Odysseys in Pastryland – a bird’s eye view of microevolution

Theory based models of microevolutionary processes are difficult to test in the wild, because the data relating to the specific predictions of the model must be disentangled from the complexity of the species’ overall ecology. Since the 1960s some evolutionary ecologists have been using field experiments involving artificial prey and wild predators – the ecology of the ‘prey’ is under the control of the experimenter, which greatly simplifies the logistics of testing specific microevolutionary models. So far, this technique – typically using prey ‘worms’ made from pastry and wild passerine birds as predators – has been used to test theoretical models of crypsis, directional vs. stabilising selection, apostatic selection, polymorphism, and mimicry systems (Allen, Cooper, Hall, and McHenry 1993). To date, the ‘Pastryland’ technique has been used by ecologists at the Universities of Reading and Southampton in the UK.Because it is a simple model of microevolution in the real world, and because individual experiments rarely require more than a few days to complete, ‘Pastryland’ has also been used to demonstrate the process of natural selection to tertiary science students (Allen, Cooper, Hall, and McHenry 1993). Natural selection is a powerful but very subtle theory, and is hard to grasp without some sort of real world demonstration or example. The logistics of Pastryland experiments mean that it can easily be performed as part of a tertiary field-based activity, with students intimately involved with the running of the experiment. Students are immersed in evolution by taking an active role in the process. Although the pastry ‘prey’ are artificial, the technique relies ultimately on the behaviour of wild predators, as a ‘real’ selective pressure, enhancing student concept acquisition in evolutionary theory. Pastryland was trialed as a group field project for third year ecology undergraduates at the University of Newcastle. They tested a specific prediction about the dynamics of mimicry systems that has not yet been tested experimentally. This was the first time (to our knowledge) that Pastryland has been used within a teaching context in Australia, and we adapted the technique to make use of common wild birds in Australian urban environments. In the UK, the most important predator was the blackbird (Turdus merula) – in coastal NSW, the main predators are noisy miners (Manorina melanocephala), magpies (Gymnorhina tibicen), and currawongs (Strepera graculina). Students also modified the experimental design to improve controls, and involved local high schools in the hope that the technique would ‘catch-on’ with science teachers

An interactive three dimensional approach to anatomical description—the jaw musculature of the Australian laughing kookaburra (Dacelo novaeguineae)

The investigation of form-function relationships requires a detailed understanding of anatomical systems. Here we document the 3-dimensional morphology of the cranial musculoskeletal anatomy in the Australian Laughing Kookaburra Dacelo novaeguineae, with a focus upon the geometry and attachments of the jaw muscles in this species. The head of a deceased specimen was CT scanned, and an accurate 3D representation of the skull and jaw muscles was generated through manual segmentation of the CT scan images, and augmented by dissection of the specimen. We identified 14 major jaw muscles: 6 in the temporal group (M. adductor mandibulae and M. pseudotemporalis), 7 in the pterygoid group (M. pterygoideus dorsalis and M. pterygoideus ventralis), and the single jaw abductor M. depressor mandibulae. Previous descriptions of avian jaw musculature are hindered by limited visual representation and inconsistency in the nomenclature. To address these issues, we: (1) present the 3D model produced from the segmentation process as a digital, fully interactive model in the form of an embedded 3D image, which can be viewed from any angle, and within which major components can be set as opaque, transparent, or hidden, allowing the anatomy to be visualised as required to provide a detailed understanding of the jaw anatomy; (2) provide a summary of the nomenclature used throughout the avian jaw muscle literature. The approach presented here provides considerable advantages for the documentation and communication of detailed anatomical structures in a wide range of taxa

