Molins A, Bacchetta G, Rosato M, Rosselló JA, Mayol M (2011) Molecular phylogeography of Thymus herba-barona (Lamiaceae): Insight into the evolutionary history of the flora of the western Mediterranean islands. Taxon 60: 1295-1305.
Mestre L., Lubin Y. (2011) Settling where the food is: Prey abundance promotes colony formation and increases group size in a web-building spider. Animal Behaviour. 81: 741-748.EnllaçDoi: 10.1016/j.anbehav.2011.01.002
The parasocial-route hypothesis postulates that coloniality in spiders is driven by the occurrence of high prey densities. This hypothesis is partially supported by comparative studies of colonial species. However, experimental evidence is lacking to confirm that prey availability directly promotes colony formation. We used the web-building spider Cyrtophora citricola (Araneidae) as a model species to investigate the effect of prey availability on coloniality. We conducted field surveys on colonies located on acacia trees in the Arava valley, Israel, to compare colony group size between sites differing markedly in insect abundance. We then performed experiments in net houses to test (1) the effect of prey remains in the females' webs on juvenile establishment decisions and (2) the effect of food supply on web site fidelity of juveniles. Colony group size and reproductive investment were greater in prey-rich sites than in poor sites. In the experiments, juveniles released on adult females' webs that contained remains of prey consumed by the adults were more likely to settle than those released on empty webs. Once established, food deprivation slightly increased the number of juveniles leaving the female's web, suggesting that they are reluctant to disperse after settlement. Relocation in C. citricola is costly, as their webs demand high energy investment. Hence, cues of prey availability are crucial, enabling spiders to acquire information about habitat quality before investing in web construction. Together, our findings provide evidence that prey availability facilitates coloniality and thus supports the parasocial route in the evolution of spider group living. © 2011 The Association for the Study of Animal Behaviour.
Mimendia A., Gutiérrez J.M., Alcañiz J.M., Del Valle M. (2011) Discrimination of soils and assessment of some soil fertility parameters using an electronic tongue. AIP Conference Proceedings. 1362: 191-192.EnllaçDoi: 10.1063/1.3626354
In this communication, a new strategy to perform soil classification and/or characterization is reported, which is the coupling of chemical sensors with a pattern recognition method, what is known as an electronic tongue. Following this approach, the system proposed in this paper uses a sensor array formed by potentiometric sensors with generic cross response against several cations and anions, plus a pattern recognition method based on Artificial Neural Networks (ANNs); the sensor-based system allows performing a simple laboratory procedure where the advanced data processing methodology permits to extract the meaningful information. In this way this work represents the first application and testing of an electronic tongue in soil analysis. Apart from the qualitative classification application, a quantitative analysis of certain chemical features related to soil fertility has also been attempted. © 2011 American Institute of Physics.
Minguillón M.C., Perron N., Querol X., Szidat S., Fahrni S.M., Alastuey A., Jimenez J.L., Mohr C., Ortega A.M., Day D.A., Lanz V.A., Wacker L., Reche C., Cusack M., Amato F., Kiss G., Hoffer A., Decesari S., Moretti F., Hillamo R., Teinilä K., Seco R., Peñuelas J., Metzger A., Schallhart S., Müller M., Hansel A., Burkhart J.F., Baltensperger U., Prévót A.S.H. (2011) Fossil versus contemporary sources of fine elemental and organic carbonaceous particulate matter during the DAURE campaign in Northeast Spain. Atmospheric Chemistry and Physics. 11: 12067-12084.EnllaçDoi: 10.5194/acp-11-12067-2011
