology to glacial microbiology. Hence, it is of great interest to assess its current state and put it in a broader context of recent glacial change. In order to achieve that goal, we conducted an analysis of archival cartographic material and combined it with field measurements of proglacial lagoon hydrography and state-of-art geodetic surveying of the glacier surface with terrestrial laser scanning and satellite imagery. Overall mass loss was largest in the beginning of 2000s, and the rate of elevation change substantially decreased between 2012–2016, with little ice front retreat and no significant surface lowering. Ice elevation change rate for the common ablation area over all analyzed periods (1979–2001–2012–2016) has decreased from −1.7 ± 0.4 m/year in 1979–2001 and −1.5 ± 0.5 m/year in 2001–2012 to −0.5 ± 0.6 m/year in 2012–2016. This reduction of ice mass loss is likely related to decreasing summer temperatures in this region of the Antarctic Peninsula.

Año: 2017

Palabras claves: glaciology; ice elevation change; glacial retreat; DEM; Terrestrial Laser Scanning; Antarctica; South Shetland Islands

Referencia APA: Pętlicki, M., Sziło, J., MacDonell, S., Vivero, S. and Bialik, R. (2017). Recent Deceleration of the Ice Elevation Change of Ecology Glacier (King George Island, Antarctica). Remote Sensing, 9(6), p.520.

The Andes Cordillera. Part I: snow distribution, properties,and trends (1979–2014)

Autores:

Mernild, S., Liston, G., Hiemstra, C., Malmros, J., Yde, J. and McPhee, J.

Resumen:

Snow cover presence, duration, properties, and water amount play a major role in Earth’s climate systemthrough its impact on the surface energy budget. Snow cover conditions and trends (1979–2014) were simulated for SouthAmerica – for the entire Andes Cordillera. Recent data sets and SnowModel developments allow relatively high-resolutionsof 3-h time step and 4-km horizontal grid increment for this domain. US Geological Survey’s Global Multi-resolution TerrainElevation Data 2010 topography, Global Land Cover (GlobCover), Randolph Glacier Inventory (v. 4.0) glacier, and NASAmodern-era retrospective analysis for research and a pplications data sets were used to simulate rst-order atmospheric forcing(e.g. near-surface air temperature and precipitation, including the fraction of precipitation falling as snow) and terrestrial snowcharacteristics (e.g. snow cover days, snow water equivalent depth, and snow density). Simulated snow conditions were veriedagainst moderate-resolution imaging spectroradiometer-derived snow cover extent and 3064 individual direct observations ofsnow depths. Regional variability in mean annual air temperature occurred: positive trends in general were seen in the highAndes Cordillera, and negative trends at relatively lower elevations both east and west of the Cordillera. Snow precipitationshowed more heterogeneous patterns than air temperature due to the inuence from atmospheric conditions, topography, andorography. Overall, for the Cordillera, much of the area north of 23∘S had a decrease in the number of snow cover days, whilethe southern half experienced the opposite. The snow cover extent changed ∼−15% during the simulation period, mostlybetween the elevations of ∼3000 and 5000 m above sea level (a.s.l.). However, below 1000 m a.s.l. (in Patagonia) the snowcover extent increased. The snow properties varied over short distances both along and across the Andes Cordillera.

Año: 2016

Palabras claves: Andes Cordillera; modelling; NASA MERRA; MODIS; SnowModel; snow; snow classication; South America

Referencia APA: Mernild, S., Liston, G., Hiemstra, C., Malmros, J., Yde, J. and McPhee, J. (2016). The Andes Cordillera. Part I: snow distribution, properties, and trends (1979-2014). International Journal of Climatology, 37(4), pp.1680-1698.

Diversification dynamics, species sorting, and changes in the functional diversity of marine benthic gastropods during the Pliocene-Quaternary at temperate western South America

Autores:

Rivadeneira MM, Nielsen SN

Resumen:

Functional diversity based on species traits is a powerful tool to investigate how changes in species richness and composition affect ecosystem functioning. However, studies aimed at understanding changes in functional diversity over large temporal and spatial scales are still scant. Here we evaluate the combined effect of diversification and species sorting on functional diversity of fossil marine gastropods during the Pliocene-Quaternary transition in the Pacific coast of South America. We analyzed a total of 172 species in 29 Pliocene and 97 Quaternary sites. Each species was characterized according to six functional traits: body size, feeding type, mobility, attachment, life-habit, and larval mode. Functional diversity was estimated according to four indexes (functional richness, evenness, divergence and dispersion) based on functional traits measured. Extrapolated species richness showed a slight yet not significant decrease from the Pliocene to the Quaternary despite the fact that a large faunal turnover took place; furthermore, a large extinction of Pliocene species (61–76%) was followed by a high pulse of appearances (49–56%) during the Quaternary. Three out of four indices of functional diversity (evenness, divergence and dispersion) increased significantly towards the Quaternary which is more than expected under a random turnover of species. The increase in functional diversity is associated with a loss of large-sized carnivore forms, which tended to be replaced by small-sized grazers. Hence, this trait-selective species turnover, even in the absence of significant changes in species richness, likely had a large effect and has shaped the functional diversity of present-day assemblages.

Año: 2017

Palabras claves: Species diversity, Species extinction, Pliocene epoch, Physiological parameters, Gastropods, Biodiversity, Malacology, Marine fossils.

Referencia APA: Rivadeneira MM, Nielsen SN. (2017). Diversification dynamics, species sorting, and changes in the functional diversity of marine benthic gastropods during the Pliocene-Quaternary at temperate western South America. PLoS ONE12(10): e0187140. https://doi.org/10.1371/journal.pone.0187140