Grčki bogovi u Indiji: umjetnost Gandhare

Rates of aerobic metabolism vary considerably across evolutionary lineages, but little is known about the proximate and ultimate factors that generate and maintain this variability. Using data for 131 teleost fish species, we performed a large-scale phylogenetic comparative analysis of how interspecific variation in resting and maximum metabolic rates (RMR and MMR, respectively) is related to several ecological and morphological variables. Mass- and temperature-adjusted RMR and MMR are highly correlated along a continuum spanning a 30- to 40-fold range. Phylogenetic generalized least squares models suggest RMR and MMR are higher in pelagic species and that species with higher trophic levels exhibit elevated MMR. This variation is mirrored at various levels of structural organization: gill surface area, muscle protein content, and caudal fin aspect ratio (a proxy for activity) are positively related with aerobic capacity. Muscle protein content and caudal fin aspect ratio are also positively correlated with RMR. Hypoxia-tolerant lineages fall at the lower end of the metabolic continuum. Different ecological lifestyles are associated with contrasting levels of aerobic capacity, possibly reflecting the interplay between selection for increased locomotor performance on one hand and tolerance to low resource availability, particularly oxygen, on the other. These results support the aerobic capacity model of the evolution of endothermy, suggesting elevated body temperatures evolved as correlated responses to selection for high activity levels

Effect of walking speed on the gait of king penguins:An accelerometric approach

International audienceLittle isknownaboutnon-humanbipedalgaits.Thisisprobablyduetothefactthatmostlargeanimalsare quadrupedalandthatnon-humanbipedalanimalsaremostlybirds,whoseprimaryformofloco-motion is flight. Verylittleresearchhasbeenconductedonpenguinpedestrianlocomotionwiththefocus insteadontheirassociatedhighenergyexpenditure.Inanimals,tri-axialaccelerometersarefre-quentlyusedtoestimatephysiologicalenergycost,aswellastodefine thebehaviourpatternofaspecies,or thekinematicsofswimming.Inthisstudy,weshowedhowanaccelerometer-basedtechniquecouldbe usedtodeterminethebiomechanicalcharacteristicsofpedestrianlocomotion.Eightkingpenguins,which representtheonlyfamilyofbirdstohaveanuprightbipedalgait,weretrainedtowalkonatreadmill. Thetrunktri-axialaccelerationswererecordedwhilethebirdwaswalkingatfourdifferentspeeds (1.0,1.2,1.4and1.6km/h),enablingtheamplitudeofdynamicbodyaccelerationalongthethreeaxes(amplitudeofDBAx, DBAy and DBAz), stridefrequency,waddlingandleaningamplitude,aswellasthe leaningangletobedefined. Themagnitudeofthemeasuredvariablesshowedasignificant increasewith increasingspeed,apartfromthebackwardsangleoflean,whichdecreasedwithincreasingspeed.The variabilityofthemeasuredvariablesalsoshowedasignificant increasewithspeedapartfromtheDBAz amplitude, thewaddlingamplitude,andtheleaningangle,wherenosignificant effectofthewalkingspeedwasfound.Thispaperisthe first approachtodescribe3Dbiomechanicswithanaccel-erometeronwildanimals,demonstratingthepotentialofthistechnique

Fat King Penguins Are Less Steady on Their Feet

Returning to the shore after a feeding sojourn at sea, king penguins often undertake a relatively long terrestrial journey to the breeding colony carrying a heavy, mostly frontal, accumulation of fat along with food in the stomach for chick-provisioning. There they must survive a fasting period of up to a month in duration, during which their complete reliance on endogenous energy stores results in a dramatic loss in body mass. Our aim was to determine if the king penguin's walking gait changes with variations in body mass. We investigated this by walking king penguins on a treadmill while instrumented with an acceleration data logger. The stride frequency, dynamic body acceleration (DBA) and posture of fat (pre-fasting; 13.2 kg) and slim (post fasting; 11 kg) king penguins were assessed while they walked at the same speed (1.4 km/h) on a treadmill. Paired statistical tests indicated no evidence for a difference in dynamic body acceleration or stride frequency between the two body masses however there was substantially less variability in both leaning angle and the leaning amplitude of the body when the birds were slimmer. Furthermore, there was some evidence that the slimmer birds exhibited a decrease in waddling amplitude. We suggest the increase in variability of both leaning angle and amplitude, as well as a possibly greater variability in the waddling amplitude, is likely to result from the frontal fat accumulation when the birds are heavier, which may move the centre of mass anteriorly, resulting in a less stable upright posture. This study is the first to use accelerometry to better understand the gait of a species within a specific ecological context: the considerable body mass change exhibited by king penguins

pamlr : A toolbox for analysing animal behaviour using pressure, acceleration, temperature, magnetic or light data in R

Light-level geolocators have revolutionised the study of animal behaviour. However, lacking spatial precision, their usage has been primary targeted towards the analysis of large-scale movements. Recent technological developments have allowed the integration of magnetometers and accelerometers into geolocator tags in addition to barometers and thermometers, offering new behavioural insights. Here, we introduce an R toolbox for identifying behavioural patterns from multisensor geolocator tags, with functions specifically designed for data visualisation, calibration, classification and error estimation. More specifically, the package allows for the flexible analysis of any combination of sensor data using k-means clustering, expectation maximisation binary clustering, hidden Markov models and changepoint analyses. Furthermore, the package integrates tailored algorithms for identifying periods of prolonged high activity (most commonly used for identifying migratory flapping flight), and pressure changes (most commonly used for identifying dive or flight events). Finally, we highlight some of the limitations, implications and opportunities of using these methods.publishe

A. Example of dynamic body acceleration (DBA) data in three axes for a king penguin walking during 15 seconds. B. The DBA data for the z axis over three seconds of the same data set.

<p>Open circles represent maximum values and closed circles indicate minimum values identified by an automated, custom-written program. These maxima represent the initial contact of one of the king penguin’s feet with the ground. The dashed lines indicate the calculations of DBA amplitude based on these maximum and minimum values. <b>Right:</b> Visual representation of the DBA axes and angle movements (Modified from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0147784#pone.0147784.ref016" target="_blank">16</a>])</p

Reassessment of the cardio-respiratory stress response, using the king penguin as a model

International audienceResearch in to short-term cardio-respiratory changes in animais in reaction to a psychologicalstressor typically describes increases in rate of oxygen consumption (Vo,) and heart rate.Consequently, the broad consensus is that they represent a fundamental stressor responsegeneralizable across adult species. However, movement levels can also change in the presenceof a stressor, yet studies have not accounted for this possible confound on heart rate. Thus thedirect effects of psychological stressors on the cardio-respiratory system are not resolved. Weused an innovative experimental design employing accelerometers attached to king penguins(Aptenodytes patagonicus) to measure and thus account for mavement levels in a sedentary yetfree-ta-mave animal model during a repeated measures stress experiment. As with previousstudies on other species, incubating king penguins (N = 6) exhibited significant increases inboth Va, and heart rate when exposed ta the stressor. Hawever, mavement levels, while stilllaw, also increased in respanse ta the stressar. Once this was accaunted for by camparingperiads oftime during the control and stress conditions when movement levels were similar asrecorded by the accelerometers, only Va, significantly increased; there was no change in heartrate. These findings offer evidence that changing movement levels have an important effect onthe measured stress response and that the cardia-respiratary respanse per se ta a psycholog icalstressor (Le. the respanse as a result of physialagical changes directly attributable to thestressar) is an increase in Vo, withaut an increase in heart rate