Browsing by Issue Date, starting with "2008-10"
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- Anais de direito de asiloPublication . Rodrigues, José NoronhaNos anais da história podemos encontrar várias referências à problemática do asilo e à migração como um fenómeno transversal da História da Humanidade. Recordar e compreender estes factos sócio-jurídicos é cimentar a alavanca imprescindível para que, sustentadamente, possamos desenvolver no século XXI, uma Convenção Internacional sobre os Asilados à semelhança da Convenção de Genebra sobre o Estatuto dos Refugiados, de 1951 e/ou um Direito Único de Asilo para a União Europeia.
- Measurements of area and the (island) species-area relationship: new directions for an old patternPublication . Triantis, Kostas A.; Nogués-Bravo, David; Hortal, Joaquín; Borges, Paulo A. V.; Adsersen, Henning; Fernández-Palacios, José María; Araújo, Miguel B.; Whittaker, Robert J.The species-area relationship is one of the strongest empirical generalizations in geographical ecology, yet controversy persists about some important questions concerning its causality and application. Here, using more accurate measures of island surface size for five different island systems, we show that increasing the accuracy of the estimation of area has negligible impact on the fit and form of the species–area relationship, even though our analyses included some of the most topographically diverse island groups in the world. In addition, we show that the inclusion of general measurements of environmental heterogeneity (in the form of the so-called choros model), can substantially improve the descriptive power of models of island species number. We suggest that quantification of other variables, apart from area, that are also critical for the establishment of biodiversity and at the same time have high explanatory power (such as island age, distance, productivity, energy, and environmental heterogeneity), is necessary if we are to build up a more predictive science of species richness variation across island systems.
- Explaining the «anomalous» distribution of Echinodium Jur. (Bryopsida) : independent evolution in Macaronesia and AustralasiaPublication . Stech, Michael; Sim-Sim, Manuela; Esquível, M. Glória; Fontinha, Susana; Tangney, Ray; Lobo, Carlos; Gabriel, Rosalina; Quandt, DietmarThe peculiar disjunction between Macaronesia and Australasia of the morphologically isolated pleurocarpous moss genus Echinodium is one of the most prominent questions in bryology. Echinodium as traditionally circumscribed comprises six extant species, four restricted to the Macaronesian archipelagos and two confined to the Australasian/Pacific regions. Molecular phylogenetic analyses based on plastid trnLUAA intron and nuclear ribosomal ITS sequences indicate that Echinodium is polyphyletic and split into three groups. Three of the four Macaronesian species (E. spinosum and the single island endemics E. renauldii and E. setigerum) are closely related to each other and treated as Echinodium s.str. (Echinodiaceae). Further clarification of the relationships of Echinodium s.str. with Orthostichella, a segregate of Lembophyllaceae, is needed. The remaining Macaronesian species, E. prolixum, is transferred to Isothecium (Lembophyllaceae); this systematic position is also strongly supported by leaf characters. The two Australasian species, E. hispidum and E. umbrosum, are molecularly unrelated to the Macaronesian species and are transferred to Thamnobryum in the Neckeraceae. While the molecular data suggest that the peculiar distribution pattern of ‘Echinodium’ is an artefact, the striking morphological similarity observed in Macaronesian and Australasian species cannot be dismissed. Possible explanations are: (i) parallel morphological evolution of the ‘Echinodium habit’ in Macaronesia and Australasia, or (ii) retention of a set of plesiomorphic characters in non-related groups in relict habitats, the Macaronesian laurel forest and the austral temperate rain forests, respectively. Of these hypotheses, the evolutionary parallelism hypothesis seems more plausible for several reasons, which are discussed.