Estudio ecofisiológico de macrolíquenes de bosques de lluvia templados en el centro-sur de Chile

La Cordillera de la Costa de la Región de los Ríos coincide dentro de los centro de mayor biodiversidad y endemismos del mundo (Myers et al., 2000). Además de enmarcarse dentro de los 35 puntos calientes o “hotspots” mundiales de biodiversidad (Mittermeier et al., 2011). Sin embargo,precisamente estas zonas (35° y 41° latitud Sur) sufren la mayor transformación del paisaje debido a la sustitución del bosque nativo por plantaciones forestales y otros usos agrícolas. Esta gestión del hábitat acarrea una pérdida de biodiversidad debido a una alta destrucción por degradación y fragmentación del bosque nativo (Lara et al., 1997), lo que se podrían agravar si consideramos un probable aumento de la temperatura (variable según el tipo de modelo utilizado) y una alteración de la cantidad como también la distribución de las precipitaciones en la zona (CEPAL, 2009; IPCC,2014). El resultado de la combinación de ambos factores es una clara amenaza a los recursos hídricos, y en consecuencia a la vegetación natural, principalmente sobre aquellas que para mantener su metabolismo activo necesitan disponibilidad de agua en el ambiente. En este contexto,se ha planteado en la siguiente tesis doctoral un estudio global que reporte la diversidad, los requerimientos ecológicos y la respuesta fisiológica ante las condiciones ambientales de especies de macrolíquenes en un bosque lluvioso templado de la Cordillera de la Costa en la Región de los Ríos dentro de un área natural protegida..

COMPARACIÓN DE MANEJOS PRATENSES DEL CENTRO-SUR DE CHILE UTILIZANDO VALORES BIOINDICADORES DE ELLENBERG

Ellenberg bioindicators values for European weeds were compared in two prairie managements with cattle and sheep on a volcanic soil of South-Central Chile. It was found that sheep grazing degrades the soil and vegetation cover much more that cattle grazing. These results corresponds to vegetation and soil differences found earlier in a plant sociological study, which found that the differences between both types of grazing established two different plant associations: Hyperico-Agrostietum capülariae (cattle grazing) and Airo-Agrostietum capülariae (sheep grazing). It was confirmed that with different kinds of management is very important the soil physical degradation, specially compactnees, that alters the quantity, size, distribution and orientation of the pores, changing the hydraulic conductivity and the air-water-soil ratio, determining the rooting of grasses. In both prairie is possible to distinguish different level of degradation, which ultimately allow the settlement of secondary shrub associations, such as Aristotelio-Rubetum constrictae (zarzamora scrub) in the cattle pasture. The degradation of the sheep prairie concluded in a not studied Hips Rose bush. The values of biological indicators plant species, show that those microclimate conditions (light and temperature) tend to focus more on small sections of the scale, while those edaphic (reaction, nitrogen and soil moisture) are dispersed throughout the spectrum of indicators values. The indifferent species to the bioindicators increased with favourable conditions but decreased in extreme conditions. Finally it confirms the usefulness of applying the values of Ellenberg bioindicators in the anthropogenic Chilean prairies, plant communities dominated by weeds of European origin, which can capture even small differences in handling, without requiring large investiment of time and money.Se compararon dos manejos pratenses: pastoreo con vacunos y pastoreo con ovejas, en un suelo volcánico, del centro-sur de Chile, con los valores bioindicadores de Ellenberg establecidos para malezas europeas, que forman esas praderas. Se comprobó que el pastoreo con ovinos degrada el suelo y la cubierta vegetal mucho más que el pastoreo con bovinos, lo que se corresponde con las diferencias vegetacionales y edáficas establecidas por un estudio anterior mediante análisis edáficos y fitosociológicos. Con estos últimos se determinó que las diferencias entre ambos tipos de pastoreo establecieron dos asociaciones pratenses diferentes: Hyperico-Agrostietum capülariae (pastoreo de vacunos) y Airo-Agrostietum capülariae (pastoreo de ovejas). Se confirmó que muy importante en el manejo pastoril es la degradación física del suelo, especialmente por compactación, que altera la cantidad, distribución por tamaño y orientación de los poros, cambiando la conductividad hidráulica y la proporción aire-agua-suelo, determinante en el arraigamiento de las hierbas pratenses. En ambos manejos es posible diferenciar distintos estadios de degradación, los que terminan por permitir el asentamiento de asociaciones arbustivas secundarias, tales como Aristotelio-Rubetum constrictae (matorral de zarzamora) en la pradera de vacuno. La degradación de la pradera de ovinos concluye en un matorral de rosa mosqueta no estudiado. Los valores indicadores biológicos por especie, muestran que los microclimáticos (luz y temperatura) tienden a concentrarse más en pocos tramos de la escala, mientras que los edáficos (reacción, nitrógeno y humedad del suelo) se dispersan en todo el espectro de valores indicadores. Las especies indiferentes a los bioindicadores aumentan con condiciones favorables, pero disminuyen en condiciones extremas. Por último, se confirma la utilidad de aplicar los valores bioindicadores de Ellenberg en comunidades vegetales pratenses chilenas dominadas por malezas de origen europeo, los cuales pueden captar incluso pequeñas diferencias en el manejo, sin necesidad de grandes inversiones de tiempo y dinero

Contribution to the knowledge of the lichen biota of Katalalixar National Reserve, Patagonia, Chile

