Life history and mating systems select for male biased parasitism mediated through natural selection and ecological feedbacks

Males are often the "sicker" sex with male biased parasitism found in a taxonomically diverse range of species. There is considerable interest in the processes that could underlie the evolution of sex-biased parasitism. Mating system differences along with differences in lifespan may play a key role. We examine whether these factors are likely to lead to male-biased parasitism through natural selection taking into account the critical role that ecological feedbacks play in the evolution of defence. We use a host-parasite model with two-sexes and the techniques of adaptive dynamics to investigate how mating system and sexual differences in competitive ability and longevity can select for a bias in the rates of parasitism. Male-biased parasitism is selected for when males have a shorter average lifespan or when males are subject to greater competition for resources. Male-biased parasitism evolves as a consequence of sexual differences in life history that produce a greater proportion of susceptible females than males and therefore reduce the cost of avoiding parasitism in males. Different mating systems such as monogamy, polygamy or polyandry did not produce a bias in parasitism through these ecological feedbacks but may accentuate an existing bias.Comment: 18 pages, 4 figure

A Model of Vascular Tumor Response to Chemotherapy Combined with Anti-Angiogenic Therapy

Flora S. Bacelar... et al.Angiogenesis is acknowledged as an essential mechanism for tumor spreading and metastasis of neoplastic diseases. Consequently, anti-angiogenic therapy has been proposed as a complementary or perhaps an alternative strategy to the traditional cytotoxic therapies. This work considers a model of ordinary di®erential equations that describe the dynamics of tumors at the vascular stage (after the angiogenic process has been triggered), under the action of chemical and anti-angiogenic ther- apies. Due to the increase of endothelial cells at the vascular stage, the cancer state prevails over the internal state in the no treatment situation. Results from the lo- cal stability analysis and numerical integration, indicate that the combination of chemotherapy and anti-angiogenic therapy is the best strategy to eliminate the tu- mor, reducing the cytotoxic e®ect. At a ¯xed infusion rate, the cure state may be reached when the combined therapy is considered but not for the anti-angiogenic therapy only. On the other hand, pure chemotherapy efectively destroys the tumor, but only when higher infusion doses are applied.Acknowledgments: STRP, RFSA thank CNPq for partial supporting the re- searchPeer reviewe

Space of memory and representation : Bouça da Cova da Moura (Ardegães, Maia, Northwest of Portugal)

Bouça da Cova da Moura is the local place-name attributed to a stretch of a plateau overlooking the Leça valley. Here, Neolithic burial mounds share their landscape setting with scatters of archaeological materials that include Bell Beaker fragments, idols and metalwork. Since these are mostly surface findings, their contexts have not yet been accurately determined. Another significant feature is the presence of prehistoric rock carvings. The plateau may thus be considered a public space, conceptually and physically built over time. Its significance and meanings were certainly created and transmitted through practices of memory construction which are representative of cultural identity and social cohesion.Le site de Bouça da Cova da Moura se trouve sur un plateau faisant face au Rio Leça. On y a identifié des tertres funéraires du Néolithique, auxquels sont associés des zones de concentration d’artefacts, incluant céramiques campaniformes, idoles et mobilier métallique. S’agissant de mobilier de surface, le contexte de ces différentes concentrations n’a pas été déterminé avec attention. Un autre fait significatif est l’apparition de gravures rupestres préhistoriques. On peut considérer le plateau comme un espace publique, qui s’est bâti physiquement et conceptuellement au cours des temps. Son importance et sa signification ont certainement été créées et transmises à travers un certain nombre de pratiques de construction mémorielle, représentatives de l’identité culturelle et de la cohésion sociale

Space of memory and representation: Bouça da Cova da Moura (Ardegães, Maia, Northwest of Portugal): a case study

Bouça da Cova da Moura is the local place-name attributed to a stretch of a plateau overlooking the Leça valley. Here, Neolithic burial mounds share their landscape setting with scatters of archaeological materials that include Bell Beaker fragments, idols and metalwork. Since these are mostly surface findings, their contexts have not yet been accurately determined. Another significant feature is the presence of prehistoric rock carvings. The plateau may thus be considered a public space, conceptually and physically built over time. Its significance and meanings were certainly created and transmitted through practices of memory construction which are representative of cultural identity and social cohesion.Le site de Bouça da Cova da Moura se trouve sur un plateau faisant face au Rio Leça. On y a identifié des tertres funéraires du Néolithique, auxquels sont associés des zones de concentration d’artefacts, incluant céramiques campaniformes, idoles et mobilier métallique. S’agissant de mobilier de surface, le contexte de ces différentes concentrations n’a pas été déterminé avec attention. Un autre fait significatif est l’apparition de gravures rupestres préhistoriques. On peut considérer le plateau comme un espace publique, qui s’est bâti physiquement et conceptuellement au cours des temps. Son importance et sa signification ont certainement été créées et transmises à travers un certain nombre de pratiques de construction mémorielle, représentatives de l’identité culturelle et de la cohésion sociale.info:eu-repo/semantics/publishedVersio

Análise da expansão da agricultura de grãos na região de Santarém e Belterra, Oeste do estado do Pará.

The images obtained from orbital platforms have been used for the analysis of many occupation processes of the Amazon region along the years. Nevertheless, analyses that have only one date of passage portray just a point in time and, for that, do not explain the occupation process of the region. The evolution of the mechanical agriculture in the towns of Belterra and Santarém, in the west side of Pará state, is causing a series of conflicts between the producers and the environmental movements because of the hypothesis of the expansion of the cultivated area in detriment of the areas of forest formation. Through a time series analysis that uses images from the sensors MSS and TM Landsat from 1975, 1986, 1997, 1999, 2004 and 2005, using digital classification and an intense field work, it was possible to observe the dynamic of the use and the discovery of the land. The results show that there was a reduction of 25% of the forest in the last 30 years. Although the main landscape is the forest formation, it was found that the use of the land with the most occupied area are the regions destinated to the agriculture and cattle activities and which are related to the producers of different levels of technology who try to combine a series of productive systems, aiming the diversity of the natural resources. In addition, it was possible to observe that, unlike other regions in the Amazon, the areas of secondary vegetation presented a high growth in the analyzed time period. Finally it is noticed that the culture of grains was implemented, mostly, in areas that were altered and used for pasture, secondary vegetation and agriculture and livestock activities (related to small and medium producers), having been converted a total of 435 km2 of forest from the year of 1999 to 2004, representing 8% of the total planted area in that year. Although we notice a smaller impact in the environmental context, the direct conversion of the agriculture and livestock class into the grain plantation seems to indicate a process of land concentration and migration of smallholder farmers to the urban areas and/ or new fronts of occupation. This social impact, already observed in Santarém suburbs, should be object of study for the government, mainly concerning the elaboration and implementation of a specific agricultural politics for the Amazon and should enable the smallholder farmer the maintenance of his land and food production