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Vincenzi S, Crivelli AJ, Munch S, Skaug HJ, Mangel M. Trade-offs between accuracy and interpretability in von Bertalanffy random-effects models of growth. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:1535-1552. [PMID: 27755751 DOI: 10.1890/15-1177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/23/2015] [Accepted: 11/05/2015] [Indexed: 06/06/2023]
Abstract
Better understanding of variation in growth will always be an important problem in ecology. Individual variation in growth can arise from a variety of processes; for example, individuals within a population vary in their intrinsic metabolic rates and behavioral traits, which may influence their foraging dynamics and access to resources. However, when adopting a growth model, we face trade-offs between model complexity, biological interpretability of parameters, and goodness of fit. We explore how different formulations of the von Bertalanffy growth function (vBGF) with individual random effects and environmental predictors affect these trade-offs. In the vBGF, the growth of an organism results from a dynamic balance between anabolic and catabolic processes. We start from a formulation of the vBGF that models the anabolic coefficient (q) as a function of the catabolic coefficient (k), a coefficient related to the properties of the environment (γ) and a parameter that determines the relative importance of behavior and environment in determining growth (ψ). We treat the vBGF parameters as a function of individual random effects and environmental variables. We use simulations to show how different functional forms and individual or group variability in the growth function's parameters provide a very flexible description of growth trajectories. We then consider a case study of two fish populations of Salmo marmoratus and Salmo trutta to test the goodness of fit and predictive power of the models, along with the biological interpretability of vBGF's parameters when using different model formulations. The best models, according to AIC, included individual variability in both k and γ and cohort as predictor of growth trajectories, and are consistent with the hypothesis that habitat selection is more important than behavioral and metabolic traits in determining lifetime growth trajectories of the two fish species. Model predictions of individual growth trajectories were largely more accurate than predictions based on mean size-at-age of fish. Our method shares information across individuals, and thus, for both fish populations investigated, allows using a single measurement early in the life of individual fish or cohort to obtain accurate predictions of lifetime individual or cohort size-at-age.
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Affiliation(s)
- Simone Vincenzi
- Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California, Santa Cruz, California, 95064, USA
- Dipartimento di Elettronica, Informazione e Bioingegneria Politecnico di Milano, Via Ponzio 34/5, I-20133, Milan, Italy
| | - Alain J Crivelli
- Station Biologique de la Tour du Valat, Le Sambuc, F-1320, France
| | - Stephan Munch
- Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 110 Shaffer Road, Santa Cruz, California, 95060, USA
| | - Hans J Skaug
- Department of Mathematics, University of Bergen, Box 7800, 5020, Bergen, Norway
| | - Marc Mangel
- Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California, Santa Cruz, California, 95064, USA
- Department of Biology, University of Bergen, 5020, Bergen, Norway
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103
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Dunlap KD, Tran A, Ragazzi MA, Krahe R, Salazar VL. Predators inhibit brain cell proliferation in natural populations of electric fish, Brachyhypopomus occidentalis. Proc Biol Sci 2016; 283:20152113. [PMID: 26842566 PMCID: PMC4760157 DOI: 10.1098/rspb.2015.2113] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 01/08/2016] [Indexed: 11/12/2022] Open
Abstract
Compared with laboratory environments, complex natural environments promote brain cell proliferation and neurogenesis. Predators are one important feature of many natural environments, but, in the laboratory, predatory stimuli tend to inhibit brain cell proliferation. Often, laboratory predatory stimuli also elevate plasma glucocorticoids, which can then reduce brain cell proliferation. However, it is unknown how natural predators affect cell proliferation or whether glucocorticoids mediate the neurogenic response to natural predators. We examined brain cell proliferation in six populations of the electric fish, Brachyhypopomus occidentalis, exposed to three forms of predator stimuli: (i) natural variation in the density of predatory catfish; (ii) tail injury, presumably from predation attempts; and (iii) the acute stress of capture. Populations with higher predation pressure had lower density of proliferating (PCNA+) cells, and fish with injured tails had lower proliferating cell density than those with intact tails. However, plasma cortisol did not vary at the population level according to predation pressure or at the individual level according to tail injury. Capture stress significantly increased cortisol, but only marginally decreased cell proliferation. Thus, it appears that the presence of natural predators inhibits brain cell proliferation, but not via mechanisms that depend on changes in basal cortisol levels. This study is the first demonstration of predator-induced alteration of brain cell proliferation in a free-living vertebrate.
