1
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Sadler DE, Watts PC, Uusi-Heikkilä S. Directional selection, not the direction of selection, affects telomere length and copy number at ribosomal RNA loci. Sci Rep 2024; 14:12162. [PMID: 38802448 PMCID: PMC11130246 DOI: 10.1038/s41598-024-63030-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 05/23/2024] [Indexed: 05/29/2024] Open
Abstract
Many fisheries exert directional selection on traits such as body size and growth rate. Whether directional selection impacts regions of the genome associated with traits related to growth is unknown. To address this issue, we characterised copy number variation in three regions of the genome associated with cell division, (1) telomeric DNA, (2) loci transcribed as ribosomal RNA (rDNA), and (3) mitochondrial DNA (mtDNA), in three selection lines of zebrafish reared at three temperatures (22 °C, 28 °C, and 34 °C). Selection lines differed in (1) the direction of selection (two lines experienced directional selection for large or small body size) and (2) whether they experienced any directional selection itself. Lines that had experienced directional selection were smaller, had lower growth rate, shorter telomeres, and lower rDNA copy number than the line that experiencing no directional selection. Neither telomere length nor rDNA copy number were affected by temperature. In contrast, mtDNA content increased at elevated temperature but did not differ among selection lines. Though directional selection impacts rDNA and telomere length, direction of such selection did not matter, whereas mtDNA acts as a stress marker for temperature. Future work should examine the consequences of these genomic changes in natural fish stocks.
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Affiliation(s)
- Daniel E Sadler
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland.
| | - Phillip C Watts
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
| | - Silva Uusi-Heikkilä
- Department of Biological and Environmental Science, University of Jyväskylä, 40014, Jyväskylä, Finland
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2
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Friesen CR, Wapstra E, Olsson M. Of telomeres and temperature: Measuring thermal effects on telomeres in ectothermic animals. Mol Ecol 2022; 31:6069-6086. [PMID: 34448287 DOI: 10.1111/mec.16154] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 07/20/2021] [Accepted: 08/23/2021] [Indexed: 01/31/2023]
Abstract
Ectotherms are classic models for understanding life-history tradeoffs, including the reproduction-somatic maintenance tradeoffs that may be reflected in telomere length and their dynamics. Importantly, life-history traits of ectotherms are tightly linked to their thermal environment, with diverse or synergistic mechanistic explanations underpinning the variation. Telomere dynamics potentially provide a mechanistic link that can be used to monitor thermal effects on individuals in response to climatic perturbations. Growth rate, age and developmental stage are all affected by temperature, which interacts with telomere dynamics in complex and intriguing ways. The physiological processes underpinning telomere dynamics can be visualized and understood using thermal performance curves (TPCs). TPCs reflect the evolutionary history and the thermal environment during an individual's ontogeny. Telomere maintenance should be enhanced at or near the thermal performance optimum of a species, population and individual. The thermal sensitivity of telomere dynamics should reflect the interacting TPCs of the processes underlying them. The key processes directly underpinning telomere dynamics are mitochondrial function (reactive oxygen production), antioxidant activity, telomerase activity and telomere endcap protein status. We argue that identifying TPCs for these processes will significantly help design robust, repeatable experiments and field studies of telomere dynamics in ectotherms. Conceptually, TPCs are a valuable framework to predict and interpret taxon- and population-specific telomere dynamics across thermal regimes. The literature of thermal effects on telomeres in ectotherms is sparse and mostly limited to vertebrates, but our conclusions and recommendations are relevant across ectothermic animals.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, The University of Wollongong, Wollongong, New South Wales, Australia.,School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Erik Wapstra
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Mats Olsson
- School of Earth, Atmospheric and Life Sciences, The University of Wollongong, Wollongong, New South Wales, Australia.,Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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3
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Metcalfe NB, Olsson M. How telomere dynamics are influenced by the balance between mitochondrial efficiency, reactive oxygen species production and DNA damage. Mol Ecol 2022; 31:6040-6052. [PMID: 34435398 DOI: 10.1111/mec.16150] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 08/02/2021] [Accepted: 08/23/2021] [Indexed: 01/31/2023]
Abstract
It is well known that oxidative stress is a major cause of DNA damage and telomere attrition. Most endogenous reactive oxygen species (ROS) are produced in the mitochondria, producing a link between mitochondrial function, DNA integrity and telomere dynamics. In this review we will describe how ROS production, rates of damage to telomeric DNA and DNA repair are dynamic processes. The rate of ROS production depends on mitochondrial features such as the level of inner membrane uncoupling and the proportion of time that ATP is actively being produced. However, the efficiency of ATP production (the ATP/O ratio) is positively related to the rate of ROS production, so leading to a trade-off between the body's energy requirements and its need to prevent oxidative stress. Telomeric DNA is especially vulnerable to oxidative damage due to features such as its high guanine content; while repair to damaged telomere regions is possible through a range of mechanisms, these can result in more rapid telomere shortening. There is increasing evidence that mitochondrial efficiency varies over time and with environmental context, as do rates of DNA repair. We argue that telomere dynamics can only be understood by appreciating that the optimal solution to the trade-off between energetic efficiency and telomere protection will differ between individuals and will change over time, depending on resource availability, energetic demands and life history strategy.
