ACT, orientación del deseo sexual y trastornos de la erección : un estudio de caso.

Resumen tomado de la publicación

Building wood debris piles benefits avian seed dispersers in burned and logged Mediterranean pine forests

Salvage logging is a common practice carried out in burned forests worldwide, and intended to mitigate the economic losses caused by wildfires. Logging implies an additional disturbance occurring shortly after fire, although its ecological effects can be somewhat mitigated by leaving wood debris on site. The composition of the bird community and its capacity to provide ecosystem services such as seed dispersal of fleshy-fruited plants have been shown to be affected by postfire logging. We assessed the effects of the habitat structure resulting from different postfire management practices on the bird community, in three burned pine forests in Catalonia (western Mediterranean). For this purpose, we focused on the group of species that is responsible for seed dispersal, a process which takes place primarily during the winter in the Mediterranean basin. In addition, we assessed microhabitat selection by seed disperser birds in such environments in relation to management practices. Our results showed a significant, positive relationship between the density of wood debris piles and the abundance of seed disperser birds. Furthermore, such piles were the preferred microhabitat of these species. This reveals an important effect of forest management on seed disperser birds, which is likely to affect the dynamics of bird-dependent seed dispersal. Thus, building wood debris piles can be a useful practice for the conservation of both the species and their ecosystem services, while also being compatible with timber harvesting

Efectes de la invasió de la formiga argentina, Linepithema humile (Mayr), sobre el procés de dispersió de llavors de plantes mediterrànies

La formiga invasora Linepithema humile (Mayr), també coneguda com la formiga argentina, és una espècie present a la península Ibèrica. En aquesta tesi s'ha estudiat com afecta la presència d'aquesta espècie plaga a la comunitat de formigues autòctones y al procés de dispersió de llavors de plantes mediterrànies. L'estudi es va dur a terme en una àrea de sureda i brolla d'estepes i bruc boal situada al nord-est peninsular, prop de la línia de costa mediterrània. Un dels primers y més notables efectes de la invasió a les nostres àrees d'estudi és la dramàtica alteració de la comunitat de formigues, en forma de una reducció de la riquesa específica i de la homogeneïtat d'abundàncies. A més, a les zones envaïdes no hi queda cap espècie de formiga autòctona dispersant de llavors. A causa de la gran abundància d'obreres de la formiga argentina a les zones envaïdes, i del seu elevat ritme d'activitat, aquesta espècie efectua un intens rastreig del sòl, la qual cosa li permet localitzar els recursos en un temps menor que les formigues autòctones de les zones no envaïdes. No obstant, la obertura mandibular de la comunitat de formigues esdevé molt disminuïda a les zones envaïdes a causa de la desaparició de les espècies autòctones, la majoria d'elles de mida més grossa que la formiga argentina, la qual cosa podria limitar la capacitat de manipulació de l'entorn que té la comunitat de formigues a les zones envaïdes, i podria explicar la falta de reemplaçament d'alguns dels rols que duien a terme les espècies de formigues autòctones abans de la invasió. La formiga argentina es mostra atreta per les llavors de les nou espècies vegetals estudiades (dues euforbiàcies: Euphorbia biumbellata i E. characias; dues compostes: Cirsium vulgare i Galactites tomentosa; i cinc papilionàcies: Genista linifolia, G. monspessulana, G. triflora, Sarothamnus arboreus i Ulex parviflorus), arribant a transportar i fins i tot introduir al niu algunes llavors, però amb probabilitats inferiors a les realitzades per les formigues autòctones de les zones no envaïdes. No obstant, el seu comportament davant les nou espècies de llavors és variable, de manera que sembla que el seu efecte sobre la dispersió de llavors podria ser diferent per a cada espècie vegetal. L'alteració del procés de dispersió no sembla alterar l'èxit reproductiu d'una espècie concreta, Euphorbia characias, a les zones envaïdes; ni el seu reclutament, ni la distribució espacial, ni la supervivència de les plàntules són significativament diferents a les zones envaïdes que a les no envaïdes. La desaparició de les espècies de formigues granívores de les zones envaïdes pot afectar la dinàmica de les llavors de plantes no mirmecòcores. Així, les llavors de tres papilionàcies (Calicotome spinosa, Psoralea bituminosa i Spartium junceum) resulten amb un menor nivell de transports (i probablement menor depredació) a les zones envaïdes per la formiga argentina.

