31 research outputs found

    Elevation drives taxonomic, functional and phylogenetic β-diversity of phyllostomid bats in the Amazon biome

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    Aim: We evaluated the relative importance of geographical and environment variables for taxonomic, phylogenetic and functional β-diversity of phyllostomid bats along the entire Amazon biome and specifically in the lowlands. Location: Amazon biome. Taxon: Chiroptera. Methods: We carried out a bibliographic review and compiled a wide and unprecedented database of 106 phyllostomid bat species at 102 sites throughout the Amazon biome. For all possible pairs of sites in both datasets, we estimated the Jaccard pairwise dissimilarity, that is, β-diversity, considering its three dimensions—taxonomic, phylogenetic and functional—for its two components—turnover (substitution of species) and differences in species richness. The association between dissimilarity measurements and geographical and environment variables was assessed using multiple regressions on distance matrices (MRM). Results: We found that turnover and differences in species richness had similar contributions to the taxonomic β-diversity. However, for phylogenetic and functional β-diversity, lineages and functions richness differences contribute slightly more than turnover for total β-diversity. In the lowlands, species, lineages and functions richness differences were slightly higher than turnover for all diversity dimensions. When accounting for all the sites, elevation was the main predictor of phyllostomid bats' taxonomic, phylogenetic and functional turnover. For lowland sites, ecoregions was the main (but relatively weak) predictor associated with all β-diversity dimensions. Main conclusions: Analysis of filtering sites according to elevation revealed that species in the Amazonian lowlands are taxonomically and phylogenetically different from species in the Andes, and present taxonomic, phylogenetic and functional redundancy between assemblages. When accounting for the whole range of distribution of bats, results showed the predominant effect of elevation over other geographical and environmental predictors. This indicates that the diversity of good dispersers such as bats is more affected by specialisation along environment and climatic gradients than by geographical barriers throughout the Amazon biomeBat Conservation International; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; National Geographic Society; Neotropical Grassland Conservancy; Rufford Foundatio

    The role of environmental filtering, geographic distance and dispersal barriers in shaping the turnover of plant and animal species in Amazonia

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    To determine the effect of rivers, environmental conditions, and isolation by distance on the distribution of species in Amazonia. Location: Brazilian Amazonia. Time period: Current. Major taxa studied: Birds, fishes, bats, ants, termites, butterflies, ferns + lycophytes, gingers and palms. We compiled a unique dataset of biotic and abiotic information from 822 plots spread over the Brazilian Amazon. We evaluated the effects of environment, geographic distance and dispersal barriers (rivers) on assemblage composition of animal and plant taxa using multivariate techniques and distance- and raw-data-based regression approaches. Environmental variables (soil/water), geographic distance, and rivers were associated with the distribution of most taxa. The wide and relatively old Amazon River tended to determine differences in community composition for most biological groups. Despite this association, environment and geographic distance were generally more important than rivers in explaining the changes in species composition. The results from multi-taxa comparisons suggest that variation in community composition in Amazonia reflects both dispersal limitation (isolation by distance or by large rivers) and the adaptation of species to local environmental conditions. Larger and older river barriers influenced the distribution of species. However, in general this effect is weaker than the effects of environmental gradients or geographical distance at broad scales in Amazonia, but the relative importance of each of these processes varies among biological groups

    Quantitative (stereological) And Qualitative Study Of Rat Epididymis After Vasectomy And Percutaneous Epididymal Sperm Aspiration.

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    We investigated whether viable spermatozoa could be obtained from the rat epididymis after vasectomy by up to 5 percutaneous epididymal sperm aspiration punctures. We analyzed the inflammatory and scar forming histological alterations to the epididymis due to these punctures. Epididymal smooth muscle fiber and collagen density were also analyzed. A total of 50 rats that underwent bilateral vasectomy were divided into 5 groups of 10 each. Groups 1 to 5 underwent 1 to 5 right transscrotal percutaneous epididymal sperm aspiration punctures, respectively. Sperm quantification, and histological and stereological analyses were done on the punctured epididymides. A mean of 48.78 x 10(6), 37.55 x 10(6), 26.33 x 10(6), 33.90 x 10(6) and 41.34 x 10(6)/ml spermatozoa were recovered in groups 1 to 5, respectively. A cumulative effect of the punctures was only observed in the variables of lymphoplasmacytic infiltrate and fibrosis, thus, showing that groups 1 and 2 differed significantly from groups 3 to 5. Stereological analysis revealed that conjunctive tissue volumetric density was 21.56%, 27.60%, 35.67%, 37.56%, 38.60% and 22.30% on the punctured side in groups 1 to 5 and controls, respectively (p <0.05). Spermatozoa were obtained from all groups. All animals showed significant histological alterations in the epididymides from the second puncture and thereafter except with regard to necrosis. The cumulative effect of percutaneous epididymal sperm aspiration was only shown by lymphoplasmacytic infiltrate and fibrosis. Stereological analysis showed increased conjunctive tissue volumetric density from the second puncture and thereafter.179381-
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