The three living species of manatees, West Indian (Trichechus manatus), Amazonian (Trichechus inunguis) and West African (Trichechus senegalensis), are distributed across the shallow tropical and subtropical waters of America and the western coast of Africa. We have sequenced the mitochondrial DNA control region in 330 Trichechus to compare their phylogeographic patterns. In T. manatus we observed a marked population structure with the identification of three haplotype clusters showing a distinct spatial distribution. A geographic barrier represented by the continuity of the Lesser Antilles to Trinidad Island, near the mouth of the Orinoco River in Venezuela, appears to have restricted the gene flow historically in T. manatus. However, for T. inunguis we observed a single expanding population cluster, with a high diversity of very closely related haplotypes. A marked geographic population structure is likely present in T. senegalensis with at least two distinct clusters. Phylogenetic analyses with the mtDNA cytochrome b gene suggest a clade of the marine Trichechus species, with T. inunguis as the most basal trichechid. This is in agreement with previous morphological analyses. Mitochondrial DNA, autosomal microsatellites and cytogenetic analyses revealed the presence of hybrids between the T. manatus and T. inunguis species at the mouth of the Amazon River in Brazil, extending to the Guyanas and probably as far as the mouth of the Orinoco River. Future conservation strategies should consider the distinct population structure of manatee species, as well as the historical barriers to gene flow and the likely occurrence of interspecific hybridization.

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-The Antillean manatee (Trichechus manatus manatus) is considered to be one of the most endangered aquatic mammals in Brazil. From 1981 through 2002 an extensive research was performed to collect information about stranding of manatees on the northeast coast of Brazil. Data were separated in two distinct periods (1981-1990 and 1991-2002) and analyzed according to specific categories: stranded dead (captured by nets, captured by harpoons and undefined cause) and stranded alive (dead in captivity and captive population). There were 74 events of stranding manatees in the period surveyed. Thirty-one events of dead manatees and 43 events of specimens that survived until December 2002 were recorded. In the last years of the study there were more strandings of alive animals than dead. The main reason for the strandings of manatee calves in northeastern Brazil is the separation from their mothers. The largest numbers of stranded manatees occurred in Ceará and Rio Grande do Norte states.Resumo -O peixe-boi marinho (Trichechus manatus manatus) é considerado um dos mamíferos aquáticos mais ameaçados do Brasil. Entre 1981 e 2002 foi realizado um extenso levantamento de informações sobre os encalhes de peixes-boi marinho na costa nordeste do Brasil. Os dados foram dispostos em dois períodos distintos (1981-1990 e 1991-2002)

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Soil compaction of different textural classes in areas of sugarcane productionThe purpose of this study was to evaluate the existence of compacted layers in three different textural classes located in production areas of sugarcane. The study was conducted in production areas of sugarcane at Fazenda Guanabara, located at municipality of New Olympia, Mato Grosso state, Brazil. Data collection was conducted using an impact penetrometer, model IAA/Planalsucar, evaluating the penetration resistance in three different texture (Loam Sandy, Sandy Clay Loam and Clay). Loam Sandy and Clay textures showed the highest penetration resistance. Loam Sandy and Clay textures behaved very similarly in all layers. There were similar values of penetration resistance of the three classes in 0.3-0.4 m layer.

R E S U M OA aplicação em solos agrícolas tem sido a principal alternativa para destinar o grande volume de dejetos líquidos suínos (DLS) gerados nos ambientes de produção. O objetivo deste trabalho foi avaliar possíveis modificações nos atributos físicos do solo decorrentes do sistema de manejo e aplicação de DLS. O estudo foi desenvolvido no município de Arapoti, PR, em agosto de 2012. Foram amostradas cinco áreas: floresta nativa, pastagem com adubação química e aplicação de DLS, plantio convencional com adubação química e aplicação de DLS, plantio direto com adubação química, plantio direto com adubação química e aplicação de DLS. Os atributos físicos do solo avaliados foram: densidade do solo (Ds), porosidade total (Pt), macroporosidade (Ma), razão macro e microporosidade (Ma/ Mi) e resistência à penetração (RP). A adoção dos diferentes sistemas de manejo agrícola alterou a qualidade física do solo elevando a Ds e a RP e reduzindo o volume de poros. O solo manejado sob pastagem apresentou os maiores valores de RP. Não foram constatadas alterações nos atributos físicos do solo pela aplicação de DLS nos diferentes sistemas de manejo avaliados. Physical quality of soil under different systems of tillage and application of pig slurry A B S T R A C TThe application in agriculture has been the main alternative to allocate the large volume of pig slurry (PS) generated in production environments. The aim of this study was to assess possible changes in physical properties of soil resulting from the management system and PS application. Five areas were sampled: native forest, pasture with mineral fertilizer and PS application, conventional tillage with mineral fertilizer and PS application, no-tillage with mineral fertilizer, no-tillage with mineral fertilizer and PS application. The evaluated physical properties of soil were: bulk density (Bd), total porosity (Pt), macroporosity (Ma), macro and microporosity ratio (Ma/Mi) and penetration resistance (PR). The adoption of different agricultural management systems altered the physical conditions of the soil, increasing the Bd and the PR and reducing the pore volume. The soil managed under pasture showed the highest values of PR. No changes were found in physical properties of soil by the application of PS in evaluated tillage systems. Palavras-chave:compactação do solo resíduos agrícolas resistência à penetração

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