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Wilbrecht L, Lin WC, Callahan K, Bateson M, Myers K, Ross R. Experimental biology can inform our understanding of food insecurity. J Exp Biol 2024; 227:jeb246215. [PMID: 38449329 PMCID: PMC10949070 DOI: 10.1242/jeb.246215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Food insecurity is a major public health issue. Millions of households worldwide have intermittent and unpredictable access to food and this experience is associated with greater risk for a host of negative health outcomes. While food insecurity is a contemporary concern, we can understand its effects better if we acknowledge that there are ancient biological programs that evolved to respond to the experience of food scarcity and uncertainty, and they may be particularly sensitive to food insecurity during development. Support for this conjecture comes from common findings in several recent animal studies that have modeled insecurity by manipulating predictability of food access in various ways. Using different experimental paradigms in different species, these studies have shown that experience of insecure access to food can lead to changes in weight, motivation and cognition. Some of these studies account for changes in weight through changes in metabolism, while others observe increases in feeding and motivation to work for food. It has been proposed that weight gain is an adaptive response to the experience of food insecurity as 'insurance' in an uncertain future, while changes in motivation and cognition may reflect strategic adjustments in foraging behavior. Animal studies also offer the opportunity to make in-depth controlled studies of mechanisms and behavior. So far, there is evidence that the experience of food insecurity can impact metabolic efficiency, reproductive capacity and dopamine neuron synapses. Further work on behavior, the central and peripheral nervous system, the gut and liver, along with variation in age of exposure, will be needed to better understand the full body impacts of food insecurity at different stages of development.
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Affiliation(s)
- Linda Wilbrecht
- Department of Psychology, University of California, Berkeley, Berkeley, CA 94720-1650, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Wan Chen Lin
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kathryn Callahan
- Psychiatric Research Institute of Montefiore and Einstein, Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Melissa Bateson
- Bioscience Institute, University of Newcastle, Newcastle upon Tyne, NE2 4HH, UK
| | - Kevin Myers
- Department of Psychology and Programs in Animal Behavior and Neuroscience, Bucknell University, Lewisburg, PA 17837, USA
| | - Rachel Ross
- Psychiatric Research Institute of Montefiore and Einstein, Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Department of Psychiatry, Montefiore Medical Center, Bronx, New York, NY 10467, USA
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Bateson M, Pepper GV. Food insecurity as a cause of adiposity: evolutionary and mechanistic hypotheses. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220228. [PMID: 37661744 PMCID: PMC10475876 DOI: 10.1098/rstb.2022.0228] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 07/27/2023] [Indexed: 09/05/2023] Open
Abstract
Food insecurity (FI) is associated with obesity among women in high-income countries. This seemingly paradoxical association can be explained by the insurance hypothesis, which states that humans possess evolved mechanisms that increase fat storage to buffer against energy shortfall when access to food is unpredictable. The evolutionary logic underlying the insurance hypothesis is well established and experiments on animals confirm that exposure to unpredictable food causes weight gain, but the mechanisms involved are less clear. Drawing on data from humans and other vertebrates, we review a suite of behavioural and physiological mechanisms that could increase fat storage under FI. FI causes short-term hyperphagia, but evidence that it is associated with increased total energy intake is lacking. Experiments on animals suggest that unpredictable food causes increases in retained metabolizable energy and reductions in energy expenditure sufficient to fuel weight gain in the absence of increased food intake. Reducing energy expenditure by diverting energy from somatic maintenance into fat stores should improve short-term survival under FI, but the trade-offs potentially include increased disease risk and accelerated ageing. We conclude that exposure to FI plausibly causes increased adiposity, poor health and shorter lifespan. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.
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Affiliation(s)
- Melissa Bateson
- Centre for Healther Lives and Biosciences Institute, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Gillian V. Pepper
- Department of Psychology, Northumbria University, Newcastle upon Tyne, NE1 8ST, UK
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Lynn SE, Lungu T, Lee SY. Unpredictable fasting transiently alters corticosterone and feeding behavior but not body mass or later HPA axis function in zebra finches (Taeniopygia guttata). Comp Biochem Physiol A Mol Integr Physiol 2023; 281:111434. [PMID: 37068728 DOI: 10.1016/j.cbpa.2023.111434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/14/2023] [Accepted: 04/14/2023] [Indexed: 04/19/2023]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis is commonly activated in response to unpredictable conditions, including unstable or inadequate food supply. Extended exposure to unpredictable food resources can alter HPA axis function, with the potential for negative fitness consequences. We addressed the interrelationships of unpredictable food resources, HPA axis activity, and food intake in adult and juvenile zebra finches (Taeniopygia guttata). Finches exposed to prolonged periods of unpredictable food elevate corticosterone (the primary avian glucocorticoid) when food is unavailable; however, whether they experience chronic elevation in baseline corticosterone during periods of unpredictability, even when food is available, is unclear. We subjected adults and juveniles to an extended period of temporally unpredictable food (consisting of a random daily fast) or predictable food supply. We investigated baseline corticosterone under fed conditions and in response to an acute fast (mimicking the daily fasting periods in the unpredictable treatment), and assessed differences in body mass, food intake, and corticosterone responses to restraint. Regardless of sex and age, individuals in both treatment groups elevated corticosterone when fasted, and baseline corticosterone under fed conditions was indistinguishable between groups. Thus, corticosterone levels were not persistently elevated in the unpredictably fed group. Treatment groups did not differ in body mass or corticosterone responses to restraint, but unpredictably fed birds consumed food more rapidly when food was available. Our findings suggest that the unpredictably fed birds experienced repeated, moderate elevations in corticosterone. Such elevations may aid birds in coping with unpredictable food sources, in part by activating compensatory changes in foraging behavior.
