Trade-offs in the choice of refuges by common wall lizards: do thermal costs affect preferences for predator-free refuges?

2004 ◽  
Vol 82 (6) ◽  
pp. 897-901 ◽  
Author(s):  
Luisa Amo ◽  
Pilar López ◽  
José Martín
Keyword(s):  
Avoidance Response ◽  
Predation Risk ◽  
Chemical Cues ◽  
Thermal Conditions ◽  
Movement Rate ◽  
Podarcis Muralis ◽  
Refuge Use ◽  
Trade Off ◽  
Trade Offs ◽  
Common Wall

Prey often respond to predator presence by increasing refuge use. However, some types of refuges may expose prey to other types of predators. In addition, in selecting refuges ectothermic animals may have a conflict between safety and thermal suitability. In this paper we examined in the laboratory whether common wall lizards, Podarcis muralis (Laurenti, 1768), (i) prefer to use warm refuges to cold ones, (ii) prefer safe refuges to those with chemical cues of a saurophagous snake, and (iii) whether lizards face a trade-off between using a warm but snake-scented refuge or a cold but odorless one. Results did not show differences in refuge use in relation to refuge temperature, because common wall lizards only entered to investigate it, but they were not forced to hide. So, common wall lizards did not have to be at suboptimal temperatures for longer times. Common wall lizards avoided the use of predator-scented refuges, regardless of thermal conditions, and they also increased their movement rate, trying to escape from the terrarium. Because snakes are inconspicuous inside refuges, an avoidance response to their chemicals may enhance the survival possibilities of common wall lizards. We conclude that in common wall lizards, predation-risk costs are more important than thermal costs in determining refuge use.

scholarly journals Foraging trade-offs, flagellar arrangements, and flow architecture of planktonic protists

2021 ◽  
Vol 118 (3) ◽  
pp. e2009930118
Author(s):  
Lasse Tor Nielsen ◽  
Thomas Kiørboe
Keyword(s):  
Food Webs ◽  
Predation Risk ◽  
Mechanistic Explanation ◽  
Flow Fields ◽  
Resource Acquisition ◽  
Trade Off ◽  
Flow Sensing ◽  
Flow Disturbances ◽  
Trade Offs ◽  
Pelagic Food Webs

Unicellular flagellated protists are a key element in aquatic microbial food webs. They all use flagella to swim and to generate feeding currents to encounter prey and enhance nutrient uptake. At the same time, the beating flagella create flow disturbances that attract flow-sensing predators. Protists have highly diverse flagellar arrangements in terms of number of flagella and their position, beat pattern, and kinematics, but it is unclear how the various arrangements optimize the fundamental trade-off between resource acquisition and predation risk. Here we describe the near-cell flow fields produced by 15 species and demonstrate consistent relationships between flagellar arrangement and swimming speed and between flagellar arrangement and flow architecture, and a trade-off between resource acquisition and predation risk. The flow fields fall in categories that are qualitatively described by simple point force models that include the drag force of the moving cell body and the propulsive forces of the flagella. The trade-off between resource acquisition and predation risk varies characteristically between flow architectures: Flagellates with multiple flagella have higher predation risk relative to their clearance rate compared to species with only one active flagellum, with the exception of the highly successful dinoflagellates that have simultaneously achieved high clearance rates and stealth behavior due to a unique flagellar arrangement. Microbial communities are shaped by trade-offs and environmental constraints, and a mechanistic explanation of foraging trade-offs is a vital part of understanding the eukaryotic communities that form the basis of pelagic food webs.

