Department of Botany and Zoology

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Browsing Department of Botany and Zoology by browse.metadata.advisor "Bengtsson, Jan"

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    Springtail diversity in the Cape floristic region
    (Stellenbosch : Stellenbosch University, 2013-03) Janion, Charlene; Scheepers, Charlene; Chown, Steven L.; Bengtsson, Jan; Deharveng, Louis; Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology.
    ENGLISH ABSTRACT: Understanding the distribution, abundance and diversity of species and the mechanisms causing these patterns has been the interest of ecologists and taxonomists for decades. The exceptionally high plant diversity in the Fynbos biome has been well studied. Whilst early arguments suggested that the high plant diversity is not reflected in the arthropod diversity and that insect species richness is low compared to other comparable areas, these observations might have been hampered by the taxonomic impediment. Despite global recognition of the significance of this below-ground component of diversity for ecosystem functioning, soil is one of the most poorly studied habitats of terrestrial ecosystems. Although knowledge is increasing for epigaeic groups, other significant groups such as the Collembola remain especially poorly understood. This thesis starts addressing this serious gap in knowledge concerning the below-ground component of biodiversity in the Fynbos biome and the effects of landscape transformation thereon. As part of the work, considerable attention was given to resolving the taxonomic impediment for the springtail fauna of the Fynbos biome using modern morphological and DNA barcoding methods, while also examining the correlates of soil animal diversity in the biome, by using Collembola (springtails) as exemplars. First, using a combination of published records of Collembola from South Africa, various sampling methods and DNA barcoding, a species list is compiled for the Western Cape. Currently 213 species are known to exist from the Western Cape. A high level of cryptic diversity was also found in several genera, together with several potential species radiations in the Ectonura, Seira, Parisotoma and Cryptopygus. A start is a made at addressing the lack of taxonomic knowledge by describing five new species. Two Ectonura Cassagnau 1980 species are described from Betty’s Bay and Grootvadersbosch respectively and a key to the Neanurinae of South Africa is provided. The first record of the genus Triacanthella Schäffer, 1897 is described from a cave in Table Mountain, while two new species of Delamarephorura are described and the genera Spicatella Thibaud 2002 and Delamarephorura Weiner & Najt 1999 are synonymized. Although fire is thought to be the main form of decomposition in the Fynbos biome, recent work has shown that biological decomposition may be more important than previously thought. I examine the resilience of Collembola after a large-scale fire in Jonkershoek Nature Reserve using quantitative sampling which is temporally replicated. The resilience of invertebrate fauna in the fynbos is not well understood, thus I investigate the diversity of Collembola before and after a major fire. Results show Collembola species richness and abundance recovered surprisingly quickly after the fire. On a larger scale, litterbags were deployed at six sites across the Western Cape using different litter types. Here, a total of 113 morphospecies species was found. Local richness was found to be highest in Kogelberg (32 species), while the turnover between sites was also high. Thus, the degradation of local habitat patches will be as much of a threat to Collembola as to the endemic plants in this region.