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Affiliation(s)
- Kent D Dunlap
- Department of Biology, Trinity College, Hartford, CT 06106, USA
| | - Alex Tran
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | | | - Rüdiger Krahe
- Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1
| | - Vielka L Salazar
- Department of Biology, Cape Breton University, Sydney, Nova Scotia, Canada B1P 6L2
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104
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Roy T, Bhat A. Learning and Memory in Juvenile Zebrafish: What makes the Difference - Population or Rearing Environment? Ethology 2016. [DOI: 10.1111/eth.12470] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Tamal Roy
- Department of Biological Sciences; Indian Institute of Science Education and Research Kolkata; Mohanpur West Bengal India
| | - Anuradha Bhat
- Department of Biological Sciences; Indian Institute of Science Education and Research Kolkata; Mohanpur West Bengal India
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105
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Clarke CN, Fraser DJ, Purchase CF. Lifelong and carry-over effects of early captive exposure in a recovery program for Atlantic salmon (Salmo salar). Anim Conserv 2016. [DOI: 10.1111/acv.12251] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- C. N. Clarke
- Fish Evolutionary Ecology Research Group; Environmental Science Graduate Program; Memorial University; St. John's NL Canada
| | - D. J. Fraser
- Department of Biology; Concordia University; Montreal QC Canada
| | - C. F. Purchase
- Department of Biology; Fish Evolutionary Ecology Research Group; Memorial University; St. John's NL Canada
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Climbing experience in glass eels: A cognitive task or a matter of physical capacities? Physiol Behav 2015; 151:448-55. [PMID: 26260433 DOI: 10.1016/j.physbeh.2015.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 07/28/2015] [Accepted: 08/01/2015] [Indexed: 12/29/2022]
Abstract
The European eel is a panmictic species, whose decline has been recorded since the last 30 years. Among human-induced environmental factors of decline, the impact of water dams during species migration is questioned. Indeed, water impoundments can be a severe obstacle for young eels trying to reach the upstream freshwater zones, even if they are equipped with fish-friendly passes. The passage by such devices could be an important event shaping the outcome of the future life and life history traits of eels. We studied what phenotypic traits were associated with the event of experience of passage by water obstacles. We analyzed specific enzyme activities and/or gene transcription levels in the muscle and brain to test whether the obstacle passage is rather a physical or cognitive task. We found that after a long period of maintenance under homogenous conditions, transcription levels of several genes linked to synaptic plasticity, neurogenesis and thyroid activity differed among the field-experience groups. In contrast, muscle gene transcription levels or enzymatic activities did not show any differences among fish groups. We suggest that cognitive processes such as learning and memory acquisition rather than swimming-related metabolic capacities are involved in passage of water obstacles by young eels.
