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Birch G, Meniri M, Cant MA, Blount JD. Defence against the intergenerational cost of reproduction in males: oxidative shielding of the germline. Biol Rev Camb Philos Soc 2024; 99:70-84. [PMID: 37698166 DOI: 10.1111/brv.13012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 08/09/2023] [Accepted: 08/11/2023] [Indexed: 09/13/2023]
Abstract
Reproduction is expected to carry an oxidative cost, yet in many species breeders appear to sustain lower levels of oxidative damage compared to non-breeders. This paradox may be explained by considering the intergenerational costs of reproduction. Specifically, a reduction in oxidative damage upon transitioning to a reproductive state may represent a pre-emptive shielding strategy to protect the next generation from intergenerational oxidative damage (IOD) - known as the oxidative shielding hypothesis. Males may be particularly likely to transmit IOD, because sperm are highly susceptible to oxidative damage. Yet, the possibility of male-mediated IOD remains largely uninvestigated. Here, we present a conceptual and methodological framework to assess intergenerational costs of reproduction and oxidative shielding of the germline in males. We discuss variance in reproductive costs and expected payoffs of oxidative shielding according to species' life histories, and the expected impact on offspring fitness. Oxidative shielding presents an opportunity to incorporate intergenerational effects into the advancing field of life-history evolution.
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Affiliation(s)
- Graham Birch
- Centre for Ecology & Conservation, Faculty of Environment, Science & Economy, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK
| | - Magali Meniri
- Centre for Ecology & Conservation, Faculty of Environment, Science & Economy, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK
| | - Michael A Cant
- Centre for Ecology & Conservation, Faculty of Environment, Science & Economy, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK
| | - Jonathan D Blount
- Centre for Ecology & Conservation, Faculty of Environment, Science & Economy, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, UK
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2
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Khera M, Arbuckle K, Mwanguhya F, Kyabulima S, Mwesige K, Businge R, Blount JD, Cant MA, Nichols HJ. Small increases in ambient temperature reduce offspring body mass in an equatorial mammal. Biol Lett 2023; 19:20230328. [PMID: 37990567 PMCID: PMC10715294 DOI: 10.1098/rsbl.2023.0328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 11/02/2023] [Indexed: 11/23/2023] Open
Abstract
Human-induced climate change is leading to temperature rises, along with increases in the frequency and intensity of heatwaves. Many animals respond to high temperatures through behavioural thermoregulation, for example by resting in the shade, but this may impose opportunity costs by reducing foraging time (therefore energy supply), and so may be most effective when food is abundant. However, the heat dissipation limit (HDL) theory proposes that even when energy supply is plentiful, high temperatures can still have negative effects. This is because dissipating excess heat becomes harder, which limits processes that generate heat such as lactation. We tested predictions from HDL on a wild, equatorial population of banded mongooses (Mungos mungo). In support of the HDL theory, higher ambient temperatures led to lighter pups, and increasing food availability made little difference to pup weight under hotter conditions. This suggests that direct physiological constraints rather than opportunity costs of behavioural thermoregulation explain the negative impact of high temperatures on pup growth. Our results indicate that climate change may be particularly important for equatorial species, which often experience high temperatures year-round so cannot time reproduction to coincide with cooler conditions.
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Affiliation(s)
- Monil Khera
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
| | - Kevin Arbuckle
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
| | - Francis Mwanguhya
- Banded Mongoose Research Project, Queen Elizabeth National Park, Kasese District, Uganda
| | - Solomon Kyabulima
- Banded Mongoose Research Project, Queen Elizabeth National Park, Kasese District, Uganda
| | - Kenneth Mwesige
- Banded Mongoose Research Project, Queen Elizabeth National Park, Kasese District, Uganda
| | - Robert Businge
- Banded Mongoose Research Project, Queen Elizabeth National Park, Kasese District, Uganda
| | | | - Michael A. Cant
- Centre for Ecology and Conservation, University of Exeter, Cornwall, UK
| | - Hazel J. Nichols
- Department of Biosciences, Swansea University, Swansea SA2 8PP, UK
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3
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Heyworth HC, Pokharel P, Blount JD, Mitchell C, Petschenka G, Rowland HM. Antioxidant availability trades off with warning signals and toxin sequestration in the large milkweed bug ( Oncopeltus fasciatus). Ecol Evol 2023; 13:e9971. [PMID: 37038513 PMCID: PMC10082154 DOI: 10.1002/ece3.9971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 04/12/2023] Open
Abstract
In some aposematic species the conspicuousness of an individual's warning signal and the concentration of its chemical defense are positively correlated. Several mechanisms have been proposed to explain this phenomenon, including resource allocation trade-offs where the same limiting resource is needed to produce both the warning signal and chemical defense. Here, the large milkweed bug (Oncopeltus fasciatus: Heteroptera, Lygaeinae) was used to test whether allocation of antioxidants, that can impart color, trade against their availability to prevent self-damage caused by toxin sequestration. We investigated if (i) the sequestration of cardenolides is associated with costs in the form of changes in oxidative state; and (ii) oxidative state can affect the capacity of individuals to produce warning signals. We reared milkweed bugs on artificial diets with increasing quantities of cardenolides and examined how this affected signal quality (brightness and chroma) across different instars. We then related the expression of warning colors to the quantity of sequestered cardenolides and indicators of oxidative state-oxidative lipid damage (malondialdehyde), and two antioxidants: total superoxide dismutase and total glutathione. Bugs that sequestered more cardenolides had significantly lower levels of the antioxidant glutathione, and bugs with less total glutathione had less luminant orange warning signals and reduced chroma of their black patches compared to bugs with more glutathione. Bugs that sequestered more cardenolides also had reduced red-green chroma of their black patches that was unrelated to oxidative state. Our results give tentative support for a physiological cost of sequestration in milkweed bugs and a mechanistic link between antioxidant availability, sequestration, and warning signals.
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Affiliation(s)
- H. Cecilia Heyworth
- Predators and Toxic Prey Research GroupMax Planck Institute for Chemical EcologyJenaGermany
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Prayan Pokharel
- Department of Applied Entomology, Institute of PhytomedicineUniversity of HohenheimStuttgartGermany
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - Georg Petschenka
- Department of Applied Entomology, Institute of PhytomedicineUniversity of HohenheimStuttgartGermany
| | - Hannah M. Rowland
- Predators and Toxic Prey Research GroupMax Planck Institute for Chemical EcologyJenaGermany
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4
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Blount JD, Rowland HM, Mitchell C, Speed MP, Ruxton GD, Endler JA, Brower LP. The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly. Proc Biol Sci 2023; 290:20222068. [PMID: 36651049 PMCID: PMC9845971 DOI: 10.1098/rspb.2022.2068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments and in protecting against oxidative damage. To test for such trade-offs, we raised monarch butterflies (Danaus plexippus) on different species of their milkweed host plants (Apocynaceae) that vary in quantities of cardenolides to test whether (i) the sequestration of cardenolides as a secondary defence is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (ii) lower oxidative state is associated with a reduced capacity to produce aposematic displays. In male monarchs conspicuousness was explained by an interaction between oxidative damage and sequestration: males with high levels of oxidative damage became less conspicuous with increased sequestration of cardenolides, whereas those with low oxidative damage became more conspicuous with increased levels of cardenolides. There was no significant effect of oxidative damage or concentration of sequestered cardenolides on female conspicuousness. Our results demonstrate a physiological linkage between the production of coloration and oxidative state, and differential costs of sequestration and signalling in monarch butterflies.
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Affiliation(s)
- Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Hannah M. Rowland
- Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, Jena, 07745, Germany
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Michael P. Speed
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7BE, UK
| | - Graeme D. Ruxton
- School of Biology, Sir Harold Mitchell Building, Greenside Place, St Andrews, UK
| | - John A. Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Lincoln P. Brower
- Department of Biology, Sweet Briar College, Sweet Briar, VA 24595, USA
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5
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Melvin ZE, Dhirani H, Mitchell C, Davenport TRB, Blount JD, Georgiev AV. Methodological confounds of measuring urinary oxidative stress in wild animals. Ecol Evol 2022; 12:e9115. [PMID: 35866020 PMCID: PMC9288928 DOI: 10.1002/ece3.9115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 05/17/2022] [Accepted: 06/02/2022] [Indexed: 12/23/2022] Open
Abstract
Biomarkers of oxidative stress (OS) are useful in addressing a wide range of research questions, but thus far, they have had limited application to wild mammal populations due to a reliance on blood or tissue sampling. A shift toward non‐invasive measurement of OS would allow field ecologists and conservationists to apply this method more readily. However, the impact of methodological confounds on urinary OS measurement under field conditions has never been explicitly investigated. We combined a cross‐sectional analysis with a field experiment to assess the impact of four potential methodological confounds on OS measurements: (1) time of sampling, (2) environmental contamination from foliage; (3) delay between sample collection and flash‐freezing in liquid nitrogen; and (4) sample storage of up to 15 months below −80°C. We measured DNA oxidative damage (8‐hydroxy‐2′‐deoxyguanosine, 8‐OHdG), lipid peroxidation (malondialdehyde, MDA), total antioxidant capacity (TAC), and uric acid (UA) in 167 urine samples collected from wild Zanzibar red colobus (Piliocolobus kirkii). We found that MDA was higher in samples collected in the morning than in the afternoon but there were no diurnal patterns in any of the other markers. Contamination of samples from foliage and length of time frozen at −80°C for up to 15 months did not affect OS marker concentrations. Freezing delay did not affect OS levels cross‐sectionally, but OS values from individual samples showed only moderate‐to‐good consistency and substantial rank‐order reversals when exposed to different freezing delays. We recommend that diurnal patterns of OS markers and the impact of storage time before and after freezing on OS marker concentrations be considered when designing sampling protocols. However, given the high stability we observed for four OS markers subject to a variety of putative methodological confounds, we suggest that urinary OS markers provide a valuable addition to the toolkit of field ecologists and conservationists within reasonable methodological constraints.
