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Morgan R, Finnøen MH, Jensen H, Pélabon C, Jutfelt F. Low potential for evolutionary rescue from climate change in a tropical fish. Proc Natl Acad Sci U S A 2020; 117:33365-33372. [PMID: 33318195 PMCID: PMC7776906 DOI: 10.1073/pnas.2011419117] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Climate change is increasing global temperatures and intensifying the frequency and severity of extreme heat waves. How organisms will cope with these changes depends on their inherent thermal tolerance, acclimation capacity, and ability for evolutionary adaptation. Yet, the potential for adaptation of upper thermal tolerance in vertebrates is largely unknown. We artificially selected offspring from wild-caught zebrafish (Danio rerio) to increase (Up-selected) or decrease (Down-selected) upper thermal tolerance over six generations. Selection to increase upper thermal tolerance was also performed on warm-acclimated fish to test whether plasticity in the form of inducible warm tolerance also evolved. Upper thermal tolerance responded to selection in the predicted directions. However, compared to the control lines, the response was stronger in the Down-selected than in the Up-selected lines in which evolution toward higher upper thermal tolerance was slow (0.04 ± 0.008 °C per generation). Furthermore, the scope for plasticity resulting from warm acclimation decreased in the Up-selected lines. These results suggest the existence of a hard limit in upper thermal tolerance. Considering the rate at which global temperatures are increasing, the observed rates of adaptation and the possible hard limit in upper thermal tolerance suggest a low potential for evolutionary rescue in tropical fish living at the edge of their thermal limits.
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Affiliation(s)
- Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway;
| | - Mette H Finnøen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Henrik Jensen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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52
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Åsheim ER, Andreassen AH, Morgan R, Jutfelt F. Rapid-warming tolerance correlates with tolerance to slow warming but not growth at non-optimal temperatures in zebrafish. J Exp Biol 2020; 223:jeb229195. [PMID: 33071218 DOI: 10.1242/jeb.229195] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 10/12/2020] [Indexed: 12/16/2022]
Abstract
Global warming is predicted to increase both acute and prolonged thermal challenges for aquatic ectotherms. Severe short- and medium-term thermal stress over hours to days may cause mortality, while longer sub-lethal thermal challenges may cause performance declines. The inter-relationship between the responses to short, medium and longer thermal challenges is unresolved. We asked if the same individuals are tolerant to both rapid and slow warming challenges, a question that has so far received little attention. Additionally, we investigated the possibility of a thermal syndrome where individuals in a population are distributed along a warm-type to cold-type axis. We tested whether different thermal traits correlate across individuals by acclimating 200 juvenile zebrafish (Danio rerio) to sub- or supra-optimal temperatures for growth (22 and 34°C) for 40 days and measuring growth and thermal tolerance at two different warming rates. We found that tolerance to rapid warming correlated with tolerance to slow warming in the 22°C treatment. However, individual tolerance to neither rapid nor slow warming correlated with growth at the supra-optimal temperature. We thus find some support for a syndrome-like organisation of thermal traits, but the lack of connection between tolerance and growth performance indicates a restricted generality of a thermal syndrome. The results suggest that tolerance to rapid warming may share underlying physiological mechanisms with tolerance to slower heating, and indicate that the relevance of acute critical thermal tolerance extends beyond the rapid ramping rates used to measure them.
