Fungal Endophytes Enhance the Photoprotective Mechanisms and Photochemical Efficiency in the Antarctic Colobanthus quitensis (Kunth) Bartl. Exposed to UV-B Radiation

Autores:

Barrera, A., Hereme, R., Ruiz-Lara, S., Larrondo, L.F., Gundel, P.E., Pollmann, S., Molina-Montenegro, M.A., and Ramos, P.

Resumen:

Antarctic plants have developed mechanisms to deal with one or more adverse factors which allow them to successfully survive such extreme environment. Certain effective mechanisms to face adverse stress factors can arise from the establishment of functional symbiosis with endophytic fungi. In this work, we explored the role of fungal endophytes on host plant performance under high level of UV-B radiation, a harmful factor known to damage structure and function of cell components. In order to unveil the underlying mechanisms, we characterized the expression of genes associated to UV-B photoreception, accumulation of key flavonoids, and physiological responses of Colobanthus quitensis plants with (E+) and without (E−) fungal endophytes, under contrasting levels of UV-B radiation. The deduced proteins of CqUVR8, CqHY5, and CqFLS share the characteristic domains and display high degrees of similarity with other corresponding proteins in plants. Endophyte symbiotic plants showed lower lipid peroxidation and higher photosynthesis efficiency under high UV-B radiation. In comparison with E−, E+ plants showed lower CqUVR8, CqHY5, and CqFLS transcript levels. The content of quercetin, a ROS-scavenger flavonoid, in leaves of E- plants exposed to high UV-B was almost 8-fold higher than that in E+ plants 48 h after treatment. Our results suggest that endophyte fungi minimize cell damage and boost physiological performance in the Antarctic plants increasing the tolerance to UV-B radiation. Fungal endophytes appear as fundamental biological partners for plants to cope with the highly damaging UV-B radiation of Antarctica.

Año: 2020

Palabras claves: UV-B stress, Antarctica, Colobanthus quitensis, molecular response, flavonols, fungal endophytes

Novel co‐occurrence of functionally redundant consumers induced by range expansion alters community structure

Autores:

Aguilera, M. A., Valdivia, N., Broitman, B. R., Jenkins, S. R., and Navarrete, S. A..

Resumen:

Ongoing climate change is shifting the geographic distributions of some species, potentially imposing rapid changes in local community structure and ecosystem functioning. Besides changes in population‐level interspecific interactions, such range shifts may also cause changes in functional structure within the host assemblages, which can result in losses or gains in ecosystem functions. Because consumer‐resource dynamics are central to community regulation, functional reorganization driven by introduction of new consumer species can have large consequences on ecosystem functions. Here we experimentally examine the extent to which the recent poleward range expansion of the intertidal grazer limpet Scurria viridula along the coast of Chile has altered the role of the resident congeneric limpet S. zebrina, and whether the net collective impacts, and functional structure, of the entire herbivore guild have been modified by the introduction of this new member. We examined the functional role of Scurria species in controlling ephemeral algal cover, bare rock availability, and species richness and diversity, and compared the effects in the region of range overlap against their respective “native” abutted ranges. Experiments showed depression of per capita effects of the range‐expanded species within the region of overlap, suggesting environmental conditions negatively affect individual performance. In contrast, effects of S. zebrina were commonly invariant at its range edge. When comparing single species versus polycultures, effects on bare rock cover were altered by the presence of the other Scurria species, suggesting competition between Scurria species. Importantly, although the magnitude of S. viridula effects at the range overlap was reduced, its addition to the herbivore guild seems to complement and intensify the role of the guild in reducing green algal cover, species richness and increasing bare space provision. Our study thus highlights that range expansion of an herbivore can modify the functional guild structure in the recipient community. It also highlights the complexity of predicting how functional structure may change in the face of natural or human‐induced range expansions. There is a need for more field‐based examination of regional functional compensation, complementarity, or inhibition before we can construct a conceptual framework to anticipate the consequences of species range expansions.

Año: 2020

Palabras claves: Animal–plant interaction strength, biogeographic transition zone, functional diversity, functional role, guild, range overlap, regional compensation

Root endophytic Penicillium promotes growth of Antarctic vascular plants by enhancing nitrogen mineralization

Autores:

Oses-Pedraza, R., Torres-Díaz, C., Lavín, P., Retamales-Molina, P., Atala, C., Gallardo-Cerda, J., Acuña-Rodríguez, I.S., & Molina-Montenegro, M.A.