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Affiliation(s)
- Zoe E Melvin
- School of Natural Sciences, Bangor University Bangor UK.,Zanzibar Red Colobus Project Bangor University Bangor UK
| | | | - Christopher Mitchell
- Centre for Ecology & Conservation, College of Life & Environmental Sciences University of Exeter, Penryn Campus Penryn UK
| | | | - Jonathan D Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences University of Exeter, Penryn Campus Penryn UK
| | - Alexander V Georgiev
- School of Natural Sciences, Bangor University Bangor UK.,Zanzibar Red Colobus Project Bangor University Bangor UK
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6
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Meniri M, Evans E, Thompson FJ, Marshall HH, Nichols HJ, Lewis G, Holt L, Davey E, Mitchell C, Johnstone RA, Cant MA, Blount JD. Untangling the oxidative cost of reproduction: An analysis in wild banded mongooses. Ecol Evol 2022; 12:e8644. [PMID: 35342583 PMCID: PMC8928901 DOI: 10.1002/ece3.8644] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 01/15/2022] [Indexed: 02/02/2023] Open
Abstract
The cost of reproduction plays a central role in evolutionary theory, but the identity of the underlying mechanisms remains a puzzle. Oxidative stress has been hypothesized to be a proximate mechanism that may explain the cost of reproduction. We examine three pathways by which oxidative stress could shape reproduction. The “oxidative cost” hypothesis proposes that reproductive effort generates oxidative stress, while the “oxidative constraint” and “oxidative shielding” hypotheses suggest that mothers mitigate such costs through reducing reproductive effort or by pre‐emptively decreasing damage levels, respectively. We tested these three mechanisms using data from a long‐term food provisioning experiment on wild female banded mongooses (Mungos mungo). Our results show that maternal supplementation did not influence oxidative stress levels, or the production and survival of offspring. However, we found that two of the oxidative mechanisms co‐occur during reproduction. There was evidence of an oxidative challenge associated with reproduction that mothers attempted to mitigate by reducing damage levels during breeding. This mitigation is likely to be of crucial importance, as long‐term offspring survival was negatively impacted by maternal oxidative stress. This study demonstrates the value of longitudinal studies of wild animals in order to highlight the interconnected oxidative mechanisms that shape the cost of reproduction.
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Affiliation(s)
- Magali Meniri
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Elsa Evans
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Faye J. Thompson
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Harry H. Marshall
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
- Whitelands College Centre for Research in Ecology, Evolution & Behaviour University of Roehampton London UK
| | | | - Gina Lewis
- Department of Biosciences Swansea University Swansea UK
| | - Lauren Holt
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Emma Davey
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Christopher Mitchell
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | | | - Michael A. Cant
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
| | - Jonathan D. Blount
- College of Life & Environmental Sciences Centre for Ecology & Conservation University of Exeter Penryn UK
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7
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Allen SF, Ellis F, Mitchell C, Wang X, Boogert NJ, Lin CY, Clokey J, Thomas KV, Blount JD. Phthalate diversity in eggs and associations with oxidative stress in the European herring gull (Larus argentatus). Mar Pollut Bull 2021; 169:112564. [PMID: 34148634 DOI: 10.1016/j.marpolbul.2021.112564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/18/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Phthalates are plastic-derived contaminants that are ubiquitous in natural environments and function as pro-oxidants. The extent to which phthalates bioaccumulate in wild animals and associations with oxidative stress are poorly understood. Here, we describe relationships between maternally-derived phthalates, lipid peroxidation (malondialdehyde, MDA) and the dietary antioxidant α-tocopherol in eggs of European herring gulls (Larus argentatus) in Cornwall, UK. Up to six phthalate parent compounds and four phthalate metabolites were detected. Egg concentrations of MDA were positively associated with dicyclohexyl phthalate (DCHP) and negatively associated with α-tocopherol, suggesting that DCHP is associated with oxidative stress in gulls. The consequences of phthalate exposure in ovo for offspring development warrants study.
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Affiliation(s)
- Simon F Allen
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | - Francesca Ellis
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | - Xianyu Wang
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Neeltje J Boogert
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | - Chun-Yin Lin
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Joseph Clokey
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Kevin V Thomas
- Queensland Alliance for Environmental Health Sciences, The University of Queensland, 20 Cornwall Street, Woolloongabba, Queensland 4102, Australia
| | - Jonathan D Blount
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK.
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8
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Jacobs PJ, Oosthuizen MK, Mitchell C, Blount JD, Bennett NC. Oxidative stress in response to heat stress in wild caught Namaqua rock mice, Micaelamys namaquensis. J Therm Biol 2021; 98:102958. [PMID: 34016369 DOI: 10.1016/j.jtherbio.2021.102958] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/03/2021] [Accepted: 04/05/2021] [Indexed: 11/27/2022]
Abstract
Modelling of anthropogenic induced climate suggests more frequent and severe heatwaves in the future, which are likely to result in the mass die-off of several species of organisms. Oxidative stress induced by severe heat stress has previously been associated with a reduction in animal cognitive performance, depressed reproduction and lower life expectancy. Little is known about the non-lethal consequences of species should they survive extreme heat exposure. We investigated the oxidative stress experienced by the Namaqua rock mouse, a nocturnal rodent, using two experimental heat stress protocols, a 6 hour acute heat stress protocol without access to water and a 3-day heatwave simulation with ad libitum water. Oxidative stress was determined in the liver, kidney and brain using malondialdehyde (MDA) and protein carbonyl (PC) as markers of oxidative damage, and superoxide dismutase (SOD) and total antioxidant capacity (TAC) as markers of antioxidant defence. Incubator heat stress (heat and dehydration stress) was brought about by increasing the body temperatures of animals to 39-40.8 °C for 6 hours. Following incubator heat stress, significantly higher levels of MDA were observed in the liver. Dehydration did not explain the variation in oxidative markers and is likely a combined effect of thermal and dehydration stress. Individual body mass was significantly negatively correlated to kidney SOD and lipid peroxidation. A heatwave was simulated using a temperature cycle that would naturally occur during a heatwave in the species' local habitat, with a maximal ambient temperature of 38 °C. Following the simulated heatwave, SOD activity of the kidney demonstrated significantly lowered activity suggesting oxidative stress. Current heat waves in this species have the potential of causing oxidative stress. Heat and dehydration stress following exacerbated temperatures are likely to incur significant oxidative stress in multiple tissues demonstrating the importance of water availability to allow for rehydration to prevent oxidative stress.
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Affiliation(s)
- Paul J Jacobs
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa.
| | - M K Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa.
| | - C Mitchell
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
| | - J D Blount
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
| | - N C Bennett
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0002, South Africa.
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9
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Jacobs PJ, Oosthuizen MK, Mitchell C, Blount JD, Bennett NC. Heat and dehydration induced oxidative damage and antioxidant defenses following incubator heat stress and a simulated heat wave in wild caught four-striped field mice Rhabdomys dilectus. PLoS One 2020; 15:e0242279. [PMID: 33186409 PMCID: PMC7665817 DOI: 10.1371/journal.pone.0242279] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/29/2020] [Indexed: 01/22/2023] Open
Abstract
Heat waves are known for their disastrous mass die-off effects due to dehydration and cell damage, but little is known about the non-lethal consequences of surviving severe heat exposure. Severe heat exposure can cause oxidative stress which can have negative consequences on animal cognition, reproduction and life expectancy. We investigated the current oxidative stress experienced by a mesic mouse species, the four striped field mouse, Rhabdomys dilectus through a heat wave simulation with ad lib water and a more severe temperature exposure with minimal water. Wild four striped field mice were caught between 2017 and 2019. We predicted that wild four striped field mice in the heat wave simulation would show less susceptibility to oxidative stress as compared to a more severe heat stress which is likely to occur in the future. Oxidative stress was determined in the liver, kidney and brain using malondialdehyde (MDA) and protein carbonyl (PC) as markers for oxidative damage, and superoxide dismutase (SOD) and total antioxidant capacity (TAC) as markers of antioxidant defense. Incubator heat stress was brought about by increasing the body temperatures of animals to 39-40.8°C for 6 hours. A heat wave (one hot day, followed by a 3-day heatwave) was simulated by using temperature cycle that wild four striped field mice would experience in their local habitat (determined through weather station data using temperature and humidity), with maximal ambient temperature of 39°C. The liver and kidney demonstrated no changes in the simulated heat wave, but the liver had significantly higher SOD activity and the kidney had significantly higher lipid peroxidation in the incubator experiment. Dehydration significantly contributed to the increase of these markers, as is evident from the decrease in body mass after the experiment. The brain only showed significantly higher lipid peroxidation following the simulated heat wave with no significant changes following the incubator experiment. The significant increase in lipid peroxidation was not correlated to body mass after the experiment. The magnitude and duration of heat stress, in conjunction with dehydration, played a critical role in the oxidative stress experienced by each tissue, with the results demonstrating the importance of measuring multiple tissues to determine the physiological state of an animal. Current heat waves in this species have the potential of causing oxidative stress in the brain with future heat waves to possibly stress the kidney and liver depending on the hydration state of animals.