L'efecte de la gestió forestal post-incendi sobre l'avifauna i la dispersió de llavors per ocells frugívors

The objective of this thesis is to analyze the effect of the transformation in the habitat that postfire salvage logging supposes on birds in Mediterranean pine forests, at different levels: species, community and ecosystem, focusing on the bird-mediated seed dispersal process. Salvage logging with commercial purposes is the main factor that determines the species composition after a fire, with the substitution of forest birds by open-habitat species, some of which hold an unfavourable conservation status in Europe. On the other hand, wood debris piles built by non-profitable burnt wood favour the presence of seed disperser frugivorous birds, and these structures show more seed dispersal than other microhabitats, and a higher abundance of bird-dispersed plants, so that it is recommendable to build them in managed burned forests.

La defensa judicial de la Constitución en el constitucionalismo colombiano. Balances y perspectivas después de dos décadas (Tema Central)

Este artículo pretende explicar el auge que, en Colombia, ha tenido la defensa judicial de la Constitución. Para tal efecto, se hace una breve caracterización del constitucionalismo colombiano, identificando y explicando ocho de sus rasgos: la existencia de una historia y de una tradición de control constitucional, la defensa de la Constitución como asunto público, la Carta Política como norma invasiva de la vida social, económica y política del país, la desconcentración del control constitucional, la construcción permanente y progresiva del constitucionalismo por vía judicial, el diálogo con otros sistemas constitucionales, la existencia de una identidad constitucional, y la continuidad relativa con el sistema y la tradición jurídica. Con fundamento en esta caracterización, se obtendrán algunas conclusiones sobre la defensa judicial de la Constitución.

Ni una mujer menos (Arte)

La víctima de feminicidio puede ser cualquiera; una mujer heterosexual, bisexual, lesbiana, transgénero, transexual, monógama, polígama, niña, joven, anciana, casada, soltera, viuda, enamorada o desilusionada, de cualquier estrato social, no se trata necesariamente de mujeres de sectores marginales de la sociedad, no matan solo a las pobres —aunque en su mayoría lo son—. Ocurre en tiempos de guerra pero también de paz, lo que algunas llaman una guerra de baja intensidad contra las mujeres.

Understanding Demographic and Behavioral Mechanisms that Guide Responses of Neotropical Migratory Birds to Urbanization: a Simulation Approach

Although studies often report that densities of many forest birds are negatively related to urbanization, the mechanisms guiding this pattern are poorly understood. Our objective was to use a population simulation to examine the relative influence of six demographic and behavioral processes on patterns of avian abundance in urbanizing landscapes. We constructed an individual-based population simulation model representing the annual cycle of a Neotropical migratory songbird. Each simulation was performed under two landscape scenarios. The first scenario had similar proportions of high- and low-quality habitat across the urban to rural gradient. Under the first scenario, avian density was negatively related to urbanization only when rural habitats were perceived to be of higher quality than they actually were. The second landscape scenario had declining proportions of high-quality habitat as urbanization increased. Under the second scenario, each mechanism generated a negative relationship between density and urbanization. The strongest effect on density resulted when birds preferentially selected habitats in landscapes from which they fledged or were constrained from dispersing. The next strongest patterns occurred when birds directly evaluated habitat quality and accurately selected the highest-quality available territories. When birds selected habitats based on the presence of conspecifics, the density–urbanization relationship was only one-third the strength of other habitat selection mechanisms and only occurred under certain levels of population survival. Although differences in adult or nest survival in the face of random habitat selection still elicited reduced densities in urban landscapes, the relationships between urbanization and density were weaker than those produced by the conspecific attraction mechanism. Results from our study identify key predictions and areas for future research, including assessing habitat quality in urban and rural areas in order to determine if habitats in urban areas are underutilized.

Suburban immigrants to wildlands disrupt honest signaling in ultra-violet plumage

Urbanization changes habitat in a multitude of ways, including altering food availability. Access to human-provided food can change the relationship between body condition and honest advertisements of fitness, which may result in changes to behavior, demography, and metapopulation dynamics. We compared plumage color, its relationship with body condition and feather growth, and use as signal of dominance between a suburban and a wildland population of Florida Scrub-Jay (Aphelocoma coerulescens). Although plumage color was not related to body condition at either site, suburban birds had plumage with a greater proportion of total reflectance in the ultra-violet (UV) and peak reflectance at shorter wavelengths. Despite the use of plumage reflectance as a signal of dominance among individuals in the wildlands, we found no evidence of status signaling at the suburban site. However, birds emigrating from the suburban site to the wildland site tended to be more successful at acquiring breeder status but less successful at reproducing than were immigrants from an adjacent wildland site, suggesting that signaled and realized quality differ. These differences in signaling content among populations could have demographic effects at metapopulation scales and may represent an evolutionary trap whereby suburban immigrants are preferred as mates even though their reproductive success relative to effort is lower.

