Browsing by Author "Measey, G John"

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    The conservation genetics of a newly recognised Cape Peninsula endemic Rose's Mountain toad (Capensibufo rosei)
    (2012) Cressey, Emily R; Tolley, Krystal A; Measey, G John
    Declines and losses of amphibian populations are a global problem involving a complexity of interacting causes. Regardless of the fact that amphibians in Africa are among those predicted to be hit the hardest by anthropogenic global change, many species remain poorly studied. Capensibufo rosei, Rose's Mountain Toad, is a restricted range species that survives in a few small, isolated montane populations in the extreme south-western Cape of South Africa. A recent study of the genus revealed that C. rosei may in fact comprise several cryptic species, with a distinctive lineage potentially being confined to the Cape Peninsula. I test the hypothesis that breeding sites on the Peninsula form a single genetic lineage, but are distinct at a population level due to limited dispersal abilities and little if any gene flow.
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    Frog eat frog: exploring variables influencing anurophagy
    (2015) Measey, G John; Vimercati, Giovanni; de Villiers, F André; Mokhatla, Mohlamatsane M; Davies, Sarah J; Edwards, Shelley; Altwegg, Res
    Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested.
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    Migration and dispersal of the western leopard toad (amietophrynus pantherinus) in a fragmented agricultural landscape
    (2012) Doucette-Riise, Stephen; Measey, G John
    Habitat alteration, primarily associated with human expansion and consumption, has been identified as the leading threat to biodiversity worldwide. The net result of an ever increasing human population is the loss of available habitat to species, affecting individual survival, together with the fragmentation of habitat across a landscape, resulting in an increased chance of a genetic bottlenecks and localized extinction. Although many organisms are experiencing the deleterious effects of these processes, amphibians appear to be suffering more than other vertebrate groups. One species that has experienced significant impact through habitat alteration and urbanization is the Western Leopard Toad (Bufonidae: Amietophrynus pantherinus). In the south-western portion of the Western Cape Province, South Africa, the population is large and genetically diverse with numerous potential breeding sites. However, extinctions in the disjunt eastern area, where there are a low number of known breeding sites (currently 7 identified), have raised concern over the conservation of this management unit. In this study radio-telemetry and population genetic data were used to investigate fine scale, short term migration patterns in Western Leopard Toads to specifically assess the role of agricultural land-use and habitat fragmentation on long-term dispersal dynamics.
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    Mind the gaps: investigating the cause of the current range disjunction in the Cape Platanna, Xenopus gilli (Anura: Pipidae)
    (2013) Fogell, Deborah J; Tolley, Krystal A; Measey, G John
    Low-lying areas of the Cape at Africa’s south-westernmost tip have undergone dramatic marine-remodelling, with regular changes in sea-level following glacial cycles. Species for which marine barriers are impenetrable underwent concomitant radical distribution changes which may account for current range disjunctions. The Cape platanna, Xenopus gilli, is a frog distributed in only three disjunt areas within low-lying regions of the southwestern Cape. We determined the relationship between frogs from these three disjunct areas, by using a combination of morphometric analysis and mtDNA (ND2 and 16S fragments) sequences of 130 frogs from eight ponds. Coalescent analyses on molecular data dated the divergence in two major clades to around 4.6 Mya, a period during which major uplifting on the eastern side of the subcontinent caused climate changes throughout southern Africa. Principal components analysis showed significant morphometric differences between each clade on head and limb measurements. Consistent differences in ventral colouration and patterning were also observed. We report on increased levels of hybridisation with X. laevis throughout the range of X. gilli, which reaches at least 27% hybrids in some ponds. Urgent conservation actions are required to control habitat loss from alien invasive vegetation, and prevent introgression with the domestic-exotic, X. laevis.