Rapid expansion of the cane toad (Bufo marinus) invasion front in tropical Australia

Abstract Cane toads (Bufo marinus) are large toxic anurans that have spread through much of tropical Australia since their introduction in 1935. Our surveys of the location of the toad invasion front in 2001 to 2005, and radiotracking of toads at the front near Darwin in 2005, reveal much faster westwards expansion than was recorded in earlier stages of toad invasion through Queensland. Since reaching the wet‐dry tropics of the Northern Territory, the toads have progressed an average of approximately 55 km year⁻¹ (mean rate of advance 264 m night⁻¹ along a frequently monitored 55‐km road transect during the wet season of 2004–2005). Radiotracking suggests that this displacement is due to rapid locomotion by free‐ranging toads rather than human‐assisted dispersal; individual toads frequently moved >200 m in a single night. One radiotracked toad moved >21 800 m in a 30‐day period; the fastest rate of movement yet recorded for any anuran. Daily displacements of radiotracked toads varied with time and local weather conditions, and were highest early in the wet season on warm, wet and windy nights. The accelerated rate of expansion of the front may reflect either, or both: (i) evolved changes in toads or (ii) that toads have now entered an environment more favourable to spread. This accelerated rate of expansion means that toads will reach the Western Australian border and their maximal range in northern Australia sooner than previously predicted.     

Coordinated approaches to quantify long‐term ecosystem dynamics in response to global change

Many serious ecosystem consequences of climate change will take decades or even centuries to emerge. Long‐term ecological responses to global change are strongly regulated by slow processes, such as changes in species composition, carbon dynamics in soil and by long‐lived plants, and accumulation of nutrient capitals. Understanding and predicting these processes require experiments on decadal time scales. But decadal experiments by themselves may not be adequate because many of the slow processes have characteristic time scales much longer than experiments can be maintained. This article promotes a coordinated approach that combines long‐term, large‐scale global change experiments with process studies and modeling. Long‐term global change manipulative experiments, especially in high‐priority ecosystems such as tropical forests and high‐latitude regions, are essential to maximize information gain concerning future states of the earth system. The long‐term experiments should be conducted in tandem with complementary process studies, such as those using model ecosystems, species replacements, laboratory incubations, isotope tracers, and greenhouse facilities. Models are essential to assimilate data from long‐term experiments and process studies together with information from long‐term observations, surveys, and space‐for‐time studies along environmental and biological gradients. Future research programs with coordinated long‐term experiments, process studies, and modeling have the potential to be the most effective strategy to gain the best information on long‐term ecosystem dynamics in response to global change.     

Correlated geographic variation in predation risk and antipredator behaviour within a wide‐ranging snake species (Notechis scutatus,Elapidae)

Geographic variation in antipredator behaviour within wide‐ranging species may be driven by both genetic and environmental influences. We quantified antipredator responses in neonatal (laboratory born, n = 555) and adult (field caught, n = 346) tiger snakes (Notechis scutatus) from 11 mainland and island sites in southern Australia. We used these data to test predictions from Bonnet et al.'s hypothesis that the vigour of antipredator responses in this species reflects behavioural plasticity (in turn, driven by an individual snake's exposure to predators during its lifetime) rather than by genetic variation in this trait. We used the number of predator taxa in each area as an index of predator risk. As predicted, adult snakes from predator‐rich areas had more vigorous defensive responses when handled, whereas neonatal behaviour (although also variable among populations) was unrelated to predator species richness. Adult males bit more readily than adult females (as expected from the greater predation exposure of males during mate searching) but no such sex difference was evident in neonates. Although alternative models remain possible, our data are most consistent with the hypothesis that geographic divergence in antipredator tactics within this species primarily reflects developmentally plastic responses to local predation risk.     

Physical illness in patients with severe mental disorders. II. Barriers to care, monitoring and treatment guidelines, plus recommendations at the system and individual level

Physical disorders are, compared to the general population, more prevalent in people with severe mental illness (SMI). Although this excess morbidity and mortality is largely due to modifiable lifestyle risk factors, the screening and assessment of physical health aspects remains poor, even in developed countries. Moreover, specific patient, provider, treatment and system factors act as barriers to the recognition and to the management of physical diseases in people with SMI. Psychiatrists can play a pivotal role in the improvement of the physical health of these patients by expanding their task from clinical psychiatric care to the monitoring and treatment of crucial physical parameters. At a system level, actions are not easy to realize, especially for developing countries. However, at an individual level, even simple and very basic monitoring and treatment actions, undertaken by the treating clinician, can already improve the problem of suboptimal medical care in this population. Adhering to monitoring and treatment guidelines will result in a substantial enhancement of physical health outcomes. Furthermore, psychiatrists can help educate and motivate people with SMI to address their suboptimal lifestyle, including smoking, unhealthy diet and lack of exercise. The adoption of the recommendations presented in this paper across health care systems throughout the world will contribute to a significant improvement in the medical and related psychiatric health outcomes of patients with SMI.     