Sources of sulphur in gypsiferous sediments and crusts and pathways of gypsum redistribution in southern Tunisia

Southern Tunisia contains one of the most extensive gypsum accumulations in Africa comprising Triassic, Cretaceous, Eocene and Mio-Pliocene marine evaporites, spring deposits, playa sediments, aeolian sands and gypsum crusts. Sulphur isotope analysis (delta(34)S) of bedrock samples, groundwater, playa brines, playa sediments, and gypsiferous crusts provides insight into the sources of gypsum in the region and sheds light on the processes that lead to gypsum crust formation. Results Suggest that recycling of marine gypsum is the most likely source of the sulphate in the groundwater, playa sediments and crusts. The low PS values found in Eocene and Mio-Pliocene samples suggest that this recycling has been going on for millions of years. Though bedrock appears to be the ultimate source of the gypsum in the crusts, transport of this sulphate to playas, concentration therein, and subsequent dispersal across the landscape by aeolian processes provides the most likely pathway for surticial gypsum crust formation. Comparison of these results with those from Australia, Chile and Namibia suggests that, although the source of the sulphur varies from region to region, the processes of surficial crust formation appear to be similar. Copyright (C) 2004 John Wiley Sons, Ltd.

Hybridization between Brassica napus and B. rapa on a national scale in the United Kingdom

Measures blocking hybridization would prevent or reduce biotic or environmental change caused by gene flow from genetically modified (GM) crops to wild relatives. The efficacy of any such measure depends on hybrid numbers within the legislative region over the life-span of the GM cultivar. We present a national assessment of hybridization between rapeseed (Brassica napus) and B. rapa from a combination of sources, including population surveys, remote sensing, pollen dispersal profiles, herbarium data, local Floras, and other floristic databases. Across the United Kingdom, we estimate that 32,000 hybrids form annually in waterside B. rapa populations, whereas the less abundant weedy populations contain 17,000 hybrids. These findings set targets for strategies to eliminate hybridization and represent the first step toward quantitative risk assessment on a national scale.

The role of satellite image-processing for national-scale estimates of gene flow from genetically modified crops: rapeseed in the UK as a model.

1. There is concern over the possibility of unwanted environmental change following transgene movement from genetically modified (GM) rapeseed Brassica napus to its wild and weedy relatives. 2. The aim of this research was to develop a remote sensing-assisted methodology to help quantify gene flow from crops to their wild relatives over wide areas. Emphasis was placed on locating sites of sympatry, where the frequency of gene flow is likely to be highest, and on measuring the size of rapeseed fields to allow spatially explicit modelling of wind-mediated pollen-dispersal patterns. 3. Remote sensing was used as a tool to locate rapeseed fields, and a variety of image-processing techniques was adopted to facilitate the compilation of a spatially explicit profile of sympatry between the crop and Brassica rapa. 4. Classified satellite images containing rapeseed fields were first used to infer the spatial relationship between donor rapeseed fields and recipient riverside B. rapa populations. Such images also have utility for improving the efficiency of ground surveys by identifying probable sites of sympatry. The same data were then also used for the calculation of mean field size. 5. This paper forms a companion paper to Wilkinson et al. (2003), in which these elements were combined to produce a spatially explicit profile of hybrid formation over the UK. The current paper demonstrates the value of remote sensing and image processing for large-scale studies of gene flow, and describes a generic method that could be applied to a variety of crops in many countries. 6. Synthesis and applications. The decision to approve or prevent the release of a GM cultivar is made at a national rather than regional level. It is highly desirable that data relating to the decision-making process are collected at the same scale, rather than relying on extrapolation from smaller experiments designed at the plot, field or even regional scale. It would be extremely difficult and labour intensive to attempt to carry out such large-scale investigations without the use of remote-sensing technology. This study used rapeseed in the UK as a model to demonstrate the value of remote sensing in assembling empirical information at a national level.

Insights into processes and deposits of hazardous vulcanian explosions at Soufrière Hills Volcano during 2008 and 2009 (Montserrat, West Indies)

During the Soufrière Hills eruption, vulcanian explosions have generally occurred 1) in episodic cycles; 2) isolated during pauses in extrusion, and 3) after major collapses of the dome. In a different eruptive context, significant vulcanian explosions occurred on 29 July 2008, 3 December 2008, and 3 January 2009. Deposits are pumiceous except for the 3 December event. We reconstructed the dispersal pattern of the deposits and their textural characteristics to evaluate erupted volume and vesicularity of the magma at fragmentation. We discuss the implications of these explosions in terms of eruptive processes and chronology, and the hazards posed by their sudden and often unheralded occurrence. We suggest that overpressurization of the conduit can develop over time-scales of months to weeks by a process of self-sealing of conduit walls and/or the cooling dome by silica polymorphs. This work provides new insights for understanding the generation of hazardous vulcanian explosions at andesitic volcanoes.