Picking up the pieces: a biosphere reserve framework for a fragmented landscape – The Coastal Lowlands of the Western Cape, South Africa

The coastal lowlands of the Western Cape (CLWC) form part of the fynbos biome, an area renowned for its high levels of plant diversity and endemism. The vegetation of the CLWC has been severely reduced and fragmented, and is currently impacted on by agricultural, pastoral, coastal resort and urban development, as well as alien plant spread. Furthermore, most of the vegetation communities are under-represented within existing protected areas. In response to this urgent need for increased conservation efforts, an initiative to establish a UNESCO-MAB biosphere reserve in the area has been launched. The aim of this project was to use biological criteria to identify areas that could potentially contain the core areas and buffer zones of a biosphere reserve. A reserve selection algorithm was chosen which provides a flexible tool for selecting representative areas for protection. The algorithm is a step-wise heuristic, which has rules for including mandatory polygons, forcing adjacency, including desirable (e.g. Red Data Book plant species) and excluding undesirable features (e.g. bisection by major roads). Farm boundaries (cadastral units) were used as selection units, resulting in a total of 1717 parcels. The selection process was conducted three times with target areas set at 10%, 25% and 50% of the original extent of each vegetation type within the study area. Areas of 62834 ha, 121199 ha and 242397 ha, respectively, or 36% 49% and 76% of the available land in the study area being selected. It is recommended that the area identified as the 50% target area be considered the future site of core areas and buffer zones for the proposed biosphere reserve. The algorithm successfully maintained a high degree of connectivity between selected areas. This is important considering the high levels of plant beta diversity associated with edaphic gradients. Rather than presenting a definitive reserve system, this study provides a tool allowing biological criteria to be included explicitly within the negotiation process. As the biosphere reserve is assembled, priorities can be re-assessed.     

The Early Triassic 'lizard'Colubrifer Campi: A Reassessment

Colubrifer campi Carroll, 1982 is a small reptile represented by a single skeleton from the Lower Triassic of South Africa. Carroll attributed the genus to the Squamata, proposing that it was a derived lizard with reduced limbs. Re-examination of the specimen permits a rather different interpretation of the skull. The holotype of Colubrifer is the skeleton of a small primitive procolophonian, almost certainly referable to the established South African genus Owenetta .     

Genetic variation of Mimetes hirtus and Mimetes fimbriifolius (Proteaceae) – a comparative analysis of two closely related fynbos species

We investigated the influence of differing life history traits on the genetic structure of the related species Mimetes fimbriifolius and Mimetes hirtus (Proteaceae), which occur in the South African fynbos. Both species are bird‐pollinated and ant‐dispersed, but differ in rarity, longevity, ecological strategy and the fragmentation of their distribution area. We used AFLPs to study genetic variation within and between 21 populations of these two species across their distribution range. AFLP analysis revealed significantly higher genetic variation within populations of M. fimbriifolius than within M. hirtus. While M. fimbriifolius clearly lacked any significant genetic differentiation between populations, a distinct geographic pattern was observed for M. hirtus. Differentiation was, however, stronger at the regional (Φ_PT = 0.57) than at the local scale (Φ_PT = 0.08). Our results clearly indicate that even closely related species that share the same mode of pollination and seed dispersal can differ in their genetic structure, depending on the magnitude of fragmentation, longevity of individuals and ecological strategy.     

Fire and the chemistry of a South African mountain stream

The effects of a late-summer prescribed burn on the chemistry of a second-order mountain stream in the south-western Cape, South Africa, were investigated. Nitrate concentrations in stream water were significantly higher during the winter of the post-burn year. Increased concentrations of chloride, bicarbonate, polyphenols and potassium and decreased sodium concentrations were also recorded. Concentrations of ammonium, phosphate, calcium, magnesium, total dissolved solids and hydrogen ions were not significantly affected by the burn. Ionic export from the catchment was generally greater in the post-burn year. Apart from nitrate, however, values probably lie within the natural range of year-to-year variation. It is predicted that enhanced losses of nitrate will decrease progressively with the recovery of the vegetation and the re-establishment of soil/plant nutrient cycles. Atmospheric losses of nutrients in smoke were unquantified, but may be of more significance to site productivity than losses through surface runoff, which, in the case of nitrogen, appear to be compensated by precipitation inputs.     

