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1
Rayner, J. M. "Estimating power curves of flying vertebrates." Journal of Experimental Biology 202, no. 23 (December 1, 1999): 3449–61. http://dx.doi.org/10.1242/jeb.202.23.3449.
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The power required for flight in any flying animal is a function of flight speed. The power curve that describes this function has become an icon of studies of flight mechanics and physiology because it encapsulates the accessible animal's flight performance. The mechanical or aerodynamic power curve, describing the increase in kinetic energy of the air due to the passage of the bird, is necessarily U-shaped, for aerodynamic reasons, and can be estimated adequately by lifting-line theory. Predictions from this and related models agree well with measured mechanical work in flight and with results from flow visualization experiments. The total or metabolic power curve also includes energy released by the animal as heat, and is more variable in shape. These curves may be J-shaped for smaller birds and bats, but are difficult to predict theoretically owing to uncertainty about internal physiological processes and the efficiency of the flight muscles. The limitations of some existing models aiming to predict metabolic power curves are considered. The metabolic power curve can be measured for birds or bats flying in wind tunnels at controlled speeds. Simultaneous determination in European starlings Sturnus vulgaris of oxygen uptake, total metabolic rate (using labelled isotopes), aerodynamic power output and heat released (using digital video thermography) enable power curves to be determined with confidence; flight muscle efficiency is surprisingly low (averaging 15–18 %) and increases moderately with flight speed, so that the metabolic power curve is shallower than predicted by models. Accurate knowledge of the power curve is essential since extensive predictions of flight behaviour have been based upon it. The hypothesis that the power curve may not in fact exist, in the sense that the cost of flight may not be perceived by a bird as a continuous smooth function of air speed, is advanced but has not yet formally been tested. This hypothesis is considered together with evidence from variation in flight behaviour, wingbeat kinematics and flight gait with speed. Possible constraints on flight behaviour can be modelled by the power curves: these include the effect of a maximum power output and a constraint on maximum speed determined by downstroke wingbeat geometry and the relationship between thrust and lift.
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Willson, Mary F., and F. H. J. Crome. "Patterns of seed rain at the edge of a tropical Queensland rain forest." Journal of Tropical Ecology 5, no. 3 (August 1989): 301–8. http://dx.doi.org/10.1017/s0266467400003680.
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ABSTRACTBoth vertebrate- and wind-dispersed seeds moved farther from rain forest into old field than from old field into forest. Vertebrate-dispersed seeds from the rain forest moved farther into the field than wind-dispersed seeds, but seeds of both types moved similar distances from field into forest.Habitat structure affected seed deposition patterns in the field, where shrubs provided perches for flying vertebrates. Vertebrate-dispersed seed deposition was significantly greater, and deposition of plumed, wind-dispersed seeds was significantly less, under shrubs than in the open. Deposition of vertebrate-dispersed seeds under fruiting shrubs was significantly less than under non-fruiting shrubs.
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Desantis, Lanna M., Jeff Bowman, Erin Faught, Rudy Boonstra, Mathilakath M. Vijayan, and Gary Burness. "Corticosteroid-binding globulin levels in North American sciurids: implications for the flying squirrel stress axis." Canadian Journal of Zoology 96, no. 10 (October 2018): 1090–96. http://dx.doi.org/10.1139/cjz-2017-0300.
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Corticosteroid-binding globulin (CBG) helps to regulate tissue bioavailability of circulating glucocorticoids (GCs), and in most vertebrates, ≥80%–90% of GCs bind to this protein. New World flying squirrels have higher plasma total cortisol levels (the primary corticosteroid in sciurids) than most vertebrates. Recent research suggests that flying squirrels have either low amounts of CBG or CBG molecules that have a low binding affinity for cortisol, as this taxon appears to exhibit very low proportions of cortisol bound to CBG. To test whether CBG levels have been adjusted over evolutionary time, we assessed the levels of this protein in the plasma of northern (Glaucomys sabrinus (Shaw, 1801)) and southern (Glaucomys volans (Linnaeus, 1758)) flying squirrels using immunoblotting, and compared the relative levels among three phylogenetically related species of sciurids. We also compared the pattern of CBG levels with cortisol levels for the same individuals. Flying squirrels had higher cortisol levels than the other species, but similar levels of CBG to their closest relatives (tree squirrels). We conclude that CBG levels in flying squirrels have not been adjusted over evolutionary time, and thus, the uncoupling of CBG levels from cortisol concentrations may represent an evolutionary modification in the lineage leading to New World flying squirrels.
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Chin, Diana D., Laura Y. Matloff, Amanda Kay Stowers, Emily R. Tucci, and David Lentink. "Inspiration for wing design: how forelimb specialization enables active flight in modern vertebrates." Journal of The Royal Society Interface 14, no. 131 (June 2017): 20170240. http://dx.doi.org/10.1098/rsif.2017.0240.
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Harnessing flight strategies refined by millions of years of evolution can help expedite the design of more efficient, manoeuvrable and robust flying robots. This review synthesizes recent advances and highlights remaining gaps in our understanding of how bird and bat wing adaptations enable effective flight. Included in this discussion is an evaluation of how current robotic analogues measure up to their biological sources of inspiration. Studies of vertebrate wings have revealed skeletal systems well suited for enduring the loads required during flight, but the mechanisms that drive coordinated motions between bones and connected integuments remain ill-described. Similarly, vertebrate flight muscles have adapted to sustain increased wing loading, but a lack of in vivo studies limits our understanding of specific muscular functions. Forelimb adaptations diverge at the integument level, but both bird feathers and bat membranes yield aerodynamic surfaces with a level of robustness unparalleled by engineered wings. These morphological adaptations enable a diverse range of kinematics tuned for different flight speeds and manoeuvres. By integrating vertebrate flight specializations—particularly those that enable greater robustness and adaptability—into the design and control of robotic wings, engineers can begin narrowing the wide margin that currently exists between flying robots and vertebrates. In turn, these robotic wings can help biologists create experiments that would be impossible in vivo .
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Padian, Kevin. "Closest relatives found for pterosaurs, the first flying vertebrates." Nature 588, no. 7838 (December 9, 2020): 400–401. http://dx.doi.org/10.1038/d41586-020-03420-z.
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Bortot, Maria, Christian Agrillo, Aurore Avarguès-Weber, Angelo Bisazza, Maria Elena Miletto Petrazzini, and Martin Giurfa. "Honeybees use absolute rather than relative numerosity in number discrimination." Biology Letters 15, no. 6 (June 2019): 20190138. http://dx.doi.org/10.1098/rsbl.2019.0138.
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Various vertebrate species use relative numerosity judgements in comparative assessments of quantities for which they use larger/smaller relationships rather than absolute number. The numerical ability of honeybees shares basic properties with that of vertebrates but their use of absolute or relative numerosity has not been explored. We trained free-flying bees to choose variable images containing three dots; one group (‘larger’) was trained to discriminate 3 from 2, while another group (‘smaller’) was trained to discriminate 3 from 4. In both cases, numbers were kept constant but stimulus characteristics and position were varied from trial to trial. Bees were then tested with novel stimuli displaying the previously trained numerosity (3) versus a novel numerosity (4 for ‘larger’ and 2 for ‘smaller’). Both groups preferred the three-item stimulus, consistent with absolute numerosity. They also exhibited ratio-dependent discrimination of numbers, a property shared by vertebrates, as performance after 2 versus 3 was better than after 3 versus 4 training. Thus, bees differ from vertebrates in their use of absolute rather than of relative numerosity but they also have some numeric properties in common.