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Affiliation(s)
- Sharon E Lynn
- The College of Wooster, Department of Biology, 931 College Mall, Wooster, OH 44691, USA.
| | - Tudor Lungu
- The College of Wooster, Department of Biology, 931 College Mall, Wooster, OH 44691, USA
| | - Seung Yeon Lee
- The College of Wooster, Department of Biology, 931 College Mall, Wooster, OH 44691, USA
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Polzin BJ, Maksimoski AN, Stevenson SA, Zhao C, Riters LV. Mu opioid receptor stimulation in the medial preoptic area or nucleus accumbens facilitates song and reward in flocking European starlings. Front Physiol 2022; 13:970920. [PMID: 36171974 PMCID: PMC9510710 DOI: 10.3389/fphys.2022.970920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 08/22/2022] [Indexed: 11/14/2022] Open
Abstract
It has been proposed that social cohesion in gregarious animals is reinforced both by a positive affective state induced by social interactions and by the prevention of a negative state that would be caused by social separation. Opioids that bind to mu opioid receptors (MORs) act in numerous brain regions to induce positive and to reduce negative affective states. Here we explored a potential role for MORs in affective states that may impact flocking behavior in mixed-sex flocks of nonbreeding European starlings, Sturnus vulgaris. Singing behavior, which is considered central to flock cohesion, and other social behaviors were quantified after infusions of the MOR agonist D-Ala2, N-Me-Phe4, glycinol5-ENK (DAMGO) into either the medial preoptic area (POM) or the nucleus accumbens (NAC), regions previously implicated in affective state and flock cohesion. We focused on beak wiping, a potential sign of stress or redirected aggression in this species, to provide insight into a presumed negative state. We also used conditioned place preference (CPP) tests to provide insight into the extent to which infusions of DAMGO into POM or NAC that stimulated song might be rewarding. We found that MOR stimulation in either POM or NAC dose-dependently promoted singing behavior, reduced beak wiping, and induced a CPP. Subtle differences in responses to MOR stimulation between NAC and POM also suggest potential functional differences in the roles of these two regions. Finally, because the location of NAC has only recently been identified in songbirds, we additionally performed a tract tracing study that confirmed the presence of dopaminergic projections from the ventral tegmental area to NAC, suggesting homology with mammalian NAC. These findings support the possibility that MORs in POM and NAC play a dual role in reinforcing social cohesion in flocks by facilitating positive and reducing negative affective states.
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Andrews CP. On the use of body mass measures in severity assessment in laboratory passerine birds. Anim Welf 2022. [DOI: 10.7120/09627286.31.1.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Criteria for assessing the severity of scientific procedures in laboratory rodents include the loss of body mass. However, guidance is limited for passerine birds and application of criteria developed for mammals risks poor welfare decisions. Here, I ask whether, and how, body mass
criteria could be incorporated into laboratory welfare assessment of passerines. Passerine birds strategically adjust their body mass to minimise combined mortality risk from starvation and predation. A systematic literature review found that strategic mass changes can be sizeable (sometimes
> 10%) even over short timescales. Many aspects of a bird's current or past environment, including husbandry and experimental procedures, may alter perceived starvation or predation risks and thus drive strategic mass change via evolved mechanisms. Therefore, body mass criteria used for
rodents may be too stringent for passerines, potentially leading to over-estimated severity. Strategic mass changes might obscure those stemming from experimental interventions yet could also offer insights into whether birds perceive an intervention or altered husbandry as a threat. Mass
criteria for severity assessment should be species- and context-specific in order to balance needs for refinement and reduction. To guide the development of appropriate criteria, a future research priority is for greater data collection and sharing based on standardised routine monitoring
of mass variation under a representative range of husbandry conditions and procedures.
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Affiliation(s)
- CP Andrews
- University of Stirling, Division of Psychology, Faculty of Natural Sciences, Stirling FK9 4LA, UK
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Abstract
The aim of this study was to identify the dietary intake correlates of food insecurity (FI) in UK adults. We recruited groups of low-income participants who were classified as food insecure (n 196) or food secure (n 198). Participants completed up to five 24 h dietary recalls. There was no difference in total energy intake by FI status (βFI = -0·06, 95 % CI - 0·25, 0·13). Food insecure participants consumed a less diverse diet, as evidenced by fewer distinct foods per meal (βFI = -0·27, 95 % CI - 0·47, -0·07), and had more variable time gaps between meals (βFI = 0·21, 95 % CI 0·01, 0·41). These associations corresponded closely to those found in a recent US study using similar measures, suggesting that the dietary intake signature of FI generalises across populations. The findings suggest that the consequences of FI for weight gain and health are not due to increased energy intake. We suggest that there may be important health and metabolic effects of temporal irregularity in dietary intake, which appears to be an important component of FI.
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Overmatching under food uncertainty in foraging pigeons. Behav Processes 2022; 201:104728. [DOI: 10.1016/j.beproc.2022.104728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/07/2022] [Accepted: 08/01/2022] [Indexed: 11/20/2022]
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Riters LV, Stevenson SA. Using seasonality and birdsong to understand mechanisms underlying context-appropriate shifts in social motivation and reward. Horm Behav 2022; 142:105156. [PMID: 35313200 PMCID: PMC9382228 DOI: 10.1016/j.yhbeh.2022.105156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 01/11/2022] [Accepted: 03/11/2022] [Indexed: 12/29/2022]
Abstract
Social motivation and reward are dynamic and flexible, shifting adaptively across contexts to meet changing social demands. This is exceptionally apparent when seasonal contexts are considered in seasonally breeding songbirds as they cycle from periods of sexual motivation and reward during the breeding season to periods of extreme gregariousness outside the breeding season when non-sexual social interactions gain reward value, motivating birds to form flocks. Here we review evidence demonstrating a key integrative role for the medial preoptic area (mPOA) in the seasonally-appropriate adjustment of behaviors, with seasonal changes in dopamine activity in mPOA adjusting social motivation and changes in opioid activity modifying social reward. Experiments demonstrate that dramatic seasonal fluctuations in steroid hormone concentrations alter patterns of opioid- and dopamine-related protein and gene expression in mPOA to modify social motivation and reward to meet seasonal changes in social demands. These studies of birdsong and seasonality provide new insights into neural and endocrine mechanisms underlying adaptive changes in social motivation and reward and highlight an underappreciated, evolutionarily conserved role for the mPOA in important social behaviors in non-reproductive contexts.
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Affiliation(s)
- Lauren V Riters
- Department of Integrative Biology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Sharon A Stevenson
- Department of Integrative Biology, 428 Birge Hall, 430 Lincoln Drive, University of Wisconsin-Madison, Madison, WI 53706, USA
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Beattie UK, Ysrael MC, Lok SE, Romero LM. The Effect of a Combined Fast and Chronic Stress on Body Mass, Blood Metabolites, Corticosterone, and Behavior in House Sparrows ( Passer domesticus). THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2022; 95:19-31. [PMID: 35370496 PMCID: PMC8961712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
One aspect of the Reactive Scope Model is wear-and-tear, which describes a decrease in an animal's ability to cope with a stressor, typically because of a period of chronic or repeated stressors. We investigated whether wear-and-tear due to chronic stress would accelerate a transition from phase II to phase III of fasting. We exposed house sparrows (Passer domesticus) to three weeks of daily fasts combined with daily intermittent repeated acute stressors to create chronic stress, followed by two weeks of daily fasts without stressors. We measured circulating glucose, β-hydroxybutyrate (a ketone), and uric acid in both fasted and fed states. We expected birds to be in phase II (high fat breakdown) in a fasted state, but if wear-and-tear accumulated sufficiently, we hypothesized a shift to phase III (high protein breakdown). Throughout the experiment, the birds exhibited elevated β-hydroxybutyrate when fasting but no changes in circulating uric acid, indicating that a transition to phase III did not occur. In both a fasted and fed state, the birds increased glucose mobilization throughout the experiment, suggesting wear-and-tear occurred, but was not sufficient to induce a shift to phase III. Additionally, the birds exhibited a significant decrease in weight, no change in corticosterone, and a transient decrease in neophobia with chronic stress. In conclusion, the birds appear to have experienced wear-and-tear, but our protocol did not accelerate the transition from phase II to phase III of fasting.
