scholarly journals Only the good die old? Ontogenetic determinants of locomotor performance in Eastern cottontail rabbits (Sylvilagus floridanus)

2022 ◽  
Author(s):  
Jesse W Young ◽  
Adam D Foster ◽  
Gabrielle A Russo ◽  
Gregory A Smith ◽  
Michael T Butcher
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Reproductive Potential ◽  
Power Production ◽  
Mechanical Power ◽  
Locomotor Performance ◽  
Sylvilagus Floridanus ◽  
Juvenile Period ◽  
In The Wild ◽  
Escape Speed

Abstract For many animals, the juvenile stage of life can be particularly perilous. Once independent, immature animals must often complete the same basic survival functions as adults despite smaller body size and other growth-related limits on performance. Because, by definition, juveniles have yet to reproduce, we should expect strong selection for mechanisms to offset these ontogenetic limitations, allowing individuals to reach reproductive adulthood and maintain Darwinian fitness. We use an integrated ontogenetic dataset on morphology, locomotor performance, and longevity in wild cottontail rabbits (Sylvilagus floridanus, Allen 1848) to test the hypothesis that prey animals are under selective pressure to maximize juvenile performance. We predicted that 1) juveniles would accelerate more quickly than adults, allowing them to reach adult-like escape speeds, and 2) juveniles with greater levels of performance should survive for longer durations in the wild, thus increasing their reproductive potential. Using high speed video and force platform measurements, we quantified burst acceleration, escape speed, and mechanical power production in 42 wild-caught S. floridanus (29 juveniles, 13 adults; all rabbits >1kg in body mass were designated to be adults, based on published growth curves and evidence of epiphyseal fusion). A subsample of 22 rabbits (16 juveniles, 6 adults) were fitted with radio-telemetry collars for documenting survivorship in the wild. We found that acceleration and escape speed peaked in the late juvenile period in S. floridanus, at an age range that coincides with a period of pronounced demographic attrition in wild populations. Differences in mass-specific mechanical power production explained ∼75% of the variation in acceleration across the dataset, indicating that juvenile rabbits outpace adults by producing more power per unit body mass. We found a positive, though non-significant, association between peak escape speed and survivorship duration in the wild, suggesting a complex relationship between locomotor performance and fitness in growing S. floridanus.

Influence of Attached Masses on Impact Forces and Running Style in Heel-Toe Running

1987 ◽  
Vol 3 (3) ◽  
pp. 264-275 ◽  
Author(s):  
Alexander Bahlsen ◽  
Benno M. Nigg
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Impact Force ◽  
Force Plate ◽  
The Body ◽  
Additional Mass ◽  
Impact Forces ◽  
Running Shoes ◽  
High Speed Film ◽  
Vertical Impact

Impact forces analysis in heel-toe running is often used to examine the reduction of impact forces for different running shoes and/or running techniques. Body mass is reported to be a dominant predictor of vertical impact force peaks. However, it is not evident whether this finding is only true for the real body mass or whether it is also true for additional masses attached to the body (e.g., running with additional weight or heavy shoes). The purpose of this study was to determine the effect of additional mass on vertical impact force peaks and running style. Nineteen subjects (9 males, 10 females) with a mean mass of 74.2 kg/56.2 kg (SD = 10.0 kg and 6.0 kg) volunteered to participate in this study. Additional masses were attached to the shoe (.05 and .1 kg), the tibia (.2, .4, .6 kg), and the hip (5.9 and 10.7 kg). Force plate measurements and high-speed film data were analyzed. In this study the vertical impact force peaks, Fzi, were not affected by additional masses, the vertical active force peaks, Fza, were only affected by additional masses greater than 6 kg, and the movement was only different in the knee angle at touchdown, ϵ0, for additional masses greater than .6 kg. The results of this study did not support findings reported earlier in the literature that body mass is a dominant predictor of external vertical impact force peaks.

scholarly journals Consequences of load carrying by birds during short flights are found to be behavioral and not energetic