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Desantis, Lanna M., Jeff Bowman, Candace V. Lahoda, Rudy Boonstra, and Gary Burness. "Responses of New World flying squirrels to the acute stress of capture and handling." Journal of Mammalogy 97, no. 1 (October 19, 2015): 80–88. http://dx.doi.org/10.1093/jmammal/gyv156.
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Abstract Northern ( Glaucomys sabrinus ) and southern ( G. volans ) flying squirrels have glucocorticoid (GC; stress hormone) levels higher than most vertebrates but virtually no binding capacity for these GCs via the carrier protein, corticosteroid-binding globulin. Thus, their total GCs are essentially all free and biologically active. However, the GC estimates come from blood samples taken after squirrels had been in live traps, and thus in a stress-induced state. Obtaining baseline values for physiological variables is valuable for assessing the response of vertebrates to stressors in their environment. We compared baseline plasma total cortisol levels (within 3min of capture) to stress-induced levels (after 30min of trap restraint) in both flying squirrel species. We recorded baseline cortisol levels that were some of the highest ever reported for mammals, indicating their stress axes operate at a higher set point than most other species. As part of the stress response, we also measured 4 indices in addition to cortisol. Total cortisol and free fatty acids increased in both species, as predicted. In contrast with our predictions, blood glucose and neutrophil/lymphocyte ratio showed no overall change, and hematocrit decreased significantly. New World flying squirrels therefore appear to have a stress response that differs from many other mammals. The selective forces driving the physiology of these animals remain elusive, but this lineage may provide an interesting comparative system for the study of stress axis function and its evolution among vertebrates.
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Palmer, C., and G. J. Dyke. "Moving on from Kirkpatrick (1994): estimating 'safety factors' for flying vertebrates." Journal of Experimental Biology 213, no. 12 (May 28, 2010): 2174. http://dx.doi.org/10.1242/jeb.044537.
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Schreer, Jason F., and Kit M. Kovacs. "Allometry of diving capacity in air-breathing vertebrates." Canadian Journal of Zoology 75, no. 3 (March 1, 1997): 339–58. http://dx.doi.org/10.1139/z97-044.
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Maximum diving depths and durations were examined in relation to body mass for birds, marine mammals, and marine turtles. There were strong allometric relationships between these parameters (log10 transformed) among air-breathing vertebrates (r = 0.71, n = 111 for depth; r = 0.84, n = 121 for duration), although there was considerable scatter around the regression lines. Many of the smaller taxonomic groups also had a strong allometric relationship between diving capacity (maximum depth and duration) and body mass. Notable exceptions were mysticete cetaceans and diving/flying birds, which displayed no relationship between maximum diving depth and body mass, and otariid seals, which showed no relationship between maximum diving depth or duration and body mass. Within the diving/flying bird group, only alcids showed a significant relationship (r = 0.81, n = 9 for depth). The diving capacities of penguins had the highest correlations with body mass (r = 0.81, n = 11 for depth; r = 0.93, n = 9 for duration), followed by those of odontocete cetaceans (r = 0.75, n = 21 for depth; r = 0.84, n = 22 for duration) and phocid seals (r = 0.70, n = 15 for depth; r = 0.59, n = 16 for duration). Mysticete cetaceans showed a strong relationship between maximum duration and body mass (r = 0.84, n = 9). Comparisons across the various groups indicated that alcids, penguins, and phocids are all exceptional divers relative to their masses and that mysticete cetaceans dive to shallower depths and for shorter periods than would be predicted from their size. Differences among groups, as well as the lack of relationships within some groups, could often be explained by factors such as the various ecological feeding niches these groups exploit, or by variations in the methods used to record their behavior.
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McCracken, Gary F., Kamran Safi, Thomas H. Kunz, Dina K. N. Dechmann, Sharon M. Swartz, and Martin Wikelski. "Airplane tracking documents the fastest flight speeds recorded for bats." Royal Society Open Science 3, no. 11 (November 2016): 160398. http://dx.doi.org/10.1098/rsos.160398.
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The performance capabilities of flying animals reflect the interplay of biomechanical and physiological constraints and evolutionary innovation. Of the two extant groups of vertebrates that are capable of powered flight, birds are thought to fly more efficiently and faster than bats. However, fast-flying bat species that are adapted for flight in open airspace are similar in wing shape and appear to be similar in flight dynamics to fast-flying birds that exploit the same aerial niche. Here, we investigate flight behaviour in seven free-flying Brazilian free-tailed bats ( Tadarida brasiliensis ) and report that the maximum ground speeds achieved exceed speeds previously documented for any bat. Regional wind modelling indicates that bats adjusted flight speeds in response to winds by flying more slowly as wind support increased and flying faster when confronted with crosswinds, as demonstrated for insects, birds and other bats. Increased frequency of pauses in wing beats at faster speeds suggests that flap-gliding assists the bats' rapid flight. Our results suggest that flight performance in bats has been underappreciated and that functional differences in the flight abilities of birds and bats require re-evaluation.
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Xu, Guang-Hui, Li-Jun Zhao, Ke-Qin Gao, and Fei-Xiang Wu. "A new stem-neopterygian fish from the Middle Triassic of China shows the earliest over-water gliding strategy of the vertebrates." Proceedings of the Royal Society B: Biological Sciences 280, no. 1750 (January 7, 2013): 20122261. http://dx.doi.org/10.1098/rspb.2012.2261.
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Flying fishes are extraordinary aquatic vertebrates capable of gliding great distances over water by exploiting their enlarged pectoral fins and asymmetrical caudal fin. Some 50 species of extant flying fishes are classified in the Exocoetidae (Neopterygii: Teleostei), which have a fossil record no older than the Eocene. The Thoracopteridae is the only pre-Cenozoic group of non-teleosts that shows an array of features associated with the capability of over-water gliding. Until recently, however, the fossil record of the Thoracopteridae has been limited to the Upper Triassic of Austria and Italy. Here, we report the discovery of exceptionally well-preserved fossils of a new thoracopterid flying fish from the Middle Triassic of China, which represents the earliest evidence of an over-water gliding strategy in vertebrates. The results of a phylogenetic analysis resolve the Thoracopteridae as a stem-group of the Neopterygii that is more crown-ward than the Peltopleuriformes, yet more basal than the Luganoiiformes. As the first record of the Thoracopteride in Asia, this new discovery extends the geographical distribution of this group from the western to eastern rim of the Palaeotethys Ocean, providing new evidence to support the Triassic biological exchanges between Europe and southern China. Additionally, the Middle Triassic date of the new thoracopterid supports the hypothesis that the re-establishment of marine ecosystems after end-Permian mass extinction is more rapid than previously thought.
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Frey, Eberhard, Marie-Céline Buchy, and David M. Martill. "Middle- and bottom-decker Cretaceous pterosaurs: unique designs in active flying vertebrates." Geological Society, London, Special Publications 217, no. 1 (2003): 267–74. http://dx.doi.org/10.1144/gsl.sp.2003.217.01.15.
