Comprehensive assessments of species’ extinction risks have documented the extinction crisis1 and underpinned strategies for reducing those risks2. Global assessments reveal that, among tetrapods, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are threatened with extinction3. Because global assessments have been lacking, reptiles have been omitted from conservation-prioritization analyses that encompass other tetrapods4–7. Reptiles are unusually diverse in arid regions, suggesting that they may have different conservation needs6. Here we provide a comprehensive extinction-risk assessment of reptiles and show that at least 1,829 out of 10,196 species (21.1%) are threatened—confirming a previous extrapolation8 and representing 15.6 billion years of phylogenetic diversity. Reptiles are threatened by the same major factors that threaten other tetrapods—agriculture, logging, urban development and invasive species—although the threat posed by climate change remains uncertain. Reptiles inhabiting forests, where these threats are strongest, are more threatened than those in arid habitats, contrary to our prediction. Birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles, although threatened reptiles with the smallest ranges tend to be isolated from other threatened tetrapods. Although some reptiles—including most species of crocodiles and turtles—require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.

Differences between sexes in physiological performance have received little attention in animals. We tested for sex differences in maximum sprint speed and maximal exertion over a range of temperatures in a population of Platysaurus intermedius wilhelmi lizards. We also examined sex-based differences in selected temperature range, mean field body temperatures (T(b)), and thermal activity limits. Finally, we conducted field studies to quantify male and female responses to a potential predator, which may be affected by their respective performance capabilities. Males were faster than females at all temperatures, and body size had no significant effect on sprint speeds. Males and females also selected similar T(b)'s when placed in a thermal gradient, but in the field, male lizards' T(b)'s were different from those of the females. However, predicted sprint speeds for males and females at their field T(b)'s are similar. No significant differences were found between males and females with regard to maximal exertion. When approached in the field, adult male lizards took refuge significantly earlier than did adult females and also fled over shorter distances, suggesting that females rely on crypsis as an escape strategy.

Quality conservation planning requires quality input data. However, the broad scale sampling strategies typically employed to obtain primary species distribution data are prone to geographic bias in the form of errors of omission. This study provides a quantitative measure of sampling bias to inform accuracy assessment of conservation plans based on the South African Frog Atlas Project. Significantly higher sampling intensity near to cities and roads is likely to result in overstated conservation priority and heightened conservation conflicts in urban areas. Particularly well sampled protected areas will also erroneously appear to contribute highly to amphibian biodiversity targets. Conversely, targeted sampling in the arid northwest and along mountain ranges is needed to ensure that these under-sampled regions are not excluded from conservation plans. The South African Frog Atlas Project offers a reasonably accurate picture of the broad scale west-to-east increase in amphibian richness and abundance, but geographic bias may limit its applicability for fine scale conservation planning. The Global Amphibian Assessment species distribution data offered a less biased alternative, but only at the cost of inflated commission error.

In ectotherms, an increase in body temperature increases metabolic rate and may increase rates of digestive processes. We measured the thermal dependence of the apparent digestive and apparent assimilation efficiencies (ADE and AAE), gut passage time (GP) and appetite in Cordylus melanotus melanotus, a medium sized Crag Lizard, which is endemic to South Africa. Trials were conducted at 20, 22, 25, 30, 32 and 35 degrees C under controlled conditions. Trials lasted 14 days, during which, lizards were fed ca. 1 g mealworms per day. Glass beads were used as markers to determine GP at the beginning and end of trials. Faeces and urates were collected daily and oven dried at 50 degrees C. The energy content of egested matter was then measured using bomb calorimetry. ADE and AAE were not affected by temperature for either males or females. The mean+/-SE ADE and AAE were 94.4+/-0.3% and 87.2+/-0.6%, respectively. GP was not significantly different between males and females at any temperature, but decreased significantly with increasing temperature. Appetite was significantly different between the different temperatures measured. The decrease of gut passage time with increasing temperature was expected, since the digestive and assimilation efficiencies are similar over the range of temperatures tested. Lizards are thus assimilating a similar proportion of ingested energy, but at faster rates at higher temperatures. The results indicate that the digestive physiology of this species results in maximum energy gain per meal in environments where food is scarce.

