69 research outputs found

    Contrasting species and functional beta diversity in montane ant assemblages

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    Aim Beta diversity describes the variation in species composition between sites and can be used to infer why different species occupy different parts of the globe. It can be viewed in a number of ways. First, it can be partitioned into two distinct patterns: turnover and nestedness. Second, it can be investigated from either a species identity or a functional-trait point of view. We aim to document for the first time how these two aspects of beta diversity vary in response to a large environmental gradient. Location Maloti-Drakensberg Mountains, southern Africa. Methods We sampled ant assemblages along an extensive elevational gradient (900–3000 m a.s.l.) twice yearly for 7 years, and collected functional-trait information related to the species’ dietary and habitat-structure preferences. We used recently developed methods to partition species and functional beta diversity into their turnover and nestedness components. A series of null models were used to test whether the observed beta diversity patterns differed from random expectations. Results Species beta diversity was driven by turnover, but functional beta diversity was composed of both turnover and nestedness patterns at different parts of the gradient. Null models revealed that deterministic processes were likely to be responsible for the species patterns but that the functional changes were indistinguishable from stochasticity. Main conclusions Different ant species are found with increasing elevation, but they tend to represent an increasingly nested subset of the available functional strategies. This finding is unique and narrows down the list of possible factors that control ant existence across elevation. We conclude that diet and habitat preferences have little role in structuring ant assemblages in montane environments and that some other factor must be driving the non-random patterns of species turnover. This finding also highlights the importance of distinguishing between different kinds of beta diversity

    Freeze-drying of Aegyptianella pullorum

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    Heparinized whole blood, parasitized with Aegyptianella pullorum, was collected from 2 fowls. Buffered lactose peptone (BLP) was added v/v as a stabilizer and the mixture lyophilized in 2ml aliquots after rapid or slow freezing. At different stages during the freeze-drying process, as well as after lyophilization and reconstitution with I ,8 ml of sterile water, samples were taken and injected into pullets. Infectivity was maintained throughout. However, the prepatent period was lengthened after freezing and particularly after lyophilization when there was some loss of viability.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

    Distribution mapping of specialized amphibian species in rare, ephemeral habitats: implications for the conservation of threatened “acid” frogs in south-east Queensland

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    The acid frogs of eastern Australia are a highly specialized group of threatened species endemic to acidic coastal wetlands of southern Queensland and New South Wales. The distribution of these species overlaps with areas of increasing development where land-use intensification poses a significant threat. Successful conservation of these species requires that areas of high conservation value for acid frogs are properly identified and protected, particularly in south-east Queensland which supports important populations of all four acid frog species: Litoria olongburensis, Litoria freycineti, Crinia tinnula, and the Queensland-endemic Litoria cooloolensis. Species distribution modeling using rigorously vetted species occurrence data was used to identify areas of potential acid frog habitat with >89% predictive power for all species. Key predictor variables for acid frog species occurrence included: soil sandiness, vegetation, presence and/or type of wetland, and soil clay content. All species' predicted distributions occurred primarily in coastal regions, overlapping with densely human-populated areas. Our modeling and analysis of species' distributions highlight local government areas where protection of wallum habitat is most important for the conservation of acid frogs, as well as areas of higher conservation value providing habitat for multiple acid frog species

    Elevation–diversity patterns through space and time: ant communities of the Maloti-Drakensberg Mountains of southern Africa

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    Aim Patterns of biological diversity are often investigated across space but little work has attempted to explore the consistency of such observations through time. Here, our aim was to understand the patterns of diversity for a functionally critical taxon, the ants (Hymenoptera: Formicidae), through space and time using an extensive dataset collected across an elevational gradient. In addition, we evaluated the importance of two key postulated drivers of elevational diversity patterns: temperature and available area. Location The Maloti-Drakensberg Mountains of southern Africa. Methods We sampled epigaeic ant communities biannually for 7 years (2006–2012) at eight different elevational sites. We then used an information theoretic approach combined with generalized linear mixed models to: (1) describe diversity patterns through space and time; (2) assess the importance of different abiotic drivers; and (3) understand how much spatio-temporal variation can be explained by these drivers. Simple regression approaches were also used to test for differences in seasonal variation along the elevational gradient. Results We found clear mid-elevational peaks of species density and evenness measures. Abundance patterns were complex. The spatial distributions of all three metrics changed across seasons and years. Temperature variables had important roles in explaining both species density and abundance patterns, whilst species density was also influenced by available area. In conjunction, we found much greater seasonal variability in species density at low elevations. This variation was independent of differences in species pool size. Main conclusions We found patterns of ant diversity that are strongly modulated by temporal change. There was a consistent and strong signature of seasonality on the elevation–diversity patterns of the ants, whilst annual changes throughout the study period had a weaker influence. We conclude that both spatial and temporal patterns are driven primarily by temperature, with only a weak influence of available elevational area. This study is the first to describe the spatio-temporal distribution of a suite of community-level metrics along an elevational gradient and implies that temporal variation should be considered more carefully in studies of invertebrate diversity, particularly with respect to elevation and the mechanisms that may be maintaining diversity patterns
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