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Affiliation(s)
- Paul J. Jacobs
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - M. K. Oosthuizen
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - C. Mitchell
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, Cornwall, United Kingdom
| | - Nigel C. Bennett
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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10
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Malod K, Roets PD, Oosthuizen C, Blount JD, Archer CR, Weldon CW. Selection on age of female reproduction in the marula fruit fly, Ceratitis cosyra (Walker) (Diptera: Tephritidae), decreases total antioxidant capacity and lipid peroxidation. J Insect Physiol 2020; 125:104084. [PMID: 32634434 DOI: 10.1016/j.jinsphys.2020.104084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 06/11/2023]
Abstract
The oxidative damage caused to cells by Reactive Oxygen Species (ROS) is one of several factors implicated in causing ageing. Oxidative damage may also be a proximate cost of reproductive effort that mediates the trade-off often observed between reproduction and survival. However, how the balance between oxidative damage and antioxidant protection affects life-history strategies is not fully understood. To improve our understanding, we selected on female reproductive age in the marula fruit fly, Ceratitis cosyra, and quantified the impact of selection on female and male mortality risk, female fecundity, male sperm transfer, calling and mating. Against expectations, upward-selected lines lived shorter lives and experienced some reductions in reproductive performance. Selection affected oxidative damage to lipids and total antioxidant protection, but not in the direction predicted; longer lives were associated with elevated oxidative damage, arguing against the idea that accumulated oxidative damage reduces lifespan. Greater reproductive effort was also associated with elevated oxidative damage, suggesting that oxidative damage may be a cost of reproduction, although one that did not affect survival. Our results add to a body of data showing that the relationship between lifespan, reproduction and oxidative damage is more complex than predicted by existing theories.
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Affiliation(s)
- Kevin Malod
- Department of Zoology and Entomology, University of Pretoria, Private bag X20, Hatfield 0028, South Africa.
| | - Petrus D Roets
- Department of Zoology and Entomology, University of Pretoria, Private bag X20, Hatfield 0028, South Africa
| | - Carel Oosthuizen
- Department of Zoology and Entomology, University of Pretoria, Private bag X20, Hatfield 0028, South Africa
| | - Jonathan D Blount
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK
| | - C Ruth Archer
- Institute for Evolutionary Ecology and Conservation Genomics, University of Ulm, Ulm, Germany
| | - Christopher W Weldon
- Department of Zoology and Entomology, University of Pretoria, Private bag X20, Hatfield 0028, South Africa
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Bodey TW, Cleasby IR, Blount JD, McElwaine G, Vigfusdottir F, Bearhop S. Consistent measures of oxidative balance predict survival but not reproduction in a long‐distance migrant. J Anim Ecol 2020; 89:1872-1882. [DOI: 10.1111/1365-2656.13237] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 03/27/2020] [Indexed: 02/06/2023]
Affiliation(s)
- Thomas W. Bodey
- Centre for Ecology & Conservation University of Exeter Penryn Campus Penryn UK
- School of Biological Sciences University of Auckland Auckland New Zealand
| | - Ian R. Cleasby
- Centre for Ecology & Conservation University of Exeter Penryn Campus Penryn UK
- Royal Society for the Protection of Birds Centre for Conservation Science Inverness UK
| | - Jonathan D. Blount
- Centre for Ecology & Conservation University of Exeter Penryn Campus Penryn UK
| | | | - Freydis Vigfusdottir
- Faculty of Life and Environmental Sciences and School of Social Sciences University of Iceland Reykjavik Iceland
| | - Stuart Bearhop
- Centre for Ecology & Conservation University of Exeter Penryn Campus Penryn UK
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12
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Bodey TW, Cleasby IR, Blount JD, Vigfusdottir F, Mackie K, Bearhop S. Measures of oxidative state are primarily driven by extrinsic factors in a long-distance migrant. Biol Lett 2019; 15:20180750. [PMID: 30958216 PMCID: PMC6371914 DOI: 10.1098/rsbl.2018.0750] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 12/05/2018] [Indexed: 01/17/2023] Open
Abstract
Oxidative stress is a likely consequence of hard physical exertion and thus a potential mediator of life-history trade-offs in migratory animals. However, little is known about the relative importance of intrinsic and extrinsic stressors on the oxidative state of individuals in wild populations. We quantified the relationships between air temperature, sex, body condition and three markers of oxidative state (malondialdehyde, superoxide dismutase and total antioxidant capacity) across hundreds of individuals of a long-distance migrant (the brent goose Branta bernicla hrota) during wintering and spring staging. We found that air temperature and migratory stage were the strongest predictors of oxidative state. This emphasizes the importance of extrinsic factors in regulating the oxidative state of migrating birds, with differential effects across the migration. The significance of abiotic effects demonstrates an additional mechanism by which changing climates may affect migratory costs.
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Affiliation(s)
- Thomas W. Bodey
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Ian R. Cleasby
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
- RSPB Centre for Conservation Science, Inverness, UK
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Freydis Vigfusdottir
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
- Faculty of Life and Environmental Sciences and School of Social Sciences, University of Iceland, Reykjavik, Iceland
| | - Kerry Mackie
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Stuart Bearhop
- Centre for Ecology and Conservation, University of Exeter Penryn Campus, Penryn, Cornwall TR10 9FE, UK
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13
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Briolat ES, Zagrobelny M, Olsen CE, Blount JD, Stevens M. No evidence of quantitative signal honesty across species of aposematic burnet moths (Lepidoptera: Zygaenidae). J Evol Biol 2018; 32:31-48. [PMID: 30317689 PMCID: PMC6378400 DOI: 10.1111/jeb.13389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 11/30/2022]
Abstract
Many defended species use conspicuous visual warning signals to deter potential predators from attacking. Traditional theory holds that these signals should converge on similar forms, yet variation in visual traits and the levels of defensive chemicals is common, both within and between species. It is currently unclear how the strength of signals and potency of defences might be related: conflicting theories suggest that aposematic signals should be quantitatively honest, or, in contrast, that investment in one component should be prioritized over the other, while empirical tests have yielded contrasting results. Here, we advance this debate by examining the relationship between defensive chemicals and signal properties in a family of aposematic Lepidoptera, accounting for phylogenetic relationships and quantifying coloration from the perspective of relevant predators. We test for correlations between toxin levels and measures of wing colour across 14 species of day‐flying burnet and forester moths (Lepidoptera: Zygaenidae), protected by highly aversive cyanogenic glucosides, and find no clear evidence of quantitative signal honesty. Significant relationships between toxin levels and coloration vary between sexes and sampling years, and several trends run contrary to expectations for signal honesty. Although toxin concentration is positively correlated with increasing luminance contrast in forewing pattern in 1 year, higher toxin levels are also associated with paler and less chromatically salient markings, at least in females, in another year. Our study also serves to highlight important factors, including sex‐specific trends and seasonal variation, that should be accounted for in future work on signal honesty in aposematic species.
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Affiliation(s)
- Emmanuelle S Briolat
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
| | - Mika Zagrobelny
- Plant Biochemistry Laboratory and Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carl E Olsen
- Plant Biochemistry Laboratory and Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonathan D Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
| | - Martin Stevens
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
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Francis ML, Plummer KE, Lythgoe BA, Macallan C, Currie TE, Blount JD. Effects of supplementary feeding on interspecific dominance hierarchies in garden birds. PLoS One 2018; 13:e0202152. [PMID: 30183709 PMCID: PMC6124729 DOI: 10.1371/journal.pone.0202152] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/27/2018] [Indexed: 11/18/2022] Open
Abstract
Individuals often differ in competitive ability, which can lead to the formation of a dominance hierarchy that governs differential access to resources. Previous studies of dominance have predominently focussed on within-species interactions, while the drivers of between-species competitive hierarchies are poorly understood. The increasing prevalence of predictable anthropogenic food subsidies, such as that provided by garden bird feeders, is likely to intensify between-species competition. However, the consequences for resource acquisition await detailed study, and in particular, whether competitive interactions are influenced by food quality is not known. Here, we examine competitive interactions amongst ten passerine species of birds utilising supplementary food sources of differing quality. We show that dominance rank is strongly predicted by body mass across species. Socially dominant, heavier species monopolised access to a food that had a relatively short handling time (sunflower hearts), spent longer on supplementary feeders, and pecked at lower rates. In contrast subordinate, lighter species were constrained to feed on a food that had a relatively long handling time (sunflower seeds with the hull intact). Our findings suggest that differences in body mass may result in between-species dominance hierarchies that place the heaviest species in the greatest control of supplementary feeding sites, gaining superior access to higher value foods. This may have important implications for the use of supplementary feeding as a conservation tool.
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Affiliation(s)
- Megan L. Francis
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Kate E. Plummer
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
- British Trust for Ornithology, The Nunnery, Thetford, Norfolk, United Kingdom
- * E-mail: (JDB); (KEP)
| | - Bethany A. Lythgoe
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Catriona Macallan
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Thomas E. Currie
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
- * E-mail: (JDB); (KEP)
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15
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Briolat ES, Zagrobelny M, Olsen CE, Blount JD, Stevens M. Sex differences but no evidence of quantitative honesty in the warning signals of six-spot burnet moths (Zygaena filipendulae L.). Evolution 2018; 72:1460-1474. [PMID: 29767461 PMCID: PMC6099377 DOI: 10.1111/evo.13505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/22/2018] [Accepted: 05/05/2018] [Indexed: 11/29/2022]
Abstract
The distinctive black and red wing pattern of six-spot burnet moths (Zygaena filipendulae, L.) is a classic example of aposematism, advertising their potent cyanide-based defences. While such warning signals provide a qualitatively honest signal of unprofitability, the evidence for quantitative honesty, whereby variation in visual traits could provide accurate estimates of individual toxicity, is more equivocal. Combining measures of cyanogenic glucoside content and wing color from the perspective of avian predators, we investigate the relationship between coloration and defences in Z. filipendulae, to test signal honesty both within and across populations. There were no significant relationships between mean cyanogenic glucoside concentration and metrics of wing coloration across populations in males, yet in females higher cyanogenic glucoside levels were associated with smaller and lighter red forewing markings. Trends within populations were similarly inconsistent with quantitative honesty, and persistent differences between the sexes were apparent: larger females, carrying a greater total cyanogenic glucoside load, displayed larger but less conspicuous markings than smaller males, according to several color metrics. The overall high aversiveness of cyanogenic glucosides and fluctuations in color and toxin levels during an individual's lifetime may contribute to these results, highlighting generally important reasons why signal honesty should not always be expected in aposematic species.