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Affiliation(s)
- Neil B Metcalfe
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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4
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Kärkkäinen T, Briga M, Laaksonen T, Stier A. Within-individual repeatability in telomere length: A meta-analysis in nonmammalian vertebrates. Mol Ecol 2022; 31:6339-6359. [PMID: 34455645 DOI: 10.1111/mec.16155] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 07/27/2021] [Accepted: 08/23/2021] [Indexed: 01/31/2023]
Abstract
Telomere length is increasingly used as a biomarker of long-term somatic state and future survival prospects. While most studies have overlooked this aspect, biological interpretations based on a given telomere length will benefit from considering the level of within-individual repeatability of telomere length through time. Therefore, we conducted a meta-analysis on 74 longitudinal studies in nonmammalian vertebrates, with the aim to establish the current pattern of within-individual repeatability in telomere length and to identify the methodological (e.g., qPCR/TRF) and biological factors (e.g., age class, phylogeny) that may affect it. While the median within-individual repeatability of telomere length was moderate to high (R = 0.55; 95% CI: 0.05-0.95; N = 82), marked heterogeneity between studies was evident. Measurement method affected the repeatability estimate strongly, with TRF-based studies exhibiting high repeatability (R = 0.80; 95% CI: 0.34-0.96; N = 25), while repeatability of qPCR-based studies was markedly lower and more variable (R = 0.46; 95% CI: 0.04-0.82; N = 57). While phylogeny explained some variance in repeatability, phylogenetic signal was not significant (λ = 0.32; 95% CI: 0.00-0.83). None of the biological factors investigated here significantly explained variation in the repeatability of telomere length, being potentially obscured by methodological differences. Our meta-analysis highlights the high variability in within-individual repeatability estimates between studies and the need to put more effort into separating technical and biological explanations. This is important to better understand to what extent biological factors can affect the repeatability of telomere length and thus the interpretation of telomere length data.
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Affiliation(s)
| | - Michael Briga
- Department of Biology, University of Turku, Turku, Finland
| | - Toni Laaksonen
- Department of Biology, University of Turku, Turku, Finland
| | - Antoine Stier
- Department of Biology, University of Turku, Turku, Finland
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5
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Friesen CR, Wilson M, Rollings N, Sudyka J, Giraudeau M, Whittington CM, Olsson M. Exercise training has morph-specific effects on telomere, body condition and growth dynamics in a color-polymorphic lizard. J Exp Biol 2021; 224:jeb.242164. [PMID: 33785504 DOI: 10.1242/jeb.242164] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/22/2021] [Indexed: 12/12/2022]
Abstract
Alternative reproductive tactics (ARTs) are correlated suites of sexually selected traits that are likely to impose differential physiological costs on different individuals. While moderate activity might be beneficial, animals living in the wild often work at the margins of their resources and performance limits. Individuals using ARTs may have divergent capacities for activity. When pushed beyond their respective capacities, they may experience condition loss, oxidative stress, and molecular damage that must be repaired with limited resources. We used the Australian painted dragon lizard that exhibits color polymorphism as a model to experimentally test the effect of exercise on body condition, growth, reactive oxygen species (ROS) and telomere dynamics - a potential marker of stress and aging and a correlate of longevity. For most males, ROS levels tended to be lower with greater exercise; however, males with yellow throat patches - or bibs - had higher ROS levels than non-bibbed males. At the highest level of exercise, bibbed males exhibited telomere loss, while non-bibbed males gained telomere length; the opposite pattern was observed in the no-exercise controls. Growth was positively related to food intake but negatively correlated with telomere length at the end of the experiment. Body condition was not related to food intake but was positively correlated with increases in telomere length. These results, along with our previous work, suggest that aggressive - territory holding - bibbed males suffer physiological costs that may reduce longevity compared with non-bibbed males with superior postcopulatory traits.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.,Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia.,Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Mark Wilson
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW 2522, Australia.,Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nicky Rollings
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Joanna Sudyka
- Institute of Environmental Sciences, Jagiellonian University, 30-060 Krakow, Poland
| | - Mathieu Giraudeau
- CREEC, UMR IRD 224-CNRS 5290-Université de Montpellier, F34394 Montpellier, France.,CREES Centre for Research on the Ecology and Evolution of Disease, 34394 Montpellier, France
| | - Camilla M Whittington