Kontrol Diri Dan Kecemasan Komunikasi Interpersonal Pada Pramuwisata

This study aim to analysis relationship of self-control and anxiety of interpersonal communicationin a tourist guide. Product moment corelation analysis (rxy) yields for 0905, to provethe relationship between self-control and interpersonal communication anxiety in a tourist guide.These results indicate a negative relationship between the variables X (Self Control) and variableY (Interpersonal Communication Anxiety in the guides). Social Learning Theory became atheories used in this study, where most of the individual behavior acquired partly the result oflearning through observation of behavior displayed other individuals whose became the model.Elaboration Likelihood Theory which states that each individual will interpret the message orinformation they receive, in accordance with the information they have and their beliefs aboutsomething related to the message. Self-control on the tour guides in Yogyakarta based on thefive major aspects of self-control, that has a very high level of measurement. Includes the abilityto anticipate events, the ability to interpret events and the ability to take decisions. Meanwhile,two other aspects of self control shows the results of measurements at very low category, whichconsists of aspects of behavior and stimulus control. While anxiety based on the three aspects ofinterpersonal communication, which consists of inhibition of the ability to express themselves,lack of interest in communicating and social interaction is interrupted, it indicates the levelmeasurement at very low category. Thus, interpersonal communication anxiety on tour guidesin Yogyakarta can be said to be very low

Oldest pathology in a tetrapod bone illuminates the origin of terrestrial vertebrates

The origin of terrestrial tetrapods was a key event in vertebrate evolution, yet how and when it occurred remains obscure, due to scarce fossil evidence. Here, we show that the study of palaeopathologies, such as broken and healed bones, can help elucidate poorly understood behavioural transitions such as this. Using high-resolution finite element analysis, we demonstrate that the oldest known broken tetrapod bone, a radius of the primitive stem tetrapod Ossinodus pueri from the mid-Viséan (333 million years ago) of Australia, fractured under a high-force, impact-type loading scenario. The nature of the fracture suggests that it most plausibly occurred during a fall on land. Augmenting this are new osteological observations, including a preferred directionality to the trabecular architecture of cancellous bone. Together, these results suggest that Ossinodus, one of the first large (>2m length) tetrapods, spent a significant proportion of its life on land. Our findings have important implications for understanding the temporal, biogeographical and physiological contexts under which terrestriality in vertebrates evolved. They push the date for the origin of terrestrial tetrapods further back into the Carboniferous by at least two million years. Moreover, they raise the possibility that terrestriality in vertebrates first evolved in large tetrapods in Gondwana rather than in small European forms, warranting a re-evaluation of this important evolutionary event

The Effects of Biting and Pulling on the Forces Generated during Feeding in the Komodo Dragon (Varanus komodoensis)

In addition to biting, it has been speculated that the forces resulting from pulling on food items may also contribute to feeding success in carnivorous vertebrates. We present an in vivo analysis of both bite and pulling forces in Varanus komodoensis, the Komodo dragon, to determine how they contribute to feeding behavior. Observations of cranial modeling and behavior suggest that V. komodoensis feeds using bite force supplemented by pulling in the caudal/ventrocaudal direction. We tested these observations using force gauges/transducers to measure biting and pulling forces. Maximum bite force correlates with both body mass and total body length, likely due to increased muscle mass. Individuals showed consistent behaviors when biting, including the typical medial-caudal head rotation. Pull force correlates best with total body length, longer limbs and larger postcranial motions. None of these forces correlated well with head dimensions. When pulling, V. komodoensis use neck and limb movements that are associated with increased caudal and ventral oriented force. Measured bite force in Varanus komodoensis is similar to several previous estimations based on 3D models, but is low for its body mass relative to other vertebrates. Pull force, especially in the ventrocaudal direction, would allow individuals to hunt and deflesh with high success without the need of strong jaw adductors. In future studies, pull forces need to be considered for a complete understanding of vertebrate carnivore feeding dynamics

The sensitivity of biological finite element models to the resolution of surface geometry:a case study of crocodilian crania

