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Journal of Experimental Biology

Nicolas R Evensen, Peter J Edmunds
In densely populated communities, such as coral reefs, organisms can modify the physical and chemical environment for neighbouring individuals. We tested the hypothesis that colony density (12 colonies each placed∼0.5 cm apart versus∼8 cm apart) can modulate the physiological response (measured through rates of calcification, photosynthesis, and respiration in the light and dark) of the coral Pocillopora verrucosa to pCO2 treatments (∼ 400 µatm and∼1200 µatm) by altering the seawater flow regimes experienced by colonies placed in aggregations within a flume at a single flow speed...
January 13, 2017: Journal of Experimental Biology
Calli R Freedman, Douglas S Fudge
Hagfishes are able to squeeze through small openings to gain entry to crevices, burrows, hagfish traps, and carcasses, but little is known about how they do this, or what the limits of this ability are. The purpose of this study was to describe this ability, and to investigate possible mechanisms by which it is accomplished. We investigated the hypothesis that the passive movement of blood within a hagfish's flaccid subcutaneous sinus allows it to squeeze through narrow apertures that it would not be able to if it were turgid...
January 13, 2017: Journal of Experimental Biology
Hiroshi Yoke, Chikako Shingyoji
Oscillatory bending movement of eukaryotic flagella is powered by orchestrated activity of dynein motor proteins that hydrolyze ATP and produce microtubule sliding. Although the ATP concentration within a flagellum is kept uniform at a few mmol l(-1) level, sliding activities of dyneins are dynamically coordinated along the flagellum in accordance with the phase of bending waves. Thus, at the organellar level the dynein not only generates force for bending but also modulates its motile activity by responding to bending of the flagellum...
January 13, 2017: Journal of Experimental Biology
Benedict D Chivers, Olivier Béthoux, Fabio A Sarria-S, Thorin Jonsson, Andrew C Mason, Fernando Montealegre-Z
Male grigs, bush-crickets and field crickets produce mating calls by tegminal stridulation: the scraping together of modified forewings functioning as sound generators. Bush- (Tettigoniidae) and field-crickets (Gryllinae) diverged some 240 million years ago, with each lineage developing unique characteristics in wing morphology and the associated mechanics of stridulation. The grigs (Prophalangopsidae), a relict lineage more closely related to bush-crickets than to field-crickets, are believed to retain plesiomorphic features of wing morphology...
January 12, 2017: Journal of Experimental Biology
Ivan Viegas, Pedro M Araújo, Afonso D Rocha, Auxiliadora Villegas, John G Jones, Jaime A Ramos, José A Masero, José A Alves
The migrant black-tailed godwit (Limosa limosa) traditionally used natural wetlands in the Iberian Peninsula preparing for migratory flights by feeding mainly in estuaries. In recent decades this species has become increasingly dependent on rice fields, thereby relying on a plant-based diet for fueling. Dietary fatty acids (FA) seem to be determinant to the composition of accumulated subcutaneous fat in migratory birds. It is still unclear whether metabolic plasticity allows for modification and/or synthesis of FA, contributing for a lipid profile that enables a successful migratory performance...
January 12, 2017: Journal of Experimental Biology
Laia Ribas, Alejandro Valdivieso, Noelia Díaz, Francesc Piferrer
Zebrafish (Danio rerio) has become a well-established experimental model in many research fields but the loss of the primary sex determining region during the process of domestication renders laboratory strains of zebrafish susceptible to the effects of environmental factors on sex ratios. Further, an essential husbandry aspect such as what is the optimal rearing density to avoid stress-induced masculinization is not known. We carried out two experiments: one focusing on the density effects on survival, growth and sex ratio by rearing zebrafish at different initial densities (9, 19, 37 and 74 fish per liter) for three months (6-90 days post fertilization, dpf), and a second experiment focusing on the effects of cortisol during the sex differentiation period (15-45 dpf) on zebrafish reared at low density...