Lichens are recognized as bioindicators of ecosystem processes associated with environmental disturbances. However, its evaluation in the time requires systematic records of biodiversity which are non-existent in the Katalalixar National Reserve. The aim of this study was to catalog the richness and distribution of lichen biota of Katalalixar National Reserve, not only by identifying the species but interpreting them in their ecological and biogeographic context. By random sampling in Nothofagus nitida, Pilgerodendron uviferum forests and peat bogs 70 species were identified, belonging to 32 families and 65 genera. A high number of endemism was found, with 34% of the species endemic to Southern South American and the Chilean endemic Pseudocyphellaria guzmanii constitutes a new record for the Aisen Region

Preliminary study of lichens of the order Peltigerales in the Ecological and Cultural Park Rucamanque in the Araucania Region, Chile

The Rucamanque Park houses some of the remnants of the Roble-Raul(-Coigue mixed forest in Central-South Chile. Cortical lichens were monitored in Renoval and in the Original Remnant Forest of Nothofagus obliqua (Mirb.) Oerst. We found differences in specific richness by tree species and between the Renoval (13 species) and the Original Remnant (7 species). The variables that affect the greatest richness are discussed, suggesting that the structure of the forest may play a key factor

Inhibition of Primary Photosynthesis in Desiccating Antarctic Lichens Differing in Their Photobionts, Thallus Morphology, and Spectral Properties

Five macrolichens of different thallus morphology from Antarctica (King George Island) were used for this ecophysiological study. The effect of thallus desiccation on primary photosynthetic processes was examined. We investigated the lichens' responses to the relative water content (RWC) in their thalli during the transition from a wet (RWC of 100%) to a dry state (RWC of 0%). The slow Kautsky kinetics of chlorophyll fluorescence (ChlF) that was recorded during controlled dehydration (RWC decreased from 100 to 0%) and supplemented with a quenching analysis revealed a polyphasic species-specific response of variable fluorescence. The changes in ChlF at a steady state (Fs), potential and effective quantum yields of photosystem II (F-V/F-M, phi(PSII)), and nonphotochemical quenching (NPQ) reflected a desiccation-induced inhibition of the photosynthetic processes. The dehydration-dependent fall in F-V/F-M and phi(PSII) was species-specific, starting at an RWC range of 22-32%. The critical RWC for phi(PSII) was below 5%. The changes indicated the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts at RWCs of below 20%. In both the wet and dry states, the spectral reflectance curves (SRC) (wavelength 400-800 nm) and indices (NDVI, PRI) of the studied lichen species were measured. Black Himantormia lugubris showed no difference in the SRCs between wet and dry state. Other lichens showed a higher reflectance in the dry state compared to the wet state. The lichen morphology and anatomy data, together with the ChlF and spectral reflectance data, are discussed in relation to its potential for ecophysiological studies in Antarctic lichens

High nitrogen contribution by Gunnera magellanica and nitrogen transfer by mycorrhizas drive an extraordinarily fast primary succession in sub‐Antarctic Chile

Chronosequences at the forefront of retreating glaciers provide information about colonization rates of bare surfaces. In the northern hemisphere, forest development can take centuries, with rates often limited by low nutrient availability. By contrast, in front of the retreating Pia Glacier (Tierra del Fuego, Chile), a Nothofagus forest is in place after only 34 yr of development, while total soil nitrogen (N) increased from near zero to 1.5%, suggesting a strong input of this nutrient. We measured N-fixation rates, carbon fluxes, leaf N and phosphorus contents and leaf δ15N in the dominant plants, including the herb Gunnera magellanica, which is endosymbiotically associated with a cyanobacterium, in order to investigate the role of N-fixing and mycorrhizal symbionts in N-budgets during successional transition. G. magellanica presented some of the highest nitrogenase activities yet reported (potential maximal contribution of 300 kg N ha−1 yr−1). Foliar δ15N results support the framework of a highly efficient N-uptake and transfer system based on mycorrhizas, with c. 80% of N taken up by the mycorrhizas potentially transferred to the host plant. Our results suggest the symbiosis of G. magellanica with cyanobacteria, and trees and shrubs with mycorrhizas, to be the key processes driving this rapid successioncyanobacteriaMinisterio de Economía y Competitividad, Gobierno de EspañaDepto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu

<i>STAT4</i> Gene Variant <i>rs7574865</i> Is Associated with Rheumatoid Arthritis Activity and Anti-CCP Levels in the Western but Not in the Southern Population of Mexico

Rheumatoid Arthritis (RA) is a multifactorial autoimmune disease. Currently, several genes play an important role in the development of the disease. The objective was to evaluate the association of the STAT4 rs7574865 and rs897200 gene variants with RA susceptibility, DAS28, RF, and anti-CCP in Western and Southern Mexico populations. Genotyping was performed on 476 samples (cases = 240; controls = 236) using the Taqman® system and qPCR probes. Disease activity was assessed using DAS28 and HAQ DI. CRP, ESR, RF, and anti-CCP were determined for clinical assessment. Our study showed there is a statistically significant association with susceptibility to RA for the rs7574865 variant in the Western population for the GT and TT genotypes. The same genotypes also showed a moderate-to-high activity according to DAS28 and positive anti-CCP compared to the control group. This association was not found in the Southern population. This work confirms the association of the rs7574865 variant with RA, as well as a moderate-to-high activity and positive anti-CCP in the Western population but not in the Southern population. No association of the rs897200 variant was found in any of the studied populations