scholarly journals Habituation and individual variation in the endocrine stress response in the Trinidadian guppy (Poecilia reticulata)

2018 ◽  
Author(s):  
T.M. Houslay ◽  
R.L. Earley ◽  
A.J. Young ◽  
A.J. Wilson
Keyword(s):  
Individual Differences ◽  
Stress Response ◽  
Chronic Stress ◽  
Individual Variation ◽  
Poecilia Reticulata ◽  
General Pattern ◽  
Small Fish ◽  
Habituation Rate ◽  
Endocrine Stress Response ◽  
Cortisol Release

AbstractThe vertebrate stress response enables individuals to react to and cope with environmental challenges. A crucial aspect of the stress response is the elevation of circulating glucocorticoids. However, continued activation of the stress response under repeated (or chronic) stress can be damaging to fitness. Under certain circumstances it may therefore be adaptive to habituate to repeated exposures to a particular stressor by reducing the magnitude of any associated release of glucocorticoids. Here, we investigate whether Trinidadian guppies (Poecilia reticulata) habituate to repeated exposure to a mild stressor, using a waterborne hormone sampling approach that has previously been shown to elicit a stress response in small fish. We also test for individual variation in the extent of habituation to this stressor. Concentrating on freely circulating cortisol, we found that the first exposure to the assay induced high cortisol release rates but that guppies tended to habituate quickly to subsequent exposures. There were consistent differences among individuals in their average cortisol release rate (after accounting for effects of variables such as body size) over repeated exposures. Our analyses did not find evidence of individual differences in habituation rate, although limitations in statistical power could account for this finding. We also present data on free 11-ketotestosterone, in addition to conjugated forms of both hormones. We discuss consistent individual differences around the general pattern of habituation in the flexible stress response, and highlight the potential for individual variation in habituation to facilitate selection against the deleterious effects of chronic stress.Summary statementTrinidadian guppies habituate quickly to repeated stress exposure, and exhibit consistent differences in their endocrine stress response. We provide a framework for analysing individual variation in habituation rate.

scholarly journals Using a robotic fish to investigate individual differences in social responsiveness in the guppy

2018 ◽  
Vol 5 (8) ◽  
pp. 181026 ◽  
Author(s):  
David Bierbach ◽  
Tim Landgraf ◽  
Pawel Romanczuk ◽  
Juliane Lukas ◽  
Hai Nguyen ◽  
...  
Keyword(s):  
Individual Differences ◽  
Individual Variation ◽  
Poecilia Reticulata ◽  
Open Loop ◽  
Social Cues ◽  
Social Responsiveness ◽  
Small Fish ◽  
Repeated Testing ◽  
Test Environment ◽  
Biomimetic Robots

Responding towards the actions of others is one of the most important behavioural traits whenever animals of the same species interact. Mutual influences among interacting individuals may modulate the social responsiveness seen and thus make it often difficult to study the level and individual variation in responsiveness. Here, open-loop biomimetic robots that provide standardized, non-interactive social cues can be a useful tool. These robots are not affected by the live animal's actions but are assumed to still represent valuable and biologically relevant social cues. As this assumption is crucial for the use of biomimetic robots in behavioural studies, we hypothesized (i) that meaningful social interactions can be assumed if live animals maintain individual differences in responsiveness when interacting with both a biomimetic robot and a live partner. Furthermore, to study the level of individual variation in social responsiveness, we hypothesized (ii) that individual differences should be maintained over the course of multiple tests with the robot. We investigated the response of live guppies ( Poecilia reticulata ) when allowed to interact either with a biomimetic open-loop-controlled fish robot—‘Robofish’—or with a live companion. Furthermore, we investigated the responses of live guppies when tested three times with Robofish. We found that responses of live guppies towards Robofish were weaker compared with those of a live companion, most likely as a result of the non-interactive open-loop behaviour of Robofish. Guppies, however, were consistent in their individual responses between a live companion and Robofish, and similar individual differences in response towards Robofish were maintained over repeated testing even though habituation to the test environment was detectable. Biomimetic robots like Robofish are therefore a useful tool for the study of social responsiveness in guppies and possibly other small fish species.

scholarly journals Psychoactive pollution suppresses individual differences in fish behaviour

2021 ◽  
Vol 288 (1944) ◽  
pp. 20202294
Author(s):  
Giovanni Polverino ◽  
Jake M. Martin ◽  
Michael G. Bertram ◽  
Vrishin R. Soman ◽  
Hung Tan ◽  
...  
Keyword(s):  
Individual Differences ◽  
Risk Taking ◽  
Strong Evidence ◽  
Environmental Contamination ◽  
Individual Variation ◽  
Poecilia Reticulata ◽  
Fish Behaviour ◽  
Adaptive Potential ◽  
Relative Contribution ◽  
Low Concentrations

Environmental contamination by pharmaceuticals is global, substantially altering crucial behaviours in animals and impacting on their reproduction and survival. A key question is whether the consequences of these pollutants extend beyond mean behavioural changes, restraining differences in behaviour between individuals. In a controlled, two-year, multigenerational experiment with independent mesocosm populations, we exposed guppies ( Poecilia reticulata ) to environmentally realistic levels of the ubiquitous pollutant fluoxetine (Prozac). Fish (unexposed: n = 59, low fluoxetine: n = 57, high fluoxetine: n = 58) were repeatedly assayed on four separate occasions for activity and risk-taking behaviour. Fluoxetine homogenized individuals' activity, with individual variation in populations exposed to even low concentrations falling to less than half that in unexposed populations. To understand the proximate mechanism underlying these changes, we tested the relative contribution of variation within and between individuals to the overall decline in individual variation. We found strong evidence that fluoxetine erodes variation in activity between but not within individuals, revealing the hidden consequences of a ubiquitous contaminant on phenotypic variation in fish—likely to impair adaptive potential to environmental change.

