Ecomorphology of Carnivora challenges convergent evolution

Convergent evolution is often reported in the mammalian order Carnivora. Their adaptations to particularly demanding feeding habits such as hypercarnivory and durophagy (consumption of tough food) appear to favour morphological similarities between distantly related species, especially in the skull. However, phylogenetic effect in phenotypic data might obscure such a pattern. We first validated the hypotheses that extant hypercarnivorous and durophagous large carnivorans converge in mandibular shape and form (size and shape). Hypercarnivores generally exhibit smaller volumes of the multidimensional shape and form space than their sister taxa, but this pattern is significantly different from random expectation only when hunting behaviour categorisations are taken into account. Durophages share areas of the morphospace, but this seems to be due to factors of contingency. Carnivorans that hunt in pack exhibit incomplete convergence while even stronger similarities occur in the mandible shape of solitary hunters due to the high functional demands in killing the prey. We identified a stronger phylogenetic signal in mandibular shape than in size. The quantification of evolutionary rates of changes suggests that mandible shape of solitary hunters evolved slowly when compared with other carnivorans. These results consistently indicate that the need for a strong bite force and robust mandible override sheer phylogenetic effect in solitary hunters

Zoonotic Diseases Report 2013

De Staat van zoönosen 2013 geeft een overzicht van de mate waarin zoönosen in Nederland voorkomen en ontwikkelingen daarin op de lange termijn. Zoönosen zijn infectieziekten die van dier op mens overgaan. Net als in voorgaande jaren waren er in 2013 geen uitgesproken veranderingen te zien in de mate waarin zoönosen in Nederland voorkomen. Zoals ieder jaar deden zich ook in 2013 enkele opmerkelijke voorvallen voor, zoals een geval van hazenpest. In deze jaarlijkse uitgave van het RIVM en de NVWA is het thema 'huis-, tuin- en keukenzoönosen': zoönosen die mensen kunnen oplopen in en om het huis. Opmerkelijke voorvallen Bij een haas afkomstig uit Noord-Limburg werd in mei 2013 hazenpest (tularemie) vastgesteld. Vervolgens werd ook bij een jongeman tularemie vastgesteld, die de infectie waarschijnlijk via een dazenbeet in een natuurgebied in Limburg had opgelopen. In 2011 is er mogelijk ook een in Nederland opgelopen geval van tularemie geweest, terwijl in de jaren daarvoor alleen sporadisch gevallen gemeld werden die in het buitenland waren opgelopen. Een andere opmerkelijke gebeurtenis betrof een uitbraak van Campylobacter onder bezoekers van een pluimveeslachthuis die waarschijnlijk via de lucht aan de ziekteverwekker waren blootgesteld. Negen mensen werden ziek. Ook blijkt uit een onderzoek naar de vossenlintworm (Echinococcus multilocularis) onder vossen en honden, dat deze lintworm bij vossen in Zuid-Limburg veel vaker voorkomt dan in voorgaande jaren. Thema: huis-, tuin- en keukenzoönosen Juist in en om het huis kunnen mensen worden blootgesteld aan allerlei zoönoseverwekkers. Duizenden mensen krijgen jaarlijks via hun huisdieren ringworm, een schimmelinfectie. Ook kunnen zoönosen afkomstig zijn van huisdieren of dieren die hun behoefte doen in de tuin. Verder komen voedselgerelateerde zoönosen aan de orde, waarbij aandacht is voor het feit dat zoönosen ook via groenten kunnen worden opgelopen.The Zoonotic Diseases Report is an annual publication of the Dutch National Institute for Public Health and the Environment (RIVM) and the Netherlands Food and Consumer Product Safety Authority (NVWA). The report provides an overview of the incidence of zoonotic diseases in the Netherlands, as well as the associated long-term trends. Zoonotic diseases or zoonoses are infectious diseases that can be transmitted from animals to humans. As in previous years, no marked changes were observed in 2013 in the incidence of zoonotic diseases in the Netherlands. Every year a number of notable incidents occurres. In 2013 this included a case of rabbit fever (tularemia). This year's edition of the Zoonotic Diseases Report focuses in particular on 'zoonoses close to home', i.e. the risk of contracting a zoonotic disease in or around the house. Notable incidents In May 2013, rabbit fever (tularemia) was discovered in a hare originating from the north of the province of Limburg. Tularemia was later also diagnosed in a young man, who had probably contracted the infection after having been bitten by a horse fly in a nature reserve in Limburg. Another person possibly contracted tularemia in the Netherlands in 2011. In previous years only incidental cases were reported, with the disease being contracted abroad. Another notable incident concerned an outbreak of Campylobacter infection among visitors to a poultry slaughterhouse who had probably been exposed to airborne pathogens. Nine people fell ill as a result of this outbreak. An investigation into the incidence of Echinococcus multilocularis in foxes and dogs showed that this tapeworm was much more common in foxes in the south of Limburg province than in previous years. 'Zoonoses close to home' Humans can be exposed to various zoonotic disease pathogens in or around the house. Every year, thousands of people contract dermatophytosis (a fungal infection commonly known in the Netherlands as 'ringworm') from their pets. Zoonotic diseases can also be contracted from pets or from animals defecating in the garden. The report also devotes attention to food-related zoonotic diseases, with a particular focus on the risk of contracting zoonoses through the consumption or handling of vegetables.NVW