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109
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Podgorniak T, Milan M, Pujolar JM, Maes GE, Bargelloni L, De Oliveira E, Pierron F, Daverat F. Differences in brain gene transcription profiles advocate for an important role of cognitive function in upstream migration and water obstacles crossing in European eel. BMC Genomics 2015; 16:378. [PMID: 25962588 PMCID: PMC4427925 DOI: 10.1186/s12864-015-1589-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/27/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND European eel is a panmictic species, whose decline has been recorded since the last 20 years. Among human-induced environmental factors of decline, the impact of water dams during species migration is questioned. The main issue of this study was to pinpoint phenotypic traits that predisposed glass eels to successful passage by water barriers. The approach of the study was individual-centred and without any a priori hypothesis on traits involved in the putative obstacles selective pressure. We analyzed the transcription level of 14,913 genes. RESULTS Transcriptome analysis of three tissues (brain, liver and muscle) from individuals sampled on three successive forebays separated by water obstacles indicated different gene transcription profiles in brain between the two upstream forebays. No differences in gene transcription levels were observed in liver and muscle samples among segments. A total of 26 genes were differentially transcribed in brain. These genes encode for, among others, keratins, cytokeratins, calcium binding proteins (S100 family), cofilin, calmodulin, claudin and thy-1 membrane glycoprotein. The functional analysis of these genes highlighted a putative role of cytoskeletal dynamics and synaptic plasticity in fish upstream migration. CONCLUSION Synaptic connections in brain are solicited while eels are climbing the obstacles with poorly designed fishways. Successful passage by such barriers can be related to spatial learning and spatial orientation abilities when fish is out of the water.
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Affiliation(s)
- Tomasz Podgorniak
- Irstea Bordeaux, UR EABX, HYNES (Irstea - EDF R&D), 50 avenue de Verdun, Cestas, 33612, Cedex, France.
| | - Massimo Milan
- University of Padova, Viale dell'Università 16, Legnaro, 35020, PD, Italy.
| | - Jose Marti Pujolar
- University of Padova, Viale dell'Università 16, Legnaro, 35020, PD, Italy. .,Department of Bioscience, Aarhus University, Ny Munkegade 114, Aarhus C, DK-8000, Denmark.
| | - Gregory E Maes
- Centre for Sustainable Tropical Fisheries and Aquaculture, Comparative Genomics Centre, College of Marine and Environmental Sciences, James Cook University, Townsville, Qld 4811, Australia. .,Laboratory of Biodiversity and Evolutionary Genomics, University of Leuven (KU Leuven), Leuven, B-3000, Belgium.
| | - Luca Bargelloni
- University of Padova, Viale dell'Università 16, Legnaro, 35020, PD, Italy.
| | - Eric De Oliveira
- EDF R&D LNHE, HYNES (Irstea-EDF R&D), 6, quai Watier, Bat Q, Chatou, 78400, France.
| | - Fabien Pierron
- Univ. Bordeaux, EPOC, UMR 5805, Talence, F-33400, France. .,CNRS, EPOC, UMR 5805, Talence, F-33400, France.
| | - Francoise Daverat
- Irstea Bordeaux, UR EABX, HYNES (Irstea - EDF R&D), 50 avenue de Verdun, Cestas, 33612, Cedex, France.
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Bhat A, Greulich MM, Martins EP. Behavioral Plasticity in Response to Environmental Manipulation among Zebrafish (Danio rerio) Populations. PLoS One 2015; 10:e0125097. [PMID: 25927838 PMCID: PMC4415955 DOI: 10.1371/journal.pone.0125097] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/12/2015] [Indexed: 01/12/2023] Open
Abstract
Plastic responses can have adaptive significance for organisms occurring in unpredictable environments, migratory species and organisms occupying novel environments. Zebrafish (Danio rerio) occur in a wide range of habitats and environments that fluctuate frequently across seasons and habitats. We expect wild populations of fish to be behaviorally more flexible than fish reared in conventional laboratory and hatchery environments. We measured three behavioral traits among 2 wild (U and PN) and 1 laboratory bred (SH) zebrafish populations in four environments differing in water flow and vegetation regimes. We found that the degree of plasticity varied with the type of behavior and also among populations. In general, vegetation increased aggression and water flow decreased latency to feed after a disturbance, but the patterns were population dependent. For example, while wild U fish fed more readily after a disturbance in vegetated and/or flowing habitats, fish from the wild PN population and lab-reared SH strain showed little variation in foraging across different environmental conditions. Zebrafish from all the three populations were more aggressive when tested in an arena with vegetation. In contrast, while there was an inter-population difference in shoaling distances, variation in shoaling distance across environmental conditions within populations was not significant. These results suggest that both foraging and aggression in zebrafish are more plastic and influenced by immediate context than is shoaling distance, which may have a stronger genetic basis. Our findings point to different underlying mechanisms influencing the expression of these traits and warrants further investigations.