The reliability of finite element analysis (FEA) in biomechanical investigations depends upon understanding the influence of model assumptions. In producing finite element models, surface mesh resolution is influenced by the resolution of input geometry, and influences the resolution of the ensuing solid mesh used for numerical analysis. Despite a large number of studies incorporating sensitivity studies of the effects of solid mesh resolution there has not yet been any investigation into the effect of surface mesh resolution upon results in a comparative context. Here we use a dataset of crocodile crania to examine the effects of surface resolution on FEA results in a comparative context. Seven high-resolution surface meshes were each down-sampled to varying degrees while keeping the resulting number of solid elements constant. These models were then subjected to bite and shake load cases using finite element analysis. The results show that incremental decreases in surface resolution can result in fluctuations in strain magnitudes, but that it is possible to obtain stable results using lower resolution surface in a comparative FEA study. As surface mesh resolution links input geometry with the resulting solid mesh, the implication of these results is that low resolution input geometry and solid meshes may provide valid results in a comparative context

Bottom-Feeding Plesiosaurs

Elasmosaurid plesiosaurs were an important part of Cretaceous marine reptile communities and are generally considered to have been predators of small, agile, free-swimming fish and cephalopods. Two elasmosaurid specimens from Aptian and Albian deposits in Queensland, Australia, include fossilized gut contents dominated by benthic invertebrates: bivalves, gastropods, and crustaceans. Both specimens also contained large numbers of gastroliths (stomach stones). These finds point to a wider niche than has previously been supposed for these seemingly specialized predators and may also influence long-running controversy over the question of gastrolith function in plesiosaurs

The Effects of Biting and Pulling on the Forces Generated during Feeding in the Komodo Dragon ('Varanus komodoensis')

In addition to biting, it has been speculated that the forces resulting from pulling on food items may also contribute to feeding success in carnivorous vertebrates. We present an in vivo analysis of both bite and pulling forces in 'Varanus komodoensis', the Komodo dragon, to determine how they contribute to feeding behavior. Observations of cranial modeling and behavior suggest that 'V. komodoensis' feeds using bite force supplemented by pulling in the caudal/ventrocaudal direction. We tested these observations using force gauges/transducers to measure biting and pulling forces. Maximum bite force correlates with both body mass and total body length, likely due to increased muscle mass. Individuals showed consistent behaviors when biting, including the typical medial-caudal head rotation. Pull force correlates best with total body length, longer limbs and larger postcranial motions. None of these forces correlated well with head dimensions. When pulling, 'V. komodoensis' use neck and limb movements that are associated with increased caudal and ventral oriented force. Measured bite force in Varanus komodoensis is similar to several previous estimations based on 3D models, but is low for its body mass relative to other vertebrates. Pull force, especially in the ventrocaudal direction, would allow individuals to hunt and deflesh with high success without the need of strong jaw adductors. In future studies, pull forces need to be considered for a complete understanding of vertebrate carnivore feeding dynamics

Novel habitat causes a shift to diurnal activity in a nocturnal species

Plastic responses may allow individuals to survive and reproduce in novel environments, and can facilitate the establishment of viable populations. But can novel environments reveal plasticity by causing a shift in a behavior as fundamental and conspicuous as daily activity? We studied daily activity times near the invasion front of the cane toad (Rhinella marina), an invasive species that has colonized much of northern Australia. Cane toads in Australia are nocturnal, probably because diurnal activity would subject them to intolerably hot and dry conditions in the tropical savannah during the dry season. Our study can demonstrate, however, that upon reaching novel environments some toad populations became diurnal. Sandstone gorges ofered cane toads novel, deeply shaded habitat. Gorges with an east-west axis (day-long northern shadow), narrow gorges and narrow sections of gorges contained toads that were primarily diurnal, while gorges with a north-south axis, wide gorges and wide sections of gorges contained mainly nocturnal toads. For example, remote camera data (1314 observations of toad activity times over 789 trap days) revealed strictly nocturnal activity at four ‘exposed’ sites (99% of 144 observations over 179 days), compared to mostly diurnal activity at a ‘shaded’ site (78% of 254 observations). Visual encounter surveys confrmed that diurnal activity occurred exclusively at shaded sites, while most nocturnal activity occurred at exposed sites. The close proximity of diurnal and nocturnal toads (4–7km) provided compelling evidence for the abovementioned physical factors as the proximate cause of the behavioral dichotomy, and for a novel (deeply shaded gorges) environment causing the shift to diurnal activit