January 12, 2017: Journal of Experimental Biology
Lumír Gvoždík, Peter Kristín
Temperature is an important factor determining distribution and abundance of organisms. Predicting the impact of warming climate on ectotherm populations requires information about species' thermal requirements, so-called 'thermal niche'. The characterization of thermal niche remains a complicated task. We compared the applicability of two indirect approaches, based on reaction norm (aerobic scope curve) and optimality (preferred body temperature) concepts, for indirect estimation of thermal niche while using newts, Ichthyosaura alpestris, as a study system...
January 12, 2017: Journal of Experimental Biology
Shi-Nan Hu, Ying-Yang Zhu, Lin Lin, Wei-Hong Zheng, Jin-Song Liu
Seasonal changes in temperature and photoperiod are important environmental cues used by small birds to adjust their body mass (Mb) and thermogenesis. However, the relative importance of these cues with respect to seasonal adjustments in Mb and thermogenesis are difficult to distinguish. In particular, the effects of temperature and photoperiod on energy metabolism and thermoregulation are not well known in many passerines. To address this problem, we measured the effects of temperature and photoperiod on Mb, energy intake, resting metabolic rate (RMR), organ mass and physiological and biochemical markers of metabolic activity, in the Chinese bulbul (Pycnonotus sinensis)...
January 12, 2017: Journal of Experimental Biology
Jana Dewenter, Peggy Gerullis, Alexander Hecker, Stefan Schuster
Archerfish are renowned for dislodging aerial prey by well-aimed shots of water. Recently it has been shown that these fish can shape their aerial jets by adjusting the dynamics of their mouth opening and closing. This allows the fish to adjust their jet to target distance so that they can forcefully hit prey over considerable distances. Here we suggest that archerfish use the same technique to also actively control jets under water. Fired from close ranges the underwater jets are powerful enough to lift up buried food particles, which the fish then can pick up...
January 12, 2017: Journal of Experimental Biology
Till S Harter, Colin J Brauner, Philip G D Matthews
The present study describes and validates a novel yet simple system for simultaneous in vivo measurements of aquatic CO2 production (MCO2) and oxygen consumption (MO2) rates, thus allowing the calculation of respiratory exchange ratios (RER). Diffusion of CO2 from the aquatic phase into a gas phase, across a hollow fibre membrane, enabled aquatic MCO2 measurements with a high-precision infrared gas CO2 analyser. MO2 was measured with a PO2 optode using a stop-flow approach. Injections of known amounts of CO2 into the apparatus yielded accurate and highly reproducible measurements of CO2 content (R(2)=0...
January 12, 2017: Journal of Experimental Biology
Deeksha Seth, Brooke E Flammang, George V Lauder, James L Tangorra
Knowledge about the stiffness of fish fins, and if stiffness is modulated during swimming, is important for understanding the mechanics of a fin's force production. However, the mechanical properties of fins have not been studied during natural swimming, in part, because of a lack of instrumentation. To remedy this, a vortex generator was developed that produces travelling vortices of adjustable strength which can be used to perturb the fins of swimming fish. Experiments were conducted to understand how the generator's settings affected the resulting vortex rings...
January 12, 2017: Journal of Experimental Biology
Monica Lodi, Joris M Koene
To increase fertilization chances compared to rivals, males are favoured to transfer accessory gland proteins to females during mating. These substances, by influencing female physiology, cause alteration of her sperm usage and remating rate. Simultaneously hermaphroditic land snails with love-darts are a case in point. During courtship, a love-dart is pierced through the partner's body wall, thereby introducing accessory mucous gland products. This mucus physiologically increases paternity by inhibiting the digestion of donated sperm...
January 6, 2017: Journal of Experimental Biology
Mélisandre A Téfit, François Leulier
Animals are naturally surrounded by a variety of microorganisms with which they constantly interact. Among these microbes, some live closely associated with a host and form its microbiota. These communities are now extensively studied, owing to their contributions to shaping various aspects of animal physiology. One of these commensal species, Lactobacillus plantarum, and in particular the L.p.(WJL) strain, has been shown to promote the growth of Drosophila larvae upon nutrient scarcity, allowing earlier metamorphosis and adult emergence compared to axenic individuals...