Co-occurring Notonecta (Hemiptera: Heteroptera: Notonectidae) Species Differ in Their Behavioral Response to Cues of Belostoma (Hemiptera: Heteroptera: Belostomatidae) Predation Risk

2019 ◽  
Vol 112 (4) ◽  
pp. 402-408
Author(s):  
Ilia Maria C Ferzoco ◽  
Celina B Baines ◽  
Shannon J McCauley
Keyword(s):  
Predation Risk ◽  
Chemical Cues ◽  
Habitat Specialization ◽  
Life History Strategies ◽  
Generalist Species ◽  
Ephemeral Ponds ◽  
Trade Offs ◽  
Specialist Species ◽  
Species Specific ◽  
Shared Predator

Abstract Predators affect prey through direct consumption as well as by inducing prey to defensively alter their phenotypes, including behavioral phenotypes, to maximize survival under predation risk. Closely related sympatric prey species with shared natural enemies may resolve behavioral trade-offs under predation risk differently. In a laboratory experiment, we investigated two co-occurring semiaquatic backswimmer congeners, which exhibit differences in their degree of habitat specialization across a gradient of habitat permanence. Notonecta irrorata Uhler primarily occur in ephemeral ponds, whereas Notonecta undulata Say are habitat generalists that are commonly found in both permanent and ephemeral ponds. We tested whether the two species differed in antipredator responses to both visual and chemical cues of a shared predator, the giant water bug, in a fully factorial design. The generalist species, N. undulata, exhibited reductions in activity in the presence of predator chemical cues only, whereas the specialist species, N. irrorata, remained consistently active across predator cue treatments. Our work shows that there are species-specific differences in how prey assess or respond to predation risk. The varying propensities of these backswimmer congeners to behaviorally respond to a shared predator, and differences in their behavior when exposed to different predation risk cues may be linked to underlying divergence in their life-history strategies.

FORAGING TRADE-OFFS AND PREDATOR INSPECTION IN AN OSTARIOPHYSAN FISH: SWITCHING FROM CHEMICAL TO VISUAL CUES

Behaviour ◽  
2000 ◽  
Vol 137 (2) ◽  
pp. 181-195 ◽  
Author(s):  
Joseph Cowan ◽  
Grant Brown
Keyword(s):  
Yellow Perch ◽  
Visual Cues ◽  
Chemical Cues ◽  
Potential Predator ◽  
Trade Off ◽  
Predator Inspection ◽  
Trade Offs ◽  
Risk Of Predation ◽  
Ad Libitum ◽  
Predator Behaviour

AbstractUnder laboratory conditions, we investigated the presence of a foraging trade-off in the chemical predator inspection behaviour of finescale dace (Chrosomus neogaeus). Dace were fed ad libitum, or food deprived for 24 or 48 hours and allowed to inspect a live yellow perch (Perca flavescens) in the presence of the chemical cues of a perch fed dace (with alarm pheromone) or swordtails (Xiphophorus helleri; without alarm pheromones). Dace exposed to the odour of a perch fed swordtails exhibited no evidence of a trade-off in either anti-predator behaviour or predator inspection behaviour. When fed ad libitum and exposed to the odour of a perch fed dace, individuals exhibited significantly greater anti-predator behaviour (increased shoaling, decreased area use and greater frequency of dashing and freezing behaviour) when compared to the swordtail diet control. Predator inspection behaviour was also significantly affected (increased latency to inspect and minimum distance approached towards the predator and fewer inspectors per visit). However, when food deprived for 24 or 48 hours, dace exhibited no differences in either anti-predator or predator inspection behaviour when exposed to the odour of perch fed dace versus perch fed swordtails. These data demonstrate that predator inspection behaviour based on the chemical cues of a potential predator is subject to foraging trade-offs and that individual prey may reduce their overall risk of predation by increasing the use of visual cues.

scholarly journals Individual willingness to leave a safe refuge and the trade-off between food and safety: a test with social fish

2019 ◽  
Vol 286 (1907) ◽  
pp. 20190826 ◽  
Author(s):  
Jesse Balaban-Feld ◽  
William A. Mitchell ◽  
Burt P. Kotler ◽  
Sundararaj Vijayan ◽  
Lotan T. Tov Elem ◽  
...  
Keyword(s):  
Predation Risk ◽  
Foraging Behaviour ◽  
Foraging Success ◽  
Group Foraging ◽  
Refuge Use ◽  
Trade Off ◽  
Individual Fish ◽  
Risk Of Predation ◽  
Group Members ◽  
The Individual

