Does urbanization influence the diet of a large snake?

Urbanization facilitates synanthropic species such as rodents, which benefit the diets of many predators in cities. We investigated how urbanization affects the feeding ecology of dugites Pseudonaja affinis, a common elapid snake in south-west Western Australia. We predicted that urban snakes: 1) more frequently contain prey and eat larger meals, 2) eat proportionally more non-native prey, 3) eat a lower diversity of prey species, and 4) are relatively heavier, than non-urban dugites. We analyzed the diet of 453 specimens obtained from the Western Australian Museum and opportunistic road-kill collections. Correcting for size, sex, season, and temporal biases, we tested whether location influenced diet for our 4 predictions. Body size was a strong predictor of diet (larger snakes had larger prey present, a greater number of prey items, and a greater diversity of prey). We identified potential collection biases: urban dugites were relatively smaller (snout-vent length) than non-urban specimens, and females were relatively lighter than males. Accounting for these effects, urban snakes were less likely to have prey present in their stomachs and were relatively lighter than non-urban snakes. Other urban-adapted carnivores appear to benefit from urbanization through increased food supplementation, but we found the opposite of this: urban dugites were less likely to contain a meal, and their meals were smaller, indicating they did not make greater use of synanthropic species than was evident for non-urban snakes. In contrast to other carnivores, snakes do not appear to fit a consistent directional pattern for size differences between urban and non-urban populations

Living on the edge: Effects of body size, group density and microhabitat selection on escape behaviour of southern leopard frogs Lithobates sphenocephalus

Models of optimal escape strategy predict that animals should move away when the costs of fleeing (metabolic and opportunity costs) are outweighed by the costs of remaining. These theoretical models predict that more vulnerable individuals should be more reactive, moving away when an approaching threat is further away. We tested whether escape behaviour (including ‘escape calling’) of Lithobates sphenocephalus approached by a human was influenced by body size or the initial microhabitat that the individual was found in. Irrespective of their size, frogs in the open tended to remain immobile, enhancing their crypsis. Frogs in cover showed different responses according to their body size, but, contrary to our initial predictions, larger frogs showed greater responsiveness (longer flight initiation distance and distances fled) than small frogs. Small frogs tended to remain closer to water and escaped into water, while larger individuals were more likely to jump to terrestrial cover and call during escape. Density of frogs near the focal animal had no effect on escape behaviour. This study indicates a range of escape responses in this species and points to the importance of divergent escape choices for organisms which live on the edge of different environments

Avian community changes following drought-induced canopy collapse in a Mediterranean-type forest

Context: Extreme drought can result in the widespread die-off of forests and dramatically altered ecosystem structure. Such changes are likly to influence fauna using resouces within these forests. Aims: Following a record hot and dry year/summer in 2010/11, large-scale canopy collapse occurred within a Mediterranean-type mixed jarrah (Eucalyptus marginata)–marri (Corymbia calophylla) forest in south-west Western Australia. We investigated the effects of this collapse on bird assemblages in 2016, 5 years after the initial collapse. Methods: We carried out bird surveys using a standardised search method for five paired drought-affected and adjacent healthy forest plots. Key results: A total of 3042 records of 51 bird species were observed across all surveys. Overall, the pooled (mean ± s.d.) reporting rates for drought-affected plots (13.84 ± 0.60 individuals/survey) were significantly less than the reporting rates for healthy plots (34.44 ± 1.03 individuals/survey) (PERMANOVA: F1 = 54.94, R2 = 0.31, P = 0.001). Species diversity was also higher in healthy plots (t26 = 11.21, P < 0.001). Foliage-searching birds were the most abundant guild across all plots and were reported less often in drought-affected plots (t6 = 2.70, P < 0.04). Conclusions: Drought-affected jarrah forest plots exhibited significant differences in bird assemblages compared to healthy plots. Overall, the drought-affected forest provides a less favourable habitat for birds compared to healthy forest. Implications: With marked variability and extreme climate events predicted for the future, understanding the impacts of such changes will contribute to how we manage forest ecosystems

Reducing wild dog impacts on livestock production industries

Wild dogs are a huge problem for Australian livestock producers, costing farmers an estimated $50 million annually in livestock losses and for their control. Here we describe outcomes of a recent project that has examined aspects of wild dog control in WA

Ontogenetic shift in diet of a large elapid snake is facilitated by allometric change in skull morphology

