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Zoology: Analysis of Complex Systems, ZACS

Itzel Sifuentes-Romero, Boris M Tezak, Sarah L Milton, Jeanette Wyneken
Experimental and field studies of different turtle species suggest that moisture influences embryonic development and sex ratios, wetter substrates tend to produce more males, and drier substrates produce more females. In this study, we used Trachemys scripta elegans to test the effect of moisture on embryonic development and sex ratios. T. s. elegans eggs were incubated under different temperature and moisture regimes. We monitored embryonic development until stage 22 (after sex determination) and, for the first time, we estimated sex ratios using a male-specific transcriptional molecular marker, Sox9...
November 28, 2017: Zoology: Analysis of Complex Systems, ZACS
Paul M Hampton
As body size increases, some predators eliminate small prey from their diet exhibiting an ontogenetic shift toward larger prey. In contrast, some predators show a telescoping pattern of prey size in which both large and small prey are consumed with increasing predator size. To explore a functional explanation for the two feeding patterns, I examined feeding effort as both handling time and number of upper jaw movements during ingestion of fish of consistent size. I used a range of body sizes from two snake species that exhibit ontogenetic shifts in prey size (Nerodia fasciata and N...
November 21, 2017: Zoology: Analysis of Complex Systems, ZACS
Piter Kehoma Boll, Ana Maria Leal-Zanchet
Land planarians have a simple anatomy and simple behavioral repertoire in relation to most bilaterian animals, which makes them adequate for the study of biological processes. In this study, we investigate the behavior of land planarians during interaction events with other invertebrates found in the same environment. We observed 16 different behavioral units, including seven different capture behaviors and three different prey ingestion behaviors. The capture behavior varied from very simple, such as simply covering the prey with the body, to more complex ones, including two forms of tube formation that are described for the first time...
November 16, 2017: Zoology: Analysis of Complex Systems, ZACS
Piotr Świątek, Pierre de Wit, Natalia Jarosz, Łukasz Chajec, Anna Z Urbisz
The genus Grania comprises over 70 species of exclusively marine clitellate annelids belonging to the family Enchytraeidae. Morphologically, this genus is well separated from other enchytraeids, with thick cuticles, anterior segments I-IV fused into a "head", chaetal bundles consisting only of one stout chaeta, and reduction of circular musculature. The aim of the present study is to describe the ovary organization and the course of oogenesis in Grania postclitellochaeta, and to compare it with other known systems of ovary organization and oogenesis in clitellate annelids, especially in enchytraeids...
November 14, 2017: Zoology: Analysis of Complex Systems, ZACS
Molly E Grear, Michael R Motley, Stephanie B Crofts, Amanda E Witt, Adam P Summers, Petra Ditsche
The skin and blubber of marine mammals provides protection from the surrounding environment, whether that be temperature, microbes, or direct mechanical impacts. To understand the ability of harbor seals' (Phoca vitulina) skin and blubber to resist blunt force trauma, we tested the material properties of these tissues. We quantified two mechanical properties of the tissue: tensile strength and tensile stiffness, at two test speeds, three sample orientations, and two age groups. We found significant differences in material properties between test speeds, orientation, and age of the animal, but did not find a large difference with orientation...
November 11, 2017: Zoology: Analysis of Complex Systems, ZACS
Raf Claes, Pieter G G Muyshondt, Joris J J Dirckx, Peter Aerts
Static pressure changes can alter the configuration and mechanical behavior of the chain of ossicles, which may affect the acoustic transfer function. In mammals, the Eustachian tube plays an important role in restoring ambient middle ear pressure, hence restoring the acoustic transfer function and excluding barotrauma of the middle and inner ear. Ambient pressure fluctuations can be potentially extreme in birds and due to the simple structure of the avian middle ear (one ossicle, one muscle), regulation of the middle ear pressure via reflexive opening of the pharyngotympanic tube appears all the more important...