Dental evidence for variation in diet over time and space in the Arctic fox, Vulpes lagopus

Studies of the effects of variation in resource availability are important for understanding the ecology of high-latitude mammals. This paper examines the potential of dental evidence (tooth wear and breakage) as a proxy for diet and food choice in Vulpes lagopus, the Arctic fox. It presents a preliminary study of dental microwear, gross wear score, and tooth breakage in a sample (n = 78 individuals) from the Yamal Peninsula of the Russian Arctic. While these measures have each been associated with feeding ecology in larger carnivorans (e.g., proportion of bone in the diet), they have yet to be combined in any study and have rarely been applied to smaller species or those from high latitudes. Arctic foxes from the north and south of the peninsula, and those from rodent peak and trough density periods, are compared to assess impact of changes in food availability across space and time. Results indicate that microwear textures vary in dispersion, with more variation in texture complexity, including higher values (suggesting more consumption of bone), in the rodent-poor period in the north of Yamal. Gross wear scores and tooth breakage are also significantly higher for the north of Yamal than the south. These data together suggest that dental evidence can provide important insights into variation in the feeding ecology of Arctic foxes and potentially into the impacts of changes in food abundance across space and time

Dental evidence for variation in diet over time and space in the Arctic fox, Vulpes lagopus

Studies of the effects of variation in resource availability are important for understanding the ecology of high-latitude mammals. This paper examines the potential of dental evidence (tooth wear and breakage) as a proxy for diet and food choice in Vulpes lagopus, the Arctic fox. It presents a preliminary study of dental microwear, gross wear score, and tooth breakage in a sample (n = 78 individuals) from the Yamal Peninsula of the Russian Arctic. While these measures have each been associated with feeding ecology in larger carnivorans (e.g., proportion of bone in the diet), they have yet to be combined in any study and have rarely been applied to smaller species or those from high latitudes. Arctic foxes from the north and south of the peninsula, and those from rodent peak and trough density periods, are compared to assess impact of changes in food availability across space and time. Results indicate that microwear textures vary in dispersion, with more variation in texture complexity, including higher values (suggesting more consumption of bone), in the rodent-poor period in the north of Yamal. Gross wear scores and tooth breakage are also significantly higher for the north of Yamal than the south. These data together suggest that dental evidence can provide important insights into variation in the feeding ecology of Arctic foxes and potentially into the impacts of changes in food abundance across space and time

Radiographs Reveal Exceptional Forelimb Strength in the Sabertooth Cat, Smilodon fatalis

Background: The sabertooth cat, Smilodon fatalis, was an enigmatic predator without a true living analog. Their elongate canine teeth were more vulnerable to fracture than those of modern felids, making it imperative for them to immobilize prey with their forelimbs when making a kill. As a result, their need for heavily muscled forelimbs likely exceeded that of modern felids and thus should be reflected in their skeletons. Previous studies on forelimb bones of S. fatalis found them to be relatively robust but did not quantify their ability to withstand loading. Methodology/Principal Findings: Using radiographs of the sabertooth cat, Smilodon fatalis, 28 extant felid species, and the larger, extinct American lion Panthera atrox, we measured cross-sectional properties of the humerus and femur to provide the first estimates of limb bone strength in bending and torsion. We found that the humeri of Smilodon were reinforced by cortical thickening to a greater degree than those observed in any living felid, or the much larger P. atrox. The femur of Smilodon also was thickened but not beyond the normal variation found in any other felid measured. Conclusions/Significance: Based on the cross-sectional properties of its humerus, we interpret that Smilodon was a powerful predator that differed from extant felids in its greater ability to subdue prey using the forelimbs. This enhanced forelimb strength was part of an adaptive complex driven by the need to minimize the struggles of prey in order to protec

