New species and combinations in the African Restionaceae

Eight new species of the African Restionaceae (Restionoideae) are described, viz.: Cannomois anfracta, Cannomois arenicola, Cannomois grandis, Nevillea vlokii, Thamnochortus kammanassiae, Willdenowia pilleata, Restio uniflorus and Restio mkambatiae. A key to the species of Cannomois is provided, as well as a table comparing the characters of the three species in Nevillea. For all new species, notes on the affinities of the species and their habitats are provided. Two new combinations, Cannomois primosii (Pillans) H.P. Linder and Cannomois robusta (Kunth) H.P. Linder, are made.     

Phylogeography of the Cape velvet worm (Onychophora: Peripatopsis capensis) reveals the impact of Pliocene/Pleistocene climatic oscillations on Afromontane forest in the Western Cape, South Africa

Habitat specialists such as soft-bodied invertebrates characterized by low dispersal capability and sensitivity to dehydration can be employed to examine biome histories. In this study, the Cape velvet worm (Peripatopsis capensis) was used to examine the impacts of climatic oscillations on historical Afromontane forest in the Western Cape, South Africa. Divergence time estimates suggest that the P. capensis species complex diverged during the Pliocene epoch. This period was characterized by dramatic climatic and topographical change. Subsequently, forest expansion and contraction cycles led to diversification within P. capensis. Increased levels of genetic differentiation were observed along a west-to-south-easterly trajectory because the south-eastern parts of the Cape Fold Mountain chain harbour larger, more stable fragments of forest patches, have more pronounced habitat heterogeneity and have historically received higher levels of rainfall. These results suggest the presence of three putative species within P. capensis, which are geographically discreet and genetically distinct.     

The Cape Peninsula, South Africa: physiographical, biological and historical background to an extraordinary hot-spot of biodiversity

The Cape Peninsula, a 470 km² area of rugged scenery and varied climate, is located at the southwestern tip of the Cape Floristic Region, South Africa. The Peninsula is home to 2285 plant species and is a globally important hot-spot of biodiversity for higher plants and invertebrates. This paper provides a broad overview of the physiography, biological attributes and history of human occupation of the Peninsula. The Peninsula is characterized physiographically by extremely high topographical heterogeneity, very long and steep gradients in annual rainfall, and a great diversity of nutrient-poor soils. Thus, the Peninsula supports a high number of habitats and ecological communities. The predominant vegetation is fynbos, a fire-prone shrubland, and 12 broadly characterized fynbos types have been described on the Peninsula. Animal community structure, especially with regard to invertebrates, is poorly known. Vertebrate community structure is probably strongly influenced by nutrient poverty and recurrent fire. Generally, most vertebrates are small and typically occur in low numbers. Some invertebrates play keystone roles in facilitating ecological processes. Human occupation of the Peninsula was limited, until relatively recently, by nutrient poverty. After Dutch colonization in 1652, direct and indirect impacts on the natural ecosystems of the Peninsula escalated dramatically, and by 1994, some 65% of original natural habitat was either transformed by urbanization and agriculture, or invaded by alien plants. Nonetheless, there is still excellent potential to conserve the Cape Peninsula's remaining biodiversity.     

Reconstructing ancestral ecologies: challenges and possible solutions

There are several ways to extract information about the evolutionary ecology of clades from their phylogenies. Of these, character state optimization and 'ancestor reconstruction' are perhaps the most widely used despite their being fraught with assumptions and potential pitfalls. Requirements for robust inferences of ancestral traits in general (i.e. those applicable to all types of characters) include accurate and robust phylogenetic hypotheses, complete species-level sampling and the appropriate choice of optimality criterion. Ecological characters, however, also require careful consideration of methods for accounting for intraspecific variability. Such methods include 'Presence Coding' and 'Polymorphism Coding' for discrete ecological characters, and 'Range Coding' and 'MaxMin Coding' for continuously variable characters. Ultimately, however, historical inferences such as these are, as with phylogenetic inference itself, associated with a degree of uncertainty. Statistically based uncertainty estimates are available within the context of model-based inference (e.g. maximum likelihood and Bayesian); however, these measures are only as reliable as the chosen model is appropriate. Although generally thought to preclude the possibility of measuring relative uncertainty or support for alternative possible reconstructions, certain useful non-statistical support measures (i.e. 'Sharkey support' and 'Parsimony support') are applicable to parsimony reconstructions.     

What can phylogenetics tell us about speciation in the Cape flora?

The spectacular diversity of the Cape flora has promoted wide speculation on the evolutionary processes behind its origins, but until recently these ideas could not be tested rigorously due to the almost complete absence of a fossil record for the region. Now, molecular phylogenetic approaches, combined with analyses of ecological and biogeographical information, offer the potential to test key hypotheses about speciation of so-called Cape clades of flowering plants. We outline the main theories and how they might be tested by phylogenetic approaches. One conclusion is that population level studies of particular species complexes are now needed to complement the growing volume of phylogenetic information for Cape clades and to provide better understanding of mechanisms of population divergence in the Cape. Another is that comparisons between Cape and non-Cape clades are needed to confirm whether speciation is indeed faster in the Cape region. An alternative possibility, that extinction rates are lower, should also be considered in these comparisons. By virtue of the ongoing, coordinated efforts by a global team of botanists, the Cape is now uniquely placed for exploring the origins and assembly of a regional assemblage or biome.     