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Affiliation(s)
- Eirik R Åsheim
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
- Organismal and Evolutionary Biology Research Programme, Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Anna H Andreassen
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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53
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Gomez Isaza DF, Cramp RL, Franklin CE. Thermal acclimation offsets the negative effects of nitrate on aerobic scope and performance. J Exp Biol 2020; 223:jeb224444. [PMID: 32647016 DOI: 10.1242/jeb.224444] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 07/06/2020] [Indexed: 08/26/2023]
Abstract
Rising temperatures are set to imperil freshwater fishes as climate change ensues unless compensatory strategies are employed. However, the presence of additional stressors, such as elevated nitrate concentrations, may affect the efficacy of compensatory responses. Here, juvenile silver perch (Bidyanus bidyanus) were exposed to current-day summer temperatures (28°C) or a future climate-warming scenario (32°C) and simultaneously exposed to one of three ecologically relevant nitrate concentrations (0, 50 or 100 mg l-1). We measured indicators of fish performance (growth, swimming), aerobic scope (AS) and upper thermal tolerance (CTmax) to test the hypothesis that nitrate exposure would increase susceptibility to elevated temperatures and limit thermal compensatory responses. After 8 weeks of acclimation, the thermal sensitivity and plasticity of AS and swimming performance were tested at three test temperatures (28, 32, 36°C). The AS of 28°C-acclimated fish declined with increasing temperature, and the effect was more pronounced in nitrate-exposed individuals. In these fish, declines in AS corresponded with poorer swimming performance and a 0.8°C decrease in CTmax compared with unexposed fish. In contrast, acclimation to 32°C masked the effects of nitrate; fish acclimated to 32°C displayed a thermally insensitive phenotype whereby locomotor performance remained unchanged, AS was maintained and CTmax was increased by ∼1°C irrespective of nitrate treatment compared with fish acclimated to 28°C. However, growth was markedly reduced in 32°C-acclimated compared with 28°C-acclimated fish. Our results indicate that nitrate exposure increases the susceptibility of fish to acute high temperatures, but thermal compensation can override some of these potentially detrimental effects.
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Affiliation(s)
- Daniel F Gomez Isaza
- School of Biological Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rebecca L Cramp
- School of Biological Science, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Craig E Franklin
- School of Biological Science, The University of Queensland, Brisbane, QLD 4072, Australia
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54
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Joyce W, Perry SF. Hypoxia inducible factor-1 α knockout does not impair acute thermal tolerance or heat hardening in zebrafish. Biol Lett 2020; 16:20200292. [PMID: 32673542 PMCID: PMC7423049 DOI: 10.1098/rsbl.2020.0292] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 06/16/2020] [Indexed: 12/25/2022] Open
Abstract
The rapid increase in critical thermal maximum (CTmax) in fish (or other animals) previously exposed to critically high temperature is termed 'heat hardening', which likely represents a key strategy to cope with increasingly extreme environments. The physiological mechanisms that determine acute thermal tolerance, and the underlying pathways facilitating heat hardening, remain debated. It has been posited, however, that exposure to high temperature is associated with tissue hypoxia and may be associated with the increased expression of hypoxia-inducible factor-1 (Hif-1). We studied acute thermal tolerance in zebrafish (Danio rerio) lacking functional Hif-1α paralogs (Hif-1aa and Hif-1ab double knockout; Hif-1α-/-), which are known to exhibit markedly reduced hypoxia tolerance. We hypothesized that Hif-1α-/- zebrafish would suffer reduced acute thermal tolerance relative to wild type and that the heat hardening ability would be lost. However, on the contrary, we observed that Hif-1α-/- and wild-type fish did not differ in CTmax, and both genotypes exhibited heat hardening of a similar degree when CTmax was re-tested 48 h later. Despite exhibiting impaired hypoxia tolerance, Hif-1α-/- zebrafish display unaltered thermal tolerance, suggesting that these traits are not necessarily functionally associated. Hif-1α is accordingly not required for short-term acclimation in the form of heat hardening.
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Affiliation(s)
- William Joyce
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ONCanada, K1N 6N5
- Zoophysiology, Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
| | - Steve F. Perry
- Department of Biology, University of Ottawa, 30 Marie Curie, Ottawa, ONCanada, K1N 6N5
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55
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Pagliaro MD, Knouft JH. Differential effects of the urban heat island on thermal responses of freshwater fishes from unmanaged and managed systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 723:138084. [PMID: 32224401 DOI: 10.1016/j.scitotenv.2020.138084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/24/2020] [Accepted: 03/19/2020] [Indexed: 06/10/2023]
Abstract
A lack of understanding exists regarding how freshwater species will respond to increases in temperature associated with ongoing changes in climate. Non-urban to urban thermal gradients generated by urban heat islands can serve as models to characterize the effects of relatively consistent increases in temperature on freshwater ecosystems over several decades. This study investigates the apparent responses of two freshwater fish species, Campostoma anomalum (Central Stoneroller) and Lepomis macrochirus (Bluegill), to directional changes in temperature over the past century across the non-urban to urban gradient in the Saint Louis, Missouri region in the central United States. Differences in air temperature across this gradient have increased by approximately 3 °C since 1920. Critical thermal maximum (CTMax) assays were conducted on individuals from fish populations across this gradient from either streams (C. anomalum) or ponds (L. macrochirus) to assess whether thermal tolerance is associated with water temperature among sites. According to expectations based on the effect of an urban heat island, maximum water temperature at stream sites was positively correlated with percent urban landcover around the sites. Moreover, CTMax among populations of C. anomalum was positively correlated with maximum water temperature at each site, suggesting that this species has likely responded to increases in temperature over the past several decades. There was no relationship between percent urban landcover and maximum water temperature in the pond systems. There was also no relationship between CTMax and maximum water temperature among L. macrochirus populations. The pond systems and populations of L. macrochirus are highly managed, which may limit local physical and biological responses to increases in air temperature. Results suggest that freshwater habitats in urban environments and the species inhabiting these areas are responding differently to recent increases in air temperature, highlighting the complexity of the physical and biological components of these systems.
