Penuelas J., Sardans J., Estiarte M., Ogaya R., Carnicer J., Coll M., Barbeta A., Rivas-Ubach A., Llusia J., Garbulsky M., Filella I., Jump A.S. (2013) Evidence of current impact of climate change on life: A walk from genes to the biosphere. Global Change Biology. 19: 2303-2338.EnllaçDoi: 10.1111/gcb.12143
We review the evidence of how organisms and populations are currently responding to climate change through phenotypic plasticity, genotypic evolution, changes in distribution and, in some cases, local extinction. Organisms alter their gene expression and metabolism to increase the concentrations of several antistress compounds and to change their physiology, phenology, growth and reproduction in response to climate change. Rapid adaptation and microevolution occur at the population level. Together with these phenotypic and genotypic adaptations, the movement of organisms and the turnover of populations can lead to migration toward habitats with better conditions unless hindered by barriers. Both migration and local extinction of populations have occurred. However, many unknowns for all these processes remain. The roles of phenotypic plasticity and genotypic evolution and their possible trade-offs and links with population structure warrant further research. The application of omic techniques to ecological studies will greatly favor this research. It remains poorly understood how climate change will result in asymmetrical responses of species and how it will interact with other increasing global impacts, such as N eutrophication, changes in environmental N : P ratios and species invasion, among many others. The biogeochemical and biophysical feedbacks on climate of all these changes in vegetation are also poorly understood. We here review the evidence of responses to climate change and discuss the perspectives for increasing our knowledge of the interactions between climate change and life. © 2013 John Wiley & Sons Ltd.
Rivas-Ubach A., Perez-Trujillo M., Sardans J., Gargallo-Garriga A., Parella T., Penuelas J. (2013) Ecometabolomics: Optimized NMR-based method. Methods in Ecology and Evolution. 4: 464-473.EnllaçDoi: 10.1111/2041-210X.12028
Metabolomics is allowing great advances in biological sciences. Recently, an increasing number of ecological studies are using a metabolomic approach to answer ecological questions (ecometabolomics). Ecometabolomics is becoming a powerful tool which allows following the responses of the metabolome of an organism environmental changes and the comparison of populations. Some Nuclear Magnetic Resonance (NMR) protocols have been published for metabolomics analyses oriented to other disciplines such as biomedicine, but there is a lack of a description of a detailed protocol applied to ecological studies. Here we propose a NMR-based protocol for ecometabolomic studies that provides an unbiased overview of the metabolome of an organism, including polar and nonpolar metabolites. This protocol is aimed to facilitate the analysis of many samples, as typically required in ecological studies. In addition to NMR fingerprinting, it identifies metabolites for generating metabolic profiles applying strategies of elucidation of small molecules typically used in natural-product research, and allowing the identification of secondary and unknown metabolites. We also provide a detailed description to obtain the numerical data from the 1H-NMR spectra needed to perform the statistical analyses. We tested and optimized this protocol by using two field plant species (Erica multiflora and Quercus ilex) sampled once per season. Both species showed high levels of polar compounds such as sugars and amino acids during the spring, the growing season. E. multiflora was also experimentally submitted to drought and the NMR analyses were sensitive enough to detect some compounds related to the avoidance of water loses. This protocol has been designed for ecometabolomic studies. It identifies changes in the compositions of metabolites between individuals and detects and identifies biological markers associated with environmental changes. © 2013 The Authors. Methods in Ecology and Evolution © 2013 British Ecological Society.
Sardans J., Rivas-Ubach A., Estiarte M., Ogaya R., Penuelas J. (2013) Field-simulated droughts affect elemental leaf stoichiometry in Mediterranean forests and shrublands. Acta Oecologica. 50: 20-31.EnllaçDoi: 10.1016/j.actao.2013.04.002
This study evaluated the change induced by the year season and by experimentally induced drought on foliar element stoichiometry of the predominant woody species (. Quercus ilex and Erica multiflora) in two Mediterranean ecosystems, a forest and a shrubland. This study is based in two long-term (11yr) field experiments that simulated drought throughout the annual cycle.The effects of experimental droughts were significant but weaker than the changes produced by ontogeny and seasonality. Leaf N and P concentrations were higher in spring (the main growing season) in E. multiflora and, in Q.ilex in autumn (a period of additional growth). Leaf N:P ratios were lower in spring. In Q.ilex, the highest leaf K concentrations and leaf K:P ratios, and the lowest leaf C:K and N:K ratios, occurred in summer, the season when water stress was greatest. In E.multiflora, leaf K concentrations and K:P ratios were highest, and leaf C:K and N:K ratios were lowest in the plants from the drought-treated plots.The plant capacity to change K concentrations in response to seasonality and to drought is at least as great as the capacity to change N and P concentrations. The results underscore the importance of K and its stoichiometry relative to C, N and P in dry environments. These results indicate first, that N:P ratio shifts are not uniquely related to growth rate in Mediterranean plants but also to drought, and second, that there is a need to take into account K in ecological stoichiometry studies of terrestrial plants. © 2013 Elsevier Masson SAS.
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