Recursos de colección

Archivo Digital UPM (106.784 recursos)

This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Biología

Mostrando recursos 1 - 20 de 801

  1. Impacto del cambio climático sobre los ecosistemas fluviales

    Santiago Saez, Jose Maria
    La temperatura del agua es de interés central en ecología del medio fluvial, ya que esta influye sobre los procesos físicos, químicos y biológicos que se producen en los ríos y, consecuentemente, sobre los organismos que en ellos desarrollan su vida o parte de ella. El régimen térmico de los ríos es un factor de gran importancia en la definición y determinación del estado de los ecosistemas acuáticos, teniendo una gran influencia en el éxito biológico de los peces. La temperatura atmosférica ha registrado una tendencia ascendente durante el pasado siglo XX, siendo especialmente patente esta tendencia desde la década...

  2. New patterns in human biogeography revealed by networks of contacts between linguistic groups

    Capitán Gómez, José Ángel; Axelsen, Jakob Bock; Manrubia, Susanna
    Human languages differ broadly in abundance and are distributed highly unevenly on the Earth. In many qualitative and quantitative aspects, they strongly resemble biodiversity distributions. An intriguing and previously unexplored issue is the architecture of the neighbouring relationships between human linguistic groups. Here we construct and characterize these networks of contacts and show that they represent a new kind of spatial network with uncommon structural properties. Remarkably, language networks share a meaningful property with food webs: both are quasi-interval graphs. In food webs, intervality is linked to the existence of a niche space of low dimensionality; in language networks, we...

  3. Effects of Previous Land-Use on Plant Species Composition and Diversity in Mediterranean Forests.

    Kouba, Yacine; Martinez Garcia, Felipe; Frutos, Angel de; Alados, Concepcion
    Se estudia el efecto del aprovechamiento tradicionales en bosque de quejidos en el prepirineo aragonés sobre la composición y diversidad de especies en la actualidad.Bosque

  4. Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling.

    López Rodríguez, Rosa Ana; Brossa, Ricard; Gil Sanchez, Luis Alfonso; Pita Andreu, Pilar
    The photosynthesis source-sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of abscisic acid found in buds which pointed to...

  5. Stream flow regime, temperature and climate change: the loss of fish habitat

    Santiago Saez, Jose Maria; Solana Gutierrez, Joaquin; Alonso González, Carlos; García de Jalón Lastra, Diego; Muñoz-Mas, Rafael; Martínez-Capel, Francisco; Ribalaygua Batalla, Jaime; Pórtoles, Javier; Monjo, Robert
    This study is aimed at forecasting the changes in the suitability of brown trout habitat (Salmo trutta L.), caused by alterations in the stream temperature and the flow regime under climate change scenarios. The stream temperature and instantaneous flow in several streams in Central Spain were modelled from daily temperature and precipitation data. Logistic models were used for stream temperature modelling whereas M5? model trees were used to develop the precipitation-runoff models. These models were utilized to simulate the running flows under the climate change scenarios RCP4.5 and RCP8.5 (5thIPCC). The resulting forecasts suggested a different response of the stream...

  6. A study of seed micromorphology in the genus Ophrys (Orchidaceae)

    Galán Cela, Pablo; Seligrat, Irene; Ortuñez, Emma; Gamarra, Roberto; Vivar Sanz, Alejandro; Scrugli, Antonio
    Seed micromorphology of 19 taxa of the genus Ophrys have been studied using SEM and light microscope. Quantitative data (length and width of seed and embryo, number of testa cells along the longitudinal axis, volume of seed and embryo, and percentage of free air space), as well as qualitative characters (seed shape, features of the anticlinal and periclinal walls, ornamentation and colour) were analysed. All the seeds are fusiform, with an asymmetrical basal pole, the periclinal walls of the medial cells have parallel and transverse to slanting ridges, and raised anticlinal walls. Statistical analyses show two large clusters according to the...

  7. How similar can co-occurring species be in the presence of competition and ecological drift?

    Capitán Gómez, José Ángel; Cuenda, Sara; Alonso Giménez, David
    If two species live on a single resource, the one with a slight advantage will out-compete the other: complete competitors cannot coexist. This is known as the competitive exclusion principle. If no extinction occurs, it is because evolutionary adaptation to slightly different niches takes place. Therefore, it is widely accepted that ecological communities are assembled by evolutionary differentiation and progressive adaptation of species to different niches. However, some ecologists have recently challenged this classic paradigm highlighting the importance of chance and stochasticity. Using a synthetic framework for community dynamics, here we show that, while deterministic descriptors predict coexistence, species similarity...