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Affiliation(s)
- Ursula K. Beattie
- To whom all correspondence should be addressed:
Ursula Beattie, Department of Biology, Tufts University, 200 College Avenue,
Medford, MA 02155; ; ORCID iD:
https://orcid.org/0000-0002-7131-3712
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Scheun J, Miller RJ, Ganswindt A, Waller LJ, Pichegru L, Sherley RB, Maneveldt GW. Urofaecal glucocorticoid metabolite concentrations in African penguin ( Spheniscus demersus) chick populations experiencing different levels of human disturbance. CONSERVATION PHYSIOLOGY 2021; 9:coab078. [PMID: 34532057 PMCID: PMC8439262 DOI: 10.1093/conphys/coab078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/02/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Despite the importance of ecotourism in species conservation, little is known about the industry's effects on wildlife. In South Africa, some African penguin (Spheniscus demersus) colonies have become tourist attractions. The species is globally endangered, with population sizes decreasing over the past 40 years. As African penguin chicks are altricial and unable to move away from anthropogenic stressors, it is important to evaluate the effect of tourist activities on baseline glucocorticoid levels as a measure of potential disturbance. Chicks at three study sites within two breeding colonies (Robben Island, Stony Point), with varying levels of exposure to tourism (low/moderate/high) were monitored. Urofaecal samples were collected to determine urofaecal glucocorticoid metabolite (ufGCM) concentrations as an indication of baseline stress physiology. Morphometric measurements were taken to compare body condition between sites. Penguin chicks experiencing low, infrequent human presence had significantly higher mean (± standard deviation) ufGCM levels [1.34 ± 1.70 μg/g dry weight (DW)] compared to chicks experiencing both medium (0.50 ± 0.40 μg/g DW, P = 0.001) and high levels of human presence (0.57 ± 0.47 μg/g DW, P = 0.003). There was no difference in chick body condition across sites. These results suggest that exposure to frequent human activity may induce habituation/desensitization in African penguin chicks. Acute, infrequent human presence was likely an important driver for comparatively higher ufGCM levels in chicks, though several other environmental stressors may also play an important role in driving adrenocortical activity. Nevertheless, as unhabituated chicks experiencing infrequent anthropogenic presence showed significantly higher ufGCM levels, managers and legislation should attempt to minimize all forms of activity around important breeding colonies that are not already exposed to regular tourism. Although the results of this study are crucial for developing enhanced conservation and management protocols, additional research on the long-term effect of anthropogenic activities on African penguin physiology is required.
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Affiliation(s)
- Juan Scheun
- Department of Life and Consumer Sciences, University of South Africa, Roodepoort, 1724, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0081, South Africa
- National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0002, South Africa
| | - Rebecca J Miller
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
| | - Andre Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0081, South Africa
| | - Lauren J Waller
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Table View, 7441, South Africa
| | - Lorien Pichegru
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute of African Ornithology and Institute for Coastal and Marine Research at the Nelson Mandela University, Port Elizabeth, 6031, South Africa
| | - Richard B Sherley
- Centre for Ecology and Conservation, University of Exeter, Penry Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Gavin W Maneveldt
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
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μ-Opioid Receptor Stimulation in the Nucleus Accumbens Increases Vocal-Social Interactions in Flocking European Starlings, Sturnus Vulgaris. eNeuro 2021; 8:ENEURO.0219-21.2021. [PMID: 34475266 PMCID: PMC8474649 DOI: 10.1523/eneuro.0219-21.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/12/2021] [Accepted: 08/25/2021] [Indexed: 12/14/2022] Open
Abstract
Social connections in gregarious species are vital for safety and survival. For these reasons, many bird species form large flocks outside the breeding season. It has been proposed that such large social groups may be maintained via reward induced by positive interactions with conspecifics and via the reduction of a negative affective state caused by social separation. Moreover, within a flock optimal social spacing between conspecifics is important, indicating that individuals may optimize spacing to be close but not too close to conspecifics. The μ-opioid receptors (MORs) in the nucleus accumbens (NAc) are well known for their role in both reward and the reduction of negative affective states, suggesting that MOR stimulation in NAc may play a critical role in flock cohesion. To begin to test this hypothesis, social and nonsocial behaviors were examined in male and female European starlings (Sturnus vulgaris) in nonbreeding flocks after intra-NAc infusion of saline and three doses of the selective MOR agonist d-Ala2-N-Me-Phe4-Glycol5-enkephalin (DAMGO). DAMGO in NAc dose-dependently increased singing behavior and facilitated social approaches while at the same time promoting displacements potentially used to maintain social spacing. These findings support the hypothesis that MORs in NAc promote social interactions important for group cohesion in nonsexual contexts and suggest the possibility that MORs in the NAc play a role in optimizing the pull of joining a flock with the push of potential agonistic encounters.
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Andrews C, Zuidersma E, Verhulst S, Nettle D, Bateson M. Exposure to food insecurity increases energy storage and reduces somatic maintenance in European starlings ( Sturnus vulgaris). ROYAL SOCIETY OPEN SCIENCE 2021; 8:211099. [PMID: 34540262 PMCID: PMC8441118 DOI: 10.1098/rsos.211099] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/24/2021] [Indexed: 05/11/2023]
Abstract
Birds exposed to food insecurity-defined as temporally variable access to food-respond adaptively by storing more energy. To do this, they may reduce energy allocation to other functions such as somatic maintenance and repair. To investigate this trade-off, we exposed juvenile European starlings (Sturnus vulgaris, n = 69) to 19 weeks of either uninterrupted food availability or a regime where food was unpredictably unavailable for a 5-h period on 5 days each week. Our measures of energy storage were mass and fat scores. Our measures of somatic maintenance were the growth rate of a plucked feather, and erythrocyte telomere length (TL), measured by analysis of the terminal restriction fragment. The insecure birds were heavier than the controls, by an amount that varied over time. They also had higher fat scores. We found no evidence that they consumed more food overall, though our food consumption data were incomplete. Plucked feathers regrew more slowly in the insecure birds. TL was reduced in the insecure birds, specifically, in the longer percentiles of the within-individual TL distribution. We conclude that increased energy storage in response to food insecurity is achieved at the expense of investment in somatic maintenance and repair.