Consequences of pH measurement errors

SUMMARY. 1. The pH range over which the effects of acidification on freshwater organisms become apparent may be quite narrow, in some cases less than half a pH unit. Therefore, accurate measurement is important, particularly in dilute surface waters near the biologically critical threshold of hydrogen ion activity.
2. A hypothetical example based on data from two species of fish illustrates the potential errors in predicting mean mortality when pH is measured by probes of varying accuracies, placing our results into an ecosystem management perspective. For a given error, there will be greater uncertainty in predicting mean mortality for species sensitive to increased hydrogen ion activity than for more tolerant species.
3. We review field pH measurement errors, and present unique laboratory (measurements at 1°C and under argon) and field comparisons of current instruments used for continuous, in situ pH monitoring, including the only instrument comparison in low conductivity waters during snow melt. Four operator or sampler-caused measurement errors and three electrode-caused pH measurement errors are illustrated with data from four common types of pH probes and meters.
4. Studies providing no confidence intervals for a set of pH measurements due to the lack of rigorous quality control and assurance procedures are of limited quantitative value to future investigators attempting to analyse temporal trends of surface water acidification. Management and policy decision attempts will remain seriously hampered until more interpretable results are routinely generated.     

Developmental differences in visceral morphology of megophryine pelobatid tadpoles in relation to their body form and mode of life

Tadpoles face severe packing constraints on viscera within the pleuro-peritoneal cavity because of their extremely short torsos—a feature they share with adult anurans—and the concomitant need for relatively slender torsos for efficient locomotion. We examined the effects of differences in body form and habits on the size, shape and development of viscera in three kinds of sympatric, stream-associated pelobatid tadpoles. Leptobrachium montanumlarvae are generalized, wide, deep-bodied tadpoles. Larval Leptolalax gracilis are very slender and live in the crevices between rocks on the bottom of riffles. Larval Megophrys nasuta are intermediate between the other two in body form, and live with L. montanum in a variety of microhabitats but feed at the surface film. In all three species, liver, gall bladder, arid kidneys begin development early and grow isometrically throughout larval life. The gut and pancreas have a growth spurt shortly after hatching, then grow at a constant rate until near metamorphosis when both shrink drastically. The spleen grows at a slower rate than the body throughout the larval period. Lungs do not appear in L. gracilis until the tadpole approaches metamorphosis, which accords with its benthic habits, whereas they grow throughout the larval period in L. montanum and M. nasuta. In M. nasuta, however, the lungs are unusually wide anteriorly; this shifts buoyancy forward and facilitates the head-up feeding posture characteristic of that species. Gonads appear early in L. montanum and L. gracilis, but not until near metamorphosis in M. nasuta. We suggest that accelerated gonadal development in tadpoles characterizes species that metamorphose close to their size at first reproduction. Leptobrachium montanum, with the bulkiest body and most generalized habits, has relatively and absolutely the largest gut, liver (x of combined gut and liver volume = 24%, of total volume), and kidneys. Leptolalax gracilis, the most slender tadpole, has relatively the smallest combined gut and liver volume (x = 10% of total volume). Other premetamorphic differences among the species were observed in gut coiling, liver, pancreas and kidney shape and left/right asymmetry of urogenital organs. The major interspecific differences we observed in the size, shape, and developmental patterns of viscera in tadpoles are clearly related to interspecific differences in torso shape, microhabitat distribution and mode of feeding.     

The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study

The Neotropical catfishes of the genus Auchenipterus Valenciennes (1840) are reviewed. The genus is hypothesized to be a monophyletic assemblage on the basis of the shared presence of grooves in the ventral surface of the head that accommodate adducted mental barbels. A possible second synapomorphy, the presence of papillae on the dorsal and medial surface of the ossified maxillary barbel of mature males, is tentatively advanced pending discovery of adult males of three species. Contrary to previous hypotheses which considered Auchenipterus to consist of a maximum of five species, we recognize 11 species, including two previously undescribed forms, A. britskii and A. menezesi: Auchenipterus is broadly distributed through the Rio Orinoco, Rio Amazonas, and Rio de La Plata basins, and the coastal drainages of the Guianas, with one species in the Rio Pindare-Mirim and Rio Parnaiba basins of northeastern Brazil. Auchenipterus nuchalis, previously thought to be broadly distributed across the range of the genus, is found to rather have a restricted distribution in the eastern portions of the Amazon basin, the lower portions of the Rio Tocantins, and lower courses of some rivers in Suriname and French Guiana. Citations of A. nuchalis from elsewhere in the range of the genus are of other species. Euanemus Müller & Troschel (1842) and Ceratocheilus Miranda Ribeiro (1918) are considered synonyms of Auchenipterus. Euanemus colymbetes Müller & Troschel (1842) is considered a synonym of Auchenipterus (fen/ata Valenciennes (1840), and A. paysanduanus Devincenzi (1933) is placed into the synonymy of A. nigripinnis Boulenger (1895). A neotype is designated for Hypopthalmus nuchalis Spix & Agassiz (1829). Lectotypes are designated for Euanemus colymbetes and Auchenipterus nigripinnis.