Robustness despite uncertainty: regional climate data reveal the dominant role of humans in explaining global extinctions of Late Quaternary megafauna

Debate over the Late Quaternary megafaunal extinctions has focussed on whether human colonisation or climatic changes were more important drivers of extinction, with few extinctions being unambiguously attributable to either. Most analyses have been geographically or taxonomically restricted and the few quantitative global analyses have been limited by coarse temporal resolution or overly simplified climate reconstructions or proxies. We present a global analysis of the causes of these extinctions which uses high‐resolution climate reconstructions and explicitly investigates the sensitivity of our results to uncertainty in the palaeological record. Our results show that human colonisation was the dominant driver of megafaunal extinction across the world but that climatic factors were also important. We identify the geographic regions where future research is likely to have the most impact, with our models reliably predicting extinctions across most of the world, with the notable exception of mainland Asia where we fail to explain the apparently low rate of extinction found in in the fossil record. Our results are highly robust to uncertainties in the palaeological record, and our main conclusions are unlikely to change qualitatively following minor improvements or changes in the dates of extinctions and human colonisation.     

The evolution of parental care in insects: A test of current hypotheses

Which sex should care for offspring is a fundamental question in evolution. Invertebrates, and insects in particular, show some of the most diverse kinds of parental care of all animals, but to date there has been no broad comparative study of the evolution of parental care in this group. Here, we test existing hypotheses of insect parental care evolution using a literature‐compiled phylogeny of over 2000 species. To address substantial uncertainty in the insect phylogeny, we use a brute force approach based on multiple random resolutions of uncertain nodes. The main transitions were between no care (the probable ancestral state) and female care. Male care evolved exclusively from no care, supporting models where mating opportunity costs for caring males are reduced—for example, by caring for multiple broods—but rejecting the “enhanced fecundity” hypothesis that male care is favored because it allows females to avoid care costs. Biparental care largely arose by males joining caring females, and was more labile in Holometabola than in Hemimetabola. Insect care evolution most closely resembled amphibian care in general trajectory. Integrating these findings with the wealth of life history and ecological data in insects will allow testing of a rich vein of existing hypotheses.     

Impacts of the live reef fish trade on populations of coral reef fish off northern Borneo

The live reef fish trade (LRFT) is one of the greatest but least-quantified sources of fishing pressure for several species of large coral reef fish across the Indo-Pacific. For the first time we quantify the localized impact of the LRFT. We collected data from three LRFT traders in northern Borneo, which yielded information on daily fishing effort and the species and mass of all fishes sold every day by individual fishers or vessels over 2, 3 and 8 years. Total monthly catch and relative abundance (catch-per-unit-effort) declined significantly in several species, including the most valuable species the Napoleon wrasse (Cheilinus undulatus, estimated changes of -98 and -78% over 8 years in catch and relative abundance, respectively) and lower-value bluelined groupers (Plectropomus oligocanthus: -99 and -81%) and Epinephelus groupers (-89 and -32%). These severe declines were rapid, species-specific and occurred in the first 2-4 years of the dataset and are, we believe, directly attributable to the LRFT. This has crucial implications for future data collection and monitoring if population collapses in other parts of the LRFT and similar wildlife trades are to be successfully detected.     

Where the wild birds go: explaining the differences in migratory destinations across terrestrial bird species

Given their large movement capacities, migratory birds have in principle a wide range of possible geographical locations for their breeding and non‐breeding destinations, yet each species migrates between consistent breeding and non‐breeding ranges. In this study, we use a macroecological approach to search for the general factors explaining the location of the seasonal ranges of migratory bird species across the globe. We develop a null model to test the hypotheses that access to resources, geographical distance, tracking of temperature, and habitat conditions (separately as well as considered together) have a major influence in the location of species’ migratory destinations, once each species’ geographical constraints are taken into account. Our results provide evidence for a trade‐off between costs associated with distance travelled and gains in terms of better access to resources. We also provide strong support to the hypotheses that all factors tested, with the exception of habitat, have a strong and additive effect on the global geography of bird migration. Indeed, our results indicate that species’ contemporary migratory destinations (i.e. the combination of their breeding and non‐breeding ranges) are such that they allow species to track a temperature regime throughout the year, to escape local competition and reach areas with better access to resources, and to minimise the spatial distance travelled, within the limitations imposed by the geographical location of each species. Our study thus sheds light on the mechanisms underpinning bird migration and provides a strong basis for predicting how migratory species will respond to future change.     

Heteroleptic oxidovanadium(IV)-malate complex improves glucose uptake in HepG2 and enhances insulin action in streptozotocin-induced diabetic rats

BioMetals - Diabetes mellitus, a complex and heterogeneous disease associated with hyperglycemia, is a leading cause of mortality and reduces life expectancy. Vanadium complexes have been studied...     

Pressure probe technique to study transpiration in phycomyces sporangiophores

The growth equation for the rate of water uptake is augmented with a transpiration term. The obtained augmented growth equations are used to develop methodology which employs the pressure probe to measure transpiration rates from single plant cells. Experiments are conducted on the sporangiophores of Phycomyces blakesleeanus to demonstrate this technique.