Avaliação da ameaça de erosão hídrica na ilha da Madeira - Portugal

Na estimativa da erosão hídrica na ilha da Madeira aplicou-se a Equação de Wischmeier. Recorreu-se a relações para estimar a erosividade (R); foi adequado o Índice Modificado de Fournier e relação IMF/R. cartografada a erosividade os restantes parâmetros resultaram da metodologia. IMF varia entre 81.0–465.0 mm. A equação R = 1.365 IMF1.408 estima a erosividade anual precipitação, com dados de Funchal-Observatório, sul de Portugal e valores da literatura, obtendo-se R ≈ 2 964 MJ mm h−1 ha−1 ano−1, variando entre 660- 8515. Erosão média é 28 t ha−1 ano−1, excedendo 100 em >4.9% da área. A ameaça de erosão adveio da divisão do volume de solo dos horizontes mobilizáveis, pela erosão anual. O resultado -número de anos- que ocorre a perda do solo de cobertura. Apesar do tempo para esgotamento do solo, ser >20 000 anos, a ameaça de erosão, alta e muito alta, é relevante. Estas ameaças (depleção <100 anos) ocorrem em 263 km2 (35.6%); na ameaça muito alta (depleção em <10 anos) a área é ≈40 km2 (5.4%). Encostas com declives muito elevados estão associadas a ameaças altas (ou muito altas). Efetuouse a análise da precipitação 20 de Fevereiro, obtendo-se um período de retorno superior a 100 anos.info:eu-repo/semantics/publishedVersio

Resolving the ancestry of Austronesian-speaking populations

There are two very different interpretations of the prehistory of Island Southeast Asia (ISEA), with genetic evidence invoked in support of both. The “out-of-Taiwan” model proposes a major Late Holocene expansion of Neolithic Austronesian speakers from Taiwan. An alternative, proposing that Late Glacial/postglacial sea-level rises triggered largely autochthonous dispersals, accounts for some otherwise enigmatic genetic patterns, but fails to explain the Austronesian language dispersal. Combining mitochondrial DNA (mtDNA), Y-chromosome and genome-wide data, we performed the most comprehensive analysis of the region to date, obtaining highly consistent results across all three systems and allowing us to reconcile the models. We infer a primarily common ancestry for Taiwan/ISEA populations established before the Neolithic, but also detected clear signals of two minor Late Holocene migrations, probably representing Neolithic input from both Mainland Southeast Asia and South China, via Taiwan. This latter may therefore have mediated the Austronesian language dispersal, implying small-scale migration and language shift rather than large-scale expansion

Structure and regional representativeness of the herpetofauna from Parque Estadual da Serra de Caldas Novas, Cerrado, Central Brazil

Amphibians and reptiles are diversified in the Cerrado biome but have been threatened by habitat loss and fragmentation, as well as lack of understanding of their distribution. Therefore, collection and organization of information about species in natural environments are essential for conservation, especially in Protected areas (PAs) and their adjacent zones. We present information about the composition and structure of the herpetofauna from Parque Estadual da Serra de Caldas Novas (PESCAN) and its representativeness in comparison to other PAs in the Cerrado. Fieldwork was conducted in 12 sampling sites from February 2009 to February 2010, using active search and pitfall traps. We recorded 41 species of amphibians, with greatest richness in sites with open vegetation and water bodies. Reptiles were represented by 32 species, with the greatest species richness in cerrado open environments. Both amphibian and reptile communities were more similar to those from geographically closer PAs and located in the central region of the Cerrado (State of Goiás and Distrito Federal). The PESCAN holds 24.85% and 17.98% of amphibians and reptiles species occurring in Cerrado PAs, respectivelly. This large representativeness and the high number of endemisms (18 amphibians and 7 reptiles) emphasize the importance of the PESCAN, together with other PAs, for the maintenance of regional biodiversity. In addition, we also encourage researches evaluating amphibian and reptile communities outside PAs, such as legal reserves, and we suggest new approaches to study the biodiversity of protected areas. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group

Papuan mitochondrial genomes and the settlement of Sahul

New Guineans represent one of the oldest locally continuous populations outside Africa, harboring among the greatest linguistic and genetic diversity on the planet. Archeological and genetic evidence suggest that their ancestors reached Sahul (present day New Guinea and Australia) by at least 55,000 years ago (kya). However, little is known about this early settlement phase or subsequent dispersal and population structuring over the subsequent period of time. Here we report 379 complete Papuan mitochondrial genomes from across Papua New Guinea, which allow us to reconstruct the phylogenetic and phylogeographic history of northern Sahul. Our results support the arrival of two groups of settlers in Sahul within the same broad time window (50–65 kya), each carrying a different set of maternal lineages and settling Northern and Southern Sahul separately. Strong geographic structure in northern Sahul remains visible today, indicating limited dispersal over time despite major climatic, cultural, and historical changes. However, following a period of isolation lasting nearly 20 ky after initial settlement, environmental changes postdating the Last Glacial Maximum stimulated diversification of mtDNA lineages and greater interactions within and beyond Northern Sahul, to Southern Sahul, Wallacea and beyond. Later, in the Holocene, populations from New Guinea, in contrast to those of Australia, participated in early interactions with incoming Asian populations from Island Southeast Asia and continuing into Oceania