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Journal of Experimental Biology

Rebecca Wheatley, Christofer J Clemente, Amanda C Niehaus, Diana O Fisher, Robbie S Wilson
Movement speed can underpin an animal's probability of success in ecological tasks. Prey often use agility to outmanoeuvre predators, however faster speeds increase inertia and reduce agility. Agility is also constrained by grip, as the foot must have sufficient friction with the ground to apply the forces required for turning. Consequently, ground surface should affect optimum turning speed. We tested the speed-agility trade-off in buff-footed antechinus ( Antechinus mysticus ) on two different surfaces. Antechinus used slower turning speeds over smaller turning radii on both surfaces, as predicted by the speed-agility trade-off...
March 20, 2018: Journal of Experimental Biology
Amanda Rodrigues Vieira, Nayara Salles, Marco Borges, Theo Mota
For more than a century, visual learning and memory has been studied in the honeybee Apis mellifera using operant appetitive conditioning. Although honeybees show impressive visual learning capacities in this well-established protocol, operant training of free-flying animals can hardly be combined with invasive protocols for studying the neurobiological basis of visual learning. In view of that, different efforts have been made to develop new classical conditioning protocols for studying visual learning in harnessed honeybees, though learning performances remain considerably poorer than those obtained in free-flying animals...
March 20, 2018: Journal of Experimental Biology
Ge Li, Xiao Lv, Jing Zhou, Cong Shen, Danyang Xia, Hang Xie, Yiping Luo
The metabolic-level boundaries (MLB) hypothesis proposes that metabolic level mediates the relative influence of surface area (SA) vs volume related metabolic processes on the body-mass scaling of metabolic rate in organisms. The variation in the scaling of SA may affect how metabolic level affects the metabolic scaling exponent. This study aimed to determine the influence of increasing metabolic level at a higher temperature on the metabolic scaling exponent of the crucian carp and determine the link between metabolic scaling exponents and SA parameters of both gills and body...
March 20, 2018: Journal of Experimental Biology
Manuela Truebano, Phillip Fenner, Oliver Tills, Simon Rundle, Enrico L Rezende
With both global surface temperatures and the incidence and intensity of extreme temperature events projected to increase, the assessment of species' sensitivities to chronic and acute changes in temperature has become crucial. Sensitivity predictions are based predominantly on adult responses, despite the fact that early life stages may be more vulnerable to thermal challenge. Here, we compared the sensitivity of different life history stages of the intertidal gastropod Littorina obtusata using thermal death time curves, which incorporate the intensity and duration of heat stress, and used these to calculate upper critical thermal limits (CTmax ) and sensitivity to temperature change (z)...
March 20, 2018: Journal of Experimental Biology
Oliver T M Cocks, Paul E Eady
The copulatory organs of male insects are generally complex, species-specific arrangements of hardened sclerotized plates bound together by flexible, less sclerotized cuticle. Their extensive morphological diversification is a recurrent pattern in the evolutionary radiation of animals, yet a clear consensus as to what selection pressures drive this divergence is still to emerge. In part, this stems from the fact that the function of individual sclerites that integrate to form the aedeagus are poorly understood...
March 20, 2018: Journal of Experimental Biology
Christabel Y L Chan, Kum C Hiong, Mel V Boo, Celine Y L Choo, Wai P Wong, Shit F Chew, Yuen K Ip
Giant clams live in nutrient-poor reef waters of the Indo-Pacific and rely on symbiotic dinoflagellates ( Symbiodinium spp., also known as zooxanthellae) for nutrients. As the symbionts are nitrogen deficient, the host clam has to absorb exogenous nitrogen and supply it to them. This study aimed to demonstrate light-enhanced urea absorption in the fluted giant clam, Tridacna squamosa , and to clone and characterize the urea active transporter, DUR3-like, from its ctenidium (gill). Results indicate that T. squamosa could absorb exogenous urea, and the rate of urea uptake in light was significantly higher than that in darkness...
March 14, 2018: Journal of Experimental Biology
Diana S Samuel, Sandra Nauwelaerts, Jeroen M G Stevens, Tracy L Kivell
Evolution of the human hand has undergone a transition from use during locomotion to use primarily for manipulation. Previous comparative morphological and biomechanical studies have focused on potential changes in manipulative abilities during human hand evolution, but few have focused on functional signals for arboreal locomotion. Here, we provide this comparative context though the first analysis of hand loading in captive bonobos during arboreal locomotion. We quantify pressure experienced by the fingers, palm and thumb in bonobos during vertical locomotion, suspension and arboreal knuckle-walking...