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Affiliation(s)
- Emmanuelle Sophie Briolat
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
| | - Mika Zagrobelny
- Plant Biochemistry Laboratory and Copenhagen Plant Science CentreDepartment of Plant and Environmental SciencesUniversity of Copenhagen40 Thorvaldsensvej, DK‐1871 Frederiksberg CCopenhagenDenmark
| | - Carl Erik Olsen
- Plant Biochemistry Laboratory and Copenhagen Plant Science CentreDepartment of Plant and Environmental SciencesUniversity of Copenhagen40 Thorvaldsensvej, DK‐1871 Frederiksberg CCopenhagenDenmark
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
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16
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Plummer KE, Bearhop S, Leech DI, Chamberlain DE, Blount JD. Effects of winter food provisioning on the phenotypes of breeding blue tits. Ecol Evol 2018; 8:5059-5068. [PMID: 29876081 PMCID: PMC5980576 DOI: 10.1002/ece3.4048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/21/2018] [Accepted: 02/23/2018] [Indexed: 01/06/2023] Open
Abstract
Throughout the Western World, huge numbers of people regularly supply food for wild birds. However, evidence of negative impacts of winter feeding on future reproduction has highlighted a need to improve understanding of the underlying mechanisms shaping avian responses to supplementary food. Here, we test the possibility that carry-over effects are mediated via their impact on the phenotypes of breeding birds, either by influencing the phenotypic structure of populations through changes in winter survival and/or by more direct effects on the condition of breeding birds. Using a landscape-scale 3-year study of blue tits (Cyanistes caeruleus), we demonstrate the importance of nutritional composition of supplementary food in determining carry-over effect outcomes. We show that breeding populations which had access to vitamin E-rich foods during the previous winter were comprised of individuals with reduced feather carotenoid concentrations, indicative of lower pre-feeding phenotypic condition, compared to fat-fed and unfed populations. This suggests that supplementary feeding in winter can result in altered population phenotypic structure at the time of breeding, perhaps by enhancing survival and recruitment of lower quality individuals. However, supplementation of a fat-rich diet during winter was detrimental to the oxidative state of breeding birds, with these phenotypic differences ultimately found to impact upon reproductive success. Our findings demonstrate the complex nature by which supplementary feeding can influence wild bird populations.
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Affiliation(s)
- Kate E. Plummer
- Centre for Ecology and ConservationCollege of Life & Environmental SciencesUniversity of ExeterPenrynCornwallUK
- British Trust for OrnithologyThe NunneryThetfordNorfolkUK
| | - Stuart Bearhop
- Centre for Ecology and ConservationCollege of Life & Environmental SciencesUniversity of ExeterPenrynCornwallUK
| | - David I. Leech
- British Trust for OrnithologyThe NunneryThetfordNorfolkUK
| | - Dan E. Chamberlain
- Dipartimento di Scienze della Vita e Biologià dei SistemiUniversità degli Studi di TorinoTurinItaly
| | - Jonathan D. Blount
- Centre for Ecology and ConservationCollege of Life & Environmental SciencesUniversity of ExeterPenrynCornwallUK
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17
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Losdat S, Blount JD, Marri V, Maronde L, Richner H, Helfenstein F. Effects of an early-life paraquat exposure on adult resistance to oxidative stress, plumage colour and sperm performance in a wild bird. J Anim Ecol 2018. [DOI: 10.1111/1365-2656.12822] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Sylvain Losdat
- Institute of Biology; University of Neuchâtel; Neuchâtel Switzerland
- Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | - Jonathan D. Blount
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn UK
| | - Viviana Marri
- Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | - Lea Maronde
- Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | - Heinz Richner
- Institute of Ecology and Evolution; University of Bern; Bern Switzerland
| | - Fabrice Helfenstein
- Institute of Biology; University of Neuchâtel; Neuchâtel Switzerland
- Institute of Ecology and Evolution; University of Bern; Bern Switzerland
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18
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Paul SC, Stevens M, Burton J, Pell JK, Birkett MA, Blount JD. Invasive Egg Predators and Food Availability Interactively Affect Maternal Investment in Egg Chemical Defense. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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19
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Christensen LL, Selman C, Blount JD, Pilkington JG, Watt KA, Pemberton JM, Reid JM, Nussey DH. Marker-dependent associations among oxidative stress, growth and survival during early life in a wild mammal. Proc Biol Sci 2017; 283:rspb.2016.1407. [PMID: 27733545 PMCID: PMC5069507 DOI: 10.1098/rspb.2016.1407] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/19/2016] [Indexed: 01/23/2023] Open
Abstract
Oxidative stress (OS) is hypothesized to be a key physiological mechanism mediating life-history trade-offs, but evidence from wild populations experiencing natural environmental variation is limited. We tested the hypotheses that increased early life growth rate increases OS, and that increased OS reduces first-winter survival, in wild Soay sheep (Ovis aries) lambs. We measured growth rate and first-winter survival for four consecutive cohorts, and measured two markers of oxidative damage (malondialdehyde (MDA), protein carbonyls (PC)) and two markers of antioxidant (AOX) protection (total AOX capacity (TAC), superoxide dismutase (SOD)) from blood samples. Faster lamb growth was weakly associated with increased MDA, but not associated with variation in the other three markers. Lambs with higher SOD activity were more likely to survive their first winter, as were male but not female lambs with lower PC concentrations. Survival did not vary with MDA or total TAC. Key predictions relating OS to growth and survival were therefore supported in some OS markers, but not others. This suggests that different markers capture different aspects of the complex relationships between individual oxidative state, physiology and fitness, and that overarching hypotheses relating OS to life-history variation cannot be supported or refuted by studying individual markers.
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Affiliation(s)
- Louise L Christensen
- Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - Colin Selman
- Glasgow Ageing Research Network (GARNER), Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow AB24 2TZ, UK
| | - Jonathan D Blount
- College of Life and Environmental Sciences, University of Exeter, Penryn Campus, TR10 9EZ, UK
| | - Jill G Pilkington
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK
| | - Kathryn A Watt
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK
| | | | - Jane M Reid
- Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - Daniel H Nussey
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JG, UK
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20
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Hares MC, Vitikainen EIK, Marshall HH, Thompson FJ, Blount JD, Cant MA. Telomere dynamics in wild banded mongooses: Evaluating longitudinal and quasi-longitudinal markers of senescence. Exp Gerontol 2017; 107:67-73. [PMID: 28964829 PMCID: PMC5956279 DOI: 10.1016/j.exger.2017.09.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 09/25/2017] [Accepted: 09/26/2017] [Indexed: 11/06/2022]
Abstract
Telomere length and the rate of telomere shortening have been suggested as particularly useful physiological biomarkers of the processes involved in senescent decline of somatic and reproductive function. However, longitudinal data on changes in telomere length across the lifespan are difficult to obtain, particularly for long-lived animals. Quasi-longitudinal studies have been proposed as a method to gain insight into telomere dynamics in long-lived species. In this method, minimally replicative cells are used as the baseline telomere length against which telomere length in highly replicative cells (which represent the current state) can be compared. Here we test the assumptions and predictions of the quasi-longitudinal approach using longitudinal telomere data in a wild cooperative mammal, the banded mongoose, Mungos mungo. Contrary to our prediction, telomere length (TL) was longer in leukocytes than in ear cartilage. Longitudinally, the TL of ear cartilage shortened with age, but there was no change in the TL of leukocytes, and we also observed many individuals in which TL increased rather than decreased with age. Leukocyte TL but not cartilage TL was a predictor of total lifespan, while neither predicted post-sampling survival. Our data do not support the hypothesis that cross-tissue comparison in TL can act as a quasi-longitudinal marker of senescence. Rather, our results suggest that telomere dynamics in banded mongooses are more complex than is typically assumed, and that longitudinal studies across whole life spans are required to elucidate the link between telomere dynamics and senescence in natural populations. We find no evidence that somatic tissues can be used as a quasi-longitudinal marker for telomere length in leukocytes. Telomere dynamics in different tissue types appear to be complex and likely to be influenced by telomerase activity. Telomere length may be a useful marker for somatic quality in wild animal populations.
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Affiliation(s)
- Michelle C Hares
- University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, United Kingdom.
| | - Emma I K Vitikainen
- University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, United Kingdom.
| | - Harry H Marshall
- Centre for Research in Ecology, University of Roehampton, London, SW15 4JD, United Kingdom
| | - Faye J Thompson
- University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, United Kingdom
| | - Jonathan D Blount
- University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, United Kingdom
| | - Michael A Cant
- University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, United Kingdom
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21
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Abstract
Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies.