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Affiliation(s)
- Clare Andrews
- Department of Psychology, University of Stirling, Stirling, UK
| | - Erica Zuidersma
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Simon Verhulst
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Daniel Nettle
- Newcastle University Population Health Sciences Institute, Newcastle University, Newcastle, UK
| | - Melissa Bateson
- Newcastle University Biosciences Institute, Newcastle University, Newcastle, UK
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Bateson M, Andrews C, Dunn J, Egger CBCM, Gray F, Mchugh M, Nettle D. Food insecurity increases energetic efficiency, not food consumption: an exploratory study in European starlings. PeerJ 2021; 9:e11541. [PMID: 34123601 PMCID: PMC8166238 DOI: 10.7717/peerj.11541] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 05/10/2021] [Indexed: 12/15/2022] Open
Abstract
Food insecurity—defined as limited or unpredictable access to nutritionally adequate food—is associated with higher body mass in humans and birds. It is widely assumed that food insecurity-induced fattening is caused by increased food consumption, but there is little evidence supporting this in any species. We developed a novel technology for measuring foraging, food intake and body mass in small groups of aviary-housed European starlings (Sturnus vulgaris). Across four exploratory experiments, we demonstrate that birds responded to 1–2 weeks of food insecurity by increasing their body mass despite eating less. Food-insecure birds therefore increased their energetic efficiency, calculated as the body mass maintained per unit of food consumed. Mass gain was greater in birds that were lighter at baseline and in birds that faced greater competition for access to food. Whilst there was variation between experiments in mass gain and food consumption under food insecurity, energetic efficiency always increased. Bomb calorimetry of guano showed reduced energy density under food insecurity, suggesting that the energy assimilated from food increased. Behavioural observations of roosting showed inconsistent evidence for reduced physical activity under food insecurity. Increased energetic efficiency continued for 1–2 weeks after food security was reinstated, indicating an asymmetry in the speed of the response to food insecurity and the recovery from it. Future work to understand the mechanisms underlying food insecurity-induced mass gain should focus on the biological changes mediating increased energetic efficiency rather than increased energy consumption.
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Affiliation(s)
- Melissa Bateson
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Clare Andrews
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jonathon Dunn
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Charlotte B C M Egger
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Francesca Gray
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Molly Mchugh
- Biosciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Daniel Nettle
- Population Health Sciences Institute/Centre for Behaviour and Evolution, Newcastle University, Newcastle upon Tyne, United Kingdom
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14
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DeSimone JG, Tobalske BW, Breuner CW. Physiology and behavior under food limitation support an escape, not preparative, response in the nomadic pine siskin ( Spinus pinus). J Exp Biol 2021; 224:jeb238774. [PMID: 33376142 DOI: 10.1242/jeb.238774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/18/2020] [Indexed: 11/20/2022]
Abstract
Migration allows animals to use resources that are variable in time and/or space, with different migratory strategies depending on the predictability of resource variation. When food varies seasonally, obligate migrants anticipate and prepare for migration. In contrast, facultative migrants, whose movements are unpredictable in timing and destination, may prepare for either migration or escape when resources are depleted. We propose and test two alternative hypotheses regarding the behavioral and physiological responses of facultative migrants to declining food availability. (1) The prepare hypothesis predicts that facultative migrants prepare for departure by increasing fuel stores in response to declining food availability, and elevations of baseline corticosterone (CORT) facilitate increased activity. (2) The escape hypothesis predicts that facultative migrants do not prepare for departure, body condition declines as food availability declines, and stress-induced levels of CORT induce escape behavior when both energetic condition and food resources are low. We conducted a 16-day experiment, measuring body composition (using quantitative magnetic resonance), activity (using force perches) and baseline CORT in pine siskins (Spinus pinus) given ad libitum food or a slow decline, fast decline or randomly changing amount of food. Our results support the escape hypothesis: body condition declined as food declined, decreases in body and fat mass were associated with increases in baseline CORT, and activity increased only when food availability was low. This work suggests that facultative migration in autumn allows birds to escape low-resource areas and that the underlying physiological mechanisms differ from those driving both seasonal, obligate migrations and spring nomadic movements.
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Affiliation(s)
- Joely G DeSimone
- Ecology and Evolution, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Bret W Tobalske
- Ecology and Evolution, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Creagh W Breuner
- Ecology and Evolution, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
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de Bruijn R, Romero LM. Chronic stress reverses enhanced neophobia following an acute stressor in European starlings. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 335:265-274. [PMID: 33231919 DOI: 10.1002/jez.2431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 11/09/2020] [Accepted: 11/10/2020] [Indexed: 11/08/2022]
Abstract
Neophobia is an animal's avoidance of novelty. Animals tend to respond to novel objects by increasing their latency to approach the objects, and they eventually habituate after repeated exposure by attenuating this increased approach latency. Interestingly, the physiological stress response does not appear to have a causal link to neophobia, although acute stress can prevent animals from habituating to novel objects, possibly through a permissive effect. Chronic stress can induce an anxiety-like state in animals, while often disrupting the ability to respond to acute stress. We thus hypothesized that chronic stress may increase neophobia and tested this by inducing chronic stress in wild-caught European starlings (Sturnus vulgaris). Four distinct anthropogenic stressors were administered daily for 30 min each in a randomized order for 21 days. We then evaluated whether exposure to chronic stress altered the latency to approach a novel object placed on or near a food dish presented after overnight fasting. Chronically stressed birds and nonstressed controls exhibited similar initial neophobic responses to novel objects and showed similar habituation in response to repeated exposure. However, when birds were exposed to 15 min of restraint before repeated exposure to the same object, habituation was eliminated in control birds (i.e., they continued to respond with neophobia), whereas chronically stressed birds continued to show habituation as measured by attenuated approach latencies. These results demonstrate that an acute stress response (restraint) has a different impact on neophobia depending upon whether the bird is or is not concurrently exposed to chronic stress.