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Gauthier, J. A., and K. Padian. "The Origin of Birds and the Evolution of Flight." Short Courses in Paleontology 2 (1989): 121–33. http://dx.doi.org/10.1017/s247526300000091x.
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One of the most salient advances in vertebrate paleontology in recent decades has been the settling of the question of the origin of birds, a problem that has vexed evolutionary biologists since well before Darwin. To be sure, the consensus is not unanimous, and many details of this branch of the phylogenetic tree are yet to be worked out, but we now have a much clearer picture of this problem than we had a decade ago. Less settled, but equally stimulating, has been the controversy over the origin of flight in birds and other flying vertebrates. Was there a gliding stage? Did flight begin from the ground up or from the trees down? Were birds initially arboreal? What selective pressures drove the ancestors of birds to take advantage of the aerial opportunity?
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Price, Edwin R., Antonio Brun, Enrique Caviedes-Vidal, and William H. Karasov. "Digestive Adaptations of Aerial Lifestyles." Physiology 30, no. 1 (January 2015): 69–78. http://dx.doi.org/10.1152/physiol.00020.2014.
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Flying vertebrates (birds and bats) are under selective pressure to reduce the size of the gut and the mass of the digesta it carries. Compared with similar-sized nonflying mammals, birds and bats have smaller intestines and shorter retention times. We review evidence that birds and bats have lower spare digestive capacity and partially compensate for smaller intestines with increased paracellular nutrient absorption.
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Warfvinge, Kajsa, Marco KleinHeerenbrink, and Anders Hedenström. "The power–speed relationship is U-shaped in two free-flying hawkmoths ( Manduca sexta )." Journal of The Royal Society Interface 14, no. 134 (September 2017): 20170372. http://dx.doi.org/10.1098/rsif.2017.0372.
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A flying animal can minimize its energy consumption by choosing an optimal flight speed depending on the task at hand. Choice of flight speed can be predicted by modelling the aerodynamic power required for flight, and this tool has previously been used extensively in bird migration research. For insects, however, it is uncertain whether any of the commonly used power models are useful, as insects often operate in a very different flow regime from vertebrates. To investigate this, we measured aerodynamic power in the wake of two Manduca sexta flying freely in a wind tunnel at 1–3.8 ms −1 , using tomographic particle image velocimetry (tomo-PIV). The expended power was similar in magnitude to that predicted by two classic models. However, the most ubiquitously used model, originally intended for vertebrates, failed to predict the sharp increase in power at higher speeds, leading to an overestimate of predicted flight speed during longer flights. In addition to measuring aerodynamic power, the tomo-PIV system yielded a highly detailed visualization of the wake, which proved to be significantly more intricate than could be inferred from previous smoke trail- and two-dimensional-PIV studies.
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Organ, Chris L., and Andrew M. Shedlock. "Palaeogenomics of pterosaurs and the evolution of small genome size in flying vertebrates." Biology Letters 5, no. 1 (October 21, 2008): 47–50. http://dx.doi.org/10.1098/rsbl.2008.0491.
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The two living groups of flying vertebrates, birds and bats, both have constricted genome sizes compared with their close relatives. But nothing is known about the genomic characteristics of pterosaurs, which took to the air over 70 Myr before birds and were the first group of vertebrates to evolve powered flight. Here, we estimate genome size for four species of pterosaurs and seven species of basal archosauromorphs using a Bayesian comparative approach. Our results suggest that small genomes commonly associated with flight in bats and birds also evolved in pterosaurs, and that the rate of genome-size evolution is proportional to genome size within amniotes, with the fastest rates occurring in lineages with the largest genomes. We examine the role that drift may have played in the evolution of genome size within tetrapods by testing for correlated evolution between genome size and body size, but find no support for this hypothesis. By contrast, we find evidence suggesting that a combination of adaptation and phylogenetic inertia best explains the correlated evolution of flight and genome-size contraction. These results suggest that small genome/cell size evolved prior to or concurrently with flight in pterosaurs. We predict that, similar to the pattern seen in theropod dinosaurs, genome-size contraction preceded flight in pterosaurs and bats.
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Alexander, R. M. "Response to "Moving on from Kirkpatrick (1994): estimating 'safety factors' for flying vertebrates"." Journal of Experimental Biology 213, no. 12 (May 28, 2010): 2175. http://dx.doi.org/10.1242/jeb.044958.
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Suarez, R. K. "Oxygen and the upper limits to animal design and performance." Journal of Experimental Biology 201, no. 8 (April 1, 1998): 1065–72. http://dx.doi.org/10.1242/jeb.201.8.1065.
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Mass-specific rates of aerobic metabolism VO2/Mb) scale in inverse proportion to body mass (Mb). Thus, small hummingbirds display the highest VO2/Mb known among vertebrates. Among all animals, higher VO2/Mb values are known only in flying insects. The high body-mass-specific rates of metabolism seen in hummingbirds are made possible by high lung O2 diffusing capacities, cardiac outputs, ratios of capillary surface area to muscle fiber surface area, mitochondrial volume densities, cristae surface densities and concentrations of enzymes involved in energy metabolism. Current evidence from control analyses of O2 transport through the respiratory and cardiovascular systems and of metabolic fluxes through pathways of energy metabolism indicates shared control of maximum flux rates among multiple steps (i.e. the absence of single rate-limiting steps). This supports the suggestion that functional capacities at each step in linear pathways or processes are matched to each other, and provides an explanation for why the up-regulation of functional capacities has occurred at virtually all steps in the evolution of the smallest vertebrate homeotherms. Flying insects make use of a tracheal system for O2 transport and, like hummingbirds, possess a highly up-regulated biochemical machinery for substrate oxidation. Studies of hummingbirds and honeybees reveal closer matches between biochemical flux capacities and maximum physiological flux rates than in animals capable of lower maximum VO2/Mb. It is proposed that the upper limits to functional capacities set the upper limit to VO2/Mb. This upper limit to aerobic metabolic rate may contribute, along with other factors, towards establishing the lower limit to vertebrate homeotherm size.
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Carpenter, Roger E. "Flight Physiology of Flying Foxes, Pteropus Poliocephalus." Journal of Experimental Biology 114, no. 1 (January 1, 1985): 619–47. http://dx.doi.org/10.1242/jeb.114.1.619.
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Oxygen consumption was measured during flight in two flying foxes (Pteropus poliocephalus) at airspeeds of 4–8.6ms−1. There was good agreement with the measured power input of the only previously measured large bat, and with an allometric equation predicting power input for flying vertebrates. Measurements of respiratory exchange ratios, pulmonary water loss, respiratory frequencies, heart rates and body temperatures of both bats flying at intermediate airspeeds were compared with equivalent measurements on other bats or birds in flight. Despite a high non-evaporative thermal conductance in flight, the P. poliocephalus became severely hyperthermic at ambient temperatures (Ta) above 25°C. The failure to dissipate heat as successfully as flying birds at high Ta is apparently the result of an inability to increase pulmonary ventilation rates, and thus increase rates of evaporative heat loss. The effect of airspeed on endurance was measured systematically on one bat. Endurance was not limited by energy reserves at all airspeeds, and flight times were significantly greater at the airspeed of minimum power input (Vmp). The endurance of both bats was so reduced at the higher airspeeds that they would not achieve maximum flight range in still air at the velocity where cost of locomotion is lowest. Contrary to a common assumption, flight range would be maximized at the Vmp.