2002 ◽  
Vol 283 (1) ◽  
pp. R249-R256 ◽  
Author(s):  
Robert L. Nudds ◽  
David M. Bryant
Keyword(s):  
Body Mass ◽  
Power Input ◽  
Mechanical Power ◽  
Zebra Finches ◽  
Mass Loading ◽  
Metabolic Power ◽  
Additional Mass ◽  
Reduced Body ◽  
Mechanical Power Output ◽  
Load Carrying

The doubly-labeled water technique and video were used to measure the effect of mass loading on energy expenditure and takeoff performance in zebra finches, Taeniopygia guttata, that were making routine (nonalarm) short flights. Finches that carried 27% additional mass did not expend more energy during flight than unloaded controls. Carrying additional mass, however, led to a reduced body mass and a decreased velocity during takeoffs (by 12%). Calculations of instantaneous mechanical power indicated that energy expended by unloaded and loaded finches at takeoff was similar, due to the observed decrease in velocity by mass-loaded finches and a lowering of their body mass. During routine short flights, zebra finches appear to maintain their metabolic power input and mechanical power output regardless of mass loading. Here, the costs of carrying additional mass during routine short flights were revealed to be behavioral and not energetic.

scholarly journals On the emergence of large clusters of acoustic power sources at the onset of thermoacoustic instability in a turbulent combustor

2019 ◽  
Vol 874 ◽  
pp. 455-482 ◽  
Author(s):  
Abin Krishnan ◽  
R. I. Sujith ◽  
Norbert Marwan ◽  
Jürgen Kurths
Keyword(s):  
High Speed ◽  
Power Production ◽  
Acoustic Power ◽  
Spatiotemporal Dynamics ◽  
Combustion Noise ◽  
Pressure Oscillations ◽  
Power Sources ◽  
Thermoacoustic Instability ◽  
Stable Combustion ◽  
Large Clusters

In turbulent combustors, the transition from stable combustion (i.e. combustion noise) to thermoacoustic instability occurs via intermittency. During stable combustion, the acoustic power production happens in a spatially incoherent manner. In contrast, during thermoacoustic instability, the acoustic power production happens in a spatially coherent manner. In the present study, we investigate the spatiotemporal dynamics of acoustic power sources during the intermittency route to thermoacoustic instability using complex network theory. To that end, we perform simultaneous acoustic pressure measurement, high-speed chemiluminescence imaging and particle image velocimetry in a backward-facing step combustor with a bluff body stabilized flame at different equivalence ratios. We examine the spatiotemporal dynamics of acoustic power sources by constructing time-varying spatial networks during the different dynamical states of combustor operation. We show that as the turbulent combustor transits from combustion noise to thermoacoustic instability via intermittency, small fragments of acoustic power sources, observed during combustion noise, nucleate, coalesce and grow in size to form large clusters at the onset of thermoacoustic instability. This nucleation, coalescence and growth of small clusters of acoustic power sources occurs during the growth of pressure oscillations during intermittency. In contrast, during the decay of pressure oscillations during intermittency, these large clusters of acoustic power sources disintegrate into small ones. We use network measures such as the link density, the number of components and the size of the largest component to quantify the spatiotemporal dynamics of acoustic power sources as the turbulent combustor transits from combustion noise to thermoacoustic instability via intermittency.

scholarly journals Mechanical power production assessment during weightlifting exercises. A systematic review

2020 ◽  
pp. 1-27
Author(s):  
Marcos A. Soriano ◽  
Kristof Kipp ◽  
Jason P. Lake ◽  
Timothy J. Suchomel ◽  
Pedro J. Marín ◽  
...  
Keyword(s):  
Systematic Review ◽  
Power Production ◽  
Mechanical Power

THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF PAPAYA (CARICA PAPAYA L.): A REVIEW

2013 ◽  
Vol 50 (2) ◽  
pp. 270-283 ◽  
Author(s):  
M. K. V. CARR
Keyword(s):  
Water Relations ◽  
Time Lag ◽  
Crop Coefficient ◽  
Juvenile Period ◽  
Abaxial Leaf Surface ◽  
Tropical America ◽  
In The Wild ◽  
High Yields ◽  
The Tropics ◽  
Changing Light