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Affiliation(s)
- Anuradha Bhat
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, United States of America
- Department of Biological Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur, India
| | - Melissa M. Greulich
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, United States of America
| | - Emília P. Martins
- Department of Biology and Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, Indiana, United States of America
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111
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White GE, Brown C. Microhabitat use affects brain size and structure in intertidal gobies. BRAIN, BEHAVIOR AND EVOLUTION 2015; 85:107-16. [PMID: 25896449 DOI: 10.1159/000380875] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 03/17/2014] [Indexed: 11/19/2022]
Abstract
The ecological cognition hypothesis poses that the brains and behaviours of individuals are largely shaped by the environments in which they live and the associated challenges they must overcome during their lives. Here we examine the effect of environmental complexity on relative brain size in 4 species of intertidal gobies from differing habitats. Two species were rock pool specialists that lived on spatially complex rocky shores, while the remainder lived on dynamic, but structurally simple, sandy shores. We found that rock pool-dwelling species had relatively larger brains and telencephalons in particular, while sand-dwelling species had a larger optic tectum and hypothalamus. In general, it appears that various fish species trade off neural investment in specific brain lobes depending on the environment in which they live. Our previous research suggests that rock pool species have greater spatial learning abilities, enabling them to navigate their spatially complex environment, which may account for their enlarged telencephalon, while sand-dwelling species likely have a reduced need for spatial learning, due to their spatially simple habitat, and a greater need for visual acuity. The dorsal medulla and cerebellum size was unaffected by the habitat in which the fish lived, but there were differences between species indicative of species-specific trade-offs in neural investment.
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Affiliation(s)
- Gemma E White
- Department of Biological Sciences, Macquarie University, North Ryde, N.S.W., Australia
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112
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Transcriptomic responses of Atlantic salmon (Salmo salar) to environmental enrichment during juvenile rearing. PLoS One 2015; 10:e0118378. [PMID: 25742646 PMCID: PMC4350989 DOI: 10.1371/journal.pone.0118378] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 01/15/2015] [Indexed: 12/30/2022] Open
Abstract
Captive rearing programs (hatcheries) are often used in conservation and management efforts for at-risk salmonid fish populations. However, hatcheries typically rear juveniles in environments that contrast starkly with natural conditions, which may lead to phenotypic and/or genetic changes that adversely affect the performance of juveniles upon their release to the wild. Environmental enrichment has been proposed as a mechanism to improve the efficacy of population restoration efforts from captive-rearing programs; in this study, we examine the influence of environmental enrichment during embryo and yolk-sac larval rearing on the transcriptome of Atlantic salmon (Salmo salar). Full siblings were reared in either a hatchery environment devoid of structure or an environment enriched with gravel substrate. At the end of endogenous feeding by juveniles, we examined patterns of gene transcript abundance in head tissues using the cGRASP-designed Agilent 4×44K microarray. Significance analysis of microarrays (SAM) indicated that 808 genes were differentially transcribed between the rearing environments and a total of 184 gene ontological (GO) terms were over- or under-represented in this gene list, several associated with mitosis/cell cycle and muscle and heart development. There were also pronounced differences among families in the degree of transcriptional response to rearing environment enrichment, suggesting that gene-by-environment effects, possibly related to parental origin, could influence the efficacy of enrichment interventions.