Aim Small range size often increases a species’ susceptibility to decline. A narrow ecological niche is one factor that may cause species to inhabit a small range. We investigated whether specialized niches have made South African amphibians more vulnerable to range contractions. Location South Africa. Methods The South African Frog Atlas Project is a comprehensive dataset that combines a recent biological survey with historical species distribution data. It provided an opportunity to quantitatively compare range sizes, niche breadth and range size changes for amphibian species. An ecological niche factor analysis supplied comparative measures of climate and habitat niche breadth for each species. Niche breadth was related to range size changes using linear regressions. Ranges of species with narrow habitat niches were spatially compared to areas of high land transformation. Results Small range size was a significant predictor of range contractions for South African amphibians (R2 = 0.35). Furthermore, species with narrow habitat (R2 = 0.25) and climate (R2 = 0.21) niches had experienced more severe range contractions than species with broader niches. Among only endemic species, climate specialization (R2 = 0.27) became a better predictor of range size change than habitat specialization (R2 = 0.21). Habitat specialists were concentrated within two areas of endemism that also had higher than average (P < 0.0001) levels of land transformation. Main conclusions Small range size increased species' likelihood of experiencing range contractions. Narrow niche breadth was also a significant predictor of range contractions, indicating that specialization may contribute to higher decline risk in small‐range species. The role of climate specialization in predicting range contractions among endemics emphasizes the potential impacts of climate change. The spatial synchrony of contracting habitat specialists in highly transformed areas of endemism suggests that conservation efforts should target specialist species and the ecosystems where many such species occur.

1 Less than 5% of a dose of the conventional oral formulation of cyclosporin, Sandimmun®, is absorbed in liver transplant recipients with external biliary drainage, necessitating intravenous administration of the drug and exposing the patient to increased risk of severe side-effects. 2 We compared the pharmacokinetics of the conventional oral formulation of cyclosporin with that of the new microemulsion formulation, Neoral®, in eight liver transplant recipients with external biliary diversion. Patients were maintained on a continuous infusion of cyclosporin until steady-state conditions had been achieved. They were then given a test dose (10 mg kg-') of either the conventional or microemulsion formulation (randomised order) followed by the same dose of the other formulation. Parent cyclosporin concentrations were measured in whole blood samples collected at timed intervals over the 24 h after the oral doses and pharmacokinetic parameters calculated. 3 The bioavailability of cyclosporin from the microemulsion formulation was, on average, 6.5-fold (95% C.I. 1.9 to 11.1-fold) greater than that of the conventional formulation, indicating the improved absorption characteristics of the new oral microemulsion formulation during external bile drainage. 4 A significant negative correlation was found between the external bile drainage volume and bioavailability of cyclosporin from the microemulsion formulation (r = -0.8; P = 0.016), suggesting that variability in cyclosporin absorption from the microemulsion formulation may still be at least partly attributable to biledependence. Paradoxically, no relationship was found between bile volume and the very low cyclosporin bioavailability from the conventional formulation, perhaps because the volume of bile reaching the gut was below a threshold required for any consistent degree of cyclosporin absorption from this formulation to occur.5 In conclusion, the use of the new oral microemulsion formulation of cyclosporin should help to minimise the problems of cyclosporin malabsorption in most patients with external biliary drainage following liver transplantation. This will reduce requirements for the initial use of the i.v. formulation with its attendant side-effects and so may also reduce hospital stay.

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Ambush foragers use a hunting strategy that places them at risk of predation by both visual and olfaction-oriented predators. Resulting selective pressures have driven the evolution of impressive visual crypsis in many ambushing species, and may have led to the development of chemical crypsis. However, unlike for visual crypsis, few studies have attempted to demonstrate chemical crypsis. Field observations of puff adders (Bitis arietans) going undetected by several scent-orientated predator and prey species led us to investigate chemical crypsis in this ambushing species. We trained dogs (Canis familiaris) and meerkats (Suricata suricatta) to test whether a canid and a herpestid predator could detect B. arietans using olfaction. We also tested for chemical crypsis in five species of active foraging snakes, predicted to be easily detectable. Dogs and meerkats unambiguously indicated active foraging species, but failed to correctly indicate puff adder, confirming that B. arietans employs chemical crypsis. This is the first demonstration of chemical crypsis anti-predatory behaviour, though the phenomenon may be widespread among ambushers, especially those that experience high mortality rates owing to predation. Our study provides additional evidence for the existence of an ongoing chemically mediated arms race between predator and prey species.