scholarly journals Solving post-prandial reduction in performance by adaptive regurgitation in a freshwater fish

2020 ◽  
Vol 287 (1938) ◽  
pp. 20202172
Author(s):  
Jian Zhao ◽  
Yanci Wen ◽  
Songming Zhu ◽  
Jinyun Ye ◽  
Junjie Zhu ◽  
...  
Keyword(s):  
Food Intake ◽  
Imperfect Information ◽  
A Posteriori ◽  
Escape Performance ◽  
Turning Angle ◽  
Trade Off ◽  
Black Carp ◽  
Extra Food ◽  
Future Risk ◽  
Novel Strategy

Foraging animals must balance benefits of food acquisition with costs induced by a post-prandial reduction in performance. Eating to satiation can lead to a reduction in locomotor and escape performance, which increases risk should a threat subsequently arises, but limiting feeding behaviour may be maladaptive if food intake is unnecessarily reduced in the prediction of threats that do not arise. The efficacy of the trade-off between continued and interrupted feeding therefore relies on information about the future risk, which is imperfect. Here, we find that black carp ( Mylopharyngodon piceus ) can balance this trade-off using an a posteriori strategy; by eating to satiation but regurgitating already ingested food when a threat arises. While degrees of satiation (DS) equal to or greater than 60% reduce elements of escape performance (turning angle, angular velocity, distance moved, linear velocity), at 40% DS or lower, performance in these tasks approaches levels comparable to that at 0% satiation. After experiencing a chasing event, we find that fish are able to regurgitate already ingested food, thereby changing the amount of food in their gastrointestinal tract to consistent levels that maintain high escape performance. Remarkably, regurgitation results in degrees of satiation between 40 and 60% DS, regardless of whether they had previously fed to 40, 60 or 100% DS. Using this response, fish are able to maximize food intake, but regurgitate extra food to maintain escape performance when they encounter a threat. This novel strategy may be effective for continual grazers and species with imperfect information about the level of threat in their environment.

scholarly journals Effects of thyroid status on insulin-like growth factor-I, growth hormone and insulin are modified by food intake

1998 ◽  
pp. 95-103 ◽  
Author(s):  
A Morovat ◽  
MJ Dauncey
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Food Intake ◽  
Insulin Like Growth Factor ◽  
Thyroid Status ◽  
Insulin Levels ◽  
Factor I ◽  
Igf I ◽  
Extra Food ◽  
Growth Factor I

Understanding the interactions between metabolic signals that regulate insulin-like growth factor-I (IGF-I) is crucial to a recognition of mechanisms that control mammalian growth. Thyroid hormones (THs) are essential for normal growth and development, and it has been suggested previously that they can modify circulating IGF-I concentrations. However, the fact that THs influence food intake, which can itself affect plasma IGF-I levels, has been ignored in previous studies. We have therefore investigated the effects of thyroid status on plasma IGF-I under conditions of controlled food intake in young growing pigs. Circulating IGF-I, growth hormone (GH) and insulin levels, were studied in hypo- and hyperthyroid animals on the same level of food intake as euthyroid controls. In addition, a separate group of hyperthyroid animals was given double the amount of food, in order to assess the influence of increased food intake, as would occur naturally in the hyperthyroid state. Hypothyroid animals and hyperthyroids with extra food had the greatest increase in body weight over the 3 weeks of treatment. These two groups had significantly higher circulating IGF-I and insulin concentrations than either the euthyroid or hyperthyroid animals on the same food intake. Integration of GH concentrations from samples taken every 20 min over a 9 h period showed that, by contrast with IGF-I and insulin levels, GH levels were significantly lower in hypothyroids and hyperthyroids on extra food compared with the euthyroids and the hyperthyroids on the same food intake. We conclude that the effects of thyroid status on IGF-I are mediated in part by the effects that THs have on energy balance, and that nutritional signals are capable of modifying the influence of thyroid status per se on circulating IGF-I concentrations.