Resumen:

Fungal endophyte associations have been suggested as a possible strategy of Antarctic vascular plants for surviving the extreme environmental conditions of Antarctica. However, the mechanisms by which this occurs are still poorly understood. The role of root fungal endophytes in nitrogen mineralization and nutrient uptake, as well as their impact on the performance of Antarctic plants, were studied. We tested root endophytes, isolated from Colobanthus quitensis and Deschampsia antarctica, for lignocellulolytic enzyme production, nitrogen mineralization, and growth enhancement of their host plants. Penicillium chrysogenum and Penicillium brevicompactum were identified using a molecular approach as the main root endophytes inhabiting C. quitensis and D. antarctica, respectively. Both root endophytes were characterized as psychrophilic fungi displaying amylase, esterase, protease, cellulase, hemicellulase, phosphatase and urease enzymatic activities, mainly at 4 °C. Moreover, the rates and percentages of nitrogen mineralization, as well as the final total biomass, were significantly higher in symbiotic C. quitensis and D. antarctica individuals. Our findings suggest that root endophytes exert a pivotal ecological role based not only to breakdown different nutrient sources but also on accelerating nitrogen mineralization, improving nutrient acquisition, and therefore promoting plant growth in Antarctic terrestrial ecosystems.

Año: 2020

Palabras claves: Endophytes, Antarctic vascular plants, Penicillium, Growth, Nitrogen, Mineralization

Effect of predation risk and ectoparasitic louse flies on physiological stress condition of the red-tailed tropicbird (Phaethon rubricauda) from Rapa Nui and Salas & Gómez islands

Autores:

Luna, N., Varela​, A.I., Luna-Jorquera, G., Brokordt, K.

Resumen:

Introduced predators at seabird colonies and parasites may have lethal and/or sub-lethal consequences for bird populations. We assessed the potential sub-lethal negative effects of these stressors in a native seabird listed as vulnerable in its south-eastern pacific distribution. This study was conducted in two red-tailed tropicbird (Phaethon rubricauda) colonies, one located in Rapa Nui Island, which is threatened by the presence of introduced predators, and the other located in Salas & Gómez Island, which has no introduced predators, but birds are infested by ectoparasitic louse flies.

Año: 2020

Palabras claves: Introduced predators, Ectoparasitic blood feeders, Sub-lethal effects, Leukocytes, H/L ratio, HSP70, Body condition, Native seabird, oceanic islands, Easter Island ecoregion

Mathematical modeling and quality parameters of Salicornia fruticosa dried by convective drying

Autores:

Rodríguez-Ramos, F., Leiva-Portilla, D., Rodríguez-Núñez, K., Pacheco, P., Briones-Labarca, V.

Resumen:

The effect of convective drying at 50, 60 and 70 °C on the drying kinetics and quality parameters of Salicornia fruticosa was investigated. To estimate the equilibrium moisture content a desorption isotherm was performed using five empirical models: Halsey, Caurie, Henderson, Smith and Oswin. The experimental data was also fitted to different drying kinetic models (Logarithmic, Two-Terms, Midilli–Kucuk and Exponential Two-Terms). A numerical simulation using the Finite Volume Method allowed us to describe the evolution of temperature and moisture content distributions during drying. The Henderson model was found to be the most suitable for predicting the equilibrium moisture content of S. fruticosa, with values of Xwe in the drying process of 1.51; 1.54 and 1.36 g water/g d.m for 50, 60 and 70 °C, respectively. A good agreement was found between the numerical and experimental results of temperature and moisture during Salicornia drying. The Midilli–Kucuk model presented the best fitting to the drying curves. The effects of drying on S. fruticosa were significant in two quality parameters. Antioxidant capacity decreased in ca. 45% and lightness (> L*) significantly increased at a drying temperature of 70 °C, compared to the fresh samples. The optimum drying temperature where drying time and nutrients loss was minimum was 70 °C. These results can be used to estimate the best drying conditions for producing dehydrated Salicornia. The use of halophytes as sustainable crops is promising, and the vision of their commercial production must be evaluated and considered, given water scarcity in many areas of the planet.