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Affiliation(s)
- Dominic L Cram
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Jonathan D Blount
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Andrew J Young
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
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22
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Vitikainen EIK, Cant MA, Sanderson JL, Mitchell C, Nichols HJ, Marshall HH, Thompson FJ, Gilchrist JS, Hodge SJ, Johnstone RA, Blount JD. Evidence of Oxidative Shielding of Offspring in a Wild Mammal. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00058] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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23
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Speakman JR, Blount JD, Bronikowski AM, Buffenstein R, Isaksson C, Kirkwood TBL, Monaghan P, Ozanne SE, Beaulieu M, Briga M, Carr SK, Christensen LL, Cochemé HM, Cram DL, Dantzer B, Harper JM, Jurk D, King A, Noguera JC, Salin K, Sild E, Simons MJP, Smith S, Stier A, Tobler M, Vitikainen E, Peaker M, Selman C. Oxidative stress and life histories: unresolved issues and current needs. Ecol Evol 2015; 5:5745-57. [PMID: 26811750 PMCID: PMC4717350 DOI: 10.1002/ece3.1790] [Citation(s) in RCA: 150] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 09/20/2015] [Indexed: 12/12/2022] Open
Abstract
Life‐history theory concerns the trade‐offs that mold the patterns of investment by animals between reproduction, growth, and survival. It is widely recognized that physiology plays a role in the mediation of life‐history trade‐offs, but the details remain obscure. As life‐history theory concerns aspects of investment in the soma that influence survival, understanding the physiological basis of life histories is related, but not identical, to understanding the process of aging. One idea from the field of aging that has gained considerable traction in the area of life histories is that life‐history trade‐offs may be mediated by free radical production and oxidative stress. We outline here developments in this field and summarize a number of important unresolved issues that may guide future research efforts. The issues are as follows. First, different tissues and macromolecular targets of oxidative stress respond differently during reproduction. The functional significance of these changes, however, remains uncertain. Consequently there is a need for studies that link oxidative stress measurements to functional outcomes, such as survival. Second, measurements of oxidative stress are often highly invasive or terminal. Terminal studies of oxidative stress in wild animals, where detailed life‐history information is available, cannot generally be performed without compromising the aims of the studies that generated the life‐history data. There is a need therefore for novel non‐invasive measurements of multi‐tissue oxidative stress. Third, laboratory studies provide unrivaled opportunities for experimental manipulation but may fail to expose the physiology underpinning life‐history effects, because of the benign laboratory environment. Fourth, the idea that oxidative stress might underlie life‐history trade‐offs does not make specific enough predictions that are amenable to testing. Moreover, there is a paucity of good alternative theoretical models on which contrasting predictions might be based. Fifth, there is an enormous diversity of life‐history variation to test the idea that oxidative stress may be a key mediator. So far we have only scratched the surface. Broadening the scope may reveal new strategies linked to the processes of oxidative damage and repair. Finally, understanding the trade‐offs in life histories and understanding the process of aging are related but not identical questions. Scientists inhabiting these two spheres of activity seldom collide, yet they have much to learn from each other.
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Affiliation(s)
- John R Speakman
- Institute of Biological and Environmental Sciences University of Aberdeen Tillydrone Avenue Aberdeen AB24 2TZ UK; State Key Laboratory of Molecular Developmental Biology Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing China
| | - Jonathan D Blount
- Centre for Ecology and Conservation University of Exeter Penryn Campus Cornwall TR10 9FE UK
| | - Anne M Bronikowski
- Department of Ecology, Evolution and Organismal Biology Iowa State University 251 Bessey Hall Ames Iowa 50011
| | - Rochelle Buffenstein
- Physiology, Barshop Institute for Aging and Longevity Research UTHSCSA 15355 Lambda Drive San Antonio Texas 78245
| | - Caroline Isaksson
- Department of Biology Lund University Solvegatan 37 Lund 223 62 Sweden
| | - Tom B L Kirkwood
- The Newcastle University Institute for Ageing Institute for Cell & Molecular Biosciences Campus for Ageing and Vitality Newcastle upon Tyne NE4 5PL UK
| | - Pat Monaghan
- Institute of Biodiversity, Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
| | - Susan E Ozanne
- University of Cambridge Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Level 4 Wellcome Trust-MRC Institute of Metabolic Science Addenbrooke's Hospital Cambridge CB2 0QQ UK
| | - Michaël Beaulieu
- Zoological Institute and Museum University of Greifswald Johann-Sebastian Bach Str. 11/12 Greifswald 17489 Germany
| | - Michael Briga
- Behavioral Biology University of Groningen Nijenborgh 7 Groningen 9747 AG The Netherlands
| | - Sarah K Carr
- University of Cambridge Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Level 4 Wellcome Trust-MRC Institute of Metabolic Science Addenbrooke's Hospital Cambridge CB2 0QQ UK
| | - Louise L Christensen
- Institute of Biological and Environmental Sciences University of Aberdeen Tillydrone Avenue Aberdeen AB24 2TZ UK
| | - Helena M Cochemé
- MRC Clinical Sciences Centre Imperial College London Hammersmith Hospital Campus Du Cane Road London W12 0NN UK
| | - Dominic L Cram
- Department of Zoology University of Cambridge Cambridge CB2 3EJ UK
| | - Ben Dantzer
- Department of Psychology University of Michigan Ann Arbor Michigan 48109
| | - Jim M Harper
- Department of Biological Sciences Sam Houston State University 1900 Avenue I LDB 100B Huntsville Texas 77341
| | - Diana Jurk
- The Newcastle University Institute for Ageing Institute for Cell & Molecular Biosciences Campus for Ageing and Vitality Newcastle upon Tyne NE4 5PL UK
| | - Annette King
- The Newcastle University Institute for Ageing Institute for Cell & Molecular Biosciences Campus for Ageing and Vitality Newcastle upon Tyne NE4 5PL UK
| | - Jose C Noguera
- Institute of Biodiversity, Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
| | - Karine Salin
- Institute of Biodiversity, Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
| | - Elin Sild
- Department of Biology Lund University Solvegatan 37 Lund 223 62 Sweden
| | - Mirre J P Simons
- Department of Animal and Plant Sciences University of Sheffield Alfred Denny Building, Western Bank Sheffield S10 2TN UK
| | - Shona Smith
- Institute of Biodiversity, Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
| | - Antoine Stier
- Department Ecology, Physiology et Ethology University of Strasbourg - IPHC (UMR7178) 23, rue Becquerel Strasbourg 67087 France
| | - Michael Tobler
- Department of Biology Lund University Solvegatan 37 Lund 223 62 Sweden
| | - Emma Vitikainen
- Centre for Ecology and Conservation University of Exeter Penryn Campus Cornwall TR10 9FE UK
| | | | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine University of Glasgow Graham Kerr Building Glasgow G12 8QQ UK
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Paul SC, Pell JK, Blount JD. Reproduction in Risky Environments: The Role of Invasive Egg Predators in Ladybird Laying Strategies. PLoS One 2015; 10:e0139404. [PMID: 26488753 PMCID: PMC4619405 DOI: 10.1371/journal.pone.0139404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/12/2015] [Indexed: 12/04/2022] Open
Abstract
Reproductive environments are variable and the resources available for reproduction are finite. If reliable cues about the environment exist, mothers can alter offspring phenotype in a way that increases both offspring and maternal fitness (‘anticipatory maternal effects’—AMEs). Strategic use of AMEs is likely to be important in chemically defended species, where the risk of offspring predation may be modulated by maternal investment in offspring toxin level, albeit at some cost to mothers. Whether mothers adjust offspring toxin levels in response to variation in predation risk is, however, unknown, but is likely to be important when assessing the response of chemically defended species to the recent and pervasive changes in the global predator landscape, driven by the spread of invasive species. Using the chemically defended two-spot ladybird, Adalia bipunctata, we investigated reproductive investment, including egg toxin level, under conditions that varied in the degree of simulated offspring predation risk from larval harlequin ladybirds, Harmonia axyridis. H. axyridis is a highly voracious alien invasive species in the UK and a significant intraguild predator of A. bipunctata. Females laid fewer, larger egg clusters, under conditions of simulated predation risk (P+) than when predator cues were absent (P-), but there was no difference in toxin level between the two treatments. Among P- females, when mean cluster size increased there were concomitant increases in both the mass and toxin concentration of eggs, however when P+ females increased cluster size there was no corresponding increase in egg toxin level. We conclude that, in the face of offspring predation risk, females either withheld toxins or were physiologically constrained, leading to a trade-off between cluster size and egg toxin level. Our results provide the first demonstration that the risk of offspring predation by a novel invasive predator can influence maternal investment in toxins within their offspring.
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Affiliation(s)
- Sarah C. Paul
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
| | - Judith K. Pell
- J. K. Pell Consulting, Luton, Bedfordshire, United Kingdom
| | - Jonathan D. Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
- * E-mail:
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25
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Christensen LL, Selman C, Blount JD, Pilkington JG, Watt KA, Pemberton JM, Reid JM, Nussey DH. Plasma markers of oxidative stress are uncorrelated in a wild mammal. Ecol Evol 2015; 5:5096-108. [PMID: 26640685 PMCID: PMC4662306 DOI: 10.1002/ece3.1771] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 09/03/2015] [Accepted: 09/17/2015] [Indexed: 01/19/2023] Open
Abstract
Oxidative stress, which results from an imbalance between the production of potentially damaging reactive oxygen species versus antioxidant defenses and repair mechanisms, has been proposed as an important mediator of life‐history trade‐offs. A plethora of biomarkers associated with oxidative stress exist, but few ecological studies have examined the relationships among different markers in organisms experiencing natural conditions or tested whether those relationships are stable across different environments and demographic groups. It is therefore not clear to what extent studies of different markers can be compared, or whether studies that focus on a single marker can draw general conclusions regarding oxidative stress. We measured widely used markers of oxidative damage (protein carbonyls and malondialdehyde) and antioxidant defense (superoxide dismutase and total antioxidant capacity) from 706 plasma samples collected over a 4‐year period in a wild population of Soay sheep on St Kilda. We quantified the correlation structure among these four markers across the entire sample set and also within separate years, age groups (lambs and adults), and sexes. We found some moderately strong correlations between some pairs of markers when data from all 4 years were pooled. However, these correlations were caused by considerable among‐year variation in mean marker values; correlation coefficients were small and not significantly different from zero after accounting for among‐year variation. Furthermore, within each year, age, and sex subgroup, the pairwise correlation coefficients among the four markers were weak, nonsignificant, and distributed around zero. In addition, principal component analysis confirmed that the four markers represented four independent axes of variation. Our results suggest that plasma markers of oxidative stress may vary dramatically among years, presumably due to environmental conditions, and that this variation can induce population‐level correlations among markers even in the absence of any correlations within contemporaneous subgroups. The absence of any consistent correlations within years or demographic subgroups implies that care must be taken when generalizing from observed relationships with oxidative stress markers, as each marker may reflect different and potentially uncoupled biochemical processes.