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Affiliation(s)
- Megan D Pagliaro
- Department of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103, USA; Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Jason H Knouft
- Department of Biology, Saint Louis University, 3507 Laclede Avenue, St. Louis, MO 63103, USA
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56
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Grinder RM, Bassar RD, Auer SK. Upper thermal limits are repeatable in Trinidadian guppies. J Therm Biol 2020; 90:102597. [DOI: 10.1016/j.jtherbio.2020.102597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/09/2020] [Accepted: 04/13/2020] [Indexed: 10/24/2022]
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57
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Bates A, Morley S. Interpreting empirical estimates of experimentally derived physiological and biological thermal limits in ectotherms. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2018-0276] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Whole-organism function is underpinned by physiological and biological processes, which respond to temperature over a range of time scales. Given that environmental temperature controls biological rates within ectotherms, different experimental protocols are needed to assess the ability of organisms to withstand extreme weather events versus gradual temperature change. Here we emphasize the importance of time in shaping ecological and evolutionary processes, and as an experimental parameter that is key when interpreting physiology studies reporting thermal limits. We discuss how acute and chronic thermal performance is underpinned by mechanisms operating at different time scales — resistance, acclimation, and adaptation. We offer definitions of common physiological and biological temperature metrics and identify challenges inherent to compiling the wealth of historical temperature limit data now available into meta-analytic frameworks. We use a case study, data across temperate fishes, to highlight that false positives may occur when differences in the thermal tolerances of species are in fact due to experimental protocols. We further illustrate that false negatives can arise if researchers fail to recognize differences in thermal limits of species emerging from macrophysiological approaches that are due to biological mechanisms. We strongly advocate for the careful design, interpretation, and reporting of experimental results to ensure that conclusions arising from data synthesis efforts are grounded in theory.
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Affiliation(s)
- A.E. Bates
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada
| | - S.A. Morley
- British Antarctic Survey, Natural Environment Research Council, Cambridge, CB30ET, U.K
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58
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O'Donnell MJ, Regish AM, McCormick SD, Letcher BH. How repeatable is CT max within individual brook trout over short- and long-time intervals? J Therm Biol 2020; 89:102559. [PMID: 32364992 DOI: 10.1016/j.jtherbio.2020.102559] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 02/20/2020] [Accepted: 02/23/2020] [Indexed: 11/17/2022]
Abstract
As stream temperatures increase due to factors such as heated runoff from impervious surfaces, deforestation, and climate change, fish species adapted to cold water streams are forced to move to more suitable habitat, acclimate or adapt to increased thermal regimes, or die. To estimate the potential for adaptation, a (within individual) repeatable metric of thermal tolerance is imperative. Critical thermal maximum (CTmax) is a dynamic test that is widely used to measure thermal tolerance across many taxa and has been used in fishes for decades, but its repeatability in most species is unknown. CTmax tests increase water temperature steadily over time until loss of equilibrium (LOE) is achieved. To determine if CTmax is a consistent metric within individual fish, we measured CTmax on the same lab-held individually-marked adult brook trout Salvelinus fontinalis at three different times (August & September 2016, September 2017). We found that CTmax is a repeatable trait (Repeatability ± S.E.: 0.48 ± 0.14). CTmax of individuals males was consistent over time, but the CTmax of females increased slightly over time. This result indicates that CTmax is a robust, repeatable estimate of thermal tolerance in a cold-water adapted fish.