Refuges offer prey animals protection from predation, but increased time spent hiding can reduce foraging opportunities. Within social groups, individuals vary in their refuge use and willingness to forage in the presence of a predator. Here, we examine the relative foraging benefits and mortality costs associated with individual refuge use and foraging behaviour within groups of goldfish ( Carassius auratus ) under predation risk from an avian predator (little egret— Egretta garzetta ). We assessed individual order of emergence from the refuge and participation over 15 group foraging outings, and assigned each fish a daily outing index score. The individual fish that emerged from the refuge earlier than the other group members and that participated in more outings received high outing index scores and consumed more food compared with fish that tended to emerge in posterior positions and participate in fewer outings. However, individual fish that attained high outing index scores suffered a higher risk of predation. Furthermore, the amount of time the egret spent at the pool affected group foraging behaviour: as predation risk increased, groups of fish consumed significantly less food. Our results exemplify the trade-off between foraging success and safety from predation that prey species regularly experience.

scholarly journals Lack of Behavioral and Chemical Interference Competition for Refuges among Native Treefrogs and Invasive Cuban Treefrogs (Osteopilus septentrionalis)

Diversity ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 78
Author(s):  
Kristine Hoffmann ◽  
Monica McGarrity ◽  
Steve Johnson
Keyword(s):  
Invasive Species ◽  
Biological Invasions ◽  
Predation Risk ◽  
Community Dynamics ◽  
Chemical Cues ◽  
Interference Competition ◽  
Refuge Use ◽  
Chemical Interference ◽  
Osteopilus Septentrionalis ◽  
Methodological Bias

The introduction of a novel competitor can dramatically alter community dynamics, and competition-mediated impacts often result from biological invasions. Interference competition can be especially problematic as a source of methodological bias for studies seeking to evaluate population and community-level impacts of invasive species. We used polyvinyl chloride (PVC) refugia to conduct laboratory trials to determine whether behavioral or chemical cues of invasive Cuban treefrogs (Osteopilusseptentrionalis) interfere with artificial refuge use by conspecifics or treefrogs native to Florida (USA). We found no evidence of behavioral or chemical competition for refuges by Cuban treefrogs or native treefrogs. The inability of native treefrogs to avoid chemical cues from Cuban treefrogs, despite living sympatrically with the invasive treefrogs for 10–20 years, has important implications for predation risk.

Dual Goals for Speed and Accuracy on the Same Performance Task

2012 ◽  
Vol 11 (3) ◽  
pp. 118-126 ◽  
Author(s):  
Olive Emil Wetter ◽  
Jürgen Wegge ◽  
Klaus Jonas ◽  
Klaus-Helmut Schmidt
Keyword(s):  
Memory Scanning ◽  
Performance Task ◽  
Performance Tasks ◽  
Trade Off ◽  
Test Experiment ◽  
Trade Offs ◽  
New Finding ◽  
Sternberg Paradigm ◽  
Speed Accuracy ◽  
Speed And Accuracy

In most work contexts, several performance goals coexist, and conflicts between them and trade-offs can occur. Our paper is the first to contrast a dual goal for speed and accuracy with a single goal for speed on the same task. The Sternberg paradigm (Experiment 1, n = 57) and the d2 test (Experiment 2, n = 19) were used as performance tasks. Speed measures and errors revealed in both experiments that dual as well as single goals increase performance by enhancing memory scanning. However, the single speed goal triggered a speed-accuracy trade-off, favoring speed over accuracy, whereas this was not the case with the dual goal. In difficult trials, dual goals slowed down scanning processes again so that errors could be prevented. This new finding is particularly relevant for security domains, where both aspects have to be managed simultaneously.

