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Zoology: Analysis of Complex Systems, ZACS

Olga Panagiotopoulou, José Iriarte-Diaz, Simon Wilshin, Paul C Dechow, Andrea B Taylor, Hyab Mehari Abraha, Sharifah F Aljunid, Callum F Ross
Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results...
September 1, 2017: Zoology: Analysis of Complex Systems, ZACS
Matthew J Ravosa, Robert J Kane
Due to their nature as tissue composites, skeletal joints pose an additional challenge in terms of evaluating the functional significance of morphological variation in their bony and cartilaginous components in response to altered loading conditions. Arguably, this complexity requires more direct means of investigating joint plasticity and performance than typically employed to analyze macro- and micro-anatomical phenomena. To address a significant gap in our understanding of the plasticity of the mammalian temporomandibular joint (TMJ), we investigated the histology and mechanical properties of condylar articular cartilage in rabbits subjected to long-term variation in diet-induced masticatory stresses, specifically cyclical loading...
August 25, 2017: Zoology: Analysis of Complex Systems, ZACS
Jose Iriarte-Diaz, Claire E Terhune, Andrea B Taylor, Callum F Ross
The location of the axis of rotation (AoR) of the mandible was quantified using the helical axis (HA) in eight individuals from three species of non-human primates: Papio anubis, Cebus apella, and Macaca mulatta. These data were used to test three hypotheses regarding the functional significance of anteroposterior condylar translation - an AoR located inferior to the temporomandibular joint (TMJ) - during chewing: minimizing impingement of the gonial region on cervical soft tissue structures during jaw opening; avoiding stretching of the inferior alveolar neurovascular bundle (IANB); and increasing jaw-elevator muscle torques...
August 23, 2017: Zoology: Analysis of Complex Systems, ZACS
Charlotte M Stinson, Stephen M Deban
During aquatic feeding salamanders use the hyobranchial apparatus to capture prey. The hyobranchial apparatus depresses the floor of the mouth, effectively expanding the oropharyngeal cavity and generating suction. Within the family Salamandridae, there is a wide range of ecological diversity, with salamanders being terrestrial, semi-aquatic, or aquatic as adults. The purpose of this research was to quantify the diverse morphology and suction feeding performance of aquatically feeding salamandrids. We hypothesized that a more robust hyobranchial apparatus morphology would yield increased aquatic feeding performance...
August 19, 2017: Zoology: Analysis of Complex Systems, ZACS
Claire E Terhune
Masticatory morphology in primates is likely under strong selective pressure to maximize feeding efficiency while simultaneously minimizing the occurrence of injury or pathology. As a result, masticatory shape, including aspects of temporomandibular joint (TMJ) morphology, varies widely across primates in relation to feeding behavior and body size. This study examines patterns of allometry in the TMJ of anthropoid primates, with the specific goal of evaluating how allometric patterns may reflect variation in loading and/or range of motion at this joint...
August 18, 2017: Zoology: Analysis of Complex Systems, ZACS
Stefan Curth, Martin S Fischer, Kornelius Kupczik
The skull shape variation in domestic dogs exceeds that of grey wolves by far. The artificial selection of dogs has even led to breeds with mismatching upper and lower jaws and maloccluded teeth. For that reason, it has been advocated that their skulls (including the teeth) can be divided into more or less independent modules on the basis of genetics, development or function. In this study, we investigated whether the large diversity of dog skulls and the frequent occurrence of orofacial disproportions can be explained by a lower integration strength between the modules of the skull and by deviations in their covariation pattern when compared to wolves...
August 17, 2017: Zoology: Analysis of Complex Systems, ZACS
Alexandra A Mushegian, Dieter Ebert
The outcomes of host-symbiont interactions may differ according to environmental context, and symbioses may enable host adaptation to diverse environments. We find that the effects of two different experimental diets, algae and yeast, on the water flea Daphnia magna depend on whether the animals possess microbiota, suggesting that the presence of microbiota determines which diet is superior. Our study hints at both diet-dependent and diet-independent effects of microbiota on Daphnia fitness.