scholarly journals Developmental plasticity of the stress response in female but not in male guppies

2018 ◽  
Vol 5 (3) ◽  
pp. 172268 ◽  
Author(s):  
L. Chouinard-Thuly ◽  
A. R. Reddon ◽  
I. Leris ◽  
R. L. Earley ◽  
S. M. Reader
Keyword(s):  
Life History ◽  
Stress Response ◽  
Stress Responses ◽  
Early Life ◽  
Developmental Plasticity ◽  
Life Experiences ◽  
Population Variation ◽  
Small Fish ◽  
Cortisol Release ◽  
Over Time

To survive, animals must respond appropriately to stress. Stress responses are costly, so early-life experiences with potential stressors could adaptively tailor adult stress responses to local conditions. However, how multiple stressors influence the development of the stress response remains unclear, as is the role of sex. Trinidadian guppies ( Poecilia reticulata ) are small fish with extensive life-history differences between the sexes and population variation in predation pressure and social density. We investigated how sex and early-life experience influence hormonal stress responses by manipulating conspecific density and perceived predation risk during development. In adults, we sampled cortisol twice to measure initial release and change over time in response to a recurring stressor. The sexes differed considerably in their physiological stress response. Males released more cortisol for their body mass than females and did not reduce cortisol release over time. By contrast, all females, except those reared at high density together with predation cues, reduced cortisol release over time. Cortisol responses of males were thus less dynamic in response to current circumstances and early-life experiences than females, consistent with life-history differences between the sexes. Our study underscores the importance of early-life experiences, interacting ecological factors and sex differences in the organization of the stress response.

scholarly journals Temporal autocorrelation: a neglected factor in the study of behavioral repeatability and plasticity

2019 ◽  
Author(s):  
David J Mitchell ◽  
Antoine M Dujon ◽  
Christa Beckmann ◽  
Peter A Biro
Keyword(s):  
Individual Differences ◽  
Individual Variation ◽  
Repeated Measures ◽  
Poecilia Reticulata ◽  
Energy Levels ◽  
Worked Examples ◽  
Reaction Norm ◽  
Physiological Data ◽  
Temporal Autocorrelation ◽  
Internal States

Abstract Quantifying individual variation in labile physiological or behavioral traits often involves repeated measures through time, so as to test for consistency of individual differences (often using repeatability, “R”) and/or individual differences in trendlines over time. Another form of temporal change in behavior is temporal autocorrelation, which predicts observations taken closely together in time to be correlated, leading to nonrandom residuals about individual temporal trendlines. Temporal autocorrelation may result from slowly changing internal states (e.g., hormone or energy levels), leading to slowly changing behavior. Autocorrelation is a well-known phenomenon, but has been largely neglected by those studying individual variation in behavior. Here, we provide two worked examples which show substantial temporal autocorrelation (r > 0.4) is present in spontaneous activity rates of guppies (Poecilia reticulata) and house mice (Mus domesticus) in stable laboratory conditions, even after accounting for temporal plasticity of individuals. Second, we show that ignoring autocorrelation does bias estimates of R and temporal reaction norm variances upwards, both in our worked examples and in separate simulations. This bias occurs due to the misestimation of individual-specific means and slopes. Given the increasing use of technologies that generate behavioral and physiological data at high sampling rates, we can now study among- and within-individual changes in behavior in more detailed ways, including autocorrelation, which we discuss from biological and methodological perspectives and provide recommendations and annotated R code to help researchers implement these models on their data.

The challenge of accounting for individual differences in folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
Benjamin C. Ruisch ◽  
Rajen A. Anderson ◽  
David A. Pizarro
Keyword(s):  
Individual Differences ◽  
Individual Variation ◽  
Political Ideologies ◽  
Economic Beliefs ◽  
Existing Data

AbstractWe argue that existing data on folk-economic beliefs (FEBs) present challenges to Boyer & Petersen's model. Specifically, the widespread individual variation in endorsement of FEBs casts doubt on the claim that humans are evolutionarily predisposed towards particular economic beliefs. Additionally, the authors' model cannot account for the systematic covariance between certain FEBs, such as those observed in distinct political ideologies.

Inter-individual variation shapes the human microbiome

2019 ◽  
Vol 42 ◽  
Author(s):  
Emily F. Wissel ◽  
Leigh K. Smith
Keyword(s):  
Individual Differences ◽  
Individual Variation ◽  
Human Microbiome ◽  
Individual Variability ◽  
Microbiota Composition ◽  
Target Article ◽  
Microbiome Research

Abstract The target article suggests inter-individual variability is a weakness of microbiota-gut-brain (MGB) research, but we discuss why it is actually a strength. We comment on how accounting for individual differences can help researchers systematically understand the observed variance in microbiota composition, interpret null findings, and potentially improve the efficacy of therapeutic treatments in future clinical microbiome research.

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