The Effects of Decision Time on Perceptions of Decisions and Decision Makers in (Moral) Trade-Off Scenarios

2019 ◽  
Author(s):  
Anna Katharina Spälti ◽  
Mark John Brandt ◽  
Marcel Zeelenberg
Keyword(s):  
Decision Process ◽  
Decision Time ◽  
Decision Makers ◽  
Process Information ◽  
Total N ◽  
Trade Off ◽  
Financial Gain ◽  
Trade Offs ◽  
Sacred Values ◽  
Moral Context

People often have to make trade-offs. We study three types of trade-offs: 1) "secular trade-offs" where no moral or sacred values are at stake, 2) "taboo trade-offs" where sacred values are pitted against financial gain, and 3) "tragic trade-offs" where sacred values are pitted against other sacred values. Previous research (Critcher et al., 2011; Tetlock et al., 2000) demonstrated that tragic and taboo trade-offs are not only evaluated by their outcomes, but are also evaluated based on the time it took to make the choice. We investigate two outstanding questions: 1) whether the effect of decision time differs for evaluations of decisions compared to decision makers and 2) whether moral contexts are unique in their ability to influence character evaluations through decision process information. In two experiments (total N = 1434) we find that decision time affects character evaluations, but not evaluations of the decision itself. There were no significant differences between tragic trade-offs and secular trade-offs, suggesting that the decisions structure may be more important in evaluations than moral context. Additionally, the magnitude of the effect of decision time shows us that decision time, may be of less practical use than expected. We thus urge, to take a closer examination of the processes underlying decision time and its perception.

Predicting Undesired Treatment Outcome in Mental Healthcare: Machine Learning Study (Preprint)

2019 ◽  
Author(s):  
Kasper Van Mens ◽  
Joran Lokkerbol ◽  
Richard Janssen ◽  
Robert de Lange ◽  
Bea Tiemens
Keyword(s):  
Machine Learning ◽  
Treatment Outcome ◽  
Mental Health Treatment ◽  
Mental Healthcare ◽  
Machine Learning Algorithms ◽  
Gradient Boosting ◽  
Trade Off ◽  
Trade Offs ◽  
Outcome Monitoring ◽  
Extreme Gradient Boosting

BACKGROUND It remains a challenge to predict which treatment will work for which patient in mental healthcare. OBJECTIVE In this study we compare machine algorithms to predict during treatment which patients will not benefit from brief mental health treatment and present trade-offs that must be considered before an algorithm can be used in clinical practice. METHODS Using an anonymized dataset containing routine outcome monitoring data from a mental healthcare organization in the Netherlands (n = 2,655), we applied three machine learning algorithms to predict treatment outcome. The algorithms were internally validated with cross-validation on a training sample (n = 1,860) and externally validated on an unseen test sample (n = 795). RESULTS The performance of the three algorithms did not significantly differ on the test set. With a default classification cut-off at 0.5 predicted probability, the extreme gradient boosting algorithm showed the highest positive predictive value (ppv) of 0.71(0.61 – 0.77) with a sensitivity of 0.35 (0.29 – 0.41) and area under the curve of 0.78. A trade-off can be made between ppv and sensitivity by choosing different cut-off probabilities. With a cut-off at 0.63, the ppv increased to 0.87 and the sensitivity dropped to 0.17. With a cut-off of at 0.38, the ppv decreased to 0.61 and the sensitivity increased to 0.57. CONCLUSIONS Machine learning can be used to predict treatment outcomes based on routine monitoring data.This allows practitioners to choose their own trade-off between being selective and more certain versus inclusive and less certain.

Challenges in the Empirical Study of Global Governance Legitimacy

2018 ◽  
Author(s):  
Steven Bernstein
Keyword(s):  
Empirical Study ◽  
Global Governance ◽  
Research Agenda ◽  
Cultural Factors ◽  
Theory Building ◽  
Trade Off ◽  
Trade Offs ◽  
Different Types ◽  
Political Communities

This commentary discusses three challenges for the promising and ambitious research agenda outlined in the volume. First, it interrogates the volume’s attempts to differentiate political communities of legitimation, which may vary widely in composition, power, and relevance across institutions and geographies, with important implications not only for who matters, but also for what gets legitimated, and with what consequences. Second, it examines avenues to overcome possible trade-offs from gains in empirical tractability achieved through the volume’s focus on actor beliefs and strategies. One such trade-off is less attention to evolving norms and cultural factors that may underpin actors’ expectations about what legitimacy requires. Third, it addresses the challenge of theory building that can link legitimacy sources, (de)legitimation practices, audiences, and consequences of legitimacy across different types of institutions.

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