Browsing by Author "Jansen van Vuuren, Bettine"

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    Population genetics of Ceratitis capitata in South Africa : implications for dispersal and pest management
    (Public Library of Science -- PLoS, 2013-01) Karsten, Minette; Jansen van Vuuren, Bettine; Barnaud, Adeline; Terblanche, J. S.
    The invasive Mediterranean fruit fly (medfly), Ceratitis capitata, is one of the major agricultural and economical pests globally. Understanding invasion risk and mitigation of medfly in agricultural landscapes requires knowledge of its population structure and dispersal patterns. Here, estimates of dispersal ability are provided in medfly from South Africa at three spatial scales using molecular approaches. Individuals were genotyped at 11 polymorphic microsatellite loci and a subset of individuals were also sequenced for the mitochondrial cytochrome oxidase subunit I gene. Our results show that South African medfly populations are generally characterized by high levels of genetic diversity and limited population differentiation at all spatial scales. This suggests high levels of gene flow among sampling locations. However, natural dispersal in C. capitata has been shown to rarely exceed 10 km. Therefore, documented levels of high gene flow in the present study, even between distant populations (.1600 km), are likely the result of human-mediated dispersal or at least some form of long-distance jump dispersal. These findings may have broad applicability to other global fruit production areas and have significant implications for ongoing pest management practices, such as the sterile insect technique.
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    Western Zambian sable : are they a geographic extension of the giant sable antelope
    (South African Wildlife Management Association, 2010-04) Jansen van Vuuren, Bettine; Robinson, Terence J.; VazPinto, Pedro; Estes, Richard; Matthee, Conrad A.
    The giant sable (Hippotragus niger variani) is one of Africa's most spectacular large antelope. Years of civil unrest in Angola, a highly localized distribution and Interbreeding with its congener the roan antelope (H. equinus) has led to this subspecies being considered as critically endangered. Sable antelope occurring ∼600 km to the east in western Zambia superficially resemble giant sable in phenotype, prompting speculation in the popular media that the distribution of giant sable may be larger than currently documented. Our aim here was to Investigate the evolutionary placement of western Zambian sable using mitochondrial DNA control region data. Phylogenese analyses (maximum likelihood and Bayesian analyses) supported the monophyly of H. n. variant (Bayesian posterior probability of >0.95, bootstrap support >80%) and nested the western Zambian sable within H. n. niger. This finding was supported by an analysis of molecular variance that discretely grouped western Zambian sable from giant sable (ΦST = 0.645, P = 0.001). Significant genetic structure was also found across the range of H. n. nigera as Indicated by our phylogenetic analyses and analysis of molecular variance (ΦST = 0.418, P = 0.001). We conclude that although the western Zambian sable antelope and those of H. n. variani resemble one another in morphology, particularly with respect to facial markings, significant genetic differences underpin these two evolutionary lineages. Our findings hold Implications for the conservation of sable and highlight the need for active management Intervention.