March 14, 2018: Journal of Experimental Biology
Ella Z Lattenkamp, Samuel Kaiser, Rožle Kaučič, Martina Großmann, Klemen Koselj, Holger R Goerlitz
Sensory systems experience a trade-off between maximizing the detail and amount of sampled information. This trade-off is particularly pronounced in sensory systems that are highly specialized for a single task and thus experience limitations in other tasks. We hypothesised that combining sensory input from multiple streams of information may resolve this trade-off and improve detection and sensing reliability. Specifically, we predicted that perceptive limitations experienced by animals reliant on specialised active echolocation can be compensated for by the phylogenetically older and less specialised process of passive hearing...
March 14, 2018: Journal of Experimental Biology
K Jeannet Oyen, Michael E Dillon
Critical thermal limits often determine species distributions for diverse ectotherms and have become a useful tool for understanding past and predicting future range shifts in response to changing climates. Despite recently documented population declines and range shifts of bumble bees (genus Bombus ), the few measurements of thermal tolerance available for the group have relied on disparate measurement approaches. We describe a novel stereotypical behavior expressed by bumble bee individuals during entry into chill coma...
March 12, 2018: Journal of Experimental Biology
Prasong J Mekdara, Margot A B Schwalbe, Laura L Coughlin, Eric D Tytell
Fish use multiple sensory systems, including vision and their lateral line system, to maintain position and speed within a school. Although previous studies have shown that ablating the lateral line alters schooling behavior, no one has examined how the behavior recovers as the sensory system regenerates. We studied how schooling behavior changes in giant danios Devario aequipinnatus when their lateral line system is chemically ablated and after the sensory hair cells regenerate. We found that fish could school normally immediately after chemical ablation, but that they had trouble schooling one to two weeks after the chemical treatment, when the hair cells had fully regenerated...
March 12, 2018: Journal of Experimental Biology
Rodrigo S B Gavira, Marina R Sartori, Manuel N Gontero-Fourcade, Bruna F Gomes, Augusto S Abe, Denis V Andrade
Tegu lizards ( Salvator merianae ) aestivate for up to 5 months during Brazil's winter, when they retreat to burrows and halt most activities. Dormant tegus reduce their gastrointestinal (GI) mass, which allows a substantial energy economy. This strategy however, implies that the first post-dormancy digestion would be more costly than subsequent feeding episodes due to GI atrophy. To address this, we determined the postprandial metabolic response (SDA) of the first (M1), second (M2) and several (RM) feeding episodes after tegus' dormancy...
March 12, 2018: Journal of Experimental Biology
Simon P Lailvaux, Andrew Z Wang, Jerry F Husak
The energetic costs of performance constitute a non-trivial component of animals' daily energetic budgets. However, we currently lack an understanding of how those costs are partitioned among the various stages of performance development, maintenance, and production. We manipulated individual investment in performance by training Anolis carolinensis lizards for endurance or sprinting ability. We then measured energetic expenditure both at rest and immediately following exercise to test whether such training alters the maintenance and production costs of performance...
March 12, 2018: Journal of Experimental Biology
Katherine A J Daniels, J F Burn
It is generally accepted that animals move in a way that minimises energy use during regular gait and there is evidence that the principle might extend more generally to locomotor behaviour and manoeuvres. Jumping during locomotion is a useful manoeuvre that contributes to the versatility of legged locomotion and is within the repertoire of many terrestrial animals. We describe a simple ballistic model that can be used to identify a single unique trajectory of the body's centre of mass that minimises the mechanical work to initiate a jump, regardless of the approach velocity or take-off position...
March 12, 2018: Journal of Experimental Biology
Corrine Jacobs, Roi Holzman
Suction feeding is a widespread prey capture strategy among aquatic vertebrates. It is almost omnipresent across fishes, and has repeatedly evolved in other aquatic vertebrates. By rapidly expanding the mouth cavity, suction-feeders generate a fluid flow outside of their mouth, drawing prey inside. Fish and other suction feeding organisms display remarkable trophic diversity, echoed in the diversity of their skull and mouth morphologies. Yet, it is unclear how variable suction flows are across species, and whether variation in suction flows supports trophic diversity...
