Includes bibliographical references. / Standard weight (Ws) equations were developed and relative weight (Wr) indices calculated for both shallow-water (Merluccius capensis) and deep-water (M . paradoxus) Cape hake. The aim was to provide fixed baselines and Wr indices to aid understanding of temporal and spatial variability in fish condition . Baselines were calculated using the empirical percentiles (EmP) method applied to length (L) – weight (W) data collected by research surveys on the South African west and south coasts, from 1983 to 2013 . Four quadratic Ws equations for each species were generated, based on the following weight statistics for each size class j : first quartile, median, third quartile and mean. Median Ws equations were chosen for the baseline for shallow-water hake (log₁₀ Ws=-2.491 + 3.33 8 *(log₁₀ L)-0.065 *(log₁₀ Lj)²) and deep-water hake (log₁₀ Ws =- 2.161 + 2.930*(log₁₀ L) + 0.0456 *(log 10Lj)²). Shallow-water hake was found to be the heavier of the two species at the same length. Wr indices display good condition values (>100%) for both species throughout all analyses . Fish condition for both species was best between 1988-2009, ranging from 50-1 65% for individual fish and 100 – 109% for annual averages. Monthly mean Wr indices peaked in June and October for shallow-water hake and July and October for deep-water hake. Mean Wr values were different for shallow-water hake on the south (105%) and west (103%) coasts. Deep-water hake showed no spatial variability in mean Wr values. There were no differences between mean Wr values of males and females between, and within, species. Future hake data may be compared to these Ws equation baselines and Wr indices to show changes in body condition for this commercially important stock.

The genus, Leucadendron, of the Cape Proteaceae family, is made up of over 70 dioecious species that vary in their degree of sexual dimorphism. Males are generally more highly ramified (branched) with smaller leaves compared to corresponding females. It has been hypothesised that sexual dimorphism in Leucadendrons is linked to serotiny (a fire-adapted reproductive strategy), where highly serotinous females may incur extra resource costs in order to keep their transpiring cones alive between fires. This hypothesis predicts that the female morphology might be associated with more efficient resource acquisition compared to males in order to support their greater resource requirements. Another hypothesis suggests that selection for greater floral display in males has lead to a higher degree of ramification as male cones are borne terminally on branches. This highly branched morphology may be associated with subsequent physiological costs. The idea that different male and female morphologies might be associated with different physiological costs or benefits was tested in this experiment with a focus on plant hydraulics. Hydraulic supply is known to affect photosynthetic capacity and maximum assimilation rate. Using a specially designed vacuum chamber, leaf-specific and xylem-specific hydraulic conductance was measured in males and females of the highly dimorphic Leucadendron rubrum and non/marginally dimorphic Leucadendron daphnoides. Using microscopic imagery, xylem anatomy was analysed in an attempt to explain the hydraulic conductance results.

'Occult' precipitation may be an important moisture source that can impact specific plant responses to water stress in certain ecosystems. Species in many ecosystems have been shown to use this moisture source via foliar moisture uptake. The Cape Peninsula and the surrounding southern coast experience high altitude mountain cloud cover in the summer dry period. Previous work on species that exist exclusively in the cloud belt found that species from the Erica and Restionaceae family were able to absorb water through their leaf surfaces, while members of the Proteaceae were unable to do so (Gibson, 2012). Adding to the body of research, this study explores whether foliar uptake occurs in species that do not exist in the cloud belt of the Cape Peninsula and the relative importance of this method of uptake in positively impacting a plants water balance during a cloud event. Direct foliar uptake was assessed at the leaf level using two methods; submersion and mist exposure. The importance of foliar uptake was measured at the whole plant level by exposing whole plants to cloud in a mist chamber. By covering the soil in a subset of plants, we were able to isolate the importance of foliar uptake relative to uptake via drip. Results found that the restios and ericas showed a stronger ability to take up moisture via their leaves than protea species, which showed little ability to do so. In contrast to this, the mist exposure method showed no significant uptake in any species except E. quadrangularis. This disparity is possibly due to specific leaf morphology. All species showed significant hydration in response to a whole plant cloud event in both the covered and uncovered treatments. The significant hydration in response to an occult event suggests that certain low land species are capable of utilizing small occult inputs despite the lack of regular summer cloud events as seen in the cloud belt species. As family patterns of foliar moisture uptake seen in cloud belt species (Gibson 2012) are conserved in the surveyed low land species, it can be concluded that moisture uptake is not a trait specific to cloud belt species, and represents a family level pattern of ability.