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Affiliation(s)
- Louise L Christensen
- Institute of Biological and Environmental Sciences University of Aberdeen Aberdeen UK
| | - Colin Selman
- Glasgow Ageing Research Network (GARNER) Institute of Biodiversity Animal Health and Comparative Medicine University of Glasgow Glasgow UK
| | - Jonathan D Blount
- College of Life and Environmental Sciences University of Exeter Penryn Campus UK
| | - Jill G Pilkington
- Institute of Evolutionary Biology University of Edinburgh Edinburgh UK
| | - Kathryn A Watt
- Institute of Evolutionary Biology University of Edinburgh Edinburgh UK
| | | | - Jane M Reid
- Institute of Biological and Environmental Sciences University of Aberdeen Aberdeen UK
| | - Daniel H Nussey
- Institute of Evolutionary Biology University of Edinburgh Edinburgh UK
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26
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Flores EE, Stevens M, Moore AJ, Rowland HM, Blount JD. Body size but not warning signal luminance influences predation risk in recently metamorphosed poison frogs. Ecol Evol 2015; 5:4603-16. [PMID: 26668726 PMCID: PMC4670055 DOI: 10.1002/ece3.1731] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/19/2015] [Accepted: 08/22/2015] [Indexed: 01/05/2023] Open
Abstract
During early development, many aposematic species have bright and conspicuous warning appearance, but have yet to acquire chemical defenses, a phenotypic state which presumably makes them vulnerable to predation. Body size and signal luminance in particular are known to be sensitive to variation in early nutrition. However, the relative importance of these traits as determinants of predation risk in juveniles is not known. To address this question, we utilized computer‐assisted design (CAD) and information on putative predator visual sensitivities to produce artificial models of postmetamorphic froglets that varied in terms of body size and signal luminance. We then deployed the artificial models in the field and measured rates of attack by birds and unknown predators. Our results indicate that body size was a significant predictor of artificial prey survival. Rates of attack by bird predators were significantly higher on smaller models. However, predation by birds did not differ between artificial models of varying signal luminance. This suggests that at the completion of metamorphosis, smaller froglets may be at a selective disadvantage, potentially because predators can discern they have relatively low levels of chemical defense compared to larger froglets. There is likely to be a premium on efficient foraging, giving rise to rapid growth and the acquisition of toxins from dietary sources in juvenile poison frogs.
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Affiliation(s)
- Eric E Flores
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK ; Sistema Nacional de Investigacion de Panama (SNI) Panama
| | - Martin Stevens
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK
| | - Allen J Moore
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK ; Department of Genetics University of Georgia 30602 Athens Georgia
| | | | - Jonathan D Blount
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK
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27
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Lane SM, Solino JH, Mitchell C, Blount JD, Okada K, Hunt J, House CM. Rival male chemical cues evoke changes in male pre- and post-copulatory investment in a flour beetle. Behav Ecol 2015; 26:1021-1029. [PMID: 26167098 PMCID: PMC4495758 DOI: 10.1093/beheco/arv047] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 03/06/2015] [Accepted: 03/10/2015] [Indexed: 11/13/2022] Open
Abstract
Males can gather information on the risk and intensity of sperm competition from their social environment. Recent studies have implicated chemosensory cues, for instance cuticular hydrocarbons (CHCs) in insects, as a key source of this information. Here, using the broad-horned flour beetle (Gnatocerus cornutus), we investigated the importance of contact-derived rival male CHCs in informing male perception of sperm competition risk and intensity. We experimentally perfumed virgin females with male CHCs via direct intersexual contact and measured male pre- and post-copulatory investment in response to this manipulation. Using chemical analysis, we verified that this treatment engendered changes to perfumed female CHC profiles, but did not make perfumed females "smell" mated. Despite this, males responded to these chemical changes. Males increased courtship effort under low levels of perceived competition (from 1-3 rivals), but significantly decreased courtship effort as perceived competition rose (from 3-5 rivals). Furthermore, our measurement of ejaculate investment showed that males allocated significantly more sperm to perfumed females than to control females. Together, these results suggest that changes in female chemical profile elicited by contact with rival males do not provide males with information on female mating status, but rather inform males of the presence of rivals within the population and thus provide a means for males to indirectly assess the risk of sperm competition.
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Affiliation(s)
- Sarah M Lane
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK
| | - Joanna H Solino
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK , ; Liverpool School of Tropical Medicine, Vector Control Department , Pembroke Place, Liverpool L3 5QA , UK
| | - Christopher Mitchell
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK , ; Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury Campus , Penrith, New South Wales 2751 , Australia , and
| | - Jonathan D Blount
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK
| | - Kensuke Okada
- Laboratory of Evolutionary Ecology, Graduate School of Environmental Science, Okayama University , Tsushima-naka 1-1-1, Okayama , Japan
| | - John Hunt
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK
| | - Clarissa M House
- Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus , Cornwall TR10 9EZ , UK
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Cram DL, Blount JD, York JE, Young AJ. Immune response in a wild bird is predicted by oxidative status, but does not cause oxidative stress. PLoS One 2015; 10:e0122421. [PMID: 25815888 PMCID: PMC4376632 DOI: 10.1371/journal.pone.0122421] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/20/2015] [Indexed: 12/26/2022] Open
Abstract
The immune system provides vital protection against pathogens, but extensive evidence suggests that mounting immune responses can entail survival and fecundity costs. The physiological mechanisms that underpin these costs remain poorly understood, despite their potentially important role in shaping life-histories. Recent studies involving laboratory models highlight the possibility that oxidative stress could mediate these costs, as immune-activation can increase the production of reactive oxygen species leading to oxidative stress. However, this hypothesis has rarely been tested in free-ranging wild populations, where natural oxidative statuses and compensatory strategies may moderate immune responses and their impacts on oxidative status. Furthermore, the possibility that individuals scale their immune responses according to their oxidative status, conceivably to mitigate such costs, remains virtually unexplored. Here, we experimentally investigate the effects of a phytohaemagglutinin (PHA) immune-challenge on oxidative status in wild male and female white-browed sparrow weavers, Plocepasser mahali. We also establish whether baseline oxidative status prior to challenge predicts the scale of the immune responses. Contrary to previous work on captive animals, our findings suggest that PHA-induced immune-activation does not elicit oxidative stress. Compared with controls (n = 25 birds), PHA-injected birds (n = 27 birds) showed no evidence of a differential change in markers of oxidative damage or enzymatic and non-enzymatic antioxidant protection 24 hours after challenge. We did, however, find that the activity of a key antioxidant enzyme (superoxide dismutase, SOD) prior to immune-activation predicted the scale of the resulting swelling: birds with stronger initial SOD activity subsequently produced smaller swellings. Our findings (i) suggest that wild birds can mount immune responses without suffering from systemic oxidative stress, and (ii) lend support to biomedical evidence that baseline oxidative status can impact the scale of immune responses; a possibility not yet recognised in ecological studies of immunity.
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Affiliation(s)
- Dominic L. Cram
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan D. Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
| | - Jennifer E. York
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
- Department of Zoology and Entomology, University of Pretoria, Pretoria, Gauteng, South Africa
| | - Andrew J. Young
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, United Kingdom
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29
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Blount JD, Vitikainen EIK, Stott I, Cant MA. Oxidative shielding and the cost of reproduction. Biol Rev Camb Philos Soc 2015; 91:483-97. [PMID: 25765468 DOI: 10.1111/brv.12179] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 01/30/2015] [Accepted: 02/12/2015] [Indexed: 02/06/2023]
Abstract
Life-history theory assumes that reproduction and lifespan are constrained by trade-offs which prevent their simultaneous increase. Recently, there has been considerable interest in the possibility that this cost of reproduction is mediated by oxidative stress. However, empirical tests of this theory have yielded equivocal support. We carried out a meta-analysis to examine associations between reproduction and oxidative damage across markers and tissues. We show that oxidative damage is positively associated with reproductive effort across females of various species. Yet paradoxically, categorical comparisons of breeders versus non-breeders reveal that transition to the reproductive state is associated with a step-change reduction in oxidative damage in certain tissues and markers. Developing offspring may be particularly sensitive to harm caused by oxidative damage in mothers. Therefore, such reductions could potentially function to shield reproducing mothers, gametes and developing offspring from oxidative insults that inevitably increase as a consequence of reproductive effort. According to this perspective, we hypothesise that the cost of reproduction is mediated by dual impacts of maternally-derived oxidative damage on mothers and offspring, and that mothers may be selected to diminish such damage. Such oxidative shielding may explain why many existing studies have concluded that reproduction has little or no oxidative cost. Future advance in life-history theory therefore needs to take account of potential transgenerational impacts of the mechanisms underlying life-history trade-offs.