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Affiliation(s)
- Robert de Bruijn
- Department of Biology, Tufts University, Medford, Massachusetts, USA
| | - L Michael Romero
- Department of Biology, Tufts University, Medford, Massachusetts, USA
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Stevenson SA, Piepenburg A, Spool JA, Angyal CS, Hahn AH, Zhao C, Riters LV. Endogenous opioids facilitate intrinsically-rewarded birdsong. Sci Rep 2020; 10:11083. [PMID: 32632172 PMCID: PMC7338348 DOI: 10.1038/s41598-020-67684-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 06/11/2020] [Indexed: 01/16/2023] Open
Abstract
Many songbirds sing in non-reproductive contexts while in flocks. Singing in such gregarious contexts is critical for maintaining and learning songs; however, song is not directed towards other individuals and has no obvious, immediate social consequences. Studies using conditioned place preference (CPP) tests of reward indicate that song production in gregarious contexts correlates positively with a bird’s intrinsic reward state and with opioid markers in the medial preoptic nucleus (mPOA). However, the causal involvement of opioids in gregarious song is unknown. Here we report that the selective mu opioid receptor (MOR) agonist fentanyl dose-dependently facilitates gregarious song and reduces stress/anxiety-related behavior in male and female European starlings. Furthermore, infusion of siRNA targeting MORs specifically in mPOA both suppresses gregarious song and disrupts the positive association between affective state and singing behavior, as revealed using CPP tests of song-associated reward. Results strongly implicate opioids in gregarious song and suggest that endogenous opioids in the mPOA may facilitate song by influencing an individual’s intrinsic reward state.
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Affiliation(s)
- Sharon A Stevenson
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Alice Piepenburg
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Jeremy A Spool
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.,Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Caroline S Angyal
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Allison H Hahn
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.,Department of Psychology, St. Norbert College, De Pere, WI, 54115, USA
| | - Changjiu Zhao
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Lauren V Riters
- Department of Integrative Biology, University of Wisconsin Madison, 428 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA.
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Cerqueira M, Millot S, Felix A, Silva T, Oliveira GA, Oliveira CCV, Rey S, MacKenzie S, Oliveira R. Cognitive appraisal in fish: stressor predictability modulates the physiological and neurobehavioural stress response in sea bass. Proc Biol Sci 2020; 287:20192922. [PMID: 32183629 PMCID: PMC7126027 DOI: 10.1098/rspb.2019.2922] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 02/23/2020] [Indexed: 12/19/2022] Open
Abstract
The role of cognitive factors in triggering the stress response is well established in humans and mammals (aka cognitive appraisal theory) but very seldom studied in other vertebrate taxa. Predictability is a key factor of the cognitive evaluation of stimuli. In this study, we tested the effects of stressor predictability on behavioral, physiological and neuromolecular responses in the European sea bass (Dicentrarchus labrax). Groups of four fish were exposed to a predictable (signalled) or unpredictable (unsignalled) stressor. Stressor predictability elicited a lower behavioural response and reduced cortisol levels. Using the expression of immediate early genes (c-fos, egr-1, bdnf and npas4) as markers of neuronal activity, we monitored the activity of three sea bass brain regions known to be implicated in stressor appraisal: the dorsomedian telencephalon, Dm (putative homologue of the pallial amygdala); and the dorsal (Dld) and ventral (Dlv) subareas of the dorsolateral telencephalon (putative homologue of the hippocampus). The activity of both the Dm and Dlv significantly responded to stressor predictability, suggesting an evolutionarily conserved role of these two brain regions in information processing related to stressor appraisal. These results indicate that stressor predictability plays a key role in the activation of the stress response in a teleost fish, hence highlighting the role of cognitive processes in fish stress.
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Affiliation(s)
- M. Cerqueira
- Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Faro, Portugal
| | - S. Millot
- Laboratoire Ressources Halieutiques, Ifremer, L'Houmeau, France
| | - A. Felix
- ISPA – Instituto Universitário, Lisbon, Portugal
| | | | - G. A. Oliveira
- ISPA – Instituto Universitário, Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - C. C. V. Oliveira
- Centro de Ciências do Mar (CCMAR), Universidade do Algarve, Faro, Portugal
| | - S. Rey
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - S. MacKenzie
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - R. Oliveira
- ISPA – Instituto Universitário, Lisbon, Portugal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Champalimaud Research, Lisbon, Portugal
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18
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Abstract
Our target article proposes that a new concept - incentive hope - is necessary in the behavioral sciences to explain animal foraging under harsh environmental conditions. Incentive hope refers to a specific motivational mechanism in the brain - considered only in mammals and birds. But it can also be understood at a functional level, as an adaptive behavioral strategy that contributes to improve survival. Thus, this concept is an attempt to bridge across different research fields such as behavioral psychology, reward neuroscience, and behavioral ecology. Many commentaries suggest that incentive hope even could help understand phenomena beyond these research fields, including food wasting and food sharing, mental energy conservation, diverse psychopathologies, irrational decisions in invertebrates, and some aspects of evolution by means of sexual selection. We are favorable to such extensions because incentive hope denotes an unconscious process capable of working against many forms of adversity; organisms do not need to hope as a subjective feeling, but to behave as if they had this feeling. In our response, we carefully discuss each suggestion and criticism and reiterate the importance of having a theory accounting for motivation under reward uncertainty.
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Nettle D, Bateson M. Food-Insecure Women Eat a Less Diverse Diet in a More Temporally Variable Way: Evidence from the US National Health and Nutrition Examination Survey, 2013-4. J Obes 2019; 2019:7174058. [PMID: 31662904 PMCID: PMC6791191 DOI: 10.1155/2019/7174058] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 08/06/2019] [Accepted: 09/07/2019] [Indexed: 12/18/2022] Open
Abstract
Food insecurity is associated with high body weight amongst women, but not men, in high-income countries. Previous research using food recalls suggests that the total energy intake of food-insecure women is not elevated, though macronutrient composition may differ from that of food-secure women. There is limited evidence on temporal patterns of food consumption. Here, we used food recalls from women in the 2013-4 cycle of the National Health and Nutrition Examination Survey (NHANES, n = 2798) to characterise temporal patterns of food consumption in relation to food insecurity. Compared to the food-secure, food-insecure women had more variable time gaps between eating; ate a smaller and less variable number of distinct foods at a time; were more variable from day to day in their time of first consumption; were more variable from day to day in the number of times they ate; and consumed relatively more carbohydrate, less protein, and less fibre. However, their overall energy intake was no higher. Food-insecure women had higher BMIs (2.25 kg/m2), and around 15% of the BMI difference between food-insecure and food-secure women was accounted for by their more variable time gaps between eating, their lower diversity of foods, and their lower fibre consumption. Food insecurity is associated with measureable differences in the temporal pattern of food consumption, and some of these differences shed light on how food-insecure women come to have higher body weights.
