Flies on vacation: evidence for the migration of Australian Syrphidae (Diptera)

1. Hover flies (Syrphidae: Diptera) are a cosmopolitan group of insects that provide important ecosystem services including pollination and pest control. The seasonal migration of hover flies is probably best known in Europe, but it remains unstudied in many other parts of the world. 2. Australia is believed to be home to around 160 hover fly species, some of which are common in urban and agricultural environments. The current evidence for hover fly migration in Australia is scarce and anecdotal, yet migration may be critical to the success of pollination and the biological control of aphids. 3. In this study, species occurrence records from an online biodiversity database (Atlas of Living Australia) were used to look for evidence of migratory behaviours in all Australian hover flies with more than 200 occurrence records. 4. Four of the 10 species displayed seasonal changes in their distribution consistent with migration, including Australia's two most abundant species: Melangyna viridiceps and Simosyrphus grandicornis. This work is an important first step in understanding the prevalence of migration in Australian hover flies. However, confirmation of our findings requires additional evidence to rule out other plausible explanations for the observed patterns. 5. Based on changes in summer and winter latitudinal distribution, it is estimated that some Australian hover flies may make annual migrations of 400–1800 km. 6. This work suggests that the management of beneficial insects requires consideration of factors at both local and continental scales, as landscape use changes may have an impact on ecosystem services delivered hundreds of kilometres away.     

Biogeographical structure and affinities of the marine demersal ichthyofauna of Australia

Aim To investigate the biogeographical structure and affinities of the Australian marine demersal ichthyofauna at the scale of provinces and bathomes for the purposes of regional marine planning. Location Australia. Methods Patterns of distribution in the Australian fish fauna, at both intra‐regional and global scales, were examined using a science‐based, management framework dividing Australia’s marine biodiversity into 16 province‐level biogeographical units. Occurrences of 3734 species in eight depth‐stratified bathomes (from the coast to the mid‐continental slope) within each province were analysed to determine the structure and local affinities of their assemblages and their association with faunas of nearby regions and oceans basins. Results Strong geographic and depth‐related structure was evident. Fish assemblages in each province, and in each bathome of each province, were distinct, with the shelf‐break bathome more similar to the adjacent continental shelf bathome than to the upper slope bathome. Data based only on endemic species performed well as a surrogate of the entire dataset, yielding comparable patterns of similarity between provinces and bathomes. Tropical and temperate elements were better discriminated than elements of the Pacific and Indian oceans, with the central western province more similar to the tropical provinces (including those in the east), and the eastern province closer to southern temperate provinces. The fauna shares the closest regional affinities with those of the adjacent south‐west Pacific, western Pacific Rim, and elements of wide‐ranging Indo‐Pacific components. Elements unique to the Pacific and Indian oceans are poorly represented. Main conclusions The complex nature of Australia’s marine ichthyofauna is confirmed. A hierarchy of provinces and bathomes, used to ensure that Australia’s developing marine reserve network is both representative and comprehensive, is equally robust when based on all known Australian fish species or on only those species endemic to this continent. Latitude and depth are more important than oceanic influences on the composition of this fauna at these scales.     

Further acetogenins from Tasmanian collections of Caulocystis cephalornithos demonstrating chemical variability

Samples of the brown alga Caulocystis cephalornithos, from five locations in southern and southeastern Tasmania, were investigated for comparison of their acetogenin content. In contrast with previously studied brown algae, including mainland Australian collections of C. cephalornithos, Tasmanian collections of C. cephalornithos were found to contain unusually high levels of tridec-1-ene, a hydrocarbon not previously reported from a marine alga. The novel metabolite (E)-nonadec-3-en-2-one was also isolated. Compounds previously described from this alga were present, together with a suite of homologues not previously observed in this species. The compounds present suggested that the alkyl chain of the orsellinic acid derivatives was present prior to cyclisation. Large variations in relative metabolite content were observed both within and between collection sites.     

Evaluating the role of the Dingo as a trophic regulator: Additional practical suggestions

Summary   A recent review paper by Glen et   al . in Austral Ecology (2007, Volume 32 , 492–501) canvassed anecdotal and scientific evidence relating to the role of the Dingo as regulator of ecosystem processes in Australian landscapes. Their review forms part of an increasing volume of literature about the ecological roles of top-order or apex predators around the globe. Although recognizing the possible functional significance of the Dingo is a noteworthy subject matter, the management of the species at an ecosystem scale is complicated by a range of practical and theoretical issues. Perhaps the most significant challenge is the degree to which the Dingo is hybridized with the domestic Dog gone wild (Feral Dog). We suggest here that there is a range of research questions that need to be experimentally addressed as a matter of urgency. This includes but is not limited to understanding the ecological significance of Dingo–Dog hybridization. Such research should precede other research initiatives suggested by Glen et   al. such as reintroducing individuals of the pure Dingo back into landscapes. This is particularly the case for south-eastern mainland Australia where the incidence of Dingo–Dog hybridization is high and the ecological consequences of this poorly understood. Finally, new terminology may be needed relating to Dingo and/or Wild Dog management that more clearly reflects both the genetic status of the species as well as its ecological function.     