  8. Linum flos-carmini (Linaceae), a new species from northern Morocco

    Ruiz-Martínez, José; Jiménez-Mejías, Pedro; Martinez Labarga, Juan Manuel; Pérez-Barrales, Rocio
    Linum bicolor is a problematic North African taxon associated with L. setaceum. A consensus on the taxonomic status of a putative form (L. setaceum var. bicolor f. robusta) has not been achieved yet. We conducted a morphological study based on herbarium and field collections, combined with nuclear (ITS) and plastid (ndhF5-8 and trnL-F) phylogenies to clarify its status. The phylogenetic analysis did not reveal molecular divergence, but a comparative morphological study revealed substantial differences in traits previously used to distinguish the two taxa (stems, leaves, corolla and calyx size). In addition, we found that the indumentum of sepals, petal colour,...

  9. Engineering nitrogen-fixing plants: multigene transfer, targeting of expression to organelles and tissues, and other challenges

    Caro Bernat, Elena
    Biological N2 fixation, catalyzed by the prokaryotic enzyme nitrogenase, is an alternative to the use of synthetic N fertilizers to increase cereal production yields. The strategy we are pursuing in an effort to increase cereal crops productivity is the direct transfer of nif prokaryotic genes into cereals. Because Nitrogenase is an O2-labile metalloenzyme which biosynthesis requires a complex pathway where numerous nif gene products are involved, the main challenges we face are the control of gene expression and protein accumulation in an O2 depleted environment and the stable and high expression of multiple transgenes. Our efforts are now focused on...

  10. Population genomics of the legume plant host specific selection of rhizobial genotypes

    Jorrin Rubio, Beatriz; Imperial Ródenas, Juan
    Rhizobium leguminosarum bv. viciae (Rlv) establish effective symbioses with four legume genera: Pisum, Lens, Lathyrus and Vicia. Classic studies using trap plants provided evidence that, given a choice, specific hosts select specific genotypes of rhizobia which are, apparently, particularly adapted to that host (Mutch & Young, 2004; Louvrier et al, 1996). OBJETIVE Pooled DNA samples from Rlv nodule isolates obtained from different legume plant hosts used as rhizobial traps should allow a test of the hypothesis that different plant hosts select specific subpopulations of rhizobia from the available population present in a given soil. MATERIALS AND METHODS We have applied...

  11. Role of poplar DNA demethylases in controlling winter dormancy

    Conde Rodriguez, Daniel; Moreno Cortés, Alicia; Hernández Verdeja, Tamara; Ramos Sanchez, Jose Manuel; Perales, Mariano; González Melendi, Pablo; Allona Alberich, Isabel Marta
    Trees have developed the mechanism of winter dormancy to survive the harsh conditions of winter in temperate and cold regions. It determines the geographical distribution of tree species and the long of the growing period. Epigenetic control of winter dormancy in woody plants is barely known. 5-methyl cytosine (5mC) is an important epigenetic mark that regulates gene expression in animals and plants. The profile of DNA methylation changes in the transition of developmental stages in plants such as chestnut bud set and burst, flowering in azalea, aging in pine trees among other. So far, the enzymes involved in the modification...

  12. Biomecánica de árboles: morfología de un haya (Fagus sylvatica L.) singular del Hayedo de Montejo de la Sierra y modelo mecánico mediante tecnología LiDAR terrestre

    Crespo Suárez, Cristina
    El presente proyecto tiene como objetivo analizar estructuralmente el tronco de un haya singular del Hayedo de Montejo, ubicado en la sierra de Madrid, con la característica particular del empleo de tecnología LiDAR (Laser Imaging Detection and Ranging) terrestre. El Hayedo de Montejo es conocido a nivel nacional e internacional, acoge hayas centenarias y singulares a una latitud meridional y poco frecuente en esta especie. La densidad en la actualidad es tan elevada, que existe una fuerte competencia entre el arbolado, sumada a las severas cortas de ramas para la tradicional obtención de leñas (que han dado lugar a pudriciones internas),...

  13. Biocircuits engineering and bio-design automation: some recent results

    Rodríguez-Patón Aradas, Alfonso

  14. BactoSim - an individual-based simulation environment for bacterial conjugation

    Prestes García, Antonio; Rodríguez-Patón Aradas, Alfonso
    BactoSim is an agent-based platform for simulating the con- jugation in spatially structured bacterial populations, which are the con- ditions typically found on naturally occurring colonies such as biofilms or in agar-based laboratory cultures. The model provides a set of key indicators which can be visualized in real time as the simulation evolves and saved as for further analysis.