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Edwards, Sarah, and Glenn A. Marsh. "Henipaviruses: bat-borne paramyxoviruses." Microbiology Australia 38, no. 1 (2017): 4. http://dx.doi.org/10.1071/ma17003.
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Found on every continent except Antarctica, bats are one of the most abundant, diverse and geographically widespread vertebrates globally, making up approximately 20% of all known extant mammal species1,2. Noted for being the only mammal with the ability of powered flight, bats constitute the order Chiroptera (from the Ancient Greek meaning ‘hand wing’), which is further divided into two suborders: Megachiroptera known as megabats or flying foxes, and Microchiroptera comprising of echolocating microbats1,3.
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Caviedes-Vidal, E., T. J. McWhorter, S. R. Lavin, J. G. Chediack, C. R. Tracy, and W. H. Karasov. "The digestive adaptation of flying vertebrates: High intestinal paracellular absorption compensates for smaller guts." Proceedings of the National Academy of Sciences 104, no. 48 (November 19, 2007): 19132–37. http://dx.doi.org/10.1073/pnas.0703159104.
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Ravi, Sridhar, Tim Siesenop, Olivier Bertrand, Liang Li, Charlotte Doussot, William H. Warren, Stacey A. Combes, and Martin Egelhaaf. "Bumblebees perceive the spatial layout of their environment in relation to their body size and form to minimize inflight collisions." Proceedings of the National Academy of Sciences 117, no. 49 (November 23, 2020): 31494–99. http://dx.doi.org/10.1073/pnas.2016872117.
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Animals that move through complex habitats must frequently contend with obstacles in their path. Humans and other highly cognitive vertebrates avoid collisions by perceiving the relationship between the layout of their surroundings and the properties of their own body profile and action capacity. It is unknown whether insects, which have much smaller brains, possess such abilities. We used bumblebees, which vary widely in body size and regularly forage in dense vegetation, to investigate whether flying insects consider their own size when interacting with their surroundings. Bumblebees trained to fly in a tunnel were sporadically presented with an obstructing wall containing a gap that varied in width. Bees successfully flew through narrow gaps, even those that were much smaller than their wingspans, by first performing lateral scanning (side-to-side flights) to visually assess the aperture. Bees then reoriented their in-flight posture (i.e., yaw or heading angle) while passing through, minimizing their projected frontal width and mitigating collisions; in extreme cases, bees flew entirely sideways through the gap. Both the time that bees spent scanning during their approach and the extent to which they reoriented themselves to pass through the gap were determined not by the absolute size of the gap, but by the size of the gap relative to each bee’s own wingspan. Our findings suggest that, similar to humans and other vertebrates, flying bumblebees perceive the affordance of their surroundings relative their body size and form to navigate safely through complex environments.
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Suthers, Roderick A. "Vocal mechanisms in birds and bats: a comparative view." Anais da Academia Brasileira de Ciências 76, no. 2 (June 2004): 247–52. http://dx.doi.org/10.1590/s0001-37652004000200009.
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Vocal signals play a very important role in the life of both birds and echolocating bats, but these two unrelated groups of flying vertebrates have very different vocal systems. They nevertheless must solve many of the same problems in producing sound. This brief review examines avian and microchiropteran motor mechanisms for: 1) coordinating the timing of phonation with the vocal motor pattern that controls its acoustic properties, and 2) achieving respiratory strategies that provide adequate ventilation for pulmonary gas exchange, while also facilitating longer duration songs or trains of sonar pulses.
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Vences, Miguel. "Origin of Madagascar's extant fauna: A perspective from amphibians, reptiles and other non‐flying vertebrates." Italian Journal of Zoology 71, sup2 (January 2004): 217–28. http://dx.doi.org/10.1080/11250000409356639.
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Wood, William F., Allyson Walsh, John Seyjagat, and Paul J. Weldon. "Volatile Compounds in Shoulder Gland Secretions of Male Flying Foxes, Genus Pteropus (Pteropodidae, Chiroptera)." Zeitschrift für Naturforschung C 60, no. 9-10 (October 1, 2005): 779–84. http://dx.doi.org/10.1515/znc-2005-9-1019.
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Abstract The shoulder gland secretions of captive males of the Indian flying fox (Pteropus giganteus), the little golden-mantled flying fox (P. pumilus), the island flying fox (P. hypomelanus), and the large flying fox (P. vampyrus) were examined by gas chromatography-mass spectrometry. Sixty-five compounds, including hydrocarbons, carboxylic acids, alcohols, aldehydes, ketones, esters, and amides, were identified among the four species. Many of these compounds, such as squalene, cholesterol, and C5-C16 straight- and branched-chain carboxylic acids, are typical of tetrapod epidermal products. Aldehydes, which were detected in all four Pteropus species, and some straight- and branched-chain ketones, which were detected in P. hypomelanus and P. pumilus, are known from other mammalian skin glands. Acetophenone, 4-acetoxyacetophenone, and 4-hydroxyacetophenone were observed in P. pumilus; the last compound comprised 37.1% of the total ion current. 2,3-Butanediol, a prominent component (5.2-19.3%) in the secretions of P. giganteus, P. hypomelanus, and P. pumilus, and C10 and C12 isopropyl esters and C10-C14 1-methylbutyl esters, observed in P. hypomelanus and P. vampyrus, have not previously been reported from vertebrates. α-Methyl-4-methoxybenzyl alcohol and dihydro-5-phenyl-2(3H)-furanone, from P. giganteus and P. pumilus, are new natural products. 1-Chloro-3-methyl-2-butene, another new natural product, and five C5 compounds exhibiting a similar isoprenoid structure were observed in P. giganteus. Striking contrasts were observed in the chemical profiles of the species we examined, with even general chemical classes differentially represented among them.
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BELL, E., B. ANDRES, and A. GOSWAMI. "Integration and dissociation of limb elements in flying vertebrates: a comparison of pterosaurs, birds and bats." Journal of Evolutionary Biology 24, no. 12 (September 29, 2011): 2586–99. http://dx.doi.org/10.1111/j.1420-9101.2011.02381.x.
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Rayner, Jeremy M. V. "Mechanics and physiology of flight in fossil vertebrates." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 80, no. 3-4 (1989): 311–20. http://dx.doi.org/10.1017/s0263593300028753.