Año: 2020

Palabras claves: Salicornia fruticosa, Hot air drying, Drying kinetics, Mathematical modeling

Foraging ecology of masked boobies (Sula dactylatra) in the world’s largest “oceanic desert”

Autores:

Lerma, M., Serratosa, J., Luna-Jorquera, G., Garthe, S.

Resumen:

The South Pacific Gyre has the most hyper-oligotrophic waters in the world and is considered the largest “oceanic desert.” Rapa Nui (Easter Island), located within the South Pacific Gyre, is a breeding ground for masked boobies (Sula dactylatra), which are seabirds with a foraging range that effectively confines them within the gyre. The foraging ecology of this species in the gyre was examined by attaching GPS and time-depth devices to chick-rearing adult birds (9 and 14 birds in 2016 and 2017, respectively) and by collecting regurgitates (18 and 15 samples in 2016 and 2017, respectively). In addition, the birds’ foraging ecology between years was compared. Masked boobies traveled in various directions, dived at unspecific locations, and explored areas < 110 km from the colony. Local environmental conditions were not significantly different between years, and differences in foraging parameters (maximum foraging range, trip duration, and dive depth) were greater among individuals than between years. The foraging characteristics of masked boobies suggest that resources were ephemerally distributed around the colony, with similar abundances across years. Under these conditions, traveling to unspecific locations may increase the area covered and the probability of prey encounter. The spatial and temporal consistencies in environmental conditions explain the uniformity of foraging parameters between years. The ability of masked boobies to exploit ephemerally distributed resources in seascapes like Rapa Nui may help explain its pantropical distribution.

Año: 2020

Palabras claves:

Streamflow elasticity, in a context of climate change, in arid Andean watersheds of north-central Chile

Autores:

Barrera, C., Núñez Cobo, J., Souvignet, M., Oyarzún, J., & Oyarzún, R.

Resumen:

Based on a future temperature increase of 0.5°C and precipitation decrease of 25%, the climate elasticity of streamflow to precipitation and temperature changes in 12 Andean watersheds of the Coquimbo Region, north-central Chile, was assessed. Also, the possible relationships between this elasticity and specific physiographic characteristics of the watersheds (area, average elevation, slope distribution, terrain roughness, slope orientation, vegetation cover) were studied. Climate elasticity of streamflow ranged between 0 and 2.8. Watersheds presenting higher elevations, with a fairly well-balanced distribution of slope exposure tend to exhibit lower elasticity, which could be explained by the contribution of snowfall to the hydrological regime, more significant in those watersheds. Results should be considered when downscaling climate model projections at the basin scale in mountain settings. Finally, uncertainties in the approach, given by factors such as streamflow seasonality, data availability and representativeness and watershed characteristics, and therefore the scope of the results, are discussed.

Año: 2020

Palabras claves: Streamflow elasticity, arid zone, Andes Mountains, climate change resilience

Taguatagua 1: New insights into the late Pleistocene fauna, paleoenvironment, and human subsistence in a unique lacustrine context in central Chile

Autores:

Labarca, R., González-Guarda, E., Lizama-Catalán, A., Villavicencio, N.A., Alarcón-Muñoz, J., Suazo-Lara, F., Oyanadel-Urbina, P., Soto-Huenchuman, P., Salazar, C., Soto-Acuña, S., Buldrini, K.E.

Resumen:


The Laguna de Tagua Tagua has yielded two important late Pleistocene archaeological sites, Taguatagua 1 and Taguatagua 2, in which a clear early human exploitation of megafauna has been recorded. Particularly in Taguatagua 1 (TT-1), here re-dated around 12,600 cal yr BP, an abundant small faunal assemblage was also recovered, which had not been previously studied in detail. Here we report the first comprehensive taxonomic and taphonomic analysis of this site. We identified 28 different taxa, including mollusks, fish, anurans, reptiles, birds, marsupials, rodents, carnivores, gomphotheres, horses and cervids, making this the richest late Pleistocene site in Chile so far. Among these, sixteen taxa are new for the Chilean late Pleistocene. Birds are the richest group, with ten taxa, followed by rodents with eight taxa. Most of the species currently inhabit the area, but we identified some locally extirpated taxa, together with extinct taxa (exclusively megamammals). Taphonomic analysis suggests a very complex depositional scenario, mostly related to lake-level oscillations which covered and exposed a mainly natural deposited small faunal assemblage. So far, we detected human-made modifications exclusively in horse and cervid bones. Current habitat requirements of the extant fauna, as well as dietary reconstruction of extinct fauna, suggest a highly variable climate and vegetation during the formation of TT-1 since taxa with preferences from semiarid to humid/wooded environments were identified. These results can be related to the changes from cold/wet to dry/warm conditions documented during the Pleistocene - Holocene transition.