SUMMARYPapaya has never been found in the wild, but is believed to have originated in tropical America from where it has spread throughout the tropics and subtropics. This fruit crop is particularly important in India and Brazil. Most research on the water relations of papaya has been undertaken in Brazil and on the island of Guam (United States of America). Papaya is a short-lived large herb, growing to a height of up to 10 m. Leaves emerge from the upper part of the unbranched stem. After a juvenile period, lasting for about two months, flowers begin to develop in leaf axils. Flowering continues throughout the year as new leaves emerge. The plants, which are dioecious, begin to bear fruit within a year after planting, sustaining high yields for two years before yields decline. The ‘effective’ root depth varies with the method of irrigation, but can reach 0.55 m. The seedlings and the trees are susceptible to wind damage, a topic that has been well researched. Stomata are only found on the abaxial leaf surface. They are sensitive to changes in the saturation deficit of the air. Stomata also respond quickly to changing light conditions. On clear days, midday suppression of photosynthesis occurs as a result of partial closure of the stomata. In the morning, there is a time lag between water loss by transpiration and sap flow, as water is taken from storage in the hollow stem. Few attempts have been made to measure the actual water use of papaya, and there are no reliable published values for the crop coefficient. Limitations to the design of the papaya irrigation experiments reported so far make it difficult to reconcile the results in practical ways. Water productivities equivalent to 1.8 to 2.8 kg (fresh fruit) m−3 (irrigation water) have been obtained. Although papaya is generally considered to be drought sensitive and responsive to irrigation, there is a shortage of good experimental evidence to support this view. There is a need to establish practical irrigation schedules for this remarkable crop. A uniformity of approach to irrigation experimentation and a common, universally agreed nomenclature would facilitate this process.

Force, Reaction Time, and Precision of Kung Fu Strikes

2009 ◽  
Vol 109 (1) ◽  
pp. 295-303 ◽  
Author(s):  
Osmar Pinto Neto ◽  
Marcos Tadeu Tavares Pacheco ◽  
Richard Bolander ◽  
Cynthia Bir
Keyword(s):  
Reaction Time ◽  
Body Mass ◽  
Pressure Sensor ◽  
Martial Arts ◽  
High Speed ◽  
Load Cell ◽  
Men And Women ◽  
Kung Fu ◽  
Force Reaction ◽  
Force Data

The goal was to compare values of force, precision, and reaction time of several martial arts punches and palm strikes performed by advanced and intermediate Kung Fu practitioners, both men and women. 13 Kung Fu practitioners, 10 men and three women, participated. Only the men, three advanced and seven intermediate, were considered for comparisons between levels. Reaction time values were obtained using two high speed cameras that recorded each strike at 2500 Hz. Force of impact was measured by a load cell. For comparisons of groups, force data were normalized by participant's body mass and height. Precision of the strikes was determined by a high speed pressure sensor. The results show that palm strikes were stronger than punches. Women in the study presented, on average, lower values of reaction time and force but higher values of precision than men. Advanced participants presented higher forces than intermediate participants. Significant negative correlations between the values of force and precision and the values of force and reaction time were also found.

Reactions of reproductively photoresponsive versus unresponsive meadow voles to simulated winter conditions

1995 ◽  
Vol 73 (8) ◽  
pp. 1479-1488 ◽  
Author(s):  
F. H. Bronson ◽  
M. C. Kerbeshian
Keyword(s):  
Body Mass ◽  
Reproductive Potential ◽  
Day Length ◽  
Ambient Conditions ◽  
Meadow Voles ◽  
Winter Condition ◽  
Winter Conditions ◽  
Extreme Phenotypes ◽  
Harsh Conditions

At least some populations of meadow voles (Microtus pennsylvanicus) comprise individuals that vary greatly in the degree to which their reproduction can be controlled by day length. Some individuals respond to the short days of winter with complete gonadal inhibition, others are insensitive to this cue and thus have the capacity to reproduce opportunistically during the winter, and still others are intermediate in their responsiveness. The relative costs and benefits associated with some of the nonreproductive dimensions of these different strategies are explored. The two extreme phenotypes, reproductively photoresponsive and unresponsive individuals, were exposed in the laboratory to winter versus summer conditions, as defined by photoperiod, temperature, and quality of diet. This was done in cages that required the voles to leave their nests and subject themselves to ambient conditions in order to feed. The winter condition exerted a potent influence on body mass, body fat, food intake, nest building, pelage depth, and the amount and temporal pattern of feeding, as well as reproductive potential. The results suggest that the major nonreproductive advantage enjoyed by the photoregulated phenotype is a decrease in body mass and hence a decrease in required foraging time that anticipates harsh winter conditions. The opportunists also may lose mass in response to harsh conditions, but this is a direct and immediate response for which they may be poorly prepared.