We present results from the international field campaign DAURE (Determination of the sources of atmospheric Aerosols in Urban and Rural Environments in the Western Mediterranean), with the objective of apportioning the sources of fine carbonaceous aerosols. Submicron fine particulate matter (PM1) samples were collected during February-March 2009 and July 2009 at an urban background site in Barcelona (BCN) and at a forested regional background site in Montseny (MSY). We present radiocarbon (14C) analysis for elemental and organic carbon (EC and OC) and source apportionment for these data. We combine the results with those from component analysis of aerosol mass spectrometer (AMS) measurements, and compare to levoglucosan-based estimates of biomass burning OC, source apportionment of filter data with inorganic composition + EC + OC, submicron bulk potassium (K) concentrations, and gaseous acetonitrile concentrations. At BCN, 87 % and 91 % of the EC on average, in winter and summer, respectively, had a fossil origin, whereas at MSY these fractions were 66 % and 79 %. The contribution of fossil sources to organic carbon (OC) at BCN was 40 % and 48 %, in winter and summer, respectively, and 31 % and 25 % at MSY. The combination of results obtained using the 14C technique, AMS data, and the correlations between fossil OC and fossil EC imply that the fossil OC at Barcelona is ∼47 % primary whereas at MSY the fossil OC is mainly secondary (∼85 %). Day-to-day variation in total carbonaceous aerosol loading and the relative contributions of different sources predominantly depended on the meteorological transport conditions. The estimated biogenic secondary OC at MSY only increased by ∼40 % compared to the order-of-magnitude increase observed for biogenic volatile organic compounds (VOCs) between winter and summer, which highlights the uncertainties in the estimation of that component. Biomass burning contributions estimated using the 14C technique ranged from similar to slightly higher than when estimated using other techniques, and the different estimations were highly or moderately correlated. Differences can be explained by the contribution of secondary organic matter (not included in the primary biomass burning source estimates), and/or by an overestimation of the biomass burning OC contribution by the 14C technique if the estimated biomass burning EC/OC ratio used for the calculations is too high for this region. Acetonitrile concentrations correlate well with the biomass burning EC determined by 14C. K is a noisy tracer for biomass burning. © 2011 Author(s).
Mayol M, Dubreuil M, González-Martínez SC, Sebastiani F, Vendramin GG, Riba M (2011) Variabilidad genética de Taxus baccata en el Mediterráneo occidental: el papel de los procesos históricos y de la fragmentación del paisaje. En: A. Caritat (ed.), II Jornades sobre el teix a la Mediterrània occidental. Documents de la delegació de la Garrotxa de la Institució Catalana d’Història Natural, 1, Olot, pp. 103-106. ISBN: 978-84-9965-053-1.
Burgarella C, Berganzo E, Zabal-Aguirre M, Prada A, Iglesias S, Riba M, Mayol M, Vendramin GG, González-Martínez SC (2011) Aspectos genéticos y demográficos de Taxus baccata en la Red de Parques Nacionales. En: L. Ramírez y B. Asensio (eds.), Proyectos de Investigación en Parques Nacionales 2007-2010. Organismo Autónomo de Parques Nacionales, pp. 125-137. ISBN: 978-84-8014-805-4.
Moré G., Serra P., Pons X. (2011) Multitemporal flooding dynamics of rice fields by means of discriminant analysis of radiometrically corrected remote sensing imagery. International Journal of Remote Sensing. 32: 1983-2011.EnllaçDoi: 10.1080/01431161003645816
An automatic classifier based on a discriminant analysis (DA) was used to classify eight classes in relation to different stages of rice fields during the flooding season. This methodology is characterized by the fact that, once the training phase has been carried out, training areas are not required to perform new classifications. If the images have been radiometrically corrected in a consistent way, the classifier can be used in a retrospective mode using past images. For this study, the training phase was conducted with data taken in October 2006 and January 2007 while the automatic classifier was applied to a total of 10 Landsat-5 Thematic Mapper (TM) images from the 2004-05 and 2006-07 seasons. An average level of accuracy of 93.4% (range 89.7-98.7%) demonstrates the capability of the method to obtain high-quality and quasi-instantaneous classifications and to carry out retrospective studies even when training areas are not available for past dates. Two examples of how the method can be used are included in this article: (i) a study of the temporal evolution of flooding covers by period and (ii) the use of vector enrichment as a thematic updating tool for the cadastre. An additional objective of the study was to analyse the importance of the different bands to ascertain the suitability of alternative sensors with spectral configurations other than those provided by Landsat. This analysis demonstrates that the absence of shortwave infrared (SWIR) bands results in a decrease of almost nine percentage points in the accuracy levels of the classification while the blue band can be excluded with minimal impact on the results. © 2011 Taylor & Francis.
