Blanes I, Zabala A, Moré G, Pons X, Serra J (2008) Classification of Hyperspectral Images Compressed through 3D-JPEG2000. Publicat a: Lovrek I, Howlett RJ, Jain LC (Eds.) KES 2008, Part III, LNAI 5179, pp. 416–423, 2008. Springer-Verlag Berlin Heidelberg 2008.
Ojeda G (2008) Esmenes orgàniques per millorar l'estabilitat estructural del sòl mediterrani. UAB Divulga, 10/2008, 1pp.
Guirado M., Pino J., Rodà F., Basnou C. (2008) Quercus and Pinus cover are determined by landscape structure and dynamics in peri-urban Mediterranean forest patches. Plant Ecology. 194: 109-119.EnllaçDoi: 10.1007/s11258-007-9278-9
Successional dynamics in Mediterranean forests have been modulated by anthropogenic disturbances during thousands of years, especially in areas densely populated since ancient times. Our objective is to determine whether pine tree cover (early-successional species) and oak tree cover (late-successional species), used as a surrogate of successional stage of peri-urban fragmented forests in the Vallès lowlands (Catalonia, NE, Spain), are primarily determined by (1) climate and topography; (2) anthropogenic disturbances; (3) patch structure; or (4) patch dynamics from 1956 to 1993. Quercus spp. and Pinus spp. tree cover were separately recorded on 252 randomly selected plots of 100 m2, within forest patches ranging in size from 0.25 to 218 ha. Multiple linear regressions indicated that forest patch history is the most important variable determining oak and pine tree cover: new forest patches showed higher pine and lower oak tree cover than recently split patches (i.e. those that became fragmented from large forest areas after 1956). Patches already existing as such in 1956 (pre-existent patches) showed higher pine cover than recently split patches. Oak cover increased and pine cover decreased with increasing forest connectivity of the patch. Finally, highly frequented forests were related to high cover of pines. Climatic and topographic variables were not significant. We conclude that pine and oak cover in these peri-urban forests are mainly determined by recent patch dynamics, but also by the spatial pattern of patches. However, human-induced disturbance can modulate this as there is some evidence for pine being associated with a high human frequentation. © 2007 Springer Science+Business Media, Inc.
Gómez J.M., Bosch J., Perfectti F., Fernández J.D., Abdelaziz M., Camacho J.P.M. (2008) Association between floral traits and rewards in Erysimum mediohispanicum (Brassicaceae). Annals of Botany. 101: 1413-1420.EnllaçDoi: 10.1093/aob/mcn053
• Background and Aims: Floral rewards may be associated with certain morphological floral traits and thus act as underlying factors promoting selection on these traits. This study investigates whether some traits that are under pollinator-mediated selection (flower number, stalk height, corolla diameter, corolla tube length and corolla tube width) in the Mediterranean herb E. mediohispanicum (Brassicaceae) are associated with rewards (pollen and nectar). • Methods: During 2005 the phenotypic traits and the visitation rate of the main pollinator functional groups were quantified in 720 plants belonging to eight populations in south-east Spain, and during 2006 the same phenotypic traits and the reward production were quantified in 400 additional plants from the same populations. • Key Results: A significant correlation was found between nectar production rate and corolla tube length, and between pollen production and corolla diameter. Visitation rates of large bees and butterflies were significantly higher in plants exhibiting larger flowers with longer corolla tubes. • Conclusions: The association between reward production and floral traits may be a factor underlying the pattern of visitation rate displayed by some pollinators. © The Author 2008. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.
Gómez J.M., Bosch J., Perfectti F., Fernández J.D., Abdelaziz M., Camacho J.P.M. (2008) Spatial variation in selection on corolla shape in a generalist plant is promoted by the preference patterns of its local pollinators. Proceedings of the Royal Society B: Biological Sciences. 275: 2241-2249.EnllaçDoi: 10.1098/rspb.2008.0512
An adaptive role of corolla shape has been often asserted without an empirical demonstration of how natural selection acts on this trait. In generalist plants, in which flowers are visited by diverse pollinator fauna that commonly vary spatially, detecting pollinator-mediated selection on corolla shape is even more difficult. In this study, we explore the mechanisms promoting selection on corolla shape in the generalist crucifer Erysimum mediohispanicum Polatschek (Brassicaceae). We found that the main pollinators of E. mediohispanicum (large bees, small bees and bee flies) discriminate between different corolla shapes when offered artificial flowers without reward. Importantly, different pollinators prefer different shapes: bees prefer flowers with narrow petals, whereas bee flies prefer flowers with rounded overlapping petals. We also found that flowers with narrow petals (those preferred by bees) produce both more pollen and nectar than those with rounded petals. Finally, different plant populations were visited by different faunas. As a result, we found spatial variation in the selection acting on corolla shape. Selection favoured flowers with narrow petals in the populations where large or small bees are the most abundant pollinator groups. Our study suggests that pollinators, by preferring flowers with high reward, exert strong selection on the E. mediohispanicum corolla shape. The geographical variation in the pollinator-mediated selection on E. mediohispanicum corolla shape suggests that phenotypic evolution and diversification can occur in this complex floral trait even without specialization. © 2008 The Royal Society.