November 7, 2017: Zoology: Analysis of Complex Systems, ZACS
Parvez Alam, Immanuel Sanka, Lilja Piuli Alam, Saka Wijaya, Erly Sintya, Niken Satuti Nur Handayani, Adolfo Rivero-Müller
The dactyl plunger of Alpheus sp. was found to be a layered composite, with mineral-rich outer and inner layers and a chitin-rich middle layer of high porosity. The chitin-rich middle layer is itself composed of several porous chitin laminae. Modelling heat conduction through the plunger cross-section revealed that the chitin-rich layer is able to insulate heat and retard its progress through the material. Heat accumulates in the plunger after a series of successive snaps and as such, its thermally resistant design can be considered most useful under the conditions of successive snapping...
November 7, 2017: Zoology: Analysis of Complex Systems, ZACS
Shelby B Creager, Marianne E Porter
In sharks, the skin is a biological composite with mineralized denticles embedded within a collagenous matrix. Swimming performance is enhanced by the dermal denticles on the skin, which have drag reducing properties produced by regional morphological variations and changes in density along the body. We used mechanical testing to quantify the effect of embedded mineralized denticles on the quasi-static tensile properties of shark skin to failure in four coastal species. We investigated regional differences in denticle density and skin properties by dissecting skin from the underlying fascia and muscle at 10 anatomical landmarks...
October 31, 2017: Zoology: Analysis of Complex Systems, ZACS
Karin B Holthaus, Lorenzo Alibardi
Corneous beta-proteins (CBPs), formerly referred to as beta-keratins, are major protein components of the epidermis in lepidosaurian reptiles and are largely responsible for their material properties. These proteins have been suggested to form filaments of 3.4nm in thickness and to interact with themselves or with other proteins, including intermediate filament (IF) keratins. Here, we performed immunocytochemical labeling of CBPs in the epidermis of different lizards and snakes and investigated by immunoblotting analysis whether the reduction of disulfide bonds or protein oxidation affects the solubility and mobility of these CBPs...
October 29, 2017: Zoology: Analysis of Complex Systems, ZACS
Steffen Bleich, Carsten H G Müller, Gerhard Graf, Wolf Hanke
The corona ciliata of Chaetognatha (arrow worms) is a circular or elliptical groove lined by a rim from which multiple lines of cilia emanate, located dorsally on the head and/or trunk. Mechanoreception, chemosensation, excretion, respiration, and support of reproduction have been suggested to be its main functions. Here we provide the first experimental evidence that the cilia produce significant water flow, and the first visualisation and quantification of this flow. In Spadella cephaloptera, water is accelerated toward the corona ciliata from dorsal and anterior of the body in a funnel-shaped pattern, and expelled laterally and caudally from the corona, with part of the water being recirculated...
October 8, 2017: Zoology: Analysis of Complex Systems, ZACS
Maja D Slijepčević, Mirela Ukropina, Branko Filipović, Ana Ivanović
Vertebral morphology, development, and evolution have been investigated for many decades, especially in the recent evo-devo era. Nevertheless, comparative data on development and ossification modes within the major tetrapod groups are scarce and frequently suffer from the use of a simplistic approach, resulting in simplistic generalizations about the formation of tetrapod vertebrae. Here, we describe the development and ossification of trunk vertebrae in Triturus ivanbureschi (Salamandridae, Caudata) and compare the results with published data on other related taxa...
October 4, 2017: Zoology: Analysis of Complex Systems, ZACS
Anna-Christin Joel, Anne Habedank, Jörg Mey
Females of the feather-legged spider Uloborus plumipes invade, and compete for, each other's orb webs. In the context of these competitive interactions the question arose how the spiders communicate. Since substrate-borne vibrations are the most important component of the sensory environment of web-building spiders, we investigated vibratory movements that might serve as signals of communication. Three behaviors were found to be associated with female-female contests and to cause propagating vibrations in the spider webs: thread pulling, abdominal trembling, and web shaking...
September 1, 2017: 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
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