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Affiliation(s)
- Daniel Nettle
- Centre for Behaviour and Evolution & Institute of Neuroscience, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle NE2 4HH, UK
| | - Melissa Bateson
- Centre for Behaviour and Evolution & Institute of Neuroscience, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle NE2 4HH, UK
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de Bruijn R, Romero LM. The role of glucocorticoids in the vertebrate response to weather. Gen Comp Endocrinol 2018; 269:11-32. [PMID: 30012539 DOI: 10.1016/j.ygcen.2018.07.007] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/29/2018] [Accepted: 07/13/2018] [Indexed: 12/18/2022]
Abstract
Changes in the environment related to inclement weather can threaten survival and reproductive success both through direct adverse exposure and indirectly by decreasing food availability. Glucocorticoids, released during activation of the hypothalamic-pituitary-adrenal axis as part of the stress response, are an important candidate for linking vertebrate coping mechanisms to weather. This review attempts to determine if there is a consensus response of glucocorticoids to exposure to weather-related stimuli, including food availability, precipitation, temperature and barometric pressure. The included studies cover field and laboratory studies for all vertebrate taxa, and are separated into four exposure periods, e.g., hours, days, weeks and months. Each reported result was assigned a score based on the glucocorticoid response, e.g., increased, no change, or decreased. Short-term exposure to weather-related stimuli, of up to 24 h, is generally associated with increased glucocorticoids (79% of studies), suggesting that these stimuli are perceived as stressors by most animals. In contrast, the pattern for exposures longer than 24 h shows more variation, even though a majority of studies still report an increase (64%). Lack of glucocorticoid increases appeared to result from instances where: (1) prolonged exposure was a predictable part of the life history of an animal; (2) environmental context was important for the ultimate effect of a stimulus (e.g., precipitation limited food availability in one environment, but increased food in another); (3) prolonged exposure induced chronic stress; and (4) long-term responses appeared to reflect adaptations to seasonal shifts, instead of to short-term weather. However, there is a strong bias towards studies in domesticated laboratory species and wild animals held in captivity, indicating a need for field studies, especially in reptiles and amphibians. In conclusion, the accumulated literature supports the hypothesis that glucocorticoids can serve as the physiological mechanism promoting fitness during inclement weather.
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Affiliation(s)
- Robert de Bruijn
- Department of Biology, Tufts University, Medford, MA 02155, USA.
| | - L Michael Romero
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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21
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Do Religious Practices and Foraging Behavior Have a Common Motivational Basis? EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2018. [DOI: 10.1007/s40806-018-0182-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Abstract
Food uncertainty has the effect of invigorating food-related responses. Psychologists have noted that mammals and birds respond more to a conditioned stimulus that unreliably predicts food delivery, and ecologists have shown that animals (especially small passerines) consume and/or hoard more food and can get fatter when access to that resource is unpredictable. Are these phenomena related? We think they are. Psychologists have proposed several mechanistic interpretations, while ecologists have suggested a functional interpretation: The effect of unpredictability on fat reserves and hoarding behavior is an evolutionary strategy acting against the risk of starvation when food is in short supply. Both perspectives are complementary, and we argue that the psychology of incentive motivational processes can shed some light on the causal mechanisms leading animals to seek and consume more food under uncertainty in the wild. Our theoretical approach is in agreement with neuroscientific data relating to the role of dopamine, a neurotransmitter strongly involved in incentive motivation, and its plausibility has received some explanatory and predictive value with respect to Pavlovian phenomena. Overall, we argue that the occasional and unavoidable absence of food rewards has motivational effects (called incentive hope) that facilitate foraging effort. We show that this hypothesis is computationally tenable, leading foragers in an unpredictable environment to consume more food items and to have higher long-term energy storage than foragers in a predictable environment.
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de Bruijn R, Reed JM, Romero LM. Chronic repeated exposure to weather-related stimuli elicits few symptoms of chronic stress in captive molting and non-molting European starlings (Sturnus vulgaris). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 327:493-503. [PMID: 29356445 DOI: 10.1002/jez.2134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 09/10/2017] [Accepted: 10/04/2017] [Indexed: 11/08/2022]
Abstract
Repeated exposure to acute stressors causes dramatic changes in an animal's stress physiology and the cumulative effects are often called chronic stress. Recently we showed that short-term exposure to weather-related stimuli, such as temperature change, artificial precipitation, and food restriction, cause acute responses in captive European starlings (Sturnus vulgaris). Here, we examined the effect of repeated exposure to weather-related stressors on heart rate and corticosterone (CORT) of captive non-molting and molting European starlings. Four times every day for 3 weeks, birds were exposed to either 30 min of a subtle (3°C) decrease in temperature, a short bout of simulated rain, or 2 hr of food removal. The order and time of presentation were randomly assigned on each day. We found no differences in heart rate or heart rate variability. Furthermore, there were no changes in baseline CORT levels, CORT negative feedback efficacy, or maximal adrenal capacity. Mass increased across the experimental period only in molting birds. CORT responses to restraint were decreased in both groups following treatment, suggesting the birds had downregulated their responses to acute stress. Molting birds showed evidence of suppression of the HPA axis compared with non-molting birds, which is consistent with previous research. Overall, our data show that repeated exposure to weather-related stressors does not elicit most of the symptoms normally associated with chronic stress.
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Affiliation(s)
- Robert de Bruijn
- Department of Biology, Tufts University, Medford, Massachusetts, USA
| | - J Michael Reed
- Department of Biology, Tufts University, Medford, Massachusetts, USA
| | - L Michael Romero
- Department of Biology, Tufts University, Medford, Massachusetts, USA
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24
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Anselme P, Otto T, Güntürkün O. How unpredictable access to food increases the body fat of small passerines: A mechanistic approach. Behav Processes 2017; 144:33-45. [DOI: 10.1016/j.beproc.2017.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 07/17/2017] [Accepted: 08/24/2017] [Indexed: 12/20/2022]
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25
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Lattin CR, Pechenenko AV, Carson RE. Experimentally reducing corticosterone mitigates rapid captivity effects on behavior, but not body composition, in a wild bird. Horm Behav 2017; 89:121-129. [PMID: 28065712 PMCID: PMC5359069 DOI: 10.1016/j.yhbeh.2016.12.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/23/2016] [Accepted: 12/29/2016] [Indexed: 01/02/2023]
Abstract
Wild animals and captives display physiological and behavioral differences, and it has been hypothesized, but rarely tested, that these differences are caused by sustained elevation of the hormone corticosterone. We used repeated computed tomography (CT) imaging to examine body composition changes in breeding male and female wild house sparrows (Passer domesticus; n=20) in response to two weeks of captivity, and assessed behavioral changes using video recordings. Half of the birds received the drug mitotane, which significantly decreased stress-induced corticosterone titers compared to controls. Based on the CT images, fat volumes increased, and pectoralis muscle density and heart and testes volumes decreased, over the two weeks of captivity in both groups of birds. However, beak-wiping, a behavior that can indicate anxiety and aggression, showed increased occurrence in controls compared to mitotane-treated birds. While our results do not support the hypothesis that these body composition changes were primarily driven by stress-induced corticosterone, our data suggest that experimentally reducing stress-induced corticosterone may mitigate some captivity-induced behavioral changes. Broadly, our results emphasize that researchers should take behavioral and physiological differences between free-living animals and captives into consideration when designing studies and interpreting results. Further, time in captivity should be minimized when birds will be reintroduced back to the wild.
