Springtail diversity in the Cape floristic region

Janion, Charlene ; Scheepers, Charlene (2013-03)

Thesis (PhD)--Stellenbosch University, 2013.

Thesis

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.

AFRIKAANSE OPSOMMING: Begrip van die verspreiding, spesierykheid en verskeidenheid van spesies en die meganismes wat hierdie patrone veroorsaak is al die belangstelling van ekoloë en taksonome vir dekades. Die buitengewoon hoë plant diversiteit in die Fynbos-bioom is goed bestudeer. Terwyl vroeë argumente voorstel dat die hoë plantdiversiteit nie weerspieël word in die geleedpotige diversiteit nie en dat insekspesierykheid laag is in vergelyking met ander gebiede, kon hierdie waarnemings nie gemaak word nie as gevolg van taksonomiese hindernisse. Ten spyte van die wêreldwye erkenning van die belangrikheid van hierdie ondergrondse komponent van diversiteit vir die funksionering van die ekosisteem, is die grond een van die swakste bestudeerde habitatte van terrestriële ekosisteme. Alhoewel kennis vermeerder vir bogrondse groepe, word ander belangrike groepe soos die Collembola swak verstaan. Hierdie tesis begin hierdie ernstige leemte in kennis aanspreek, met betrekking tot die ondergrondse komponent van biodiversiteit in die Fynbos bioom en die gevolge van die landskap transformasie daarop. As deel van die werk, is heelwat aandag gegee aan die oplossing van die taksonomiese hindernis vir die springstert fauna van die fynbos bioom met behulp van moderne morfologiese en DNA metodes, terwyl dit ook die ooreenkomste van grond diere diversiteit ondersoek in die bioom, deur gebruik te maak van Collembola (springsterte) as voorbeelde. Eerste, met behulp van 'n kombinasie van gepubliseerde rekords van Collembola van Suid-Afrika, verskillende kolleksie metodes en DNA metodes is 'n spesielys saamgestel vir die Wes-Kaap. Tans is 213 spesies bekend vir die Wes-Kaap. 'n Hoë vlak van kriptiese diversiteit is ook gevind in verskeie genera, saam met verskeie potensiële spesies radiasies in die Ectonura, Seira, Parisotoma en Cryptopygus. 'n Begin is gemaak op die aanspreek van die gebrek van taksonomiese kennis deur vyf nuwe spesies te beskryf. Twee Ectonura Cassagnau 1980 spesies van Bettiesbaai en Grootvadersbosch is beskryf en 'n sleutel tot die Neanurinae van Suid-Afrika word verskaf. Die eerste rekord van die genus Triacanthella Schaffer, 1897 word beskryf van 'n grot in Tafelberg, terwyl twee nuwe spesies van Delamarephorura beskryf word en die genera Spicatella Thibaud 2002 en Delamarephorura Weiner & Najt 1999 gesinomiseer word. Hoewel vuur beskou word as die belangrikste vorm van ontbinding in die Fynbos bioom, het onlangse werk getoon dat die biologiese ontbinding belangriker mag wees as wat voorheen vermoed was. Ek ondersoek die veerkragtigheid van Collembola na 'n groot skaal vuur in Jonkershoek Natuurreservaat met behulp van kwantitatiewe steekproefneming wat tydelik herhaal. Die veerkragtigheid van ongewerwelde fauna in die fynbos word nie goed verstaan nie, dus het ek ondersoek ingestel na die diversiteit van Collembola voor en na 'n groot vuur. Resultate toon dat Collembola se spesierykheid en hoveelheid verbasend vinnig herstel na die vuur. Op 'n groter skaal, is kolleksies by ses plekke regoor die Wes-Kaap gebruik en verskillende blaarafval word vergelyk. Hier word 'n totaal van 113 morfologiese spesies gevind. Daar is gevind dat die hoogste aantal spesies in Kogelberg is (32 spesies), terwyl die omset tussen plekke baie hoog was. So sal die agteruitgang van plaaslike habitatte net soveel van 'n bedreiging inhou vir Collembola as vir die endemiese plante in hierdie streek.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/79796
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