Evolution of Skull and Mandible Shape in Cats (Carnivora: Felidae)

The felid family consists of two major subgroups, the sabretoothed and the feline cats, to which all extant species belong, and are the most anatomically derived of all carnivores for predation on large prey with a precision killing bite. There has been much controversy and uncertainty about why the skulls and mandibles of sabretoothed and feline cats evolved to become so anatomically divergent, but previous models have focused on single characters and no unifying hypothesis of evolutionary shape changes has been formulated. Here I show that the shape of the skull and mandible in derived sabrecats occupy entirely different positions within overall morphospace from feline cats, and that the evolution of skull and mandible shape has followed very different paths in the two subgroups. When normalised for body-size differences, evolution of bite forces differ markedly in the two groups, and are much lower in derived sabrecats, and they show a significant relationship with size and cranial shape, whereas no such relationship is present in feline cats. Evolution of skull and mandible shape in modern cats has been governed by the need for uniform powerful biting irrespective of body size, whereas in sabrecats, shape evolution was governed by selective pressures for efficient predation with hypertrophied upper canines at high gape angles, and bite forces were secondary and became progressively weaker during sabrecat evolution. The current study emphasises combinations of new techniques for morphological shape analysis and biomechanical studies to formulate evolutionary hypotheses for difficult groups

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

Anatomy of STEM Teaching in American Universities: A Snapshot from a Large-Scale Observation Study

National and local initiatives focused on the transformation of STEM teaching in higher education have multiplied over the last decade. These initiatives often focus on measuring change in instructional practices, but it is difficult to monitor such change without a national picture of STEM educational practices, especially as characterized by common observational instruments. We characterized a snapshot of this landscape by conducting the first large scale observation-based study. We found that lecturing was prominent throughout the undergraduate STEM curriculum, even in classrooms with infrastructure designed to support active learning, indicating that further work is required to reform STEM education. Additionally, we established that STEM faculty’s instructional practices can vary substantially within a course, invalidating the commonly-used teaching evaluations based on a one-time observation

Statistical support for the hypothesis of developmental constraint in marsupial skull evolution.

Background: In contrast to placental neonates, in which all cranial bones are ossified, marsupial young have only the bones of the oral region and the exoccipital ossified at birth, in order to facilitate suckling at an early stage of development. In this study, we investigated whether this heterochronic shift in the timing of cranial ossification constrains cranial disparity in marsupials relative to placentals. Methods: We collected three-dimensional (3D) landmark data about the crania of a wide range of extant placentals and marsupials, and from six fossil metatherians (the clade including extant marsupials and their stem relatives), using a laser scanner and a 3D digitizer. Principal components analysis and delta variance tests were used to investigate the distribution and disparity of cranial morphology between different landmark sets (optimizing either number of landmarks or number of taxa) of the whole skull and of individual developmental or functional regions (neurocranium, viscerocranium, oral region) for extant placentals and marsupials. Marsupial and placental data was also compared based on shared ecological aspects including diet, habitat, and time of peak activity. Results: We found that the extant marsupial taxa investigated here occupy a much smaller area of morphospace than the placental taxa, with a significantly (P<0.01) smaller overall variance. Inclusion of fossil taxa did not significantly increase the variance of metatherian cranial shape. Fossil forms generally plotted close to or within the realm of their extant marsupial relatives. When the disparities of cranial regions were investigated separately, significant differences between placentals and marsupials were seen for the viscerocranial and oral regions, but not for the neurocranial region. Conclusion: These results support the hypothesis of developmental constraint limiting the evolution of the marsupial skull, and further suggest that the marsupial viscerocranium as a whole, rather than just the early-ossifying oral region, is developmentally constrained