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Affiliation(s)
- Christine R Lattin
- Department of Radiology and Biomedical Imaging, Yale University, 801 Howard Avenue, PO Box 208048, New Haven, CT 06520-8048, United States.
| | - Anita V Pechenenko
- Department of Radiology and Biomedical Imaging, Yale University, 801 Howard Avenue, PO Box 208048, New Haven, CT 06520-8048, United States
| | - Richard E Carson
- Department of Radiology and Biomedical Imaging, Yale University, 801 Howard Avenue, PO Box 208048, New Haven, CT 06520-8048, United States
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26
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Jimeno B, Hau M, Verhulst S. Strong association between corticosterone and temperature dependent metabolic rate in individual zebra finches. J Exp Biol 2017; 220:4426-4431. [DOI: 10.1242/jeb.166124] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 09/26/2017] [Indexed: 12/22/2022]
Abstract
Glucocorticoid hormones (GCs) are often assumed to be indicators of stress. At the same time, one of their fundamental roles is to facilitate metabolic processes to accommodate changes in energetic demands. While the metabolic function of GCs is thought to be ubiquitous across vertebrates, we are not aware of experiments which tested this directly, i.e., in which metabolic rate was manipulated and measured together with GCs. We therefore tested for a relationship between plasma corticosterone (CORT, ln transformed) and metabolic rate (MR, measured using indirect calorimetry) in a between- and within-individual design in captive zebra finches (Taeniopygia guttata) of both sexes. In each individual, CORT and MR were measured at two different temperature levels: ‘warm’ (22°C) and ‘cold’ (12 °C). CORT and MR were both increased in colder compared to warmer conditions, within individuals, but also across individuals. At the between-individual level, we found a positive relationship between CORT and MR, with an accelerating slope towards higher MR and CORT values. In contrast, the within individual changes in CORT and MR in response to colder conditions were linearly correlated between individuals. The CORT-MR relationship did not differ between the sexes. Our results illustrate the importance of including variation at different levels to better understand physiological modulation. Furthermore, our findings support the interpretation of CORT variation as indicator of metabolic needs.
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Affiliation(s)
- Blanca Jimeno
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands
- Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Michaela Hau
- Max Planck Institute for Ornithology, Seewiesen, Germany
- University of Konstanz, Germany
| | - Simon Verhulst
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands
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27
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Anselme P. Motivational control of sign-tracking behaviour: A theoretical framework. Neurosci Biobehav Rev 2016; 65:1-20. [DOI: 10.1016/j.neubiorev.2016.03.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 02/25/2016] [Accepted: 03/21/2016] [Indexed: 12/14/2022]
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28
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Hau M, Casagrande S, Ouyang J, Baugh A. Glucocorticoid-Mediated Phenotypes in Vertebrates. ADVANCES IN THE STUDY OF BEHAVIOR 2016. [DOI: 10.1016/bs.asb.2016.01.002] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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29
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Homberger B, Jenni-Eiermann S, Jenni L. Distinct responses of baseline and stress-induced corticosterone levels to genetic and environmental factors. Gen Comp Endocrinol 2015; 210:46-54. [PMID: 25307951 DOI: 10.1016/j.ygcen.2014.09.020] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 09/24/2014] [Accepted: 09/30/2014] [Indexed: 12/31/2022]
Abstract
Glucocorticoid (GC) hormones, i.e. corticosterone (CORT) in birds, support physiological homeostasis and facilitate adaptations to stressful situations. However, maintaining high GC levels are energetically costly and interfere with other physiological processes. To keep the balance of costs and benefits of GC hormones, various mechanisms act to adapt GC levels to environmental conditions on different timescales, i.e. over generations, between parents and their offspring and within the life-time of a single individual. We elucidated whether two strains (domesticated and wild) of grey partridges (Perdix perdix) differed in the developmental trajectories of baseline and stress response CORT throughout the first 80 days of life. We also explored the potential of prenatal and postnatal factors, e.g. parental origin, predictable vs. unpredictable food treatments, individual and social factors to modify these trajectories. Baseline CORT was similar between strains and unaffected by perinatal food treatments. It was negatively related to body size and body condition. Conversely, the CORT stress response was not markedly affected by physiological condition. It was stronger in wild than in domesticated birds and it increased with age. Birds subjected to prenatal unpredictable food supply exhibited an accelerated development of the CORT stress response which could reflect an adaptive maternal effect. We conclude that the vital role of baseline CORT may allow little adaptive scope since changes can quickly become detrimental. In contrast, the CORT stress response may show considerable adaptive potential which might ultimately support homeostasis in a changing environment.
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30
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Davies S, Deviche P. At the crossroads of physiology and ecology: food supply and the timing of avian reproduction. Horm Behav 2014; 66:41-55. [PMID: 24727023 DOI: 10.1016/j.yhbeh.2014.04.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/01/2014] [Accepted: 04/05/2014] [Indexed: 01/19/2023]
Abstract
This article is part of a Special Issue “Energy Balance”. The decision of when to breed is crucial to the reproductive success and fitness of seasonally breeding birds. The availability of food for adults prior to breeding has long been thought to play a critical role in timing the initiation of seasonal reproductive events, in particular laying. However, unequivocal evidence for such a role remains limited and the physiological mechanisms by which an increase in food availability results in seasonal activation of the reproductive system are largely speculative. This lack of mechanistic information partly reflects a lack of integration of ecological and physiological approaches to study seasonal reproduction. Indeed, most work pertaining to the role of food availability for adults on the timing of avian reproduction has been ecological and has focused almost exclusively on female traits associated with reproductive timing (e.g., lay date and clutch size). By contrast, most work on the physiological bases of the relationship between food availability and the timing of reproduction has investigated male traits associated with reproductive development (e.g., reproductive hormones and gonadal development). To advance our understanding of these topics, we review the role of proximate factors including food availability, social factors, and ambient temperature in the control of breeding decisions, and discuss the role of three potential candidates (leptin, glucocorticoids, and GnIH-neuropeptide Y) that may mediate the effects of food availability on these decisions. We emphasize that future progress in this area is heavily contingent upon the use of physiology-based approaches and their integration into current ecological frameworks.