  15. Variabilidad ambiental y productividad en Pinus halepensis Mill.

    García Fernández, Pablo
    El pino carrasco (Pinus halepensis Mill.) es una especie de gran importancia en restauraciones y repoblaciones en la península Ibérica, capaz de subsistir en zonas secas y ambientes desfavorables, y crucial en el estudio del cambio climático al situarse en un enclave tan representativo como la cuenca mediterránea. A pesar de ello, es muy poca la información que se tiene sobre el comportamiento de esta especie. Por este motivo en el presente trabajo se ha estudiado la productividad del pino carrasco -a través del índice de sitio-, y su relación con la variabilidad climática y edáfica de distintos lugares de España...

  16. Origen, dispersión y diversidad del chirimoyo (Annona cherimola Mill.) en el continente americano

    Larrañaga González, Nerea
    En este trabajo se ha profundizado en las razones que pueden explicar la distribución actual de la diversidad genética del chirimoyo (Annona cherimola Mill.), una especie frutal adaptada a climas subtropicales, con claras implicaciones para su uso y conservación. Gracias a un estudio de código de barras, se pudo comprobar el poder de discriminación del gen cloroplastídico maturasa K (matK) entre las especies con mayor importancia agronómica del género. Además, sobre los polimorfismos de nucleótido único (SNPs) interespecíficos, se diseñaron marcadores que permitieron la identificación mediante presencia o ausencia de bandas en geles de electroforesis de dichas especies tras PCR....

  17. Towards understanding RAV1 transcriptional network during the growth-dormancy cycle in poplar

    Triozzi, Paolo M.; Ramos Sanchez, Jose Manuel; Moreno Cortés, Alicia; Conde Rodriguez, Daniel; González Melendi, Pablo; Allona Alberich, Isabel Marta; Perales, Mariano
    As plants are sessile organisms, the decision to grow or to stop growing is fundamental for their survival. To survive to the harsh condition of the winter, temperate and boreal trees undergo a self-protective developmental reprograming known as winter dormancy. Its mechanism involves an intricate interplay between endogenous growth regulators and the winter external signal, such as shortening of photoperiod and cold temperatures. Currently, only few factors including circadian and developmental transcription factors and hormonal signaling molecules have been shown to modulate the extension of the dormancy period in woody plants. In our laboratory, the circadian controlled transcription factor RAV...

  18. New insights on winter-associated regulators of the circadian clock in poplar

    Ramos Sanchez, Jose Manuel; Moreno Cortés, Alicia; Conde Rodriguez, Daniel; Hernández Verdeja, Tamara; Perales, Mariano; Allona Alberich, Isabel Marta
    Winter dormancy is an adaptive mechanism that allows trees from temperate and cold regions to survive the harsh conditions of this season. This process is strongly influenced by daylength and temperature, which are signals that are integrated by the circadian clock. Low temperatures cause the disruption of the circadian clock in trees, which consists in a transcriptional activation followed by an arrhythmic expression. In this work we uncover winter-associated regulators of the circadian clock in poplar. We generated transgenic poplars that express a transcriptional fusion between the promoter of a circadian clock gene and the luciferase gene. Setting up a...

  19. Effect of antioxidants on the genetic stability of cryopreserved mint shoot tips by encapsulation-dehydration

    González Benito, Elena; Kremer Morales, María Carolina; Ibáñez Ruiz, Miguel Ángel; Martín Fernández, Carmen
    The effect of antioxidants applied in one step of a cryopreservation protocol by encapsulation?dehydration on recovery and genetic stability of mint shoot tips has been studied. Glutathione (0.16 or 0.24 mM), ascorbic acid (0.28 or 0.43 mM) and ?-tocopherol (vitamin E) were added to the preculture medium (0.3 M sucrose). DNA was extracted from three different types of samples: leaves from shoots, callus at the base of shoots and callus. RAPD and AFLP markers were used to assess the genetic stability. The use of antioxidants did not improve recovery after cryopreservation. One of the genotypes, ?MEN 198?, showed higher percentage...

  20. Fruit maturity and post-harvest environmental conditions influence the pre-penetration stages of Monilinia infections in peaches

    Garcia Benitez, Carlos; Melgarejo, Paloma; Cal Cotina, Antonieta De
    Brown rot caused by the fungi Monilinia laxa (Aderhold and Ruhland) Honey, M. fructicola (Winter) Honey, or M. fructigena (Aderhold and Ruhland) is a serious fungal disease of peaches. The fungal infection process begins when fungal conidia germinate on the fruit surface to produce germtubes and/or appressoria, and the incidence of brown rot increases as fruit approaches maturity. The interaction between the fungal infection process, peach maturity, and the environmental conditions is not well understood. Accordingly, the objectives of this investigation were to investigate germ tube and appressorial formation by M. laxa and M. fructicola when they were exposed to...

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