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ABSTRACTFlight—defined as the ability to produce useful aerodynamic forces by flapping wings—is one of the most demanding adaptations in vertebrates. The mechanical problems of flight ensure considerable external morphological homogeneity and behavioural similarity in extant fliers. Observations of the vortex wakes and wingbeat geometry of modern birds and bats confirm that the two groups are mechanically very similar, despite differences in phylogeny, anatomy and physiology. With this background it is possible to attack two problems: the evolution of flight in vertebrates, and the flight performance of extinct animals such as pterosaurs and Archaeopteryx.The origin of flight has been surrounded by considerable controversy, due in part to terminological inconsistencies, in part to phylogenetic uncertainty over the relationships of birds, bats and pterosaurs, in part to disagreement over the interpretation of the available fossil evidence, and in part to argument over the relative importance of morphological, mechanical and ecological specialisations. The mechanical changes needed in the course of the evolution of flight favour a gliding origin of tetrapod flight, and on mechanical and ecological grounds the alternative cursorial hypothesis may be discounted. This argument is particularly strong in bats, but has been thought to be weaker in birds owing to apparent inconsistencies with the fossil evidence. However, fossils of the Jurassic theropod dinosaur Archaeopteryx also support a gliding origin for flight, and suggest that this animal was adapted for flapping flight at moderately high speeds associated with gliding; it could fly less well at the slow speeds which would have been required for incipient flight in a running cursor, and at which the wingbeat is aerodynamically and kinematically considerably more complex. Slow flight in birds and bats is the more derived condition, and vertebrate flapping flight apparently evolved through a gliding stage.The pterosaurs have become the subject of much controversy over the nature of their stance, the wing surface, and the degree of involvement of the leg in the wing membrane. Reconstruction of their wings indicates proficient flying animals, and comparison with birds suggests that most pterosaurs probably occupied marine or coastal/estuarine habitat.
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Novacek, Michael J. "The Radiation of Placental Mammals." Short Courses in Paleontology 7 (1994): 220–37. http://dx.doi.org/10.1017/s2475263000001331.
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The placental or eutherian mammals comprise about twenty living orders and several extinct ones. The morphological and adaptive range of this group is extraordinary; diversification has produced lineages as varied as humans and their primate relatives, flying bats, swimming whales, ant-eating anteaters, pangolins and aardvarks, a baroque extravagance of horned, antlered, and trunk-nosed herbivores (ungulates), as well as the supremely diverse rats, mice, beavers and porcupines of the order Rodentia. Such adaptive diversity, and the emergence of thousands of living and fossil species, apparently resulted from a radiation beginning in the late Mesozoic between 65 and 80 million years ago (Novacek, 1990). This explosive radiation (Figure 1) is one of the more intriguing chapters of vertebrate history, and the problem has attracted interest from unusually varied perspectives. As a result, eutherian mammals are known from a rapidly growing molecular database, as well as a wealth of morphological characters and a comparatively enriched fossil record. The interplay of molecular and morphological investigation is more apparent in the case of placental mammals that in any other vertebrates, perhaps more than in any other group of organisms.
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Shyy, Wei, Chang-kwon Kang, Pakpong Chirarattananon, Sridhar Ravi, and Hao Liu. "Aerodynamics, sensing and control of insect-scale flapping-wing flight." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2186 (February 2016): 20150712. http://dx.doi.org/10.1098/rspa.2015.0712.
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There are nearly a million known species of flying insects and 13 000 species of flying warm-blooded vertebrates, including mammals, birds and bats. While in flight, their wings not only move forward relative to the air, they also flap up and down, plunge and sweep, so that both lift and thrust can be generated and balanced, accommodate uncertain surrounding environment, with superior flight stability and dynamics with highly varied speeds and missions. As the size of a flyer is reduced, the wing-to-body mass ratio tends to decrease as well. Furthermore, these flyers use integrated system consisting of wings to generate aerodynamic forces, muscles to move the wings, and sensing and control systems to guide and manoeuvre. In this article, recent advances in insect-scale flapping-wing aerodynamics, flexible wing structures, unsteady flight environment, sensing, stability and control are reviewed with perspective offered. In particular, the special features of the low Reynolds number flyers associated with small sizes, thin and light structures, slow flight with comparable wind gust speeds, bioinspired fabrication of wing structures, neuron-based sensing and adaptive control are highlighted.
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Bahlman, Joseph W., Sharon M. Swartz, Daniel K. Riskin, and Kenneth S. Breuer. "Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels ( Glaucomys sabrinus )." Journal of The Royal Society Interface 10, no. 80 (March 6, 2013): 20120794. http://dx.doi.org/10.1098/rsif.2012.0794.
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Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60–125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels ( Glaucomys sabrinus ) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight.
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López-del-Toro, Paulina, Ellen Andresen, Laura Barraza, and Alejandro Estrada. "Attitudes and Knowledge of Shade-Coffee Farmers Towards Vertebrates and Their Ecological Functions." Tropical Conservation Science 2, no. 3 (September 2009): 299–318. http://dx.doi.org/10.1177/194008290900200303.
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The purpose of this study was to assess farmers' attitudes, as well as perceptions and knowledge that shape those attitudes, toward the ecological role of vertebrates inhabiting shaded-coffee farms. We also aimed to determine whether differences existed among two groups of farmers: one that had attended environmental education workshops, and one that had not. We conducted 36 oral interviews of farmers in the region of Cuetzalan, Mexico. All farmers were members of an important regional cooperative, Tosepan Titataniske. In general, farmers' attitudes towards birds were positive. Snakes were perceived as useful but dangerous animals. Attitudes towards non-flying mammals were mostly indifferent. Bats were poorly understood and badly perceived. Seed dispersal was perceived as an important ecological function performed by animals. Pollination was also perceived as important, but to a lesser degree. Knowledge about ecological functions was high for seed dispersal, and low for pollination. We found a positive correlation between attendance of educational workshops and the presence of “environmentally-friendly” attitudes, perceptions, and knowledge. However, a cause-effect relationship could not be clearly established. We suggest that environmental education programs include the objective of increasing the knowledge of people about the ecological functions played by different groups of animals that live in agroecosystems. Particular efforts should be directed toward improving the way in which certain non-charismatic groups of animals, such as bats, are perceived.
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Chen, Jun, Haichun Zhang, Bo Wang, Xiaoting Zheng, and Xiaoli Wang. "New Jurassic Sinopalaeocossus and related genera with notes on their evolutionary implications (Hemiptera, Palaeontinidae)." Insect Systematics & Evolution 47, no. 2 (May 11, 2016): 113–29. http://dx.doi.org/10.1163/1876312x-47022136.
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SinopalaeocossusHong, 1983 and related genera (Hemiptera, Palaeontinidae) are revised on the basis of newly discovered materials from the Middle Jurassic of Daohugou, northern China. The genusHamicossusWang and Ren, 2007 is considered to be a junior synonym ofSinopalaeocossus, resulting inS. laevis(Wang and Ren, 2007), comb. nov. The new speciesSinopalaeocossus amoenusChen, Zhang and Wang is described based on fore and hindwings. TheSinopalaeocossusand related genera resembleMartynovocossusWang and Zhang, 2008 and were likely derived from the latter. TheSinopalaeocossusand related genera bear high diversity on wing venations. As compared toMartynovocossus, the crossveinm3+4-cuaof hindwing is absent forSynapocossusWang, Shih and Ren, 2013 and certain species ofSinopalaeocossus, and the crossveinr-mof forewing is absent forSynapocossus. The rapid evolution of wing venations is likely due to intense predation pressures of the newly evolved flying and insectivorous vertebrates.
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Aromaa, Suvi, Jaakko J. Ilvonen, and Jukka Suhonen. "Body mass and territorial defence strategy affect the territory size of odonate species." Proceedings of the Royal Society B: Biological Sciences 286, no. 1917 (December 18, 2019): 20192398. http://dx.doi.org/10.1098/rspb.2019.2398.