Changes in ‘extra’ food intake among Australian children between 1995 and 2007

2011 ◽  
Vol 5 (1) ◽  
pp. e55-e63 ◽  
Author(s):  
Anna M. Rangan ◽  
Janis Kwan ◽  
Victoria M. Flood ◽  
Jimmy Chun Yu Louie ◽  
Timothy P. Gill
Keyword(s):  
Food Intake ◽  
Extra Food

The scent of stress: Pintado catfish differentially respond to chemical cues from stressed conspecifics

Behaviour ◽  
2012 ◽  
Vol 149 (9) ◽  
pp. 941-951 ◽  
Author(s):  
Percília C. Giaquinto ◽  
Anette Hoffmann
Keyword(s):  
Food Intake ◽  
Predator Avoidance ◽  
Chemical Cues ◽  
Stress Condition ◽  
Stress Conditions ◽  
Food Ingestion ◽  
Trade Off ◽  
Confinement Stress ◽  
Predator Stress

We examined whether pintado catfish (Pseudoplatystoma corruscans) can discriminate between scents of non-injured conspecifics stressed by a predator or by confinement and how fish use this information in the trade-off between feeding and predator avoidance. In the confinement stress condition, fish ingested the food, whereas in the predator stress condition, fish did not eat. This finding and comparisons of the latency to food ingestion and the time spent swimming between the confinement and predator-stress conditions indicated that pintado catfish can discriminate between conspecifics stressed by a predator or confinement using chemical cues, and use this information for adjusting the trade-off between food intake and predator avoidance.

A Semantic Conception of Truthmaking

Aboutness ◽  
2014 ◽  
Author(s):  
Stephen Yablo
Keyword(s):  
The Other ◽  
Formal Models ◽  
A Posteriori ◽  
Trade Off ◽  
Semantic Conception ◽  
Alfred Tarski ◽  
First Approximation ◽  
The World ◽  
Metaphysical Notion ◽  
David Armstrong

Truth for Aristotle was a metaphysical notion. Alfred Tarski showed how to conceive truth semantically, that is, in such a way that it could play a foundational role in semantics. David Armstrong, the Aristotle of truthmaking, conceives it metaphysically, as the a posteriori necessitation of truths by “things in the world.” This chapter, in a Tarskian spirit, seeks a semantic conception of truthmakers. It suggests two formal models, the recursive and the reductive. They represent tendencies in truthmaker assignment that pull, at times, in different directions. Where one can be indulged at no cost to the other, as in the case of quantifiers, that is the way to go. Otherwise a compromise has to be struck. How the tendencies trade off depends on the application. To a first approximation, though, semantic truthmakers are facts that imply truths and proportionally explain them.

scholarly journals Productive fitness in diversity-aware evolutionary algorithms

2021 ◽  
Author(s):  
Thomas Gabor ◽  
Thomy Phan ◽  
Claudia Linnhoff-Popien
Keyword(s):  
Evolutionary Algorithms ◽  
Evolutionary Process ◽  
Evolutionary Optimization ◽  
Optimization Process ◽  
A Posteriori ◽  
Evolutionary Path ◽  
Trade Off ◽  
Exploration Exploitation ◽  
Insight Into ◽  
The Ideal

AbstractIn evolutionary algorithms, the notion of diversity has been adopted from biology and is used to describe the distribution of a population of solution candidates. While it has been known that maintaining a reasonable amount of diversity often benefits the overall result of the evolutionary optimization process by adjusting the exploration/exploitation trade-off, little has been known about what diversity is optimal. We introduce the notion of productive fitness based on the effect that a specific solution candidate has some generations down the evolutionary path. We derive the notion of final productive fitness, which is the ideal target fitness for any evolutionary process. Although it is inefficient to compute, we show empirically that it allows for an a posteriori analysis of how well a given evolutionary optimization process hit the ideal exploration/exploitation trade-off, providing insight into why diversity-aware evolutionary optimization often performs better.

Anabolic effects of testosterone are preserved during inhibition of 5α-reductase

2007 ◽  
Vol 293 (2) ◽  
pp. E507-E514 ◽  
Author(s):  
Stephen E. Borst ◽  
Christine F. Conover ◽  
Christy S. Carter ◽  
Chris M. Gregory ◽  
Emanuele Marzetti ◽  
...  
Keyword(s):  
Food Intake ◽  
Muscle Fibers ◽  
Hemoglobin Concentration ◽  
Male Rats ◽  
Type I ◽  
Mineral Density ◽  
Cross Sectional ◽  
Prostate Enlargement ◽  
Testosterone Administration ◽  
Novel Strategy

