Publication: Fotosíntesis, crecimiento y resistencia a ambientes extremos en líquenes de regiones polares y alpinas.
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2013-10-02
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Universidad Complutense de Madrid
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Abstract
Los líquenes dominan alrededor de un 8% de los ecosistemas terrestres, siendo especialmente representativos en regiones polares y alpinas. Ambas regiones están consideradas como zonas de riesgo en posibles futuros escenarios de cambio ambiental, por lo que existe un creciente interés en entender los mecanismos que regulan la presencia de estos organismos en dichos ecosistemas. Esta tesis doctoral utiliza la fotosíntesis como hilo conductor para, a lo largo de cinco capítulos, aclarar las relaciones entre metabolismo y crecimiento y tratar de acotar la capacidad de resistencia de estos organismos a condiciones ambientales extremas. Los capítulos I, II, III y IV abordan sobre todo el primer aspecto, aportando información novedosa. Se incluyen relaciones entre biotipo y metabolismo en distintos líquenes alpinos, y se refuerza el uso de la liquenometría desde el punto de vista fisiológico, ya que no se han encontrado relaciones entre tamaño de talo y fotosíntesis en el género alpino Rhizocarpon. Los capítulos III y IV pasan de las regiones alpinas a las polares, con un estudio ecofisiológico global del género Placopsis en Tierra de Fuego y una comparativa de actividad metabólica y microclima entre distintas especies en dos extremos climáticos del continente antártico. Dicha comparativa explica las diferencias en tasas de crecimiento, biomasa y cobertura entre ambos lugares. El segundo objetivo, los límites de la resistencia de los líquenes a ambientes extremos, se aborda a lo largo de toda la memoria, pero especialmente en los capítulos IV y V. En ellos se explican los mecanismos de resistencia de dos especies distintas de líquenes a un desierto polar en la Antártida continental y se explican los resultados de la exposición real a condiciones espaciales del liquen Circinaria gyrosa. Los resultados demuestran que los límites de la capacidad de resistencia de los líquenes a condiciones extremas aún no han sido establecidos.
Lichens are the most important organisms in the 8% of the terrestrial ecosystems, being especially relevant in polar and alpine regions. Both regions are considered under risk in possible future climate change scenarios and there is a rising interest in understanding the mechanisms controlling the distribution of these organisms in such ecosystems. This work uses photosynthesis as the main driver to clarify the relationships between growth and metabolism and to try to establish a limit for the resistance of lichens to extreme environments. The chapters I, II, III and IV are focused mainly in the first objective, showing new information about it. Relationships between biotype and metabolism are included in different alpine lichens, and the use of lichenometry is reinforced from a physiological perspective because no links have been found between photosynthesis and thallus size in the alpine crustose genus Rhizocarpon. The chapters III and IV change from alpine to polar regions, with a general ecophysiological study of the crustose tripartite genus Placopsis in Tierra de Fuego and a comparison of physiological and microclimatic activity of different lichen species between two climatic extremes in Antarctica. The second objective, the limits of the resistance to extreme environments, is studied trough the whole work but is present mainly in chapters IV and V. The resistance mechanisms of two different species in a Polar Desert in Contienetal Anatrctica are explained, and the resistance of the lichen Circinaria gyrosa to real space conditions is evaluated. The results show that the limits of the resistance of lichens to extreme environmental conditions are still open.
Lichens are the most important organisms in the 8% of the terrestrial ecosystems, being especially relevant in polar and alpine regions. Both regions are considered under risk in possible future climate change scenarios and there is a rising interest in understanding the mechanisms controlling the distribution of these organisms in such ecosystems. This work uses photosynthesis as the main driver to clarify the relationships between growth and metabolism and to try to establish a limit for the resistance of lichens to extreme environments. The chapters I, II, III and IV are focused mainly in the first objective, showing new information about it. Relationships between biotype and metabolism are included in different alpine lichens, and the use of lichenometry is reinforced from a physiological perspective because no links have been found between photosynthesis and thallus size in the alpine crustose genus Rhizocarpon. The chapters III and IV change from alpine to polar regions, with a general ecophysiological study of the crustose tripartite genus Placopsis in Tierra de Fuego and a comparison of physiological and microclimatic activity of different lichen species between two climatic extremes in Antarctica. The second objective, the limits of the resistance to extreme environments, is studied trough the whole work but is present mainly in chapters IV and V. The resistance mechanisms of two different species in a Polar Desert in Contienetal Anatrctica are explained, and the resistance of the lichen Circinaria gyrosa to real space conditions is evaluated. The results show that the limits of the resistance of lichens to extreme environmental conditions are still open.
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Farmacia, Departamento de Biología Vegetal II, leída el 20/06/2013