Hulme P.E., Bacher S., Kenis M., Klotz S., Kühn I., Minchin D., Nentwig W., Olenin S., Panov V., Pergl J., Pyšek P., Roques A., Sol D., Solarz W., Vilà M. (2008) Grasping at the routes of biological invasions: A framework for integrating pathways into policy. Journal of Applied Ecology. 45: 403-414.EnllaçDoi: 10.1111/j.1365-2664.2007.01442.x
1. Pathways describe the processes that result in the introduction of alien species from one location to another. A framework is proposed to facilitate the comparative analysis of invasion pathways by a wide range of taxa in both terrestrial and aquatic ecosystems. Comparisons with a range of data helped identify existing gaps in current knowledge of pathways and highlight the limitations of existing legislation to manage introductions of alien species. The scheme aims for universality but uses the European Union as a case study for the regulatory perspectives. 2. Alien species may arrive and enter a new region through three broad mechanisms: importation of a commodity, arrival of a transport vector, and/or natural spread from a neighbouring region where the species is itself alien. These three mechanisms result in six principal pathways: release, escape, contaminant, stowaway, corridor and unaided. 3. Alien species transported as commodities may be introduced as a deliberate release or as an escape from captivity. Many species are not intentionally transported but arrive as a contaminant of a commodity, for example pathogens and pests. Stowaways are directly associated with human transport but arrive independently of a specific commodity, for example organisms transported in ballast water, cargo and airfreight. The corridor pathway highlights the role transport infrastructures play in the introduction of alien species. The unaided pathway describes situations where natural spread results in alien species arriving into a new region from a donor region where it is also alien. 4. Vertebrate pathways tend to be characterized as deliberate releases, invertebrates as contaminants and plants as escapes. Pathogenic micro-organisms and fungi are generally introduced as contaminants of their hosts. The corridor and unaided pathways are often ignored in pathway assessments but warrant further detailed consideration. 5. Synthesis and applications. Intentional releases and escapes should be straightforward to monitor and regulate but, in practice, developing legislation has proved difficult. New introductions continue to occur through contaminant, stowaway, corridor and unaided pathways. These pathways represent special challenges for management and legislation. The present framework should enable these trends to be monitored more clearly and hopefully lead to the development of appropriate regulations or codes of practice to stem the number of future introductions. © 2007 The Authors.
Huntzinger C.I., James R.R., Bosch J., Kemp W.F. (2008) Laboratory bioassays to evaluate fungicides for chalkbrood control in larvae of the Alfalfa leafcutting bee (Hymenoptera: Megachilidae). Journal of Economic Entomology. 101: 660-667.EnllaçDoi: 10.1603/0022-0493(2008)101[660:LBTEFF]2.0.CO;2
Chalkbrood, a fungal disease in bees, is caused by several species of Ascosphaera. A. aggregata is a major mortality factor in populations of the alfalfa leafcutting bee, Megachile rotundata (F.) (Hymenoptera: Megachilidae) used in commercial alfalfa seed production. Four formulated fungicides, Benlate 50 WP, Captan, Orbit, and Rovral 50 WP were tested in the laboratory for efficacy against hyphal growth of A. aggregata cultures. The same fungicides, with the addition of Rovral 4 F, were tested for their effects on incidence of chalkbrood disease, and toxicity to M. rotundata larvae. Benlate, Rovral 50 WP, and Rovral 4 F reduced incidence of chalkbrood with minimal mortality on larval bees. Benlate and Rovral 50 WP also reduced hyphal growth. Orbit was effective in reducing hyphal growth, but it did not reduce incidence of chalkbrood and was toxic to bee larvae. Captan was not effective in reducing hyphal growth or chalkbrood incidence, and it was toxic to bee larvae. Fungicides that reduce incidence of chalkbrood and larval mortality in this laboratory study are candidates for further study for chalkbrood control.
Huntzinger C.I., James R.R., Bosch J., Kemp W.P. (2008) FunGicide tests on adult alfalfa leafcutting bees (Hymenoptera: Megachilidae). Journal of Economic Entomology. 101: 1088-1094.EnllaçDoi: 10.1603/0022-0493(2008)101[1088:FTOAAL]2.0.CO;2
Chalkbrood is a serious disease of alfalfa leafcutting bee Megachile rotundata (F.) (Hymenoptera: Megachilidae) larvae, causing upward of 20% infection in the field. The causative agent is the fungus Ascosphaera aggregata. This bee is used extensively for alfalfa seed pollination in the United States. Using laboratory bioassays, we previously demonstrated that fungicides can reduce chalkbrood levels in the larvae. Here, we evaluate the toxicity of four fungicides, Benlate, Captan, Orbit, and Rovral, to adult bees by using three different bioassays. In the first test, fungicides were applied to bees' thoraces. In the second test, mimicking foliage residue, a piece of filter paper soaked in fungicide was placed on the bottom of a container of bees. The third test evaluated oral toxicity by incorporating fungicides into a sugar-water solution that was fed to the bees. The filter paper test did not discriminate among the fungicides well, and the oral test resulted in the greatest mortality. Toxicity to males was greater than to females. The use of fungicides for chalkbrood control is a logical choice, but caution should be used in how they are applied in the presence of bees.
Traveset A, Morales C, Nogales M, Padrón B, Bartomeus I (2008) Los mutualismos facilitan las invasiones, y las invasoras impactan sobre los mutualismos nativos. A: Vilà M. F. Valladares, A. Traveset, L. Santamaría y P. Castro (eds.). Invasiones Biológicas. CSIC-Divulgación. Madrid. Pp. 77- 90.
Andreu J, Vilà M (2008) Coste de eliminación de plantas invasoras en España. In: (Vilà M, Valladares F, Traveset A, Santamaría L, Castro P Eds.). Invasiones Biológicas. CSIC-Divulgación. Madrid. pp. 207-210.
Dona't d'alta al Newsletter per rebre totes les novetats del CREAF al teu e-mail.
© 2016 CREAF | Avís legal