Browsing by Author "Chimimba, C. T."

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    Food web properties vary with climate and land use in South African streams
    (Wiley Online, 2020) Jackson, M. C.; Fourie, H. E.; Dalu, T.; Woodford, D. J.; Wasserman, R. J.; Zengeya, T. A.; Ellender, B. R.; Kimberg, P. K.; Jordaan, M. S.; Chimimba, C. T.; Weyl, O. L. F.
    Land use intensification and climate change are two prominent drivers of variation in biological communities. However, we know very little about how these two potential environmental stressors interact. Here we use a stable isotope approach to quantify how animal communities respond to urban and agriculture land use, and to latitudinal variation in climate (rainfall and temperature), in 29 streams across South Africa. Community structure was shaped by both land use and climatic factors. The taxonomic diversity of invertebrates was best explained by an independent negative effect of urbanization, while abundance declined in summer. However, we could not use our variables to predict fish diversity (suggesting that other factors may be more important). Both trophic functional diversity (quantifed usingisotopic richness) and food chain length declined with increasing temperature. Functional redundancy (quantifed usingisotopic uniqueness) in the invertebrate community was high in wet areas, and a synergistic interaction with urbanization caused the lowest values in dry urban regions. There was an additive effect of agriculture and rainfall on abundance-weighted vertebrate functional diversity (quantified usingisotopic dispersion), with the former causing a decline in dispersion, with this partially compensated for by high rainfall. In most cases, we found that a single dominant driver (either climate or land use) explained variation between streams. We only found two incidences of combined effects improving the model, one of which was amplified (i.e. the drivers combined to cause an effect larger than the sum of their independent effects), indicating that management should first focus on mitigating the dominant stressor in stream ecosystems for successful restoration efforts. Overall, our study indicates subtle food web responses to multiple drivers of change, only identified by using functional isotope metrics-these are a useful tool for a whole-systems biology understanding of global change. A freePlain Language Summarycan be found within the Supporting Information of this article.
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    Inter-island dispersal of flightless Bothrometopus huntleyi (Coleoptera: Curculionidae) from the sub-Antarctic Prince Edward Island archipelago
    (Cambridge University Press, 2011) Grobler, G. C.; Bastos, A. D. S.; Chimimba, C. T.; Chown, S. L.
    Bothrometopus huntleyi is a flightless weevil endemic to the volcanically-formed sub-Antarctic Prince Edward Islands archipelago that arose approximately 0.5 million years ago (m.y.a.). Since emergence, a series of volcanic and glaciation events have occurred on Marion Island, whilst Prince Edward Island, the second island constituting the archipelago, has remained largely unaffected by glaciation. Cytochrome oxidase I gene analyses indicate that major historical dispersal events in this species are linked to the geologically discrete histories of these islands and underlie the high haplotype diversity (0.995) recovered for the Prince Edward Islands archipelago. The estimated time to haplotype coalescence of ? 0.723 m.y.a. is in keeping with estimated dates of island emergence, and the majority of individuals appear to have descended from a relict, high-altitude population that is still present on Marion Island. The first major inter-island dispersal event occurred ? 0.507 m.y.a., coinciding with the oldest dated rocks on Marion Island. Apart from this early inter-island colonization, only one other between-island dispersal event was detected. The genetically discrete B. huntleyi complexes on each of the islands of the Prince Edward Islands archipelago together with the low levels of inter-island gene flow reaffirm the need to control alien invasive mice, which are restricted to Marion Island, and which prey on this weevil species. © Antarctic Science Ltd 2011.
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    A revised systematic checklist of the extant mammals of the southern African subregion
    ( Durban Natural Sciences Museum, 2003) Bronner, G. N.; Hoffmann, M.; Taylor, P. J.; Chimimba, C. T.; Best, P. B.; Matthee, C. A.; Robinson, T. J.
    ENGLISH ABSTRACT: The current paper presents a revised, annotated, systematic checklist of 351 extant mammal species, in 190 genera, currently known to occur in southern Africa (south of the Zambezi and Cunene Rivers) and its coastal waters. The checklist includes each species' scientific and English common name, details concerning original description, occurrence or possible occurrence in each o f the seven countries falling within the Subregion, and, where relevant, the IUCN global Category of Threat. Taxonomic notes, together with the relevant literature, are provided to justify the proposed classification adopted at each hierarchical level. The new classification we present is founded on the philosophy of phylogenetic systematics, and represents not only a summary o f new information, but also tremendous advances in the methods and philosophy of mammalian systematics during the past two decades.