THE EVOLUTION OF REPRODUCTIVE EFFORT IN LIZARDS AND SNAKES

Life history theory suggests that the optimal evolved level of reproductive effort (RE) for an organism depends upon the degree to which additional current reproductive investment reduces future reproductive output. Future reproduction can be decreased in two ways, through (i) decreases in the organism's survival rate, and/or (ii) decreases in the organism's growth (and hence subsequent fecundity). The latter tradeoff–that is, the “potential fecundity cost”—should affect the evolution of RE only in species with relatively high survival rate, a relatively high rate of fecundity increase with body size, or a relatively high reproductive frequency per annum. Unless these conditions are met, the probable benefit in future fecundity obtained from decreasing present reproductive output is too low for natural selection to favor any reduction in RE below the maximum physiologically possible. Published data on survival rate, reproductive frequency and relative clutch mass (RCM) suggest that many lizard species fall well below the level at which natural selection can be expected to influence RE through such “potential fecundity” tradeoffs. Hence, the relative allocation of resources between growth and reproduction is unlikely to be directly optimized by natural selection in these animals. Instead, energy allocation should influence the evolution of RE only indirectly, via effects on an organism's probability of survival during reproduction. Survival costs of reproduction may be the most important evolutionary determinants of RE in many reptiles, and information on the nature and extent of such costs is needed before valid measures of reptilian RE can be constructed.     

Ancient forest fragmentation or recent radiation? Testing refugial speciation models in chameleons within an African biodiversity hotspot

Aim East Africa is one of the most biologically diverse regions, especially in terms of endemism and species richness. Hypotheses put forward to explain this high diversity invoke a role for forest refugia through: (1) accumulation of new species due to radiation within refugial habitats, or (2) retention of older palaeoendemic species in stable refugia. We tested these alternative hypotheses using data for a diverse genus of East African forest chameleons, Kinyongia. Location East Africa. Methods We constructed a dated phylogeny for Kinyongia using one nuclear and two mitochondrial markers. We identified areas of high phylogenetic diversity (PD) and evolutionary diversity (ED), and mapped ancestral areas to ascertain whether lineage diversification could best be explained by vicariance or dispersal. Results Vicariance best explains the present biogeographic patterns, with divergence between three major Kinyongia clades (Albertine Rift, southern Eastern Arc, northern Eastern Arc) in the early Miocene/Oligocene (> 20 Ma). Lineage diversification within these clades pre‐dates the Pliocene (> 6 Ma). These dates are much older than the Plio‐Pleistocene climatic shifts associated with cladogenesis in other East African taxa (e.g. birds), and instead point to a scenario whereby palaeoendemics are retained in refugia, rather than more recent radiations within refugia. Estimates of PD show that diversity was highest in the Uluguru, Nguru and East Usambara Mountains and several lineages (from Mount Kenya, South Pare and the Uluguru Mountains) stand out as being evolutionarily distinct as a result of isolation in forest refugia. PD was lower than expected by chance, suggesting that the phylogenetic signal is influenced by an unusually low number of extant lineages with long branch lengths, which is probably due to the retention of palaeoendemic lineages. Main conclusions The biogeographic patterns associated with Kinyongia are the result of long evolutionary histories in isolation. The phylogeny is dominated by ancient lineages whose origins date back to the early Miocene/Oligocene as a result of continental wide forest fragmentation and contraction due to long term climatic changes in Africa. The maintenance of palaeoendemic lineages in refugia has contributed substantially to the remarkably high biodiversity of East Africa.     

A partial systematic revision of the day geckos, Phelsuma Gray, of Madagascar (Reptilia: Squamata: Gekkonidae)

Recent survey work in Madagascar has led to significant changes in the systematics of Madagascan Phelsuma. A new species from the Masoala Peninsula in northeastern Madagascar is described, which has a nostril position typical of Phelsuma from Mauritius, Reunion and Rodriguez islands. Phelsuma breviceps was rediscovered in extreme southern Madagascar and is resurrected from the synonymy of P. mutabilis. Phelsuma breviceps has fragile skin, a probable predator escape mechanism, similar to the condition found in geckos of the genera Ailuronyx and Geckokpis. Three new synonyms are recognized. Phelsuma befotahensis and P. checki are junior synonyms of P. abbotti , and P. minuthi is a junior synonym of P. lineata. Twenty species of Phelsuma occur in Madagascar, of which 16 are endemic. A checklist and identification key are provided. Conservation problems of Phelsuma in the coastal regions of Madagascar are briefly discussed.     

Use of statistical models based on radiographic measurements to predict oviposition date and clutch size in rock iguanas (Cyclura nubila)

The ability to noninvasively estimate clutch size and predict oviposition date in reptiles can be useful not only to veterinary clinicians but also to managers of captive collections and field researchers. Measurements of egg size and shape, as well as position of the clutch within the coelomic cavity, were taken from diagnostic radiographs of 20 female Cuban rock iguanas, Cyclura nubila, 81 to 18 days prior to laying. Combined with data on maternal body size, these variables were entered into multiple regression models to predict clutch size and timing of egg laying. The model for clutch size was accurate to 0.53 ± 0.08 eggs, while the model for oviposition date was accurate to 6.22 ± 0.81 days. Equations were generated that should be applicable to this and other large Cyclura species. © 1995 Wiley-Liss, Inc.