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113
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Manuel R, Gorissen M, Stokkermans M, Zethof J, Ebbesson LOE, van de Vis H, Flik G, van den Bos R. The effects of environmental enrichment and age-related differences on inhibitory avoidance in zebrafish (Danio rerio Hamilton). Zebrafish 2015; 12:152-65. [PMID: 25646635 DOI: 10.1089/zeb.2014.1045] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The inhibitory avoidance paradigm allows the study of mechanisms underlying learning and memory formation in zebrafish (Danio rerio Hamilton). For zebrafish, the physiology and behavior associated with this paradigm are as yet poorly understood. We therefore assessed the effects of environmental enrichment and fish age on inhibitory avoidance learning. Fish raised in an environmentally enriched tank showed decreased anxiety-like behavior and increased exploration. Enrichment greatly reduced inhibitory avoidance in 6-month (6M)- and 12-month (12 M)-old fish. Following inhibitory avoidance, telencephalic mRNA levels of proliferating cell nuclear antigen (pcna), neurogenic differentiation (neurod), cocaine- and amphetamine-regulated transcript 4 (cart4), and cannabinoid receptor 1 (cnr1) were lower in enriched-housed fish, while the ratios of mineralocorticoid receptor (nr3c2)/glucocorticoid receptor α [nr3c1(α)] and glucocorticoid receptor β [nr3c1(β)]/glucocorticoid receptor α [nr3c1(α)] were higher. This was observed for 6M-old fish only, not for 24-month (24 M) old fish. Instead, 24 M-old fish showed delayed inhibitory avoidance, no effects of enrichment, and reduced expression of neuroplasticity genes. Overall, our data show strong differences in inhibitory avoidance behavior between zebrafish of different ages and a clear reduction in avoidance behavior following housing under environmental enrichment.
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Affiliation(s)
- Remy Manuel
- 1 Department of Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University , Nijmegen, The Netherlands
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114
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Morand-Ferron J, Cole EF, Quinn JL. Studying the evolutionary ecology of cognition in the wild: a review of practical and conceptual challenges. Biol Rev Camb Philos Soc 2015; 91:367-89. [PMID: 25631282 DOI: 10.1111/brv.12174] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 12/11/2014] [Accepted: 12/19/2014] [Indexed: 12/24/2022]
Abstract
Cognition is defined as the processes by which animals collect, retain and use information from their environment to guide their behaviour. Thus cognition is essential in a wide range of behaviours, including foraging, avoiding predators and mating. Despite this pivotal role, the evolutionary processes shaping variation in cognitive performance among individuals in wild populations remain very poorly understood. Selection experiments in captivity suggest that cognitive traits can have substantial heritability and can undergo rapid evolution. However only a handful of studies have attempted to explore how cognition influences life-history variation and fitness in the wild, and direct evidence for the action of natural or sexual selection on cognition is still lacking, reasons for which are diverse. Here we review the current literature with a view to: (i) highlighting the key practical and conceptual challenges faced by the field; (ii) describing how to define and measure cognitive traits in natural populations, and suggesting which species, populations and cognitive traits might be examined to greatest effect; emphasis is placed on selecting traits that are linked to functional behaviour; (iii) discussing how to deal with confounding factors such as personality and motivation in field as well as captive studies; (iv) describing how to measure and interpret relationships between cognitive performance, functional behaviour and fitness, offering some suggestions as to when and what kind of selection might be predicted; and (v) showing how an evolutionary ecological framework, more generally, along with innovative technologies has the potential to revolutionise the study of cognition in the wild. We conclude that the evolutionary ecology of cognition in wild populations is a rapidly expanding interdisciplinary field providing many opportunities for advancing the understanding of how cognitive abilities have evolved.
