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Session Schedule & Abstracts
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|Sunday 3rd July, 2016|
|Moderator(s): Davis JS, Kupczik K|
FED5-1 4:30 pm Loss of a tongue muscle improves prey-capture performance in salamanders. Bloom SV*, University of South Florida; Deban SM, University of South Florida email@example.com |
Abstract: Many salamanders in the family Plethodontidae have evolved a high-powered elastic tongue projection mechanism, allowing them to project their tongue with high acceleration and power. Within plethodontids, the musculature of the tongue projection apparatus varies in its degree of complexity. The subarcualis rectus projects the tongue from the mouth, the rectus cervicis retracts the tongue, and the genioglossus rotates the tongue pad. The genioglossus muscle connects the tongue pad to the tip of the mandibles in the ancestral state that is retained in some taxa, and this may limit projection distance and tongue aiming relative to the head. Within the clade of plethodontids, tribe Bolitoglossini has lost the genioglossus muscle. In other taxa, the genioglossus is elongated, originating more posteriorly on the mandible. We examined how the presence or length of this muscle affects tongue projection performance. Using morphological examination and high-speed imaging, we compared tongue projection of salamanders with varying length or presence of the genioglossus muscle across the family Plethodontidae. We found that the presence of the genioglossus muscle reduces tongue directional versatility and that it may limit tongue projection length. These results provide insight into some of the constraints on salamander feeding performance and aiming ability.
FED5-2 4:45 pm Robust hyobranchial apparatus yields increased aquatic feeding performance in newts. Stinson C.M.*, University of South Florida, Tampa; Deban S.M., University of South Florida, Tampa firstname.lastname@example.org |
Abstract: Salamanders use the hyobranchial apparatus to capture prey via tongue projection on land and suction feeding in water. Within the Salamandridae, salamanders are ecologically and morphologically diverse and can be terrestrial, semi-aquatic, or aquatic. The purpose of this study was to quantify suction feeding performance in aquatically feeding salamandrids and to determine how differences in morphology affect feeding performance. We predicted that newts with more robust hyobranchial apparatus morphologies would have increased aquatic feeding performance. High speed video of five aquatic and semi-aquatic newts were analyzed using kinematics and inverse dynamics of aquatic feeding events. Dissections and cleared and stained specimens were used to obtain morphological data of the feeding apparatus and relevant musculature. The fully aquatic newt, Paramesotriton labiatus, was found to have increased feeding performance when compared to other salamandrids. Maximum velocity and acceleration of mouth opening exceeded the performance of other salamandrids by two and four times, respectively. Also, hyobranchial depression velocity peaked at 0.22 m/s, almost twice that of other aquatically feeding newts, and acceleration was four times greater, peaking at 49 m/s/s. Increased hyobranchial depression velocity was found to be correlated with more robust hyobranchial apparatuses, including broader ceratohyals and second ceratobranchials. Differences in performance could be due to functional trade-offs in semi-aquatic species that must perform various feeding modes in multiple habitats.
FED5-3 5:00 pm Aquatic prey capture in snakes: the link between morphology, behavior and hydrodynamics. Segall M*, MNHN - ESPCI; Godoy-Diana R, ESPCI; Herrel A, MNHN email@example.com |
Abstract: Aquatic animals have to face the physical constraints imposed by the mechanical properties of the fluid through which they move. Movement under water is resisted by drag and acceleration reaction forces, which can impair the displacement of the animal. The forward strike during prey capture will generate a pressure wave that can trigger the escape response of a mobile prey and thus decrease the capture success. Most animals have circumvented these constraints by developing a suction feeding system, but some animals cannot because of anatomical limits. As the physical constraints are highly dependent on the shape of the object, we hypothesize that the animals that cannot perform suction will have morphologically converged to be more streamlined. Moreover, we hypothesize that the behavior of species that do not present a streamlined head will aim to reduce the hydrodynamic forces associated with a strike under water. We chose snakes as biological model to test our hypotheses, as these animals cannot use suction and have evolved aquatic life-styles convergently. We predict that the head shape of aquatic snake species is more streamlined in comparison with that of non-aquatic species. The variability in the head shape of aquatic snakes is large and some species have a large, massive head. We suggest that these species have adapted their behavioral strategies to efficiently capture prey. To test our predictions, we compared 3D scans of the head shape of 83 species. We also developed a 3D printed model to mimic a snake attack under water in a laboratory experiment, characterizing the fluid flow associated with different head shapes and different behaviors using flow field velocimetry and force measurements.