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Affiliation(s)
- Scott Davies
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
| | - Pierre Deviche
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
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31
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Grava T, Fairhurst GD, Avey MT, Grava A, Bradley J, Avis JL, Bortolotti GR, Sturdy CB, Otter KA. Habitat quality affects early physiology and subsequent neuromotor development of juvenile black-capped chickadees. PLoS One 2013; 8:e71852. [PMID: 23951257 PMCID: PMC3741205 DOI: 10.1371/journal.pone.0071852] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 07/05/2013] [Indexed: 11/18/2022] Open
Abstract
In songbirds, the ability to learn and render the species-specific song is influenced by the development of both the song nuclei in the brain and the syrinx (bird's vocal apparatus) early in the bird's life. In black-capped chickadees (Poecille atricapillus), habitat quality is known to affect song structure, with birds in high-quality habitat (mature forest) having a higher song consistency than birds in low-quality habitat (young forest). Although this difference is suspected to stem from differences in development, the developmental status of juvenile birds in either habitat remains unexplored. In this study, we used ptilochronology and feather corticosterone to compare the conditional state of juvenile chickadees in young and mature forest during two distinct periods of song learning - the sensory phase, which occurs prior to settlement, and the sensorimotor phase, which occurs post-settlement. A sample of juvenile males was captured and euthanized several weeks prior to their first breeding season to compare the development of song center nuclei and syrinx in both habitats. The corticosterone levels of natally-grown feathers were greater among birds that settled in mature than young forests - as these feathers were grown pre-settlement, they reflect differences in physiology during the sensory phase. This difference in conditional state is reflected by differences in syrinx and song center nuclei development later during the sensorimotor phase - birds in young forest have smaller syrinx, and moderately-larger RA, than birds in mature forest. Those differences could be responsible for the difference in consistency in song structure observed across habitats. The difference in physiological state across habitats, combined with potential compounding effect of differences in winter resources between habitats, could influence the difference in syrinx and neural development seen in juvenile males during the early spring, and influence the male's ability to learn and render their species-specific song.
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Affiliation(s)
- Thibault Grava
- Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, British Columbia, Canada.
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32
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Homberger B, Jenni-Eiermann S, Roulin A, Jenni L. The impact of pre- and post-natal contexts on immunity, glucocorticoids and oxidative stress resistance in wild and domesticated grey partridges. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12092] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
| | | | - Alexandre Roulin
- Department of Ecology and Evolution, Biophore; University of Lausanne; 1015; Lausanne; Switzerland
| | - Lukas Jenni
- Swiss Ornithological Institute; Seerose 1; 6204; Sempach; Switzerland
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Fokidis HB, des Roziers MB, Sparr R, Rogowski C, Sweazea K, Deviche P. Unpredictable food availability induces metabolic and hormonal changes independent of food intake in a sedentary songbird. ACTA ACUST UNITED AC 2012; 215:2920-30. [PMID: 22837467 DOI: 10.1242/jeb.071043] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Environments often vary with regard to their temporal resource availability, but little is understood concerning how resource predictability impacts animals. The adaptive regulation hypothesis suggests that organisms act to conserve their current energetic state during periods of diminished food access and recuperate their energetic reserves (fat and muscle) during periods of greater food availability. In contrast, the chronic stress hypothesis suggests that variation in access to food can induce a prolonged stress response, resulting in maladaptive usage of energy reserves and increased behavioral activity. To distinguish between these hypotheses we compared the behavioral, hormonal and metabolic responses of captive curve-billed thrashers, Toxostoma curvirostre, fed varying amounts each day (variable group) with those of birds fed a constant amount every day (constant feeding group). Birds of both groups consumed, on average, a similar total amount of food during the course of the study, but birds in the variable feeding group lost mass and increased their circulating initial levels of the stress hormone corticosterone, showed evidence for increased secretion of a hypothalamic stress peptide, vasotocin, used greater amounts of fat and protein energy reserves, and were more behaviorally active than birds in the constant feeding group. Overall, these findings support the chronic stress hypothesis and suggest that birds such as thrashers may be particularly susceptible to the perception of unpredictable variation in food supplies independent of actual energetic constraints.
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Affiliation(s)
- H Bobby Fokidis
- Department of Psychology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
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Echeverry-Galvis MA, Hau M. Molt–breeding overlap alters molt dynamics and behavior in zebra finches, Taeniopygia guttata castanotis. J Exp Biol 2012; 215:1957-64. [DOI: 10.1242/jeb.065474] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
SUMMARY
Costly events in the life history cycle of organisms such as reproduction, migration and pelage/plumage replacement are typically separated in time to maximize their outcome. Such temporal separation is thought to be necessitated by energetical trade-offs, and mediated through physiological processes. However, certain species, such as tropical birds, are able to overlap two costly life history stages: reproduction and feather replacement. It has remained unclear how both events progress when they co-occur over extended periods of time. Here we determined the consequences and potential costs of such overlap by comparing molt and behavioral patterns in both sexes of captive zebra finches (Taeniopygia guttata castanotis) that were solely molting or were overlapping breeding and molt. Individuals overlapping the early stages of breeding with molt showed a roughly 40% decrease in the growth rate of individual feathers compared with birds that were molting but not breeding. Further, individuals that overlapped breeding and molt tended to molt fewer feathers simultaneously and exhibited longer intervals between shedding consecutive feathers on the tail or the same wing as well as delays in shedding corresponding flight feathers on opposite sides. Overlapping individuals also altered their time budgets: they devoted more than twice the time to feeding while halving the time spent for feather care in comparison to molt-only individuals. These data provide experimental support for the previously untested hypothesis that when molt and reproduction overlap in time, feather replacement will occur at a slower and less intense rate. There were no sex differences in any of the variables assessed, except for a tendency in females to decline body condition more strongly over time during the overlap than males. Our data indicate the existence of major consequences of overlapping breeding and molt, manifested in changes in both molt dynamics and time budgets of both sexes. It is likely that under harsher conditions in natural environments such consequences will be more severe and may result in fitness consequences.
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Affiliation(s)
- Maria A. Echeverry-Galvis
- Department of Ecology and Evolutionary Biology, Princeton University, 106A Guyot Hall, Princeton, NJ 08544, USA
| | - Michaela Hau
- Max Planck Institute for Ornithology, Department of Migration and Immuno-ecology, Am Obstberg 1, D-78315 Radolfzell, Germany
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