Muñoz A., Aparicio J.M., Bonal R. (2011) Male barn swallows use different signalling rules to produce ornamental tail feathers. Evolutionary Ecology. 25: 1217-1230.EnllaçDoi: 10.1007/s10682-011-9512-8
The evolution of secondary sexual characters is the subject of controversial debate between those defending their role as 'viability indicators' and those arguing that ornaments are purely 'attractive traits' selected by females. Recent theoretical studies suggest that these hypotheses are not mutually exclusive, as both viability and attractiveness can contribute to improve the reproductive success of progeny and could thus simultaneously underlie female choices. If that is the case, strategies of cheaper advertisement, allowing the expression of larger ornaments for the same cost, could proliferate even in species in which honest signalling of viability prevails. Under this scenario, different males could invest a different amount of resources per ornament unit of expression, thus using different signalling rules. We studied the relationship between tail feather length (a trait that is the subject of a female mate preference) and feather mass (a measure of investment in feather production) in a barn swallow Hirundo rustica population. Different males used different and consistent signalling rules when developing ornamental feathers. That is, to produce a feather of a given length, each male used a constant amount of resources across different years, but this amount varied between males. Although the amount of material invested in feathers (feather mass) is a condition-dependent trait, the organization of this material in ornamental feathers (i. e. the signalling rules) was not. Neither survival nor risk of feather breakage was related to the signalling rules. Thus, these results suggest that both 'viability' and 'runaway' mechanisms are independent determinants of the evolution of ornamental sexual feathers in the barn swallow. A preference for long tails will ensure that females either obtain a sire with high viability, or one transferring the capability to produce longer and more attractive tails at a lower cost of production to its offspring. © 2011 Springer Science+Business Media B.V.
Muñoz A., Bonal R. (2011) Linking seed dispersal to cache protection strategies. Journal of Ecology. 99: 1016-1025.EnllaçDoi: 10.1111/j.1365-2745.2011.01818.x
1.The spatial distribution of dispersed seeds results from the combined action of the caching strategies followed by different granivores. Hence, it is essential to study the factors that influence seed predation and caching decisions to achieve a better understanding of the dispersal process. 2.In this study, we document how seed dispersal and the spatial patterns of natural recruitment are linked to the strategies used by granivores to protect their cached seeds from pilferage. We present a theoretical model showing that those strategies may convey benefits for both seed cachers and plants. 3.We studied the relationships among seed production, seed predation/caching, cache pilferage and plant recruitment in a savanna-like landscape of oaks dispersed by scatter-hoarding rodents. 4.Our results show that acorn-dispersing rodents were concentrated under the canopies of scattered oaks, where the theft of cached acorns increased by 77% as compared to that of the surrounding open landscape. Acorns were thus cached selectively in the open areas to reduce pilferage; in fact, none of the few seeds cached beneath tree canopies survived predation by granivores (pilferage+recovery). Meanwhile, some acorns cached in the surrounding open areas were neither pilfered nor recovered and then recruited successfully. Accordingly, natural recruitment of newly emerged seedlings was higher outside than under canopies, suggesting that rodent caching strategies have direct implications for the directed dispersal of oaks. 5.Synthesis. The spatial patterns of seed dispersal shape the fitness of both the plant because they influence dispersal and recruitment efficiency, and the granivores that cache and predate its seeds because they influence their foraging efficiency. Cache protection strategies reduce pilferage significantly and enhance seed recovery rates by the cache owner. At the same time, more seeds remain dispersed and unrecovered. Thus, cache protection strategies can provide net benefits to the plant in terms of effective directed dispersal. © 2011 The Authors. Journal of Ecology © 2011 British Ecological Society.
Niinemets Ü., Flexas J., Peñuelas J. (2011) Evergreens favored by higher responsiveness to increased CO 2. Trends in Ecology and Evolution. 26: 136-142.EnllaçDoi: 10.1016/j.tree.2010.12.012
Physical CO 2 diffusion from sub-stomatal cavities to the chloroplasts where photosynthesis takes place is an important limitation of photosynthesis largely neglected in research related to global climate change. This limitation is particularly important in leaves with robust structures such as evergreen sclerophylls. In these leaves, photosynthesis is less sensitive to changes in stomatal openness, which is considered to be the primary limitation of photosynthesis. In this review we state that, because of large limitations in internal diffusion in C 3 plants, photosynthesis and the intrinsic efficiency of the use of plant water responds more strongly to elevated levels of CO 2 in leaves with more robust structures. This provides an additional explanation for the current apparent expansion of evergreen sclerophylls in many Earth ecosystems, and adds a new perspective to research of the biological effects of increasing atmospheric CO 2. © 2010 Elsevier Ltd.
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