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The territory is a distinct mating place that a male defends against intruding conspecific males. The size of a territory varies between species and most of the variation between species has been found to scale allometrically with body mass. The variation that could not be explained by body mass has been explained with several variables such as habitat productivity, trophic level, locomotion strategy and thermoregulation. All previous interspecific comparative studies have been done on vertebrate species such as birds, mammals, reptiles and fishes, meaning that studies using invertebrate species are missing. Here, we studied the relationship of a species's territory size with its fresh body mass (FBM) in addition to other ecologically relevant traits using 86 damselfly and dragonfly (Odonata) species. We found that territory size is strongly affected by species FBM, following an allometric relationship similar to vertebrates. We also found that the territory size of a species was affected by its territorial defence strategy, constantly flying species having larger territories than species that mostly perch. Breeding habitat or the presence of sexual characters did not affect territory sizes, but lotic species and species without wing spots had steeper allometric slopes. It seems that an increase in a species’s body mass increases its territory size and may force the species to shift its territory defence strategy from a percher to a flier.
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Upchurch, Paul, Brian Andres, Richard J. Butler, and Paul M. Barrett. "An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates." Historical Biology 27, no. 6 (July 28, 2014): 697–717. http://dx.doi.org/10.1080/08912963.2014.939077.
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Howard, Scarlett R., Aurore Avarguès-Weber, Jair E. Garcia, Andrew D. Greentree, and Adrian G. Dyer. "Numerical cognition in honeybees enables addition and subtraction." Science Advances 5, no. 2 (February 2019): eaav0961. http://dx.doi.org/10.1126/sciadv.aav0961.
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Many animals understand numbers at a basic level for use in essential tasks such as foraging, shoaling, and resource management. However, complex arithmetic operations, such as addition and subtraction, using symbols and/or labeling have only been demonstrated in a limited number of nonhuman vertebrates. We show that honeybees, with a miniature brain, can learn to use blue and yellow as symbolic representations for addition or subtraction. In a free-flying environment, individual bees used this information to solve unfamiliar problems involving adding or subtracting one element from a group of elements. This display of numerosity requires bees to acquire long-term rules and use short-term working memory. Given that honeybees and humans are separated by over 400 million years of evolution, our findings suggest that advanced numerical cognition may be more accessible to nonhuman animals than previously suspected.
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Saffer, V. M. "Are diel patterns of nectar production and anthesis associated with other floral traits in plants visited by potential bird and mammal pollinators?" Australian Journal of Botany 52, no. 1 (2004): 87. http://dx.doi.org/10.1071/bt02056.
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Plants pollinated predominantly by vertebrates are thought to have suites of floral traits (e.g.�colour, conspicuousness, odour) that favour either birds or mammals, with brightly coloured, conspicuous flowers associated with birds and drab, concealed flowers with non-flying mammals. This study examined two other floral traits, diel patterns of nectar production and pollen presentation (anthesis). It would be expected that these would be nocturnal in putatively mammal-pollinated plants and diurnal in bird-pollinated plants. In four Banksia and two Dryandra species, all known to be visited by honeyeater birds and small marsupials at one site in south-western Australia, there was no clear correspondence between visual cues and diel patterns of resource presentation. This lack of correlation between floral traits does not support the idea of specialised pollination syndromes, but rather is consistent with generalised pollination systems.
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MCGOWAN, A. J., and G. J. DYKE. "A morphospace-based test for competitive exclusion among flying vertebrates: did birds, bats and pterosaurs get in each other's space?" Journal of Evolutionary Biology 20, no. 3 (May 2007): 1230–36. http://dx.doi.org/10.1111/j.1420-9101.2006.01285.x.
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Wester, Petra. "First observations of nectar-drinking lizards on the African mainland." Plant Ecology and Evolution 152, no. 1 (March 25, 2019): 78–83. http://dx.doi.org/10.5091/plecevo.2019.1513.
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Background and aims – Pollination of flowers is performed mainly by insects, but also by vertebrates. In South Africa, beside birds, non-flying mammals contribute to pollination. During video surveillance of plants adapted to non-flying mammal pollination, surprisingly, lizards were observed at the flowers. The question was addressed whether the lizards consume nectar and whether they could be potential pollinators of these plants.Methods – Flowering Massonia grandiflora in the Cederberg and Eucomis regia (both Asparagaceae) in Namaqualand of South Africa were monitored with camcorders and camera traps for potential flower visitors. The footage was analysed for the type of floral visitor, foraging behaviour, contact areas of the plants’ reproductive organs on the animals as well as potential pollen transfer between animals and flowers.Key results – The Cape cliff lizard Hemicordylus capensis (Cordylidae) visited the flowers of M. grandiflora and the Namaqua day gecko Rhoptropella ocellata (Gekkonidae) visited E. regia flowers, both licking nectar. Thereby, the lizards touched the reproductive organs of the flowers and got dusted with pollen (at least H. capensis) on the same area of their head.Conclusions – Visitation and pollination of flowers by lizards is a rarely observed phenomenon, especially in continental ecosystems. These are the first observations of lizards drinking floral nectar on the African mainland. As the areas on the animals’ head where pollen got deposited by the flowers’ anthers overlapped with the areas that touched the flowers’ stigma, it is very likely that the lizards contribute to pollination. However, the lizards’ role and importance as pollinators of the small-mammal-pollinated plants have to be proven by further observations and experiments.
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Pedó, Ezequiel, Ana C. Tomazzoni, Sandra M. Hartz, and Alexandre U. Christoff. "Diet of crab-eating fox, Cerdocyon thous (Linnaeus) (Carnivora, Canidae), in a suburban area of southern Brazil." Revista Brasileira de Zoologia 23, no. 3 (September 2006): 637–41. http://dx.doi.org/10.1590/s0101-81752006000300005.
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The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), is a small canid with twilight and nocturnal habits from savannas and forests of South America. In this study, we seasonally determined and quantified the diet of C. thous in Lami Biological Reserve, a conservation unit with 179.78ha situated in a suburban area in the municipality of Porto Alegre, southern Brazil. During the year 2000, we collected 80 fecal samples - 20 for each season - in two or three week sampling intervals, along trails inside the Reserve. Samples were dried in an oven for 24h at 60ºC, immersed in 70% alcohol, and prey items were identified using a stereomicroscope. The diet of the crab-eating fox was essentially carnivorous (87.62% composed by vertebrates), with seasonal variation (p = 0.0009) and absence of fruits. Small non-flying mammals and birds were the most frequent prey, being proportionally more preyed in autumn and summer, respectively. Arthropods were more preyed in winter and spring and bird/reptile eggs only in summer and spring, in the reproduction period of these groups.
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Cooper, William E. "Risk factors and escape strategy in the grasshopper Dissosteira carolina." Behaviour 143, no. 10 (2006): 1201–18. http://dx.doi.org/10.1163/156853906778691595.
