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Ersoz E.S.,University of California at Davis | Ersoz E.S.,Syngenta Biotechnology | Wright M.H.,Cornell University | Gonzalez-Martinez S.C.,University of California at Davis | And 4 more authors.
PLoS ONE | Year: 2010

Background: Host-pathogen interactions that may lead to a competitive co-evolution of virulence and resistance mechanisms present an attractive system to study molecular evolution because strong, recent (or even current) selective pressure is expected at many genomic loci. However, it is unclear whether these selective forces would act to preserve existing diversity, promote novel diversity, or reduce linked neutral diversity during rapid fixation of advantageous alleles. In plants, the lack of adaptive immunity places a larger burden on genetic diversity to ensure survival of plant populations. This burden is even greater if the generation time of the plant is much longer than the generation time of the pathogen. Methodology/Principal Findings: Here, we present nucleotide polymorphism and substitution data for 41 candidate genes from the long-lived forest tree loblolly pine, selected primarily for their prospective influences on host-pathogen interactions. This dataset is analyzed together with 15 drought-tolerance and 13 wood-quality genes from previous studies. A wide range of neutrality tests were performed and tested against expectations from realistic demographic models. Conclusions/Significance: Collectively, our analyses found that axr (auxin response factor), caf1 (chromatin assembly factor) and gatabp1 (gata binding protein 1) candidate genes carry patterns consistent with directional selection and erd3 (early response to drought 3) displays patterns suggestive of a selective sweep, both of which are consistent with the arm-race model of disease response evolution. Furthermore, we have identified patterns consistent with diversifying selection at erf1- like (ethylene responsive factor 1), ccoaoemt (caffeoyl-CoA-O-methyltransferase), cyp450-like (cytochrome p450-like) and pr4.3 (pathogen response 4.3), expected under the trench-warfare evolution model. Finally, a drought-tolerance candidate related to the plant cell wall, lp5, displayed patterns consistent with balancing selection. In conclusion, both arms-race and trenchwarfare models seem compatible with patterns of polymorphism found in different disease-response candidate genes, indicating a mixed strategy of disease tolerance evolution for loblolly pine, a major tree crop in southeastern United States.

Ruiz-Benito P.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Ruiz-Benito P.,University of Alcalá | Ruiz-Benito P.,University of Cambridge | Lines E.R.,University of Cambridge | And 4 more authors.
PLoS ONE | Year: 2013

Tree mortality is a key process underlying forest dynamics and community assembly. Understanding how tree mortality is driven by simultaneous drivers is needed to evaluate potential effects of climate change on forest composition. Using repeat-measure information from c. 400,000 trees from the Spanish Forest Inventory, we quantified the relative importance of tree size, competition, climate and edaphic conditions on tree mortality of 11 species, and explored the combined effect of climate and competition. Tree mortality was affected by all of these multiple drivers, especially tree size and asymmetric competition, and strong interactions between climate and competition were found. All species showed L-shaped mortality patterns (i.e. showed decreasing mortality with tree size), but pines were more sensitive to asymmetric competition than broadleaved species. Among climatic variables, the negative effect of temperature on tree mortality was much larger than the effect of precipitation. Moreover, the effect of climate (mean annual temperature and annual precipitation) on tree mortality was aggravated at high competition levels for all species, but especially for broadleaved species. The significant interaction between climate and competition on tree mortality indicated that global change in Mediterranean regions, causing hotter and drier conditions and denser stands, could lead to profound effects on forest structure and composition. Therefore, to evaluate the potential effects of climatic change on tree mortality, forest structure must be considered, since two systems of similar composition but different structure could radically differ in their response to climatic conditions. © 2013 Ruiz-Benito et al.

Moreno-de las Heras M.,University of Newcastle | Diaz-Sierra R.,Spanish University for Distance Education (UNED) | Nicolau J.M.,University of Zaragoza | Zavala M.A.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Zavala M.A.,University of Alcalá
Earth Surface Processes and Landforms | Year: 2011

The management of reclaimed slopes derived from industrial and civil activities (e.g. surface mining and road construction) requires the development of practical stability analysis approaches that integrate the processes and mechanisms that rule the dynamics of these ubiquitous emerging ecosystems. This work describes a new modelling approach focused on stability analysis of water-limited reclaimed slopes, where interactive relationships between rill erosion and vegetation regulate ecosystem stability. Our framework reproduces two main groups of possible trends along the temporal evolution of reclaimed slopes: successful trends, characterized by widespread vegetation development and the effective control of rill erosion processes; and gullying trends, characterized by the progressive loss of vegetation and a sharp logistic increase in erosion rates. Furthermore, this analytical approach allows the determination of threshold values for the state variables (i.e. vegetation cover and rill erosion) that drive the system's stability, facilitating the identification of critical situations that require specific human intervention (e.g. revegetation or, in very problematic cases, revegetation combined with rill network destruction) to ensure the long-term sustainability of the restored ecosystem. The application of our threshold analysis framework in Mediterranean-dry reclaimed slopes derived from surface coal mining (the Teruel coalfield in central-eastern Spain) showed a good field-based performance. Therefore, we believe that this model is a valuable contribution for the management of water-limited reclaimed systems, including those associated with rill erosion, as it provides a tool for the evaluation of restoration success and can play an important role in decision-making during ecosystem restoration in severely disturbed landscapes. © 2011 John Wiley & Sons, Ltd.

Madrigal J.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Guijarro M.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Hernando C.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Diez C.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia | Marino E.,Instituto Nacional Of Investigacion Y Tecnologia Agraria Y Alimentaria Cifor Inia
Journal of Fire Sciences | Year: 2011

Experimental tests were carried out with an adapted bench-scale mass loss calorimeter (MLC) and also in an outdoor wind tunnel to estimate the heat release rate (HRR) of a forest fuel bed. The MLC apparatus uses a calibrated thermopile to quantify the HRR, as an alternative to the classical measurement of oxygen consumption due to combustion. Additional calibration of thermocouples to measure gas temperatures enabled estimation of HRR in experimental burnings conducted in the wind tunnel. The results showed a reasonable agreement between peak HRR (PHRR) values obtained in the MLC and in the wind tunnel, and also demonstrated that PHRR was significantly affected by the wind speed and the rate of spread. The proposed procedure is potentially useful as an initial step in monitoring HRR in outdoor forest fire experiments. © The Author(s), 2011.

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