Entosthodon Schwägr. (Funariaceae) is a genus of soil-inhabiting, annual to biennial mosses occurring worldwide in temperate to tropical-montane climates. Although a number of regional revisions and treatments exist for the genus, in many parts of the world, it remains poorly known. This is perhaps especially true in Africa, where the identities of most species names are obscure. Furthermore, recent work on the Funariaceae suggests that the sporophytes, long used as the main basis for classification and identification in the group, exhibit high levels of homoplasy and that Entosthodon is paraphyletic as currently circumscribed. I further test the monophyly of Entosthodon, and its relationships to other members of the Funarioideae, through phylogenetic analysis of DNA sequences from four chloroplast regions. These analyses included 45 Entosthodon species (ca. 50 % of those currently recognised), as well as an additional 22 species comprising representatives of all genera of the subfamily (except the rare, monotypic genera Cygnicollum, Clavitheca, Nanomitrella and Brachymeniopsis and the recently described monotypic Afoninia). Bayesian analyses of these data strongly contradict the monophyly of Entosthodon, and it is instead resolved as paraphyletic to a large clade comprising mostly members of Physcomitrium and Physcomitrella. Within this grade, five well supported lineages are resolved - the first comprises 3 species of Entosthodon and is sister to the second lineage, the monotypic Physcomitrellopsis. The third is sister to the afore mentioned i clades and comprises 11 species of Entosthodon within which the monotypic genus Funariella is embedded. The fourth lineage comprises 7 species of Entosthodon and is sister to a clade within which a Physcomitrium-Physcomitrella group is sister to the fifth lineage - a large clade comprising 24 species of Entosthodon. Entosthodon hungaricus is shown to belong in the Physcomitrium clade instead, consistent with its rostrate operculum. Based on the phylogeny, a new classification of Entosthodon sensu lato is proposed. The genus is split into 4 genera (Amphoritheca, Fifeobryum gen nov., Funariella and Entosthodon sens. str.) and the monophyletic Physcomitrellopsis is also maintained. Because of a lack of diagnostic morphological taxonomic characters this new classification is based largely on the molecular circumscription of clades. Nonetheless, particular character combinations do largely characterise most of these genera, albeit that frequent reversals render particular character states non-diagnostic. A revision of these five genera for Africa results in the recognition of twentysix species in total: three in Amphoritheca, 12 in Entosthodon, one in Physcomitrellopsis, one in Fifeobryum, and nine in Funariella. Six of these species, 4 in Entosthodon and 2 in Funariella, are newly described based on specimens from East and southern Africa. A key to the sub-Saharan species is provided, and each is fully described, mapped and illustrated.

Few studies of rock-lobster diet have included analyses of mature females or juveniles of either sex. This study focused on the diet of male and female West Coast rock lobsters (Jasus lalandii) in three size classes (viz.: 10 - 35 mm CL (carapace length) - small, 40 - 59 mm CL - medium and 70 - 85 mm CL - large), using visual analyses of stomach contents. The principle aims were to examine potential differences in diet between: (1) male and female rock lobsters; (2) changes in diet with size and (3) a comparison of rock-lobster diet between areas of known fast- and slow-growth rates. The primary prey items of rock lobsters are shown to be the black mussel (Choromytilus meridianalis), ribbed mussel (Aulacomya ater), barnacle (Notomegabalanus algicola), sea urchin (Parechinus angulosus), sponge and crustacean remains. There was no difference in diet between male and female rock lobsters within any size class. Bray-Curtis similarity dendograms and Multi-Dimensional scaling plots revealed differences between small, medium and large rock-lobster diets. Small rock lobsters consumed mainly ribbed and black mussels, whereas medium rock lobsters consumed higher percentages of barnacle and sponge. Sea urchins comprised a substantial percentage of large rock-lobster diet. ANOSIM (Primer v 4.0) established significant differences (p < 0.05) among diets of the three size classes. Differences in diet were also observed between areas of fast- and slow-growth rates, but these were limited to the small and medium size classes. Key prey items responsible for this difference in diet were black mussel and rock-lobster remains. The gut fullness index decreased with increasing rock-lobster size. In conclusion, there appears to be no difference in diet between male and female rock lobsters, regardless of their size. However, rock-lobster diet does appear to vary with size. The inverse relationship between gut fullness indices and size, suggests that small rock lobsters, which have a higher moult frequency, feed relatively more frequently than larger rock lobsters. Diet composition plays a role in determining the growth rate of rock lobsters from different areas.

Since its proposal by Darwin (1876), the concept of reproductive assurance (RA) has been much discussed, modified and tested. It is hypothesized to occur under pollen- and/or mate-limitation, each of which can arise in a multitude of manners, and RA itself takes many forms. Here its evolution and prevalence in the genus Lachenalia (Asparagaceae) is investigated. The genus exhibits many of the characteristics suggested in the literature to be associated with reproductive assurance, including intraspecific polyploids, vegetative reproduction and self-compatibility. Of the 27 study species, 20 were found to be self-compatible and four were capable of autonomous self-pollination. Pollinator-dependent species were found to have more attractive floral display structures. The five species exhibiting intraspecific polyploidy were all self-compatible. Offset production, known to occur in many Lachenalia species, was thought to exhibit a negative association with self-compatibility. No significant association, however, was found. A deeper understanding of the patterns of reproductive assurance in the genus requires study of the mechanisms enforcing self-incompatibility, and of the ecological and physiological correlates of reproductive assurance, is needed.