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Affiliation(s)
- Julie Morand-Ferron
- Department of Biology, University of Ottawa, 30 Marie Curie, Gendron Hall, room 160, Ottawa, Ontario K1N 6N5, Canada
| | - Ella F Cole
- Edward Grey Institute, Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, U.K
| | - John L Quinn
- School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, Ireland
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115
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Johnsson JI, Brockmark S, Näslund J. Environmental effects on behavioural development consequences for fitness of captive-reared fishes in the wild. JOURNAL OF FISH BIOLOGY 2014; 85:1946-1971. [PMID: 25469953 DOI: 10.1111/jfb.12547] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 09/23/2014] [Indexed: 06/04/2023]
Abstract
Why do captive-reared fishes generally have lower fitness in natural environments than wild conspecifics, even when the hatchery fishes are derived from wild parents from the local population? A thorough understanding of this question is the key to design artificial rearing environments that optimize post-release performance, as well as to recognize the limitations of what can be achieved by modifying hatchery rearing methods. Fishes are generally very plastic in their development and through gene-environment interactions, epigenetic and maternal effects their phenotypes will develop differently depending on their rearing environment. This suggests that there is scope for modifying conventional rearing environments to better prepare fishes for release into the wild. The complexity of the natural environment is impossible to mimic in full-scale rearing facilities. So, in reality, the challenge is to identify key modifications of the artificial rearing environment that are practically and economically feasible and that efficiently promote development towards a more wild-like phenotype. Do such key modifications really exist? Here, attempts to use physical enrichment and density reduction to improve the performance of hatchery fishes are discussed and evaluated. These manipulations show potential to increase the fitness of hatchery fishes released into natural environments, but the success is strongly dependent on adequately adapting methods to species and life stage-specific conditions.
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Affiliation(s)
- J I Johnsson
- University of Gothenburg, Department of Biological and Environmental Sciences, Box 463, SE 405 30 Gothenburg, Sweden
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Roberts LJ, Taylor J, Gough PJ, Forman DW, Garcia de Leaniz C. Silver spoons in the rough: can environmental enrichment improve survival of hatchery Atlantic salmon Salmo salar in the wild? JOURNAL OF FISH BIOLOGY 2014; 85:1972-91. [PMID: 25469954 DOI: 10.1111/jfb.12544] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/12/2014] [Indexed: 05/18/2023]
Abstract
This study tested the 'silver spoon' hypothesis which posits that individuals that develop under favourable conditions should enjoy a fitness advantage later in life because they are more likely to recognize and settle in high-quality habitats. Atlantic salmon Salmo salar of two age classes (0+ and 1+ years) were reared in environmentally enriched or standard hatchery tanks for a short period (c. 10 weeks), were then released into a natural river and sampled on repeated occasions to test for silver-spoon effects. Compared with controls, enriched fish had a 6.4% higher recapture rate and settled in higher velocity habitats when they were stocked as 0+ year fry, but not when they were stocked as 1+ year parr. The opportunity for selection was generally higher for environmentally enriched fish than for controls, and also higher for 0+ than for 1+ year fish. Selection favoured individuals with high condition factor, extensive fat reserves and longer than average pectoral fins in both age classes but favoured a small body size in 1+ year and a large body size in 0+ year releases. Stomach analysis showed that enriched fish ate more, and adapted quicker to natural prey than controls. These results provide support for silver-spoon effects in fish and indicate that enrichment can improve post-release performance in conservation programmes, but seemingly only if fish are not kept in captivity for too long.
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Affiliation(s)
- L J Roberts
- Swansea University, Centre for Sustainable Aquatic Research, Department of Biosciences, Swansea SA2 8PP, U.K
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117
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McCallum ES, Capelle PM, Balshine S. Seasonal plasticity in telencephalon mass of a benthic fish. JOURNAL OF FISH BIOLOGY 2014; 85:1785-1792. [PMID: 25229327 DOI: 10.1111/jfb.12507] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/18/2014] [Indexed: 06/03/2023]
Abstract
To gain a deeper understanding of how environmental conditions affect brain plasticity, brain size was explored across different seasons using the invasive round goby Neogobius melanostomus. The results show that N. melanostomus had heavier telencephalon in the spring compared to the autumn across the two years of study. Furthermore, fish in reproductive condition had heavier telencephala, indicating that tissue investment and brain plasticity may be related to reproductive needs in N. melanostomus.
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Affiliation(s)
- E S McCallum
- Department of Psychology, Neuroscience and Behaviour, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada
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118
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