March 6, 2018: Journal of Experimental Biology
A J Turko, A Tatarenkov, S Currie, R L Earley, A Platek, D S Taylor, P A Wright
Fishes acclimated to hypoxic environments often increase gill surface area to improve O2 uptake. In some species, surface area is increased via reduction of an interlamellar cell mass (ILCM) that fills water channels between gill lamellae. Amphibious fishes, however, may not increase gill surface area in hypoxic water because these species can instead leave water and breathe air. To differentiate between these possibilities, we compared wild amphibious mangrove rivulus Kryptolebias marmoratus from two habitats that varied in O2 availability - a hypoxic freshwater pool versus nearly anoxic crab burrows...
March 6, 2018: Journal of Experimental Biology
Priscilla Salas, Vall Vinaithirthan, Erin Newman-Smith, Matthew J Kourakis, William C Smith
The swimming tadpole larva of Ciona has one of the simplest central nervous systems known, with only 177 neurons. Despite its simplicity, the Ciona CNS shares common structure with the CNS of its close chordate relatives, the vertebrates. The recent completion of a larval Ciona CNS connectome creates enormous potential for detailed understanding of chordate CNS function, yet our understanding of Ciona larval behavior is incomplete. We show here that Ciona larvae have a surprisingly rich and dynamic set of visual responses, including a looming-object escape behavior characterized by erratic circular swims, as well as negative phototaxis characterized by sustained directional swims...
March 6, 2018: Journal of Experimental Biology
Ksenija D Velickovic, Mirela M Ukropina, Radmila M Glisic, Maja M Cakic-Milosevic
The aim of this study was to determine the effects of long-term sucrose overfeeding on functional capacity and ultrastructural characteristics of the rat brown adipose tissue (BAT). For the study, sixteen male Wistar rats, chow-fed and kept under standard laboratory conditions were divided into 2 equal groups. The rats from a control group drank tap water, while those from a sucrose overfed group were allowed to drink 10% sucrose solution for 21 days. Structural changes of BAT were analysed at the level of light and electron microscopy on routinely prepared tissue sections or using immunohistochemical staining, in combination with stereological methods...
March 1, 2018: Journal of Experimental Biology
Amanda Bundgaard, Andrew M James, William Joyce, Michael P Murphy, Angela Fago
Freshwater turtles ( Trachemys scripta ) are among the very few vertebrates capable of tolerating severe hypoxia and reoxygenation without suffering from damage to the heart. As myocardial ischemia and reperfusion causes a burst of mitochondrial reactive oxygen species (ROS) in mammals, the question arises as to whether, and if so how, this ROS burst is prevented in the turtle heart. We find here that heart mitochondria isolated from turtles acclimated to anoxia produce less ROS than mitochondria from normoxic turtles when consuming succinate...
March 1, 2018: Journal of Experimental Biology
Clare C Rittschof, Hemendra J Vekaria, Joseph H Palmer, Patrick G Sullivan
Neuronal function demands high-level energy production, and as such, a decline in mitochondrial respiration characterizes brain injury and disease. A growing number of studies, however, link brain mitochondrial function to behavioral modulation in non-diseased contexts. In the honey bee, we show for the first time that an acute social interaction, which invokes an aggressive response, may also cause a rapid decline in brain mitochondrial bioenergetics. The degree and speed of this decline has only been previously observed in the context of brain injury...
March 1, 2018: Journal of Experimental Biology
Jan Rozsypal, Martin Moos, Petr Šimek, Vladimír Koštál
Some insects rely on the strategy of freeze tolerance for winter survival. During freezing, extracellular body water transitions from the liquid to solid phase and cells undergo freeze-induced dehydration. Here we present results of a thermal analysis (from differential scanning calorimetry) of ice fraction dynamics during gradual cooling after inoculative freezing in variously acclimated larvae of two drosophilid flies, Drosophila melanogaster and Chymomyza costata. Although the species and variants ranged broadly between 0 and close to 100% survival of freezing, there were relatively small differences in ice fraction dynamics...
March 1, 2018: Journal of Experimental Biology
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