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AbstractTo determine aspects of escape strategy by the Carolina grasshopper, Dissosteira carolina, and applicability of models of escape behavior applied primarily to vertebrates, I conducted three field experiments by simulating an approaching predator. Escape theory predicts that flight initiation distance (distance from predator when escape begins) and distance fled increase as predation risk increases. Some aspects of escape are not predicted, and theory does not identify escape strategies including several components. I examined effects of risk factors (predator approach speed, directness of approach, and repeated approach) on flight initiation distance, distance fled, and the initial direction of escape. Flight initiation distance and distance fled were predicted to increase with approach speed. Because predators approaching directly may bypass prey without detecting it, probability of fleeing and flight initiation distance were predicted to increase with directness of approach. Because a persistent predator poses greater threat, flight initiation distance and distance fled were predicted to be greater for the second of two successive approaches. All findings were consistent with predictions of the Ydenberg & Dill (1986) model, suggesting that risk assessment and escape decisions by visually oriented insects may be similar to those of vertebrates. Although escape directly away from the predator might be expected to minimize risk, most grasshoppers escaped by flying at nearly right angles to the approach path. Lateral escape may be part of an escape strategy in which dark wing colour during flight rapidly disappears upon landing. With sudden change in colour and movement, the grasshopper becomes cryptic and difficult to relocate. Lateral escape may increase difficulty of maintaining visual contact with the grasshopper until it lands. It also avoids need for further escape from a predator that continues in its initial direction.
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Hammond, D. S. "Post-dispersal seed and seedling mortality of tropical dry forest trees after shifting agriculture, Chiapas, Mexico." Journal of Tropical Ecology 11, no. 2 (May 1995): 295–313. http://dx.doi.org/10.1017/s0266467400008762.
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ABSTRACTVertebrate attack accounted for 98.4% of all seed loss during the two months following dispersal. This accounted for, across all habitat types, 94% ofBursera, 76% ofSpondias, 37% ofSwieteniaand 25% ofErythrinaseeds artificially dispersed.Bursera, SpondiasandSwieteniaseeds in early successional habitat suffered significantly greater predation than in either older abandoned (30 y) or mature forest plots.Erythrinashowed generally low loss to predation in all plots. Seeds attacked were more often removed from, rather than buried or eaten at, the dispersal site. In young secondary habitats, however, seeds ofBurseraandSpondiaswere more frequently eaten at the site. Seeds dispersed individually rather than in larger aggregations (5, 10) were more likely to survive in mature forest and late secondary habitat. This advantage was lost inBurseraandSwieteniawhen they were dispersed to younger successional habitats.At the early seedling stage, recruitment ofBurseraandSwieteniawas highest in the older secondary habitats. Seedlings ofErythrinashowed the lowest overall losses to any of the mortality factors identified during the first two months of establishment. Seeds of forest tree species arriving in secondary habitat were more vulnerable to attack by non-flying vertebrates than in mature forest. Survival of seedlings of these species was most closely related to the moisture-conserving status of the habitat.
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Chan, Nicholas R. "Morphospaces of functionally analogous traits show ecological separation between birds and pterosaurs." Proceedings of the Royal Society B: Biological Sciences 284, no. 1865 (October 18, 2017): 20171556. http://dx.doi.org/10.1098/rspb.2017.1556.
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Birds originated and radiated in the presence of another group of flying vertebrates, the pterosaurs. Opinion is divided as to whether birds competitively displaced pterosaurs from small-body size niches or whether the two groups coexisted with little competition. Previous studies of Mesozoic birds and pterosaurs compared measurements of homologous limb bones to test these hypotheses. However, these characters probably reflect differing ancestries rather than ecologies. Here, competition and ecological separation were tested for using multivariate analyses of functionally equivalent morphological characters. As well as using characters from the fore- and hindlimbs, these analyses also included measurements of the lower jaw. The results of this study indicate that pterosaurs had relatively longer jaws, shorter metatarsals and shorter brachial regions compared with birds of similar size. Contrary to the results of previous studies, the distal wing was not important for separating the two clades in morphospace owing to the inclusion of the primary feathers in this unit. The differences found here indicate ecological separation based on differences in size, locomotory features and feeding adaptations. Thus, instead of one group displacing the other, birds and pterosaurs appear to have adopted distinctive ecological strategies throughout their period of coexistence.
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Fatma, Araf, Aisha Perveen, Sana Ur Rehman, and Rabia Khan. "Unani Medicine: Significance of Asbab-e-Sitta Zarooriya in times of Pandemic COVID-19." Journal of Drug Delivery and Therapeutics 11, no. 1 (January 15, 2021): 156–61. http://dx.doi.org/10.22270/jddt.v11i1.4636.
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SARS COV-2 belongs to the beta coronavirus genera, it is believed that bats as warm-blooded flying vertebrates are ideal hosts for coronavirus gene source. COVID-19 caused by novel coronavirus was originated from Wuhan city of Hubei Province in China in December 2019. The common symptoms comprise fever, cough, malaise, and shortness of breath. The incubation period is between 2 - 14 days. In this paper we have deliberated the structure of viruses; varying symptoms among COVID-19, SARS, MERS, and approach to tackling this problem with utmost effective Unani alternatives. Unani medicine endeavors to find the best conceivable ways by which a person can lead a hale and hearty life with minimum or zero sicknesses. Unani scholars believe by practicing important things like the use of fresh and clean water, breathing clean air and eating fresh food, upholding a balance between the mind and the body so that the metabolic processes can function effortlessly and the body wastes are evacuated, by enhancing immunity, and keeping an equilibrium between (Asbab-e-Sitta Zarooriya) six essential factors for life one can stay away from diseases.
Keywords: COVID-19, Unani Medicine, SARS COV-2, Asbab-e-Sitta Zarooriya.
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Groom, Derrick J. E., M. Cecilia B. Toledo, Donald R. Powers, Bret W. Tobalske, and Kenneth C. Welch. "Integrating morphology and kinematics in the scaling of hummingbird hovering metabolic rate and efficiency." Proceedings of the Royal Society B: Biological Sciences 285, no. 1873 (February 28, 2018): 20172011. http://dx.doi.org/10.1098/rspb.2017.2011.
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Wing kinematics and morphology are influential upon the aerodynamics of flight. However, there is a lack of studies linking these variables to metabolic costs, particularly in the context of morphological adaptation to body size. Furthermore, the conversion efficiency from chemical energy into movement by the muscles (mechanochemical efficiency) scales with mass in terrestrial quadrupeds, but this scaling relationship has not been demonstrated within flying vertebrates. Positive scaling of efficiency with body size may reduce the metabolic costs of flight for relatively larger species. Here, we assembled a dataset of morphological, kinematic, and metabolic data on hovering hummingbirds to explore the influence of wing morphology, efficiency, and mass on hovering metabolic rate (HMR). We hypothesize that HMR would decline with increasing wing size, after accounting for mass. Furthermore, we hypothesize that efficiency will increase with mass, similarly to other forms of locomotion. We do not find a relationship between relative wing size and HMR, and instead find that the cost of each wingbeat increases hyperallometrically while wingbeat frequency declines with increasing mass. This suggests that increasing wing size is metabolically favourable over cycle frequency with increasing mass. Further benefits are offered to larger hummingbirds owing to the positive scaling of efficiency.
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Berg, K. S., S. Delgado, and A. Mata-Betancourt. "Phylogenetic and kinematic constraints on avian flight signals." Proceedings of the Royal Society B: Biological Sciences 286, no. 1911 (September 18, 2019): 20191083. http://dx.doi.org/10.1098/rspb.2019.1083.