August 14, 2017: Zoology: Analysis of Complex Systems, ZACS
Natalin S Vicente, Monique Halloy
Multimodal communication involves the use of signals and cues across two or more sensory modalities. The genus Liolaemus (Iguania: Liolaemidae) offers a great potential for studies on the ecology and evolution of multimodal communication, including visual and chemical signals. In this study, we analyzed the response of male and female Liolaemus pacha to chemical, visual and combined (multimodal) stimuli. Using cue-isolation tests, we registered the number of tongue flicks and headbob displays from exposure to signals in each modality...
August 12, 2017: Zoology: Analysis of Complex Systems, ZACS
Alejandra I Echeverría, Federico Becerra, Guido N Buezas, Aldo I Vassallo
The subterranean genus Ctenomys (∼60 species, ∼100-1000g) constructs its burrows by using both forefeet and teeth throughout a wide range of habitats in South America. They show a high variation in the incisors' angle of attack (procumbency) and a mostly conserved skull morphology, not only amongst their congeners, but within the caviomorph rodents. Traditionally, procumbency has been largely related to tooth-digging. Looking for the possible influence of incisor procumbency on the mechanical advantage (MA) of each of the seven jaw adductor muscles in the genus, we examined 165 skulls representing 24 species...
August 8, 2017: Zoology: Analysis of Complex Systems, ZACS
Giacomo Zaccone, Eugenia Rita Lauriano, Michał Kuciel, Gioele Capillo, Simona Pergolizzi, Alessio Alesci, Atsushi Ishimatsu, Yuen Kwong Ip, Jose M Icardo
Mudskippers are amphibious fishes living in mudflats and mangroves. These fishes hold air in their large buccopharyngeal-opercular cavities where respiratory gas exchange takes place via the gills and higher vascularized epithelium lining the cavities and also the skin epidermis. Although aerial ventilation response to changes in ambient gas concentration has been studied in mudskippers, the localization and distribution of respiratory chemoreceptors, their neurochemical coding and function as well as physiological evidence for the gill or skin as site for O2 and CO2 sensing are currently not known...
August 5, 2017: Zoology: Analysis of Complex Systems, ZACS
Szczepan M Bilinski, Ali Halajian, Waclaw Tworzydlo
The Dermaptera are traditionally classified in three taxa: the free living Forficulina and two viviparous (matrotrophic) groups, the Hemimerina and Arixeniina. Recent molecular and histological analyses suggest that both matrotrophic groups should be nested among the most derived taxon of the Forficulina, the Eudermaptera. We present results of ultrastructural analyses of ovary/ovariole morphology and oogenesis in a representative of the Hemimerina, Hemimerus talpoides (Walker, 1871). Our results strongly reinforce the idea that the Hemimerina should be classified within the Eudermaptera...
August 2, 2017: Zoology: Analysis of Complex Systems, ZACS
Paola A Olivero, Camilo I Mattoni, Alfredo V Peretti
Courtship and mating behavior generally evolve rapidly in diverging populations and species. The adaptation to different environments may cause behavioral divergence in characteristics involved in mate choice. Our objective in this study was to compare the sexual behavior of two distant populations of the scorpion Bothriurus bonariensis. This species has a broad distribution in South America, inhabiting Central Argentina, Uruguay and south-eastern Brazil. It is known that in this species there is a divergence in morphological patterns (body size, coloration, allometry and fluctuating asymmetry indexes) among distant populations...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Kathryn S Peiman, Kim Birnie-Gauvin, Martin H Larsen, Scott F Colborne, Kathleen M Gilmour, Kim Aarestrup, William G Willmore, Steven J Cooke
The causes and consequences of trait relationships within and among the categories of physiology, morphology, and life-history remain poorly studied. Few studies cross the boundaries of these categories, and recent reviews have pointed out not only the dearth of evidence for among-category correlations but that trait relationships may change depending on the ecological conditions a population faces. We examined changes in mean values and correlations between traits in a partially migrant population of brown trout when migrant sea-run and resident stream forms were breeding sympatrically...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Sergey A Abramov, Natalya V Lopatina, Yuri N Litvinov