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Affiliation(s)
- M J O'Donnell
- US Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Laboratory, One Migratory Way, Turners Falls, MA, 01376, USA.
| | - A M Regish
- US Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Laboratory, One Migratory Way, Turners Falls, MA, 01376, USA
| | - S D McCormick
- US Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Laboratory, One Migratory Way, Turners Falls, MA, 01376, USA
| | - B H Letcher
- US Geological Survey, Leetown Science Center, S.O. Conte Anadromous Fish Research Laboratory, One Migratory Way, Turners Falls, MA, 01376, USA
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59
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Rodgers EM, De Boeck G. Nitrite-induced reductions in heat tolerance are independent of aerobic scope in a freshwater teleost. ACTA ACUST UNITED AC 2019; 222:jeb.212035. [PMID: 31704898 DOI: 10.1242/jeb.212035] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 10/29/2019] [Indexed: 11/20/2022]
Abstract
Nitrite is a widespread form of pollution that directly lowers the blood oxygen carrying capacity of aquatically respiring species. It is unknown if this impairment of oxygen transport translates into an increased susceptibility to elevated temperatures. We hypothesised that nitrite exposure would lower blood oxygen carrying capacity and decrease both aerobic scope (maximum-standard metabolic rate) and heat tolerance. To test these hypotheses, juvenile European carp (Cyprinus carpio) were exposed to two levels of nitrite (0 mmol l-1 or 1 mmol l-1) for 7 days and haematological parameters, critical thermal maxima (CTmax) and aerobic scope were assessed. Nitrite exposure reduced total haemoglobin by 32.9%. Aerobic scope remained unchanged in fish exposed to nitrite; however, marked declines in CTmax (1.2°C reduction) were observed in nitrite-exposed fish. These findings demonstrate that nitrite exposure can significantly impair heat tolerance, even when aerobic capacity is maintained.
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Affiliation(s)
- Essie M Rodgers
- Systemic Physiological and Ecotoxicological Research (SPHERE), Department of Biology, University of Antwerp, Antwerp 2020, Belgium
| | - Gudrun De Boeck
- Systemic Physiological and Ecotoxicological Research (SPHERE), Department of Biology, University of Antwerp, Antwerp 2020, Belgium
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60
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Marchant JL, Farrell AP. Membrane and calcium clock mechanisms contribute variably as a function of temperature to setting cardiac pacemaker rate in zebrafish Danio rerio. JOURNAL OF FISH BIOLOGY 2019; 95:1265-1274. [PMID: 31429079 DOI: 10.1111/jfb.14126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 08/19/2019] [Indexed: 06/10/2023]
Abstract
Here, we show that heart rate in zebrafish Danio rerio is dependent upon two pacemaking mechanisms and it possesses a limited ability to reset the cardiac pacemaker with temperature acclimation. Electrocardiogram recordings, taken from individual, anaesthetised zebrafish that had been acclimated to 18, 23 or 28°C were used to follow the response of maximum heart rate (fHmax ) to acute warming from 18°C until signs of cardiac failure appeared (up to c. 40°C). Because fHmax was similar across the acclimation groups at almost all equivalent test temperatures, warm acclimation was limited to one significant effect, the 23°C acclimated zebrafish had a significantly higher (21%) peak fHmax and reached a higher (3°C) test temperature than the 18°C acclimated zebrafish. Using zatebradine to block the membrane hyperpolarisation-activated cyclic nucleotide-gated channels (HCN) and examine the contribution of the membrane clock mechanisms to cardiac pacemaking, f Hmax was significantly reduced (by at least 40%) at all acute test temperatures and significantly more so at most test temperatures for zebrafish acclimated to 28°C vs. 23°C. Thus, HCN channels and the membrane clock were not only important, but could be modified by thermal acclimation. Using a combination of ryanodine (to block sarcoplasmic calcium release) and thapsigargin (to block sarcoplasmic calcium reuptake) to examine the contribution of sarcoplasmic reticular handling of calcium and the calcium clock, f Hmax was again consistently reduced independent of the test temperature and acclimation temperature, but to a significantly lesser degree than zatebradine for zebrafish acclimated to both 28 and 18°C. Thus, the calcium clock mechanism plays an additional role in setting pacemaker activity that was independent of temperature. In conclusion, the zebrafish cardiac pacemaker has a limited temperature acclimation ability compared with known effects for other fishes and involves two pacemaking mechanisms, one of which was independent of temperature.