As snakes are limbless, gape-limited predators, their skull is the main feeding structure involved in prey handling, manipulation and feeding. Ontogenetic changes in prey type and size are likely to be associated with distinct morphological changes in the skull during growth. We investigated ontogenetic variation in diet from stomach contents of 161 Dugite specimens (Pseudonaja affinis, Elapidae) representing the full range of body size for the species, and skull morphology of 46 specimens (range 0.25–1.64 m snout-vent-length; SVL). We hypothesised that changes in prey type throughout postnatal ontogeny would coincide with distinct changes in skull shape. Dugites demonstrate a distinct size-related shift in diet: the smallest individuals ate autotomised reptile tails and reptiles, medium-sized individuals predominantly ate mammals, and the largest individuals had the most diverse diet, including large reptiles. Morphometric analysis revealed that ~40% of the variation in skull shape was associated with body size (SVL). Through ontogeny, skulls changed from a smooth, bulbous cranium with relatively small trophic bones (upper and lower jaws and their attachments), to more rugose bones (as a likely reflection of muscle attachment) and relatively longer trophic bones that would extend gape. Individual shape variation in trophic bone dimensions was greater in larger adults and this likely reflects natural plasticity of individuals feeding on different prey sizes/types. Rather than a distinct morphological shift with diet, the ontogenetic changes were gradual, but positive allometry of individual trophic bones resulted in disproportionate growth of the skull, reflected in increased gape size and mobility of jaw bones in adults to aid the ingestion of larger prey and improve manipulation and processing ability. These results indicate that allometric scaling is an important mechanism by which snakes can change their dietary niche

Resummation of Nonalternating Divergent Perturbative Expansions

A method for the resummation of nonalternating divergent perturbation series is described. The procedure constitutes a generalization of the Borel-Pad\'{e} method. Of crucial importance is a special integration contour in the complex plane. Nonperturbative imaginary contributions can be inferred from the purely real perturbative coefficients. A connection is drawn from the quantum field theoretic problem of resummation to divergent perturbative expansions in other areas of physics.Comment: 5 pages, LaTeX, 2 tables, 1 figure; discussion of the Carleman criterion added; version to appear in Phys. Rev.

A Class of Partially Solvable Two-Dimensional Quantum Models with Periodic Potentials

The supersymmetrical approach is used to analyse a class of two-dimensional quantum systems with periodic potentials. In particular, the method of SUSY-separation of variables allowed us to find a part of the energy spectra and the corresponding wave functions (partial solvability) for several models. These models are not amenable to conventional separation of variables, and they can be considered as two-dimensional generalizations of Lame, associated Lame, and trigonometric Razavy potentials. All these models have the symmetry operators of fourth order in momenta, and one of them (the Lame potential) obeys the property of self-isospectrality.Comment: 22 pages; some typos corrected; new reference adde

Oncolytic Viruses: Do They Have a Role in Anti-Cancer Therapy?

Oncolytic viruses are replication competent, tumor selective and lyse cancer cells. Their potential for anti-cancer therapy is based upon the concept that selective intratumoral replication will produce a potent anti-tumor effect and possibly bystander or remote cell killing, whilst minimizing normal tissue toxicity. Viruses may be naturally oncolytic or be engineered for oncolytic activity, and possess a host of different mechanisms to provide tumor selectivity. Clinical use of live replicating viruses is associated with a unique set of safety issues. Clinical experience has so far provided evidence of limited efficacy and a favourable toxicity profile. The interaction with the host immune system is complex. An anti-viral immune response may limit efficacy by rapidly clearing the virus. However, virally-induced cell lysis releases tumor associated antigens in a ‘dangerous’ context, and limited evidence suggests that this can lead to the generation of a specific anti-tumor immune response. Combination therapy with chemotherapy or radiotherapy represents a promising avenue for ongoing translation of oncolytic viruses into clinical practice. Obstacles to therapy include highly effective non-specific host mechanisms to clear virus following systemic delivery, immune-mediated clearance, and intratumoral barriers limiting virus spread. A number of novel strategies are now under investigation to overcome these barriers. This review provides an overview of the potential role of oncolytic viruses, highlighting recent progress towards developing effective therapy and asks if they are a realistic therapeutic option at this stage

Derivation of the human embryonic stem cell line RCe008-A (RC-4)

The human embryonic stem cell line RCe008-A (RC-4) was derived from a blastocyst voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to ectoderm and mesoderm in vitro. It has a mixed 46XX/45X female karyotype and microsatellite PCR identity and blood group typing data is available

Derivation of the human embryonic stem cell line RCe011-A (RC-7)

The human embryonic stem cell line RCe011-A (RC-7) was derived from a failed to fertilise oocyte voluntarily donated as unsuitable and surplus to fertility requirements following ethics committee approved informed consent under licence from the UK Human Fertilisation and Embryology Authority. The cell line shows normal pluripotency marker expression and differentiation to the three germ layers in vitro. It has a normal 46XY male karyotype and microsatellite PCR identity, HLA and blood group typing data are available