scholarly journals Comparative three-dimensional kinematics of the hindlimb for high-speed bipedal and quadrupedal locomotion of lizards

1999 ◽  
Vol 202 (9) ◽  
pp. 1047-1065 ◽  
Author(s):  
D.J. Irschick ◽  
B.C. Jayne
Keyword(s):  
Morphological Variation ◽  
High Speed ◽  
Three Dimensional ◽  
Distinct Species ◽  
Model Organisms ◽  
Locomotor Performance ◽  
Lizard Species ◽  
Quadrupedal Locomotion ◽  
Foot Posture ◽  
Sprinting Speed

Although lizards have been model organisms for testing locomotor performance and in ecomorphological studies, the limb movements of lizards during high-speed locomotion are poorly understood. Thus, we quantified the three-dimensional kinematics of the hindlimb, body and tail for five morphologically distinct species of lizard during steady-speed locomotion near maximum sprinting speed (2–5 m s-1). The kinematics of different species had little multivariate overlap. More than half of the strides of all species had digitigrade foot posture, but the frequency of using digitigrade foot posture varied among species. The combination of digitigrade foot posture and large foot size of the lizards contributed substantially to the high values of hip height. For each species, different suites of kinematic variables distinguished bipedal from quadrupedal strides. Interspecific morphological variation did not correspond globally to variation in kinematics, although lizard species with elongated hindlimbs took longer strides than species with shorter hindlimbs. The Froude numbers and relative stride lengths of all lizards running near maximal speeds were large compared with those reported previously for other vertebrates.

Negative effects of parasitic lung nematodes on the fitness of a Neotropical toad (Rhinella horribilis)

Parasitology ◽  
2019 ◽  
Vol 146 (07) ◽  
pp. 928-936 ◽  
Author(s):  
Crystal Kelehear ◽  
Kristin Saltonstall ◽  
Mark E. Torchin
Keyword(s):  
Molecular Data ◽  
Amphibian Declines ◽  
Locomotor Performance ◽  
Negative Effects ◽  
Common Toad ◽  
Intensity Of Infection ◽  
Mean Intensity ◽  
In The Wild ◽  
Dose Dependent ◽  
Rhabdias Pseudosphaerocephala

AbstractPathogens are increasingly implicated in amphibian declines but less is known about parasites and the role they play. We focused on a genus of nematodes (Rhabdias) that is widespread in amphibians and examined their genetic diversity, abundance (prevalence and intensity), and impact in a common toad (Rhinella horribilis) in Panama. Our molecular data show that toads were infected by at least four lineages of Rhabdias, most likely Rhabdias pseudosphaerocephala, and multiple lineages were present in the same geographic locality, the same host and even the same lung. Mean prevalence of infection per site was 63% and mean intensity of infection was 31 worms. There was a significant effect of host size on infection status in the wild: larger toads were more likely to be infected than were smaller conspecifics. Our experimental infections showed that toadlets that were penetrated by many infective Rhabdias larvae grew less than those who were penetrated by few larvae. Exposure to Rhabdias reduced toadlet locomotor performance (both sustained speed and endurance) but did not influence toadlet survival. The effects of Rhabdias infection on their host appear to be primarily sublethal, however, dose-dependent reduction in growth and an overall impaired locomotor performance still represents a significant reduction in host fitness.

scholarly journals Phylogenetic and kinematic constraints on avian flight signals

2019 ◽  
Vol 286 (1911) ◽  
pp. 20191083
Author(s):  
K. S. Berg ◽  
S. Delgado ◽  
A. Mata-Betancourt
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Vocal Learning ◽  
Power Stroke ◽  
Future Research ◽  
Vocal Production ◽  
Vocal Plasticity ◽  
Avian Flight ◽  
Physiological Limits ◽  
Kinematic Relationship

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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