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Affiliation(s)
- Jonathan D Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, U.K
| | - Emma I K Vitikainen
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, U.K
| | - Iain Stott
- Environment & Sustainability Institute, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, U.K
| | - Michael A Cant
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Cornwall, TR10 9FE, U.K
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30
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Affiliation(s)
- Dominic L. Cram
- Centre for Ecology & Conservation College of Life & Environmental Sciences University of Exeter Penryn Campus Cornwall TR10 9FE UK
- Department of Zoology University of Cambridge Cambridge CB2 3EJ UK
| | - Jonathan D. Blount
- Centre for Ecology & Conservation College of Life & Environmental Sciences University of Exeter Penryn Campus Cornwall TR10 9FE UK
| | - Andrew J. Young
- Centre for Ecology & Conservation College of Life & Environmental Sciences University of Exeter Penryn Campus Cornwall TR10 9FE UK
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31
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Plummer KE, Bearhop S, Leech DI, Chamberlain DE, Blount JD. Winter food provisioning reduces future breeding performance in a wild bird. Sci Rep 2014; 3:2002. [PMID: 23788126 PMCID: PMC6504817 DOI: 10.1038/srep02002] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 05/28/2013] [Indexed: 11/09/2022] Open
Abstract
Supplementation of food to wild birds occurs on an enormous scale worldwide, and is often cited as an exemplar of beneficial human-wildlife interaction. Recently it has been speculated that winter feeding could have negative consequences for future reproduction, for example by enabling low quality individuals to recruit into breeding populations. However, evidence that winter feeding has deleterious impacts on reproductive success is lacking. Here, in a landscape-scale study of blue tits (Cyanistes caeruleus) across multiple years, we show that winter food supplementation reduced breeding performance the following spring. Compared to unfed populations, winter-fed birds produced offspring that weighed less, were smaller, and had lower survival. This impairment was observed in parents that had received fat only, or in combination with vitamin E, suggesting some generality in the mechanism by which supplementary feeding affected reproduction. Our results highlight the potential for deleterious population-level consequences of winter food supplementation on wild birds.
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Affiliation(s)
- K E Plummer
- 1] Centre for Ecology and Conservation, College of Life & Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, Cornwall, TR10 9EZ, UK [2]
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32
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Winters AE, Stevens M, Mitchell C, Blomberg SP, Blount JD. Maternal effects and warning signal honesty in eggs and offspring of an aposematic ladybird beetle. Funct Ecol 2014. [DOI: 10.1111/1365-2435.12266] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anne E. Winters
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn Campus Cornwall TR10 9EZ UK
- School of Biological Sciences; The University of Queensland; Brisbane Queensland 4072 Australia
| | - Martin Stevens
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn Campus Cornwall TR10 9EZ UK
- Department of Zoology; University of Cambridge; Cambridge CB2 3EJ UK
| | - Chris Mitchell
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn Campus Cornwall TR10 9EZ UK
| | - Simon P. Blomberg
- School of Biological Sciences; The University of Queensland; Brisbane Queensland 4072 Australia
| | - Jonathan D. Blount
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn Campus Cornwall TR10 9EZ UK
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33
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Flores EE, Stevens M, Moore AJ, Blount JD. Diet, development and the optimization of warning signals in post‐metamorphic green and black poison frogs. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12084] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eric E. Flores
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Cornwall Campus Penryn TR10 9EZ UK
| | - Martin Stevens
- Department of Zoology University of Cambridge Downing Street Cambridge CB2 3EJ UK
| | - Allen J. Moore
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Cornwall Campus Penryn TR10 9EZ UK
- Department of Genetics University of Georgia Athens GA 30602 USA
| | - Jonathan D. Blount
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Cornwall Campus Penryn TR10 9EZ UK
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Plummer KE, Bearhop S, Leech DI, Chamberlain DE, Blount JD. Fat provisioning in winter impairs egg production during the following spring: a landscape-scale study of blue tits. J Anim Ecol 2013; 82:673-82. [DOI: 10.1111/1365-2656.12025] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 10/18/2012] [Indexed: 11/30/2022]
Affiliation(s)
- Kate E. Plummer
- Centre for Ecology and Conservation; College of Life & Environmental Sciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
| | - Stuart Bearhop
- Centre for Ecology and Conservation; College of Life & Environmental Sciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
| | - David I. Leech
- British Trust for Ornithology; The Nunnery; Thetford; Norfolk; IP24 2PU; UK
| | - Dan E. Chamberlain
- Dipartimento di Biologiá Animale e dell'Uomo; Universitá degli Studi di Torino; Via Accademia Albertina 13; Turin; 10123; Italy
| | - Jonathan D. Blount
- Centre for Ecology and Conservation; College of Life & Environmental Sciences; University of Exeter; Cornwall Campus; Penryn; Cornwall; TR10 9EZ; UK
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35
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Losdat S, Helfenstein F, Blount JD, Marri V, Maronde L, Richner H. Nestling erythrocyte resistance to oxidative stress predicts fledging success but not local recruitment in a wild bird. Biol Lett 2012; 9:20120888. [PMID: 23097463 DOI: 10.1098/rsbl.2012.0888] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Stressful conditions experienced by individuals during their early development have long-term consequences on various life-history traits such as survival until first reproduction. Oxidative stress has been shown to affect various fitness-related traits and to influence key evolutionary trade-offs but whether an individual's ability to resist oxidative stress in early life affects its survival has rarely been tested. In the present study, we used four years of data obtained from a free-living great tit population (Parus major; n = 1658 offspring) to test whether pre-fledging resistance to oxidative stress, measured as erythrocyte resistance to oxidative stress and oxidative damage to lipids, predicted fledging success and local recruitment. Fledging success and local recruitment, both major correlates of survival, were primarily influenced by offspring body mass prior to fledging. We found that pre-fledging erythrocyte resistance to oxidative stress predicted fledging success, suggesting that individual resistance to oxidative stress is related to short-term survival. However, local recruitment was not influenced by pre-fledging erythrocyte resistance to oxidative stress or oxidative damage. Our results suggest that an individual ability to resist oxidative stress at the offspring stage predicts short-term survival but does not influence survival later in life.
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Affiliation(s)
- Sylvain Losdat
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
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36
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Müller W, Vergauwen J, Eens M, Blount JD. Environmental effects shape the maternal transfer of carotenoids and vitamin E to the yolk. Front Zool 2012; 9:17. [PMID: 22876878 PMCID: PMC3502133 DOI: 10.1186/1742-9994-9-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 08/03/2012] [Indexed: 11/10/2022] Open
Abstract
UNLABELLED INTRODUCTION Maternal effects occur when the phenotype of the offspring is influenced by the phenotype of the mother, which in turn depends on her heritable state as well as on influences from the current and past environmental conditions. All of these pathways may, therefore, form significant sources of variation in maternal effects. Here, we focused on the maternal transfer of carotenoids and vitamin E to the egg yolk, using canaries as a model species. Maternal yolk carotenoids and vitamin E are known to generate significant phenotypic variation in offspring, representing examples of maternal effects. We studied the intra-individual consistency in deposition patterns across two years and the mother-daughter resemblance across two generations in order to estimate the level of heritable variation. The effects of the current environmental conditions were studied via a food supplementation experiment, while the consequences of past environmental conditions were estimated on the basis of the early growth trajectories. RESULTS There was a significant effect of the current environmental conditions on the yolk carotenoid and vitamin E deposition, but this effect varied between antioxidant components. The deposition of yolk carotenoids and vitamin E were linked to the process of yolk formation. Past environmental conditions did not contribute to the variation in yolk carotenoid and vitamin E levels nor did we find significant heritable variation. CONCLUSIONS The transfer of carotenoids or vitamin E may be an example where current environmental variation is largely passed from the mother to the offspring, despite the numerous intermediate physiological steps that are involved. Differences in the effect of the environmental conditions as experienced by the mother during laying may be due to differences in availability as well as physiological processes such as competitive exclusion or selective absorption.
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Affiliation(s)
- Wendt Müller
- Department of Biology-Ethology, University of Antwerp, 2610, Wilrijk, Belgium.
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37
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Selman C, Blount JD, Nussey DH, Speakman JR. Oxidative damage, ageing, and life-history evolution: where now? Trends Ecol Evol 2012; 27:570-7. [PMID: 22789512 DOI: 10.1016/j.tree.2012.06.006] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 06/06/2012] [Accepted: 06/15/2012] [Indexed: 01/09/2023]
Abstract
The idea that resources are limited and animals can maximise fitness by trading costly activities off against one another forms the basis of life-history theory. Although investment in reproduction or growth negatively affects survival, the mechanisms underlying such trade-offs remain obscure. One plausible mechanism is oxidative damage to proteins, lipids, and nucleic acids caused by reactive oxygen species (ROS). Here, we critically evaluate the premise that ROS-induced oxidative damage shapes life history, focussing on birds and mammals, and highlight the importance of ecological studies examining free-living animals within this experimental framework. We conclude by emphasising the value of using multiple assays to determine oxidative protection and damage. We also highlight the importance of using standardised and appropriate protocols, and discuss future research directions.
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Affiliation(s)
- Colin Selman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK.