Are Cape floral clades the same age? Contemporaneous origins of two lineages in the genistoids s.l. (Fabaceae)

The hypothesis that the elements of the modern species-rich flora of the Cape Floristic Region (CFR), South Africa, originated more or less simultaneously at the Miocene/Pliocene boundary, in response to the development of a mediterranean climate, has been challenged by numerous molecular dating estimates of Cape floral clades. These studies reveal a more gradual emergence, with the oldest clades originating in the Eocene, but others appearing later, some as recently as the Pliocene. That there are factors which might affect the dates recovered, such as choice of calibration point, analysis method, sampling density and the delimitation of Cape floral clades, suggests a need for further critical evaluation of the age estimates presented to date. In this study, the dates of origin of two Cape floral clades (the legume Crotalarieae p.p. and Podalyrieae) are estimated, constrained by a shared calibration point in a single analysis using an rDNA ITS phylogeny in which 633 taxa are sampled. The results indicate that these two clades arose contemporaneously 44-46 mya, not at the Miocene/Pliocene boundary as had been previously supposed. The contemporaneous origin of these Cape floral clades suggests that additional more inclusive analyses are needed before rejecting the hypothesis that a single environmental trigger explains the establishment of Cape floral clades.     

Montane Refugia for Endemic and Red Listed Dragonflies in the Cape Floristic Region Biodiversity Hotspot

One of the features of many endemic organisms is that they are highly spatially restricted, and habitat specialists. The Kogelberg Biosphere Reserve (KBR) is a major centre of plant endemism within a global hotspot, the Cape Floristic Region (CFR). Dragonflies in this botanical hotspot have a range of habitat specialization from narrow-range specialists to widespread generalists, with an unusually strong bias towards the specialists. A huge 53% of dragonfly individuals and 26% of taxa recorded are national endemics, and three species are Red Listed. Thus, a group of predatory insects, which are largely not dependent on plant composition, mirrors the level of habitat specialization and restricted distributions of the plants at the spatial scale of the whole reserve. Although some studies caution the use of one taxon as a surrogate for another, the results here show that at the reserve scale in this global hotspot there can be remarkable concordance, suggesting further studies on other taxa should be carried out to determine the full extent of taxonomic concordance in this irreplaceable area.     

Biogeographic patterns and phylogeography of dwarf chameleons (Bradypodion) in an African biodiversity hotspot

The southern African landscape appears to have experienced frequent shifts in vegetation associated with climatic change through the mid-Miocene and Plio-Pleistocene. One group whose historical biogeography may have been affected by these fluctuations are the dwarf chameleons (Bradypodion), due to their associations with distinct vegetation types. Thus, this group provides an opportunity to investigate historical biogeography in light of climatic fluctuations. A total of 138 dwarf chameleons from the Cape Floristic Region of South Africa were sequenced for two mitochondrial genes (ND2 and 16S), and resulting phylogenetic analyses showed two well-supported clades that are distributed allopatrically. Within clades, diversity among some lineages was low, and haplotype networks showed patterns of reticulate evolution and incomplete lineage sorting, suggesting relatively recent origins for some of these lineages. A dispersal-vicariance analysis and a relaxed Bayesian clock suggest that vicariance between the two main clades occurred in the mid-Miocene, and that both dispersal and vicariance have played a role in shaping present-day distributions. These analyses also suggest that the most recent series of lineage diversification events probably occurred within the last 3-6 million years. This suggests that the origins of many present-day lineages were founded in the Plio-Pleistocene, a time period that corresponds to the reduction of forests in the region and the establishment of the fynbos biome.     

Patterns of endemism in the limestone flora of South African lowland fynbos

Taxonomie and biological aspects of endemism and Red Data Book status were studied amongst the limestone endemics of the lowland fynbos in the Cape Floristic Region, South Africa. Of the 110 limestone endemics, 1.8% are widely distributed in the Cape Floristic Region and 56.4% are regional endemics. Relative to flora of non-limestone lowland fynbos (n=538 species), the families which were overrepresented in terms of limestone endemics included the Ericaceae, Fabaceae, Polygalaceae, Rutaceae and Sterculiaceae. The Restionaceae was the only underrepresented family. The local limestone endemics were not significantly different from regional endemics in terms of their biological attributes. An analysis of the frequency of the biological traits associated with the limestone-endemic flora established a biological profile for a limestone endemic: a dwarf-to-low shrub with soil-stored seeds which are ant or wind dispersed. In terms of the species richness of limestone endemics, the De Hoop Nature Reserve was the hotspot within the region. Relative to the total species richness, the Hagelkraal and Stilbaai areas contained higher-than-predicted numbers of rare species. These areas require urgent attention if the unique floral diversity associated with limestone substrata within the Bredasdorp-Riversdale centre of endemism is to be conserved.     

Impact of a dam on benthic macroinvertebrates in a small river in a biodiversity hotspot: Cape Floristic Region, South Africa

Suitable reservoirs and monitoring methods are needed to manage scarce water supplies in dry countries. We assessed here the impact on aquatic macroinvertebrates of the only dam on the Eerste River, which runs through the heart of a biodiversity hotspot, the Cape Floristic Region, South Africa. The dam and associated activities, were the only forms of disturbance in this otherwise pristine area. We sampled over 20,000 macroinvertebrate individuals and illustrated some categorical effects of the impoundment and its effects on macroinvertebrate assemblages. Macroinvertebrate species diversity below the dam was only half of that in the pristine catchment area above the dam. Furthermore, Ephemeroptera, Plecoptera and Trichoptera diversity and abundance dropped to almost zero as a result of the impoundment. In contrast, the abundance of the Diptera family Chironomidae increased substantially below the dam. These changes in macroinvertebrate diversity mirrored those recorded in biologically less diverse areas, but are of major concern in this biodiversity hotspot with its rich endemic fauna. We conclude that such an impoundment, while important for human welfare, results in a high price being paid in terms of loss of local biodiversity.