Springtail diversity in the Cape floristic region

[摘要] ENGLISH ABSTRACT: Understanding the distribution, abundance and diversity of species and the mechanismscausing these patterns has been the interest of ecologists and taxonomists for decades. Theexceptionally high plant diversity in the Fynbos biome has been well studied. Whilst earlyarguments suggested that the high plant diversity is not reflected in the arthropod diversityand that insect species richness is low compared to other comparable areas, theseobservations might have been hampered by the taxonomic impediment. Despite globalrecognition of the significance of this below-ground component of diversity for ecosystemfunctioning, soil is one of the most poorly studied habitats of terrestrial ecosystems.Although knowledge is increasing for epigaeic groups, other significant groups such as theCollembola remain especially poorly understood. This thesis starts addressing this seriousgap in knowledge concerning the below-ground component of biodiversity in the Fynbosbiome and the effects of landscape transformation thereon. As part of the work,considerable attention was given to resolving the taxonomic impediment for the springtailfauna of the Fynbos biome using modern morphological and DNA barcoding methods, whilealso examining the correlates of soil animal diversity in the biome, by using Collembola(springtails) as exemplars. First, using a combination of published records of Collembolafrom South Africa, various sampling methods and DNA barcoding, a species list is compiledfor the Western Cape. Currently 213 species are known to exist from the Western Cape. Ahigh level of cryptic diversity was also found in several genera, together with severalpotential species radiations in the Ectonura, Seira, Parisotoma and Cryptopygus. A start is amade at addressing the lack of taxonomic knowledge by describing five new species. TwoEctonura Cassagnau 1980 species are described from Betty's Bay and Grootvadersboschrespectively and a key to the Neanurinae of South Africa is provided. The first record of thegenus Triacanthella Schäffer, 1897 is described from a cave in Table Mountain, while twonew species of Delamarephorura are described and the genera Spicatella Thibaud 2002 andDelamarephorura Weiner & Najt 1999 are synonymized. Although fire is thought to be themain form of decomposition in the Fynbos biome, recent work has shown that biologicaldecomposition may be more important than previously thought. I examine the resilience ofCollembola after a large-scale fire in Jonkershoek Nature Reserve using quantitativesampling which is temporally replicated. The resilience of invertebrate fauna in the fynbos isnot well understood, thus I investigate the diversity of Collembola before and after a majorfire. 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 Capeusing different litter types. Here, a total of 113 morphospecies species was found. Localrichness was found to be highest in Kogelberg (32 species), while the turnover between siteswas also high. Thus, the degradation of local habitat patches will be as much of a threat toCollembola as to the endemic plants in this region.

[发布机构] Stellenbosch University