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Affiliation(s)
- James L Marchant
- Zoology Department, University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony P Farrell
- Zoology Department, University of British Columbia, Vancouver, British Columbia, Canada
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
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61
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Sundin J, Morgan R, Finnøen MH, Dey A, Sarkar K, Jutfelt F. On the Observation of Wild Zebrafish ( Danio rerio) in India. Zebrafish 2019; 16:546-553. [PMID: 31670616 DOI: 10.1089/zeb.2019.1778] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Zebrafish is one of the world's most widely used laboratory species, and it is utilized to answer important research questions in disparate fields such as biomedicine, genetics, developmental biology, pharmacology, toxicology, physiology, and evolution. Despite their popularity, very little is known about the biology of zebrafish in their natural habitat. This may, in part, be due to the difficulties associated with undertaking field trips to the remote areas of northern India, Nepal, and Bangladesh, which is the natural distribution range of zebrafish. Here, we present a field report describing a recent trip where we, together with local collaborators, visited several rivers in West Bengal, India, to observe wild zebrafish and their habitat. We present an overview of our observations on the biology of wild zebrafish, and the great variability of the different environments where they were found. We also include data collected on water chemistry parameters at 12 zebrafish sites, and weight data and photos of fish from these sites. We present extensive underwater videos of wild zebrafish and photographs of the sites, including video footage of courtship behavior. We show that the breeding period of wild zebrafish can be extended from the previous record of April-August to April-October. In addition, we provide practical advice for future zebrafish expeditions to this rural and inaccessible area. The goals of this article are to shed some light on the ecology of wild zebrafish, and to facilitate scientists in their future research trips. We hope that by observing zebrafish in the wild, we can increase our understanding of the natural ecology of this important model organism.
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Affiliation(s)
- Josefin Sundin
- Department of Neuroscience, Uppsala University, Uppsala, Sweden.,Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mette H Finnøen
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Arpita Dey
- Department of Zoology, University of North Bengal, Siliguri, India
| | | | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
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62
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Jutfelt F, Roche DG, Clark TD, Norin T, Binning SA, Speers-Roesch B, Amcoff M, Morgan R, Andreassen AH, Sundin J. Brain cooling marginally increases acute upper thermal tolerance in Atlantic cod. ACTA ACUST UNITED AC 2019; 222:jeb.208249. [PMID: 31527178 DOI: 10.1242/jeb.208249] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 09/12/2019] [Indexed: 01/15/2023]
Abstract
Physiological mechanisms determining thermal limits in fishes are debated but remain elusive. It has been hypothesised that motor function loss, observed as loss of equilibrium during acute warming, is due to direct thermal effects on brain neuronal function. To test this, we mounted cooling plates on the heads of Atlantic cod (Gadus morhua) and quantified whether local brain cooling increased whole-organism acute upper thermal tolerance. Brain cooling reduced brain temperature by 2-6°C below ambient water temperature and increased thermal tolerance by 0.5 and 0.6°C on average relative to instrumented and uninstrumented controls, respectively, suggesting that direct thermal effects on brain neurons may contribute to setting upper thermal limits in fish. However, the improvement in thermal tolerance with brain cooling was small relative to the difference in brain temperature, demonstrating that other mechanisms (e.g. failure of spinal and peripheral neurons, or muscle) may also contribute to controlling acute thermal tolerance.