The Olkhon mountain vole (Alticola olchonensis) is an endemic species of the Lake Baikal area with an extremely restricted range. We investigated the pattern of differentiation of cranial shape and size in five isolated insular populations of A. olchonensis from the Baikal islands (Olkhon, Hubyn, Borokchin, Ogoy, and Zamogoy). The ventral aspect of the cranium was analysed using landmark-based geometric morphometric methods While the sexes of A. olchonensis did not differ regarding cranium size and shape, multivariate statistical analyses showed that there were inter-island differences in skull morphology...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Gary C Packard
Logarithmic transformation is often assumed to be necessary in allometry to accommodate the kind of variation that accompanies multiplicative growth by plants and animals; and the traditional approach to allometric analysis is commonly believed to have important application even when the bivariate distribution of interest is curvilinear on the logarithmic scale. Here I examine four arguments that have been tendered in support of these perceptions. All the arguments are based on misunderstandings about the traditional method for allometric analysis and/or on a lack of familiarity with newer methods of nonlinear regression...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Alexandra Lolavar, Jeanette Wyneken
Many reptiles have temperature-dependent sex determination (TSD). Sex determination in marine turtles is described by a cool-male, warm-female pattern. Nest sand temperature strongly influences sea turtle embryo development and sex differentiation. Yet, variation in hatchling sex ratios is explained only partially by nest temperature and can be predicted only at the warmest and coolest temperatures. Hence, other factors during development influence sex determination. Rainfall is a common environmental variable that may impact development and sex determination...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Alejandro Rico-Guevara, Margaret A Rubega
Nectarivores are animals that have evolved adaptations to efficiently exploit floral nectar as the main source of energy in their diet. It is well known that hummingbirds can extract nectar with impressive speed from flowers. However, despite decades of study on nectar intake rates, the mechanism by which feeding is ultimately achieved - the release of nectar from the tongue so that it can pass into the throat and be ingested - has not been elucidated. By using microCT scanning and macro high-speed videography we scrutinized the morphology and function of hummingbird bill tips, looking for answers about the nectar offloading process...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Cristina Rodríguez, Miguel Lorenzale, Miguel A López-Unzu, Borja Fernández, Francisca Salmerón, Valentín Sans-Coma, Ana C Durán
This study was designed to determine whether the outflow tract of the holocephalan heart is composed of a myocardial conus arteriosus and a non-myocardial bulbus arteriosus, as is the case in elasmobranchs. This is a key issue to verify the hypothesis that these two anatomical components existed from the onset of the jawed vertebrate radiation. The Holocephali are the sister group of the elasmobranchs, sharing with them a common, still unknown Palaeozoic ancestor. The sample examined herein consisted of hearts from individuals of four species, two of them belonging to the Chimaeridae and the other two to the Rhinochimaeridae...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Puli Chandramouli Reddy, Suyog Ubhe, Neha Sirwani, Rasika Lohokare, Sanjeev Galande
Histones are fundamental components of chromatin in all eukaryotes. Hydra, an emerging model system belonging to the basal metazoan phylum Cnidaria, provides an ideal platform to understand the evolution of core histone components at the base of eumetazoan phyla. Hydra exhibits peculiar properties such as tremendous regenerative capacity, lack of organismal senescence and rarity of malignancy. In light of the role of histone modifications and histone variants in these processes it is important to understand the nature of histones themselves and their variants in hydra...
August 2017: Zoology: Analysis of Complex Systems, ZACS
Raffaele Nardone, Cristina Florea, Yvonne Höller, Francesco Brigo, Viviana Versace, Piergiorgio Lochner, Stefan Golaszewski, Eugen Trinka
In this narrative review we aimed to assess the usefulness of the different animal models in identifying injury mechanisms and developing therapies for humans suffering from spinal cord injury (SCI). Results obtained from rodent studies are useful but, due to the anatomical, molecular and functional differences, confirmation of these findings in large animals or non-human primates may lead to basic discoveries that cannot be made in rodent models and that are more useful for developing treatment strategies in humans...
August 2017: Zoology: Analysis of Complex Systems, ZACS
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