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38
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Flores EE, Moore AJ, Blount JD. Unusual whitish eggs in the poison frogDendrobates auratusGirard, 1855. Tropical Zoology 2012. [DOI: 10.1080/03946975.2012.696401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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39
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Sepp T, Karu U, Blount JD, Sild E, Männiste M, Hõrak P. Coccidian infection causes oxidative damage in greenfinches. PLoS One 2012; 7:e36495. [PMID: 22615772 PMCID: PMC3352913 DOI: 10.1371/journal.pone.0036495] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 04/03/2012] [Indexed: 12/22/2022] Open
Abstract
The main tenet of immunoecology is that individual variation in immune responsiveness is caused by the costs of immune responses to the hosts. Oxidative damage resulting from the excessive production of reactive oxygen species during immune response is hypothesized to form one of such costs. We tested this hypothesis in experimental coccidian infection model in greenfinches Carduelis chloris. Administration of isosporan coccidians to experimental birds did not affect indices of antioxidant protection (TAC and OXY), plasma triglyceride and carotenoid levels or body mass, indicating that pathological consequences of infection were generally mild. Infected birds had on average 8% higher levels of plasma malondialdehyde (MDA, a toxic end-product of lipid peroxidation) than un-infected birds. The birds that had highest MDA levels subsequent to experimental infection experienced the highest decrease in infection intensity. This observation is consistent with the idea that oxidative stress is a causative agent in the control of coccidiosis and supports the concept of oxidative costs of immune responses and parasite resistance. The finding that oxidative damage accompanies even the mild infection with a common parasite highlights the relevance of oxidative stress biology for the immunoecological research.
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Affiliation(s)
- Tuul Sepp
- Department of Zoology, Institute of Ecology and Earth Sciences, The Centre of Excellence FIBIR, Tartu University, Tartu, Estonia.
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Sepp T, Sild E, Blount JD, Männiste M, Karu U, Hõrak P. Individual Consistency and Covariation of Measures of Oxidative Status in Greenfinches. Physiol Biochem Zool 2012; 85:299-307. [DOI: 10.1086/664827] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Orledge JM, Blount JD, Hoodless AN, Royle NJ. Antioxidant supplementation during early development reduces parasite load but does not affect sexual ornament expression in adult ring-necked pheasants. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2012.01977.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Blount JD, Rowland HM, Drijfhout FP, Endler JA, Inger R, Sloggett JJ, Hurst GDD, Hodgson DJ, Speed MP. How the ladybird got its spots: effects of resource limitation on the honesty of aposematic signals. Funct Ecol 2012. [DOI: 10.1111/j.1365-2435.2012.01961.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Orledge JM, Blount JD, Hoodless AN, Pike TW, Royle NJ. Synergistic effects of supplementation of dietary antioxidants during growth on adult phenotype in ring-necked pheasants,Phasianus colchicus. Funct Ecol 2011. [DOI: 10.1111/j.1365-2435.2011.01932.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
The effect of climate warming on the reproductive success of ectothermic animals is currently a subject of major conservation concern. However, for many threatened species, we still know surprisingly little about the extent of naturally occurring adaptive variation in heat-tolerance. Here, we show that the thermal tolerances of green turtle (Chelonia mydas) embryos in a single, island-breeding population have diverged in response to the contrasting incubation temperatures of nesting beaches just a few kilometres apart. In natural nests and in a common-garden rearing experiment, the offspring of females nesting on a naturally hot (black sand) beach survived better and grew larger at hot incubation temperatures compared with the offspring of females nesting on a cooler (pale sand) beach nearby. These differences were owing to shallower thermal reaction norms in the hot beach population, rather than shifts in thermal optima, and could not be explained by egg-mediated maternal effects. Our results suggest that marine turtle nesting behaviour can drive adaptive differentiation at remarkably fine spatial scales, and have important implications for how we define conservation units for protection. In particular, previous studies may have underestimated the extent of adaptive structuring in marine turtle populations that may significantly affect their capacity to respond to environmental change.
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Affiliation(s)
- Sam B Weber
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, UK
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Abstract
Mounting an immune response against pathogens incurs costs to organisms by its effects on important life-history traits, such as reproductive investment and survival. As shown recently, immune activation produces large amounts of reactive species and is suggested to induce oxidative stress. Sperm are highly susceptible to oxidative stress, which can negatively impact sperm function and ultimately male fertilizing efficiency. Here we address the question as to whether mounting an immune response affects sperm quality through the damaging effects of oxidative stress. It has been demonstrated recently in birds that carotenoid-based ornaments can be reliable signals of a male's ability to protect sperm from oxidative damage. In a full-factorial design, we immune-challenged great tit males while simultaneously increasing their vitamin E availability, and assessed the effect on sperm quality and oxidative damage. We conducted this experiment in a natural population and tested the males' response to the experimental treatment in relation to their carotenoid-based breast coloration, a condition-dependent trait. Immune activation induced a steeper decline in sperm swimming velocity, thus highlighting the potential costs of an induced immune response on sperm competitive ability and fertilizing efficiency. We found sperm oxidative damage to be negatively correlated with sperm swimming velocity. However, blood resistance to a free-radical attack (a measure of somatic antioxidant capacity) as well as plasma and sperm levels of oxidative damage (lipid peroxidation) remained unaffected, thus suggesting that the observed effect did not arise through oxidative stress. Towards the end of their breeding cycle, swimming velocity of sperm of more intensely colored males was higher, which has important implications for the evolution of mate choice and multiple mating in females because females may accrue both direct and indirect benefits by mating with males having better quality sperm.
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Affiliation(s)
- Sylvain Losdat
- Evolutionary Ecology Lab, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
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Weber SB, Blount JD, Godley BJ, Witt MJ, Broderick AC. Rate of egg maturation in marine turtles exhibits ‘universal temperature dependence’. J Anim Ecol 2011; 80:1034-41. [DOI: 10.1111/j.1365-2656.2011.01850.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Affiliation(s)
- Thomas W. Pike
- Division of Ecology and Evolutionary Biology, Faculty of Biomedical & Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Bjørn Bjerkeng
- Nofima Marine AS (formerly Akvaforsk, Institute of Aquaculture Research AS), N‐6600 Sunndalsøra, Norway
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, School of Biosciences, University of Exeter, Cornwall Campus, Penryn, Cornwall TR10 9EZ, UK
| | - Jan Lindström
- Division of Ecology and Evolutionary Biology, Faculty of Biomedical & Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
| | - Neil B. Metcalfe
- Division of Ecology and Evolutionary Biology, Faculty of Biomedical & Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
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Abstract
1. Carry-over effects occur when processes in one season influence the success of an individual in the following season. This phenomenon has the potential to explain a large amount of variation in individual fitness, but so far has only been described in a limited number of species. This is largely due to difficulties associated with tracking individuals between periods of the annual cycle, but also because of a lack of research specifically designed to examine hypotheses related to carry-over effects. 2. We review the known mechanisms that drive carry-over effects, most notably macronutrient supply, and highlight the types of life histories and ecological situations where we would expect them to most often occur. We also identify a number of other potential mechanisms that require investigation, including micronutrients such as antioxidants. 3. We propose a series of experiments designed to estimate the relative contributions of extrinsic and intrinsic quality effects in the pre-breeding season, which in turn will allow an accurate estimation of the magnitude of carry-over effects. To date this has proven immensely difficult, and we hope that the experimental frameworks described here will stimulate new avenues of research vital to advancing our understanding of how carry-over effects can shape animal life histories. 4. We also explore the potential of state-dependent modelling as a tool for investigating carry-over effects, most notably for its ability to calculate optimal rates of acquisition of a multitude of resources over the course of the annual cycle, and also because it allows us to vary the strength of density-dependent relationships which can alter the magnitude of carry-over effects in either a synergistic or agonistic fashion. 5. In conclusion carry-over effects are likely to be far more widespread than currently indicated, and they are likely to be driven by a multitude of factors including both macro- and micronutrients. For this reason they could feasibly be responsible for a large amount of the observed variation in performance among individuals, and consequently warrant a wealth of new research designed specifically to decompose components of variation in fitness attributes related to processes across and within seasons.
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Affiliation(s)
- Xavier A Harrison
- Centre for Ecology and Conservation, University of Exeter, Tremough, Penryn, Cornwall TR10 9EZ, UK
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Mougeot F, Martínez-Padilla J, Blount JD, Pérez-Rodríguez L, Webster LMI, Piertney SB. Oxidative stress and the effect of parasites on a carotenoid-based ornament. ACTA ACUST UNITED AC 2010; 213:400-7. [PMID: 20086124 DOI: 10.1242/jeb.037101] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Oxidative stress, the physiological condition whereby the production of reactive oxygen and nitrogen species overwhelms the capacity of antioxidant defences, causes damage to key bio-molecules. It has been implicated in many diseases, and is proposed as a reliable currency in the trade-off between individual health and ornamentation. Whether oxidative stress mediates the expression of carotenoid-based signals, which are among the commonest signals of many birds, fish and reptiles, remains controversial. In the present study, we explored interactions between parasites, oxidative stress and the carotenoid-based ornamentation of red grouse Lagopus lagopus scoticus. We tested whether removing nematode parasites influenced both oxidative balance (levels of oxidative damage and circulating antioxidant defences) and carotenoid-based ornamentation. At the treatment group level, parasite purging enhanced the size and colouration of ornaments but did not significantly affect circulating carotenoids, antioxidant defences or oxidative damage. However, relative changes in these traits among individuals indicated that males with a greater number of parasites prior to treatment (parasite purging) showed a greater increase in the levels of circulating carotenoids and antioxidants, and a greater decrease in oxidative damage, than those with initially fewer parasites. At the individual level, a greater increase in carotenoid pigmentation was associated with a greater reduction in oxidative damage. Therefore, an individual's ability to express a carotenoid-based ornament appeared to be linked to its current oxidative balance and susceptibility to oxidative stress. Our experimental results suggest that oxidative stress can mediate the impact of parasites on carotenoid-based signals, and we discuss possible mechanisms linking carotenoid-based ornaments to oxidative stress.
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Affiliation(s)
- F Mougeot
- Estación Experimental de Zonas Aridas, CSIC, General Segura 1, 04001 Almeria, Spain.
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