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Affiliation(s)
- Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Dominique G Roche
- Département d'Éco-Éthologie, Institut de Biologie, Université de Neuchâtel, 2000 Neuchâtel, Switzerland.,Department of Biology and Institute of Environmental and Interdisciplinary Sciences, Carleton University, Ottawa, ON, Canada, K1S 5B6
| | - Timothy D Clark
- Deakin University, School of Life and Environmental Sciences, Geelong, VIC 3216, Australia
| | - Tommy Norin
- DTU Aqua: National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Sandra A Binning
- Département d'Éco-Éthologie, Institut de Biologie, Université de Neuchâtel, 2000 Neuchâtel, Switzerland.,Département de Sciences Biologiques, Université de Montréal, Montréal, QC, Canada, H2V 2S9
| | - Ben Speers-Roesch
- Department of Biological Sciences, University of New Brunswick, Saint John, NB, Canada, E2L 4L5
| | - Mirjam Amcoff
- Department of Zoology/Functional Zoomorphology, Stockholm University, 106 91 Stockholm, Sweden
| | - Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Anna H Andreassen
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Josefin Sundin
- Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway.,Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
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63
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Morgan R, Sundin J, Finnøen MH, Dresler G, Vendrell MM, Dey A, Sarkar K, Jutfelt F. Are model organisms representative for climate change research? Testing thermal tolerance in wild and laboratory zebrafish populations. CONSERVATION PHYSIOLOGY 2019; 7:coz036. [PMID: 31249690 PMCID: PMC6589993 DOI: 10.1093/conphys/coz036] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 04/29/2019] [Accepted: 05/24/2019] [Indexed: 05/31/2023]
Abstract
Model organisms can be useful for studying climate change impacts, but it is unclear whether domestication to laboratory conditions has altered their thermal tolerance and therefore how representative of wild populations they are. Zebrafish in the wild live in fluctuating thermal environments that potentially reach harmful temperatures. In the laboratory, zebrafish have gone through four decades of domestication and adaptation to stable optimal temperatures with few thermal extremes. If maintaining thermal tolerance is costly or if genetic traits promoting laboratory fitness at optimal temperature differ from genetic traits for high thermal tolerance, the thermal tolerance of laboratory zebrafish could be hypothesized to be lower than that of wild zebrafish. Furthermore, very little is known about the thermal environment of wild zebrafish and how close to their thermal limits they live. Here, we compared the acute upper thermal tolerance (critical thermal maxima; CTmax) of wild zebrafish measured on-site in West Bengal, India, to zebrafish at three laboratory acclimation/domestication levels: wild-caught, F1 generation wild-caught and domesticated laboratory AB-WT line. We found that in the wild, CTmax increased with increasing site temperature. Yet at the warmest site, zebrafish lived very close to their thermal limit, suggesting that they may currently encounter lethal temperatures. In the laboratory, acclimation temperature appeared to have a stronger effect on CTmax than it did in the wild. The fish in the wild also had a 0.85-1.01°C lower CTmax compared to all laboratory populations. This difference between laboratory-held and wild populations shows that environmental conditions can affect zebrafish's thermal tolerance. However, there was no difference in CTmax between the laboratory-held populations regardless of the domestication duration. This suggests that thermal tolerance is maintained during domestication and highlights that experiments using domesticated laboratory-reared model species can be appropriate for addressing certain questions on thermal tolerance and global warming impacts.
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Affiliation(s)
- Rachael Morgan
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Josefin Sundin
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Neuroscience, Uppsala University, Uppsala, Sweden
| | - Mette H Finnøen
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Gunnar Dresler
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
| | - Marc Martínez Vendrell
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Biology, University of Barcelona, Barcelona, Spain
| | - Arpita Dey
- Department of Zoology, University of North Bengal, Darjeeling, Siliguri, West Bengal, India
| | - Kripan Sarkar
- Rainbow Ornamental Fish Farm, Baxipara, Raninagar, Mohitnagar, Jalpaiguri, West Bengal, India
| | - Fredrik Jutfelt
- Department of Biology, Norwegian University of Science and Technology, Trondheim, Norway
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64
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Bard B, Kieffer JD. The effects of repeat acute thermal stress on the critical thermal maximum (CTmax) and physiology of juvenile shortnose sturgeon (Acipenser brevirostrum). CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0157] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The shortnose sturgeon (Acipenser brevirostrum Lesueur, 1818) is a species of special concern in Canada, but little is known about their thermal biology. Information on the upper thermal tolerance of shortnose sturgeon becomes valuable for predicting future survival particularly with climate change and improving species management. Using a modified critical thermal maximum (CTmax) methodology, the objective is to determine whether previous thermal stress affects the thermal tolerance of juvenile shortnose sturgeon when exposed to a second thermal stress event. Prior exposure to thermal stress (CTmax1) did not affect the thermal tolerance (CTmax2) of juvenile shortnose sturgeon when a 24 h recovery period was allotted between tests. However, a significant increase in thermal tolerance occurred when the recovery time between the two thermal challenges was 1 h. Plasma glucose, lactate, and osmolality were all significantly affected by thermal stress, but values returned to control levels within 24 h. Hematocrit and plasma chloride concentrations were not significantly affected by thermal stress. All fish survived the CTmax testing. The data indicate that the thermal tolerance of juvenile shortnose sturgeon is modified when multiple thermal stresses occur closer together (1 h) but not if separated by a longer time period (24 h).