Patterns in body size and melanism along a latitudinal cline in the wingless grasshopper,Phaulacridium vittatum

Aim We explore geographic variation in body size within the wingless grasshopper, Phaulacridium vittatum, along a latitudinal gradient, and ask whether melanism can help explain the existence of clinal variation. We test the hypotheses that both male and female grasshoppers will be larger and lighter in colour at lower latitudes, and that reflectance and size will be positively correlated, as predicted by biophysical theory. We then test the hypothesis that variability in size and reflectance is thermally driven, by assessing correlations with temperature and other climatic variables. Location Sixty‐one populations were sampled along the east coast of Australia between latitudes 27.63° S and 43.10° S, at elevations ranging from 10 to 2000 m a.s.l. Methods Average reflectance was used as a measure of melanism and femur length as an index of body size for 198 adult grasshoppers. Climate variables were generated by BIOCLIM for each collection locality. Hierarchical partitioning was used to identify those variables with the most independent influence on grasshopper size and reflectance. Results Overall, there was no simple relationship between size and latitude in P. vittatum. Female body size decreased significantly with latitude, while male body size was largest at intermediate latitudes. Rainfall was the most important climatic variable associated with body size of both males and females. Female body size was also associated with radiation seasonality and male body size with reflectance. The reflectance of females was not correlated with latitude or body size, while male reflectance was significantly higher at intermediate latitudes and positively correlated with body size. Analyses of climate variables showed no significant association with male reflectance, while female reflectance was significantly related to the mean temperature of the driest quarter. Main conclusions Geographic variation in the body size of the wingless grasshopper is best explained in terms of rainfall and radiation seasonality, rather than temperature. However, melanism is also a significant influence on body size in male grasshoppers, suggesting that thermal fitness does play a role in determining adaptive responses to local conditions in this sex.     

Niche models tell half the story: spatial context and life‐history traits influence species responses to global change

Aim While niche models are typically used to assess the vulnerability of species to climate change, they have been criticized for their limited assessment of threats other than climate change. We attempt to evaluate this limitation by combining niche models with life‐history models to investigate the relative influence of climate change and a range of fire regimes on the viability of a long‐lived plant population. Specifically, we investigate whether range shift due to climate change is a greater threat to an obligate seeding fire‐prone shrub than altered fire frequency and how these two threatening processes might interact. Location Australian sclerophyll woodland and heathland. Methods The study species is Leucopogon setiger, an obligate seeding fire‐prone shrub. A spatially explicit stochastic matrix model was constructed for this species and linked with a dynamic niche model and fire risk functions representing a suite of average fire return intervals. We compared scenarios with a variety of hypothetical patches, a patch framework based upon current habitat suitability and one with dynamic habitat suitability based on climate change scenarios A1FI and A2. Results Leucopogon setiger was found to be sensitive to fire frequency, with shorter intervals reducing expected minimum abundances (EMAs). Spatial decoupling of fires across the landscape reduced the vulnerability of the species to shortened fire frequencies. Shifting habitat, while reducing EMAs, was less of a threat to the species than frequent fire. Main conclusions Altered fire regime, in particular more frequent fires relative to the historical regime, was predicted to be a strong threat to this species, which may reflect a vulnerability of obligate seeders in general. Range shifts induced by climate change were a secondary threat when habitat reductions were predicted. Incorporating life‐history traits into habitat suitability models by linking species distribution models with population models allowed for the population‐level evaluation of multiple stressors that affect population dynamics and habitat, ultimately providing a greater understanding of the impacts of global change than would be gained by niche models alone. Further investigations of this type could elucidate how particular bioecological factors can affect certain types of species under global change.     

Retirement and Unexpected Health Shocks

Is retirement good for your health? We complement previous studies by exploring the effect of retirement on unexpected health evolution. Using panel data from the Household, Income and Labour Dynamics in Australia survey (2001-2014), we construct measures of the mismatch between individual expected and actual health evolution (hereafter “health shocks”). In our approach, reverse causation running from health shocks to retirement is highly unlikely, because we look at shocks that happen after retirement, and those shocks are, by definition, unanticipated. We find that retirement decreases the probability of negative shocks (by approximately 16% to 24% for men and 14% to 23% for women) while increasing the likelihood of positive shocks (by 9% to 14% for men and 10% to 13% for women). This result is robust to the use of different lead-lag structures and of alternative measures of health change. Our findings are thus consistent with a positive impact of retirement on health.     

Hormone changes in relation to the time of fetal death after prostaglandin-induced abortion

The changes in unconjugated estradiol-17β and estriol, progesterone and chorionic somatomammotropin (HCS) in peripheral plasma have been studied in 18 women at 30-minute intervals following intra-uterine prostaglandin E₂ administration for therapeutic termination of second trimester pregnancy. The hormonal changes were related to the time of fetal death detected by the disappearance of fetal heart pulsations. Prostaglandin E₂ was given by the intra-amniotic route with urea (5 patients) or with intravenous oxytocin (5 patients), or by the extra-amniotic route with intravenous oxytocin (8 patients). Fetal death occurred rapidly with intra-amniotic PGE₂, but usually at a late stage with extra-amniotic PGE₂. Three fetuses in the extra-amniotic group died at or just before abortion. A variety of fetal heart changes were noted and the time of fetal death did not appear to influence the time of abortion within each treatment subgroup.Estradiol and estriol showed a slight but persistent fall over 24 hours prior to induction of abortion. A more rapid fall usually occurred after induction, with a consistent fall around the time of fetal death. Progesterone and HCS usually fell much less before and immediately after fetal death. A marked rise in estradiol sometimes occurred before fetal death, particularly in the intra-amniotic PGE₂ and urea subgroup. Estriol levels declined more rapidly before than after fetal death, whereas fetal death had less consistent effects on the other hormones. All hormones had usually fallen considerably at the time of abortion, and in some individuals marked fluctuations in hormone levels were seen.