Año: 2020

Palabras claves: Pleistocene, South America, Megafauna, Small fauna, Taphonomy, Paleoenvironment

Socio-environmental conflicts: An underestimated threat to biodiversity conservation in Chile

Autores:

Carranza, D.M., Varas-Belemmi, K., De Veer, D., Iglesias-Müller, C., Coral-Santacruz, D., Méndez, F.A., Torres-Lagos, E., Squeo, F.A., Gaymer, C.F.

Resumen:

Biodiversity is vital in the functioning of ecosystems, but it’s permanently being threatened by anthropic impacts derived from productive activities. Thus, conservation has become a global challenge. In Chile, the dissociation between economic activities and conservation has triggered numerous socio-environmental conflicts in recent decades. This work explores how different projects that give rise to these conflicts can represent an underestimated threat to biodiversity.

We identified socio-environmental conflicts in Chile and their associated projects by carrying out an online review of 1035 news articles published between 2004 and 2018 using the key words “environmental conflict”. We selected articles describing a socio-environmental conflict between parties caused by a project or productive sector. Conflict-generating projects were classified by productive sector and capital origin. In addition, their geographical distribution with respect to High Conservation Value Areas (HCVAs, protected areas and priority sites for conservation) was determined.

A total of 283 projects were identified from 14 different productive sectors, most of them related to energy and mining, which threaten biodiversity and human well-being mainly due to pollution and habitat destruction. Chilean companies finance most of the projects, but international companies finance over half of the energy and mining projects. Moreover, 37 % of the projects were located within HCVAs either for the establishment of future protected areas or where protected areas are currently established. As countries make new efforts to maintain and recover biodiversity, it is contradictory not to consider the threats posed by conflict-generating projects to key areas for conservation, both in public policies and in spatial planning instruments.

Año: 2020

Palabras claves: Threat to biodiversity, Socio-environmental conflict, Conflict-generating project, High Conservation Value Areas, Public policies

Geographic Variation of UV Stress Tolerance in Red Seaweeds Does Not Scale with Latitude Along the SE Pacific Coast

Autores:

Véliz, K., Chandía, N., Bischof, K., Thiel, M.

Resumen:

Geographic variation of phenotypic traits affects the capacity of species to withstand and adapt to environmental stress. Here, we examined how geographic origin influences UV stress tolerance of the red seaweeds Chondracanthus chamissoi and Gelidium lingulatum distributed along the South‐East Pacific coast between 20° S and 42° S. Seaweeds from six (C. chamissoi) and five (G. lingulatum) populations were grown under common‐garden conditions and then exposed to consecutive UV stress events and essential biological traits (e.g., growth, photosynthetic responses, antioxidant capacity, and UV‐absorbing compounds) were analyzed. In C. chamissoi, a strong UV sensitivity occurred in populations from mid‐latitudes (27° S and 29° S) where the lowest recovery of maximum quantum yield (Fv/Fm; between 32.3% and 66.8% of control) and growth rate were observed. Likewise, the lowest amount of mycosporine‐like amino acids (MAAs) and a significant decrease in phycobilins were registered in these populations. In G. lingulatum, recovery of Fv/Fm ranged from 82.0% to 97.7% of control, and antioxidant activity, carotenoid, and MAA contents were positively influenced by UV exposure. The multivariate analysis indicated a significant influence of PAR, cloud cover, and UV index on physiological traits, depending on species. The ecotypic differentiation index (EDI) indicated a higher phenotypic variation in C. chamissoi (EDI = 0.10) than G. lingulatum (EDI = 0.03). This study shows that the spatial distribution of UV stress tolerance in the studied seaweeds does not follow linear latitudinal or central–edge gradients. Instead, among‐site variability of solar intensities driven by specific climatic conditions seems to act as driver of phenotypic variation.

Año: 2020

Palabras claves: Ecotypic, differentiation, latitudinal gradient, photoinhibition, seaweeds, ultraviolet radiation