January 6, 2017: Journal of Experimental Biology
Colin Olito, Craig R White, Dustin J Marshall, Diego R Barneche
Accessing many fundamental questions in biology begins with empirical estimation of simple monotonic rates of underlying biological processes. Across a variety of disciplines, ranging from physiology to biogeochemistry, these rates are routinely estimated from non-linear and noisy time series data using linear regression and ad hoc manual truncation of non-linearities. Here, we introduce the R package LoLinR, a flexible toolkit to implement local linear regression techniques to objectively and reproducibly estimate monotonic biological rates from non-linear time series data, and demonstrate possible applications using metabolic rate data...
January 3, 2017: Journal of Experimental Biology
Jinhong Luo, Andrea Lingner, Uwe Firzlaff, Lutz Wiegrebe
Auditory feedback plays an important role in vocal learning and, more generally, in fine-tuning the acoustic features of communication signals. So far, only a few studies have assessed the developmental onset of auditory feedback. The Lombard effect, a well-studied audio-vocal phenomenon, refers to an increase in vocal loudness of a subject in response to an increase in background noise. Here, we studied the time course of the Lombard effect in developing bats, Phyllostomus discolor We show that infant bats produced louder vocalizations in noise than in silence at an age of only two weeks...
December 23, 2016: Journal of Experimental Biology
Shelley A Adamo, Russell H Easy, Ilya Kovalko, Jenna MacDonald, Ashleigh McKeen, Taylor Swanburg, Kurtis F Turnbull, Catherine Reeve
Although predator exposure increases the risk of wound infections, it typically induces immunosuppression. A number of non-mutually exclusive hypotheses have been put forward to explain this immunosuppression, including: trade-offs between the immune system and other systems required for anti-predator behaviour, redistribution of immune resources towards mechanisms needed to defend against wound infections, and reconfiguration of the immune system to optimize defense under the physiological state of fight-or-flight readiness...
December 23, 2016: Journal of Experimental Biology
Danielle A Ludeman, Matthew A Reidenbach, Sally P Leys
Sponges (Porifera) are abundant in most marine and freshwater ecosystems and as suspension feeders they play a crucial role in filtering the water column. Their active pumping enables them to filter up to 900 times their body volume of water per hour, recycling nutrients and coupling a pelagic food supply with benthic communities. Despite the ecological importance of sponge filter feeding, little is known about how sponges control the water flow through their canal system or how much energy it costs to filter the water...
December 23, 2016: Journal of Experimental Biology
Sean J Blamires, Matthew Hasemore, Penny J Martens, Michael M Kasumovic
The adaptive benefits of extended phenotypic plasticity are imprecisely defined due to a paucity of experiments examining traits that are manipulable and measurable across environments. Spider webs are often used as models to explore the adaptive benefits of variations in extended phenotypes across environments. Nonetheless, our understanding of the adaptive nature of the plastic responses of spider webs is impeded when web architectures and silk physicochemical properties appear to co-vary. An opportunity to examine this co-variation is presented by modifying prey items while measuring web architectures and silk physiochemical properties...
December 23, 2016: Journal of Experimental Biology
Verner P Bingman, Jacob M Graving, Eileen A Hebets, Daniel D Wiegmann
Amplypygids, or whip spiders, are nocturnal, predatory arthropods that display a robust ability to navigate to their home refuge. Prior field observations and displacement studies in amblypygids demonstrated an ability to home from distances as far away as 10 meters. In the current study, micro-transmitters were used to take morning position fixes of individual Paraphrynus laevifrons following an experimental displacement of 10 m from their home refuge. The intent was to assess the relative importance of vision compared to sensory input acquired from the antenniform legs for navigation as well as other aspects of their spatial behavior...
December 23, 2016: Journal of Experimental Biology
Charlotte L Barkan, Erik Zornik, Darcy B Kelley
The neural circuits underlying divergent courtship behaviors of closely related species provide a framework for insight into the evolution of motor patterns. In frogs, male advertisement calls serve as unique species identifiers and females prefer conspecific to heterospecific calls. Advertisement calls of three relatively recently (∼8.5mya) diverged species - Xenopus laevis, X. petersii and X. victorianus - include rapid trains of sound pulses (fast trills). We show that while fast trills are similar in pulse rate (∼60 pulses/second) across the 3 species, they differ in call duration and period (time from onset of call to the onset of the following call)...
December 23, 2016: Journal of Experimental Biology
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