FED5-4 5:15 pm Masticatory jaw movements in two species of musteloid carnivorans with divergent dietary specializations: an XROMM and EMG study. Davis JS*, High Point University; Klimovich CM, Ohio University; Williams SH, Ohio University firstname.lastname@example.org |
Abstract: Despite decades of research on mammalian mastication, there are still surprising gaps in our understanding of the functional implications of diversity in craniodental morphology among mammals. To begin to address these limitations, we used X-ray Reconstruction of Moving Morphology (XROMM) and electromyography (EMG) to quantify jaw movements and jaw adductor activity patterns during mastication in two species of musteloid carnivorans. Ferrets (Mustelidae: Mustela putorius furo) possess many ancestral carnivoran traits, including a hypercarnivorous diet, tall shearing dental cusps, a “fixed” hinge-like temporomandibular joint (TMJ), and an unfused mandibular symphysis. In contrast, kinkajous (Procyonidae: Potos flavus) specialize on a frugivorous diet, have broad flat teeth, and possess an ossified or fused mandibular symphysis. We show that both species exhibit nearly-simultaneous activity of almost all jaw muscles, producing rapid vertical jaw adduction, but the morphological differences in their dentition and jaw contribute to notable differences in movement. In ferrets, the unfused mandibular symphysis allows the hemimandibles to move semi-independently. The working-side (WS) dentary translates laterally and rotates around its Y and Z axes to allow vertical occlusion of the cheekteeth—movements which would dislocate the contralateral TMJ if the symphysis were rigid. Kinkajous differ from known carnivorans in that a late burst of their WS deep masseter produces transverse translation of the jaw at the end of the closing phase. This likely necessitates symphyseal fusion while facilitating grinding of fruit with the horizontally-occluding cheekteeth. These data improve our understanding of the functional significance of mandibular symphyseal structure and shed light on the integrated evolutionary patterns of both adaptation and constraint associated with dietary specialization--patterns which may also be present in other mammalian taxa.
FED5-5 5:30 pm Fibre type composition in the masticatory muscles of wolves (Carnivora: Canis lupus) and domestic dogs: implications for canine chewing efficiency and feeding ecology. Kupczik K*, Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; Unterhitzenberger G, Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena; Szentiks CA, Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany; Fischer MS, Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena email@example.com |
Abstract: Bite force generation and chewing efficiency depend on the mass, fascicle architecture and fibre type composition of the jaw-moving muscles. The masseter, temporalis and medial pterygoid muscles of carnivores and some other mammals consist of the slow contracting and enduring type I fibre and the fast contracting and fast fatiguing IIM fibre. Here we compare the muscle fibre type composition of the wolf, Canis lupus L. 1758, to that of its domestic form, the dog (C. lupus f. familiaris), to assess whether the relaxation of selection pressures as the result of the domestication process had any bearing on muscle morphology and function. To this end, the intraspecific and regional distribution of the two fibre types was analysed in the temporalis-masseter muscle complex of ten wolves originating from the German resident population. The comparative sample constituted muscles from 17 dog breeds. Using an immunohistochemical protocol we found that the proportion of type I fibres increased from more superficial to deeper portions of the muscles in both wolves and dogs. Yet, on average the proportion of slow fibres in the temporalis and masseter muscles was significantly higher in wolves (20% in both muscles) than dogs (14% and 15%, respectively). These results concur with previous studies showing that the deep slow contracting muscle portions serve as stabilizers, while the superficial fast contracting muscles are both mobilizers and stabilizers. Moreover, the higher percentage of slow fibres in wolves compared to dogs suggests that the former are capable of a more stable and enduring bite which is particularly important when subduing prey and in processing of bone and meat. In dogs, in turn, the reduction in relative type I fibre proportion is likely linked to a diminished chewing efficiency as a result of a diet of processed and starch-rich foods.
FED5-6 5:45 pm Exploring the value of anatomy ontologies: testing the Mammalian Feeding Muscle Ontology. Druzinsky RE*, U. of Illinois at Chicago; German RZ, Northeast Ohio Medical University; Haendel MA, Oregon Health and Science University; Herring SW, University of Washington; Lapp H, Duke University; Muller HM, California Institute of Technology; Mungall CJ, Lawrence Berkeley National Laboratory; Sternberg PW, California Institute of Technology; Van Auken K, California Institute of Technology; Vinyard CJ, Northeast Ohio Medical University; Williams SH, Ohio University; Wall CE, Duke University firstname.lastname@example.org |
Abstract: In recent years large bibliographic databases have made much of the published literature of biology available for searches. However, the capabilities of the search engines integrated into these databases for text-based bibliographic searches are limited. To enable searches that deliver the results expected by comparative anatomists, an underlying logical structure known as an ontology is required. An ontology is a set of terms that are organized into a network structure that can be operated on by computer. The Mammalian Feeding Muscle Ontology (MFMO; http://purl.obolibrary.org/obo/mfmo.owl) is an anatomy ontology (AO) focused on anatomical structures that participate in feeding and other oral/pharyngeal behaviors. The MFMO is an outgrowth of the Feeding End-User Database (FEED) Project (Wall, et al., 2011; http://feedexp.org), an ongoing effort to develop an online repository for data from physiological studies of feeding in mammals. Further, it provides a template for muscles that will be useful in extending any anatomy ontology. Currently the MFMO is integrated into FEED and also into two literature-specific implementations of Textpresso, a text-mining system that facilitates powerful searches of a corpus of scientific publications. We evaluate the MFMO by asking questions that test the ability of the ontology to return appropriate answers (competency questions). We compare the results of queries of the MFMO to results from similar searches in PubMed and Google Scholar.Our tests demonstrate that the MFMO is competent to answer queries formed in the common language of comparative anatomy, but PubMed and Google Scholar are not. Overall, our results show that by incorporating anatomical ontologies into searches, an expanded and anatomically comprehensive set of results can be obtained. Supported by NSF DBI-0960508, NSF - DBI 1062350, EF-0423641, and a Collaboration Exchange Grant from Phenotype RCN to RED.
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