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Biodiversity/Evolutionary Biology

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Browsing Biodiversity/Evolutionary Biology by Author "Poynton, John Charles."

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    An avifaunal study of Pigeon Valley Park as a biogeographic island in an urban area with special reference to the Natal Robin (Cossypha natalensis Smith)
    (1992) Boon, Richard Graham Campbell.; Poynton, John Charles.
    Pigeon Valley Park, on Durban's Berea Ridge, is an approximately 10-ha remnant of coastal forest, which is totally surrounded by suburban housing and roads. As such it is ideal as a study area for investigating the applicability of the MacArthur-Wilson Theory of Island Biogeography (1963,1967) and Diamond's (1975) geometric reserve-design principles to fragmented Coastal Forests in Durban. This study began in January 1989 and the results are reported as at October 1992. Field notes from as far back as 1981 were used to augment the findings of the current work. Research focused on the forest-dwelling, Natal Robin Cossypha natalensis, and territory mapping showed that the reserve supports up to 53 individuals during the breeding season. An annotated checklist and its comparison to historical and regional checklists revealed where localised extinctions may have occurred, and thus identifies a set of coastal forest species which are susceptible to habitat fragmentation. Work on two potential dispersal corridors for bird movement into and out of the valley showed that the reserve is not yet fully isolated to most species which are currently present. On the other hand, there are some forest species which have isolated populations at Pigeon Valley Park, as well as others which do not seem able to establish and maintain viable populations. A set of 'indicator', forest bird species which are susceptible to habitat fragmentation, is defined. Practical management suggestions with the aim of increasing the long-term viability of the area as an avifaunal preserve, are presented.
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    The herpetofauna of the Orange Free State : with special emphasis on biogeographical patterning.
    (1992) Bates, Michael Francis.; Poynton, John Charles.
    The taxonomic status, distribution and ecology of the herpetofauna of the Orange Free State are discussed, based on the examination of 10 096 specimens housed in various southern African museums. The majority of specimens were collected during the years 1972 - 1978 and 1983 - 1992, and are housed at the National Museum, Bloemfontein. A total of 25 amphibian and 95 reptilian (one translocated species) forms have been determined as occurring in the Orange Free State, 12 (three amphibians, nine reptiles) of which are new (or recently published) records for the province. An additional 10 amphibian and 28 reptilian forms have been determined as occurring nearby but extralimitally to the O.F.S., and several of these forms are expected to occur in the province. New distributional records have resulted in the amendment of the ranges of several species. Detailed taxonomic data on new material, including rare species, have been given. Some problem areas in the taxonomy of O.F.S. taxa have been higlighted. An analysis of habit utilization indicated that 84,0% of amphibians and 61,1% of reptiles are terricolous, whereas up to 21,5% of reptiles are rupicolous. The majority of snakes (72,2%) are terrestrial in habits, but 13,9% are fossorial. More than half of all lizards (52,8%) are terrestrial, although 34,6% are rupicolous. A total of six amphibian and 27 reptile forms utilize inactive termitaria as a microhabitat, including several basically terrestrial forms. Snake forms were particularly well represented in termitaria, 60,6% of all forms known from the O.F.S. having been recorded from inactive termitaria. General features of the ecology of O.F.S. amphibians and reptiles have also been discussed. The biogeographical analysis indicated that O.F.S. amphibian forms can be classified into one of nine range clusters (common patterns of distribution), and reptiles into 13 such cluster groups. By testing these classifications by means of a transect through the northern O.F.S. (from eastern to western borders), it was determined that a fairly distinct east-west subtraction of amphibian and reptilian species and subspecies occurs in the O.F.S. Clustering of range boundaries and high species and subspecies diversity at the western and eastern ends of the transect zone suggest dynamic biogeographical situations occurring in those areas - the western group being associated with the transition from grassland to bushveld, and the eastern group associated with the transition from Highveld Grassland to Drakensberg Mountains. The general eastern and western groupings of taxa appear to be associated with the cooler, wetter and mountainous east vs the warmer, drier and lower-lying west, respectively. Despite a great deal of collecting having been conducted in the O.F.S. from 1972 to 1992, an analysis of the number of taxa collected in each quarter-degree unit in the O.F.S. indicated that additional collecting would be required in order to conduct effectively a mathematically-based biogeographical analysis.
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    A herpetofaunal survey of Swaziland.
    (1992) Boycott, Richard Charlton.; Poynton, John Charles.
    The present report, based on a survey conducted over four years and on the accumulation of museum records, provides the most detailed documentation yet of the herpetofauna of Swaziland. One hundred and two new forms are recorded from the country bringing the total number of forms to 154, consisting of 44 amphibians and 110 reptiles. Up-to-date checklists of the amphibians and reptiles are presented and effectively indicate a rich and diverse herpetofauna. The biogeography of the Swaziland herpetofauna is discussed based on distribution records derived from collected specimens as well as reliable sight and audio records. Swaziland does not constitute a distinctive biogeographical unit. The present study indicates that the herpetofauna shows affinities with both the Afrotemperate and Afrotropical biomes. The traditional biogeographical classification in southern Africa, of the presence of a Cape temperate fauna and a tropical East African lowland fauna, is tested by means of a transect and is reinforced. It is also shown that Swaziland, together with Natal and southern Mozambique, forms an integral part of the tropical subtraction zone of south-east Africa. Amphibian diversity and species turnover in southern Africa are investigated by means of a transect from the east coast, through Swaziland, to the interior plateau, and a north to south transect down the eastern lowveld. The Dice-Sorenson Similarity index gives a value of 41% for the entire east-west transect and 89% for the north-south transect. The conservation status of the amphibians and reptiles of Swaziland is discussed. Conservation measures are proposed.