I describe the spider biodiversity for a savanna ecosystem, assess sampling techniques, investigate surrogate measures of species richness and measure the biotic and abiotic processes affecting spider diversity. Spiders were sampled at Makalali Game Reserve, Northern Province, South Africa from February to December 1999 using pitfall traps, sweep netting, beating and active searching. A total of 4832 individuals from 268 species (14 potentially new), 147 genera (8 endemic and 2 new records for South Africa) and 37 families (1 new record for South Africa) were recorded. There was no overall significant difference in spider diversity among different physiognomic habitat types. However, analysing the results at a functional group level revealed that the web builders were significantly affected by the habitat type. Mopane woodland habitat type had the greatest number of web builders and general bushveld the least. Sweeping and active searching sampled the greatest number of individuals and species respectively. I recommend a combination of at least beating and active searching, which together sampled the highest number of unique species, for efficient and cost effective surveys. There was a significant relationship between the spider species richness and other invertebrate richness. However, the relationship is not significant when functional groups are considered separately. There was also a significant relationship between the number of species and families and species and genera. However, species level identifications remain ideal for conservation purposes. Inexperienced participants significantly overestimate the number of species. The use of surrogates is not supported by the work conducted in this study. It is still unclear what biotic and abiotic processes or combination of processes influence spider diversity patterns at the local scale. Different spider functional groups are significantly influenced by different factors. However, habitat diversity (branches and vegetation density) was the most common factor influencing spider diversity . Predicted diversity (modelled using GIS and beta-coefficients from multiple regression analyses) was higher than measured diversity values. While further research into the role of other environmental variables is clearly required, current reserve management should aim to maximise microhabitat structural diversity. / Thesis (M.Sc.)-University of Natal, Durban, 2000.

Stegodyphus mimosarum Pavesi,1883 and S. dumicola Pocock, 1898 are two species of philopatric, inbred, permanently communal, non-territorial spiders that co-occur in parts of South Africa. The patchiness of colony distribution, limited dispersal capabilities and the observation of periodic, but rare mass dispersal events raised interest in factors influencing dispersal. The aim of this project was firstly, to determine which factors influence the spiders' readiness to leave a colony (two laboratory experiments), and secondly, to map nest dispersion in Weenen Nature Reserve, Kwa-Zulu Natal, and to use this to explain nest distribution. The first experiment assessed whether group size and variance in access to resources influenced the decision to disperse. Four colony sizes (8, 16,32 and 64) of S. mimosarum were established under a proportional feeding regime. I expected more spiders to leave larger colonies due to intra-group competition. However, there was no significant increase in the number of spiders leaving with increasing group size. Significantly more spiders left a colony during spring and when spiders were large. In the second experiment, I assessed whether the mean amount of food available, in liberally fed or starved colonies influenced the decision to disperse. Five colonies were fed daily on an abundance of prey items and five were starved. I expected more spiders to leave the starved colonies. However, a significant number of spiders left colonies where food was abundant. During a field survey nests were tagged within 40 plots of 50 m radius, and randomly. Retreat dimensions, height above ground, nest position, nearest neighbouring nests, and species were recorded. Nest status was tracked over six months to three years. I confirmed that nest height above ground was significantly higher for S. mimosarum. The two species differed in retreat volume and nearest neighbour distances. Most nests occurred on the northern aspect of trees. Few nests survived beyond three years, although many new nests were established. Access to resources influenced the decision to disperse. However, only well-fed (larger) spiders had the resources to relocate. Patchy nest distribution could be a consequence of nest site selection, short distance dispersal by budding and bridging, and long distance dispersal by ballooning. / Thesis (M.Sc.)-University of Natal, Durban, 2002.

M.Sc. (Zoology) / Spiders of the genus Cyrtophora Simon, 1864 are commonly called tropical tent‒web spiders due to the unique shape of their webs. Forty three Cyrtophora species are known throughout the world and five of them have been recorded from Africa, but none formally from South Africa (SA). The only species of Cyrtophora so far suspected to occur in SA is the cosmopolitan species C. citricola (Forsskål, 1775). The South African Cyrtophora species show extensive morphologic variation, especially in colouration and abdominal characteristics. In SA they frequently make their webs in aloes and cycads and live solitary or in small to large aggregations. This social behaviour offers many advantages but also subjects the community to threats such as birds. A behavioural trait that is fairly uncommon in spiders, but is exhibited by Cyrtophora, is that the webs are only repaired when small holes, due to prey capture, are made; new webs are only built above the old webs in cases where extensive damage occurs. Morphologically, sexual dimorphism is prevalent, and juveniles vary greatly from adults. This causes several problems for traditional taxonomy. Both males and females have the ability to alter the degree of colour in the abdomen in response to the environment. This is usually a defence mechanism and is used for camouflage. DNA barcoding of the mitochondrial cytochrome c oxidase 1 (CO1) gene was done on fresh and museum specimens sampled from 2006‒2011. Barcoding of the nuclear histone H3 gene was done on some of the male and female specimens for use as a comparison. Analysis was done using the SPIDER programme. Morphological analysis of the genitalia was used to compare the species determined by the genetic results. Abdomen traits were observed to determine morphologic variation between and within species. General behaviour was recorded through observation of a study site and photographs previously taken around SA, noting specifically reproduction, prey capture, colour change and other general behavioural characteristics. Ecological patterns such as seasonality (phenology) and distribution patterns were recorded using collection data from museum and freshly collected specimens. Genetic results of the H3 gene indicate three species whereas the CO1 gene indicates 10 species. Both genes were concordant regarding two species, one of which was a specimen from Madagascar (and as this is a study on South African species was therefore not included in morphological analysis). A combined analysis of both gene datasets indicated three species. However, the CO1 gene had strong support but the H3 gene had poor resolution. For this reason the H3 gene was not recommended for analysis of Cyrtophora. Morphologically, the specimens showed diverse abdominal variation but genitalia assessment determined the presence of only two species. The two species indicated by genetics and morphology combined were C. citricola and an unidentified species from Malelane, Mpumalanga. In conclusion, it is evident that C. citricola is not the only species under this genus in SA. Even though morphology indicates only two species, the CO1 gene indicates a minimum of eight species, possibly 10. Comprehensive morphological and ecological study could show characteristics that correspond with the genetic results. This information will help to aid future biodiversity assessments and conservation programmes. The behavioural information obtained may also help initiatives such as the South African National Survey of Arachnida (SANSA) and red list authorities. The effectiveness of the CO1 gene for identification of this species will also help initiatives

Thesis (MSc. (Zoology)) --University of Limpopo, 2008 / Refer to document / National Research Foundation - Thuthuka programme

MSc (Zoology) / Department of Zoology / See the attached abstract below

MSc (Zoology) / Department of Zoology / See the attached abstract below