A central goal of ecology is to understand the influence of biodiversity on ecosystem functioning and the processes that determine the composition and diversity of biological assemblages. In this thesis, I investigate the regional and global context of the bryophytes of Madagascar, an ecologically important but poorly studied group, and the factors affecting epiphytic bryophyte diversity, distribution and assemblage of communities along an elevational gradient in Marojejy National Park, north-eastern Madagascar. Firstly, based on literature reviews and available herbarium data, I examined the bryophytes of Madagascar through a historical, floristic and phytogeographic synthesis. Secondly, the ecological survey of bryophytes from a range of diversity and functional perspectives provided insight on: (1) the pattern of species richness and range-size distribution of epiphytic bryophytes and the factors affecting the distribution patterns. (2) The variations in species composition between sites. I documented how the two components of beta-diversity (turnover and nestedness) are influenced by elevational variation. (3) The relationship between bryophyte species functional diversity and community assembly based on a morphological trait-based approach. I tested how bryophyte species functionally interact with their abiotic and biotic environments and how habitat filtering and niche differentiation influence bryophyte assemblages along an elevational gradient. The bryoflora of Madagascar, with its 1188 species and infraspecific taxa is relatively rich and highly diversified. Along the Marojejy elevational gradient, 254 epiphytic bryophytes species including 157 liverworts and 97 mosses were reported. Species richness distribution has a hump-shaped pattern along the elevational gradient, with a richness peaking at mid-elevation, 1250 m. My results suggest that middomain-effect was the most effective in predicting species richness, but environmental variables such as mean temperature, relative humidity, vapour deficit pressure and canopy height also play important roles in shaping richness pattern. Throughout the gradient, species dissimilarity due to replacement (species turnover) contribute the most to variation in species composition between sites. Both habitat filtering and niche differentiation were found to be involved in structuring species abundances within the studied communities. This combination of biogeographic, taxic, and community ecology approaches, is the first detailed study on the bryoflora of Madagascar and contributes to the direct application of bryological data to conservation planning for Madagascar’s unique ecosystems.

Includes abstract. / Includes bibliographical references. / Impacts of invasive predators may be influenced by whether or not native predators which function in the same way as the invasive predator exist in the recipient system. Impacts are expected to be strong in isolated systems lacking functionally similar predators because native species will be naïve to the foraging behaviour of the introduced predator, and because the invasion is likely to change the role which the native predator assemblage performs. In this thesis I studied how the introduction of a functionally novel predatory fish, rainbow trout Oncorhynchus mykiss, has affected native fish, and how changes in the functioning of the predator assemblage have influenced lower trophic levels, in headwater streams in a catchment area within the Cape Floristic Region, South Africa. Fish populations, benthic invertebrate assemblages, benthic algae and particulate organic matter were surveyed in each of 24 minimally-disturbed headwater streams in the upper Breede River catchment, and relevant environmental variables in each stream measured, over one summer.

Ehrharta calycina J. E. Sm. (Poaceae) is a widespread and often abundant species whose core distribution lies within the Greater Cape Floristic Region (GCFR). Importantly, it shows a high degree of morphological and ploidy level variation. Based on observations of distinct forms co-occurring at multiple sites, the hypothesis that E. calycina comprises more than one species was tested. Morphological analysis of herbarium specimens using a multivariate approach found strong evidence for the presence of two distinct phenetic clusters among specimens from sites of sympatry, and these were termed ‘robust’ and ‘slender’ forms. This translated to a broader sampling of specimens from across the GCFR (n = 516), of which over 91% could be attributed to one or other form with >90% confidence using linear discriminant analysis. Importantly, chromosome counts supported the hypothesis that these phenetic clusters represent distinct cytotypes, with slender forms being diploid (n = 12) and robust forms tetraploid (n = 24), thus providing the primary reproductive isolating mechanism between the forms. Furthermore, differences in climatic niche suggest that these forms represent ecologically independent entities. Finally, evidence that the forms differ in palatability has considerable practical implications given that E. calycina is regarded as having high pasture value. Together, our results provide multiple lines of evidence for the existence of at least two morphologically distinct, reproductively isolated species within E. calycina, and suggest that the role of polyploidy in generating floral diversity in the GCFR may be more important than previously thought.

Alien Eucalyptus and Acacia species are amongst the most prolific invaders of the Berg River catchment, in the Western Cape. This study assessed the effects of invasive species and the potential for passive successional restoration in a heavily invaded riparian site (>80% aerial cover), a cleared riparian site and a pristine reference site. Three plots were demarcated per site, and transects were taken perpendicular to the river on the lower, middle and upper bank. Three 2m2 quadrats were intensively sampled per transect. Species diversity and community composition of indigenous and alien species were compared by measuring herbaceous, shrub and tree cover. Soil conditions, such as texture, salinity, acidity and moisture, were also compared. Distinctly different plant communities were found in each site, although cleared and invaded sites were more similar to each other. Cleared sites showed >45% cover by invasive successional species and grasses atypical of natural succession patterns. It was proposed that restoration constraints (e.g. method of clearance, intensity of prior invasion, land-use) were encouraging alien re-colonisation. However, there was evidence that the overall the trajectory of successional was favourable for indigenous trees and species. It was suggested that active re-vegetation of indigenous tree species, and adherence to correct clearance methods would aid site restoration.