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Many birds vocalize in flight. Because wingbeat and respiratory cycles are often linked in flying vertebrates, birds in these cases must satisfy the respiratory demands of vocal production within the physiological limits imposed by flight. Using acoustic triangulation and high-speed video, we found that avian vocal production in flight exhibits a largely phasic and kinematic relationship with the power stroke. However, the sample of species showed considerable flexibility, especially those from lineages known for vocal plasticity (songbirds, parrots and hummingbirds), prompting a broader phylogenetic analysis. We thus collected data from 150 species across 12 avian orders and examined the links between wingbeat period, flight call duration and body mass. Overall, shorter wingbeat periods, controlling for ancestry and body mass, were correlated with shorter flight call durations. However, species from vocal learner lineages produced flight signals that, on average, exceeded multiple phases of their wingbeat cycle, while vocal non-learners had signal periods that were, on average, closer to the duration of their power stroke. These results raise an interesting question: is partial emancipation from respiratory constraints a necessary step in the evolution of vocal learning or an epiphenomenon? Our current study cannot provide the answer, but it does suggest several avenues for future research.
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Riskin, Daniel K., Attila Bergou, Kenneth S. Breuer, and Sharon M. Swartz. "Upstroke wing flexion and the inertial cost of bat flight." Proceedings of the Royal Society B: Biological Sciences 279, no. 1740 (April 11, 2012): 2945–50. http://dx.doi.org/10.1098/rspb.2012.0346.
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Flying vertebrates change the shapes of their wings during the upstroke, thereby decreasing wing surface area and bringing the wings closer to the body than during downstroke. These, and other wing deformations, might reduce the inertial cost of the upstroke compared with what it would be if the wings remained fully extended. However, wing deformations themselves entail energetic costs that could exceed any inertial energy savings. Using a model that incorporates detailed three-dimensional wing kinematics, we estimated the inertial cost of flapping flight for six bat species spanning a 40-fold range of body masses. We estimate that folding and unfolding comprises roughly 44 per cent of the inertial cost, but that the total inertial cost is only approximately 65 per cent of what it would be if the wing remained extended and rigid throughout the wingbeat cycle. Folding and unfolding occurred mostly during the upstroke; hence, our model suggests inertial cost of the upstroke is not less than that of downstroke. The cost of accelerating the metacarpals and phalanges accounted for around 44 per cent of inertial costs, although those elements constitute only 12 per cent of wing weight. This highlights the energetic benefit afforded to bats by the decreased mineralization of the distal wing bones.
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Marden, J. H., M. R. Wolf, and K. E. Weber. "Aerial performance of Drosophila melanogaster from populations selected for upwind flight ability." Journal of Experimental Biology 200, no. 21 (November 1, 1997): 2747–55. http://dx.doi.org/10.1242/jeb.200.21.2747.
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A computerized system for three-dimensional tracking of large numbers of individual free-flying insects was used to assess the performance of Drosophila melanogaster from populations that had undergone 160 generations of selection for upwind flight ability. Compared with control lines, the selected lines showed significant increases in mean flight velocity, decreases in angular trajectory and a significant change in the interaction between velocity and angular trajectory. Maximal flight velocity was apparent as a sharply defined upper boundary of the distribution of horizontal and vertical velocity as a function of angular trajectory; this upper bound (0.85 ms-1) differed little between the selected and control lines, although individuals from the selected lines attained maximal performance levels much more frequently. Maximum induced power output was calculated directly from the product of maximum vertical velocity and body weight. This measure (28 W kg-1 muscle) was closely predicted by a scaling relationship derived from the load-lifting limits of larger insects and vertebrates, as well as tethered D. melanogaster stimulated via their optomotor reflex to produce maximal lift. These results indicate that selection for flight performance can readily alter the relative effort and/or the frequency of phenotypes capable of attaining population-wise maximal performance levels, but shows little ability to increase population-wise maximal performance.
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Butler, Richard J., Paul M. Barrett, Stephen Nowbath, and Paul Upchurch. "Estimating the effects of sampling biases on pterosaur diversity patterns: implications for hypotheses of bird/pterosaur competitive replacement." Paleobiology 35, no. 3 (2009): 432–46. http://dx.doi.org/10.1666/0094-8373-35.3.432.
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Pterosaurs were the first flying vertebrates and formed important components of terrestrial and marginal marine ecosystems during the Mesozoic. They became extinct during the latest Cretaceous (latest Maastrichtian), at, or near, the Cretaceous/Paleogene boundary, following an apparent decline in diversity in the Late Cretaceous. This reduction in species richness has been linked to the ecological radiation of birds in the Early Cretaceous and the proposal that birds competitively excluded pterosaurs from many key niches. However, although competition is often posited as a causal mechanism for many of the clade-clade replacements observed in the fossil record, these hypotheses are rarely tested. Here we present a detailed examination of pterosaur diversity through time, including both taxic and phylogenetically corrected diversity estimates and comparison of these estimates with a model describing temporal variation in the number of pterosaur-bearing formations (a proxy for rock availability). Both taxic and phylogenetic diversity curves are strongly correlated with numbers of pterosaur-bearing formations, suggesting that a significant part of the signal contained within pterosaur diversity patterns may be controlled by geological and taphonomic megabiases rather than macroevolutionary processes. There is no evidence for a long-term decline in pterosaur diversity through the Cretaceous, although a reduction in morphological, ecological, and phylogenetic diversity does appear to have occurred in the latest Cretaceous. Competitive replacement of pterosaurs by birds is difficult to support on the basis of diversity patterns.
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Ducci, L., F. Roscioni, M. L. Carranza, P. Agnelli, D. Russo, L. Frate, A. Loy, G. Santini, and M. Di Febbraro. "The role of protected areas in preserving habitat and functional connectivity for mobile flying vertebrates: the common noctule bat (Nyctalus noctula) in Tuscany (Italy) as a case study." Biodiversity and Conservation 28, no. 6 (March 15, 2019): 1569–92. http://dx.doi.org/10.1007/s10531-019-01744-5.
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Bockhorst, Tobias, and Uwe Homberg. "Amplitude and dynamics of polarization-plane signaling in the central complex of the locust brain." Journal of Neurophysiology 113, no. 9 (May 2015): 3291–311. http://dx.doi.org/10.1152/jn.00742.2014.
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The polarization pattern of skylight provides a compass cue that various insect species use for allocentric orientation. In the desert locust, Schistocerca gregaria, a network of neurons tuned to the electric field vector ( E-vector) angle of polarized light is present in the central complex of the brain. Preferred E-vector angles vary along slices of neuropils in a compasslike fashion (polarotopy). We studied how the activity in this polarotopic population is modulated in ways suited to control compass-guided locomotion. To this end, we analyzed tuning profiles using measures of correlation between spike rate and E-vector angle and, furthermore, tested for adaptation to stationary angles. The results suggest that the polarotopy is stabilized by antagonistic integration across neurons with opponent tuning. Downstream to the input stage of the network, responses to stationary E-vector angles adapted quickly, which may correlate with a tendency to steer a steady course previously observed in tethered flying locusts. By contrast, rotating E-vectors corresponding to changes in heading direction under a natural sky elicited nonadapting responses. However, response amplitudes were particularly variable at the output stage, covarying with the level of ongoing activity. Moreover, the responses to rotating E-vector angles depended on the direction of rotation in an anticipatory manner. Our observations support a view of the central complex as a substrate of higher-stage processing that could assign contextual meaning to sensory input for motor control in goal-driven behaviors. Parallels to higher-stage processing of sensory information in vertebrates are discussed.