At replacement doses, testosterone produces only modest increases in muscle strength and bone mineral density in older hypogonadal men. Although higher doses of testosterone are more anabolic, there is concern over increased adverse effects, notably prostate enlargement. We tested a novel strategy for obtaining robust anabolic effects without prostate enlargement. Orchiectomized (ORX) male rats were treated for 56 days with 1.0 mg testosterone/day, with and without 0.75 mg/day of the 5α-reductase inhibitor MK-434. Testosterone administration elevated the prostate dihydrotestosterone concentration and caused prostate enlargement. Both effects were inhibited by MK-434. ORX produced a catabolic state manifested in reduced food intake, blunted weight gain, reduced hemoglobin concentration, decreased kidney mass, and increased bone resorption, and in the proximal tibia there was both decreased cancellous bone volume and a decreased number of trabeculae. In soleus and extensor digitorum longus muscles, ORX reduced both the percentage of type I muscle fibers and the cross-sectional area of type 1 and 2 fibers. Testosterone administration caused a number of anabolic effects, including increases in food intake, hemoglobin concentration, and grip strength, and reversed the catabolic effects of ORX on bone. Testosterone administration also partially reversed ORX-induced changes in muscle fibers. In contrast to the prostate effects of testosterone, the effects on muscle, bone, and hemoglobin concentration were not blocked by MK-434. Our study demonstrates that the effects of testosterone on muscle and bone can be separated from the prostate effects and provides a testable strategy for combating sarcopenia and osteopenia in older hypogonadal men.

scholarly journals The response of foraging Argentine ants, Linepithema humile, to disturbance

2001 ◽  
Vol 49 (1) ◽  
pp. 59 ◽  
Author(s):  
Julianne D. Halley ◽  
Mark A. Elgar
Keyword(s):  
Food Intake ◽  
Social Insects ◽  
Feeding Behaviour ◽  
Food Source ◽  
Linepithema Humile ◽  
Argentine Ants ◽  
Trade Off ◽  
Risk Of Predation ◽  
Large Groups ◽  
Food Value

Reducing the risk of predation is an important feature of the feeding behaviour of most animals. In social insects, foraging workers are particularly vulnerable, and the ability to trade-off mortality risk against food value may provide a considerable competitive advantage for the colony. We investigated the response of Argentine ants, Linepithema humile, to different kinds of disturbance while workers foraged on food of differing quality. The behaviour of disturbed individuals was influenced by group size, by the behaviour of nearby nestmates and by how much food had already been consumed. When in large groups, workers were less likely to leave the foraging arena and resumed feeding more rapidly. This response was even more marked among workers whose gasters were only partially replete. However, individuals took more time to resume feeding and became more likely to run away from a food source when greater numbers of ants were disturbed. These influences may allow foraging groups to maximise food intake while minimising the mortality of workers.

scholarly journals Unpredictable hummingbirds: Flight path entropy is constrained by speed and wing loading

2020 ◽  
Author(s):  
Ilias Berberi ◽  
Paolo S. Segre ◽  
Douglas L. Altshuler ◽  
Roslyn Dakin
Keyword(s):  
Information Theory ◽  
Flight Path ◽  
Escape Performance ◽  
Wing Loading ◽  
Trade Off ◽  
Underlying Basis ◽  
Varying Environments ◽  
Short Flight

ABSTRACTUnpredictable movement can provide an advantage when animals avoid predators and other threats. Previous studies have examined how varying environments can elicit unpredictable movement, but the intrinsic causes of complex, unpredictable behavior are not yet known. We addressed this question by analyzing >200 hours of flight performed by hummingbirds, a group of aerial specialists noted for their extreme agility and escape performance. We used information theory to calculate unpredictability based on the positional entropy of short flight sequences during 30-min and 2-hour trials. We show that a bird’s entropy is repeatable, with stable differences among individuals that are negatively correlated with wing loading: birds with lower wing loading are less predictable. Unpredictability is also positively correlated with a bird’s overall acceleration and rotational performance, and yet we find that moment-to-moment changes in acceleration and rotational velocities do not directly influence entropy. This indicates that biomechanical performance must share an underlying basis with a bird’s ability to combine maneuvers into unpredictable sequences. Contrary to expectations, hummingbirds achieve their highest entropy at relatively slow speeds, pointing to a fundamental trade-off whereby individuals must choose to be either fast or unpredictable.

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