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Affiliation(s)
- Brittany Bard
- Department of Biological Sciences and MADSAM Eco-Physiology Lab, University of New Brunswick, Saint John, NB E2L 4L5, Canada
- Department of Biological Sciences and MADSAM Eco-Physiology Lab, University of New Brunswick, Saint John, NB E2L 4L5, Canada
| | - James D. Kieffer
- Department of Biological Sciences and MADSAM Eco-Physiology Lab, University of New Brunswick, Saint John, NB E2L 4L5, Canada
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Harada AE, Healy TM, Burton RS. Variation in Thermal Tolerance and Its Relationship to Mitochondrial Function Across Populations of Tigriopus californicus. Front Physiol 2019; 10:213. [PMID: 30930787 PMCID: PMC6429002 DOI: 10.3389/fphys.2019.00213] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 02/19/2019] [Indexed: 12/22/2022] Open
Abstract
Variation in thermal tolerance plays a key role in determining the biogeographic distribution of organisms. Consequently, identifying the mechanistic basis for thermal tolerance is necessary for understanding not only current species range limits but also the capacity for range limits to shift in response to climate change. Although variation in mitochondrial function likely contributes to variation in thermal tolerance, the extent to which mitochondrial function underlies local thermal adaptation is not fully understood. In the current study, we examine variation in thermal tolerance and mitochondrial function among three populations of the intertidal copepod Tigriopus californicus found across a latitudinal thermal gradient along the coast of California, USA. We tested (1) acute thermal tolerance using survivorship and knockdown assays, (2) chronic thermal tolerance using survivorship of nauplii and developmental rate, and (3) mitochondrial performance at a range of temperatures using ATP synthesis fueled by complexes I, II, and I&II, as well as respiration of permeabilized fibers. We find evidence for latitudinal thermal adaptation: the southernmost San Diego population outperforms the northernmost Santa Cruz in measures of survivorship, knockdown temperature, and ATP synthesis rates during acute thermal exposures. However, under a chronic thermal regime, survivorship and developmental rate are more similar in the southernmost and northernmost population than in the mid-range population (Abalone Cove). Though this pattern is unexpected, it aligns well with population-specific rates of ATP synthesis at these chronic temperatures. Combined with the tight correlation of ATP synthesis decline and knockdown temperature, these data suggest a role for mitochondria in setting thermal range limits and indicate that divergence in mitochondrial function is likely a component of adaptation across latitudinal thermal gradients.
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Affiliation(s)
- Alice E Harada
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
| | - Timothy M Healy
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
| | - Ronald S Burton
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, United States
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MacMillan HA. Dissecting cause from consequence: a systematic approach to thermal limits. J Exp Biol 2019; 222:222/4/jeb191593. [DOI: 10.1242/jeb.191593] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
ABSTRACT
Thermal limits mark the boundaries of ectotherm performance, and are increasingly appreciated as strong correlates and possible determinants of animal distribution patterns. The mechanisms setting the thermal limits of ectothermic animals are under active study and rigorous debate as we try to reconcile new observations in the lab and field with the knowledge gained from a long history of research on thermal adaptation. Here, I provide a perspective on our divided understanding of the mechanisms setting thermal limits of ectothermic animals. I focus primarily on the fundamental differences between high and low temperatures, and how animal form and environment can place different constraints on different taxa. Together, complexity and variation in animal form drive complexity in the interactions within and among levels of biological organization, creating a formidable barrier to determining mechanistic cause and effect at thermal limits. Progress in our understanding of thermal limits will require extensive collaboration and systematic approaches that embrace this complexity and allow us to separate the causes of failure from the physiological consequences that can quickly follow. I argue that by building integrative models that explain causal links among multiple organ systems, we can more quickly arrive at a holistic understanding of the varied challenges facing animals at extreme temperatures.
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