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Mats Olsson
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.,Department of Biological & Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
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6
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Ensminger DC, Siegel SR, Owen DAS, Sheriff MJ, Langkilde T. Elevated glucocorticoids during gestation suggest sex-specific effects on offspring telomere lengths in a wild lizard. Comp Biochem Physiol A Mol Integr Physiol 2021; 257:110971. [PMID: 33933630 DOI: 10.1016/j.cbpa.2021.110971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 04/06/2021] [Accepted: 04/26/2021] [Indexed: 12/30/2022]
Abstract
The effects of maternal glucocorticoids (e.g. corticosterone, CORT) on offspring interest biologists due to increasing environmental perturbations. While little is known about the impact of maternal CORT on offspring fitness, it may modulate telomere length and compromise offspring health. Here, we use a modified real-time quantitative PCR assay to assess telomere length using small DNA quantities (<60 ng). We tested the hypothesis that increased maternal CORT during gestation decreases offspring telomere length. While CORT-driven telomere shortening is well established within individuals, cross-generational effects remain unclear. We treated wild-caught gravid female eastern fence lizards (Sceloporus undulatus) with daily transdermal applications of CORT, at ecologically relevant levels, from capture to laying. Maternal CORT treatment did not alter maternal telomere length, although baseline maternal CORT concentrations had a weak, negative correlation with maternal telomere length. There was no relation between mother and offspring telomere length. There was a trend for maternal CORT treatment to shorten telomeres of sons but not daughters. Our treatment replicated exposure to a single stressor per day, likely underestimating effects seen in the wild where stressors may be more frequent. Future research should further explore fitness consequences of maternal CORT effects.
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Affiliation(s)
- David C Ensminger
- Department of Ecosystem Science and Management, The Pennsylvania State University, Forest Resources Building, University Park, PA 16802, United States of America; Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America.
| | - Sue R Siegel
- Department of Biobehavioral Health, The Pennsylvania State University, Biomarker Core Lab, University Park, PA 16802, United States of America
| | - Dustin A S Owen
- Department of Ecosystem Science and Management, The Pennsylvania State University, Forest Resources Building, University Park, PA 16802, United States of America; Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America; Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, United States of America
| | - Michael J Sheriff
- Biology Department, University of Massachusetts Dartmouth, Dartmouth, MA 02747, United States of America
| | - Tracy Langkilde
- Department of Biology, The Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, United States of America; Intercollege Graduate Degree Program in Ecology, The Pennsylvania State University, University Park, PA 16802, United States of America
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7
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Vernasco BJ, Dakin R, Majer AD, Haussmann MF, Brandt Ryder T, Moore IT. Longitudinal dynamics and behavioural correlates of telomeres in male wire‐tailed manakins. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13715] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Ben J. Vernasco
- Department of Biological Sciences Virginia Tech Blacksburg VA USA
| | - Roslyn Dakin
- Migratory Bird Center Smithsonian Conservation Biology Institute Washington DC USA
| | | | | | - T. Brandt Ryder
- Migratory Bird Center Smithsonian Conservation Biology Institute Washington DC USA
| | - Ignacio T. Moore
- Department of Biological Sciences Virginia Tech Blacksburg VA USA
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8
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Lindsay WR, Friesen CR, Sihlbom C, Bergström J, Berger E, Wilson MR, Olsson M. Vitellogenin offsets oxidative costs of reproduction in female painted dragon lizards. J Exp Biol 2020; 223:jeb221630. [PMID: 32393548 DOI: 10.1242/jeb.221630] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 05/05/2020] [Indexed: 12/18/2022]
Abstract
Vitellogenesis ('yolking' of follicles) is a bioenergetically costly stage of reproduction requiring enlargement of the liver to produce vitellogenin (VTG) yolk precursor proteins, which are transported and deposited at the ovary. VTG may, however, serve non-nutritive anti-oxidant functions, a hypothesis supported by empirical work on aging and other life-history transitions in several taxa. We test this hypothesis in female painted dragon lizards (Ctenophorus pictus) by examining covariation in VTG with the ovarian cycle, and relative to reactive oxygen species (ROS) including baseline superoxide (bSO). Plasma VTG decreased prior to ovulation, when VTG is deposited into follicles. VTG, however, remained elevated post-ovulation when no longer necessary for yolk provisioning and was unrelated to reproductive investment. Instead, VTG was strongly and positively predicted by prior bSO. ROS, in turn, was negatively predicted by prior VTG, while simultaneously sampled VTG was a positive predictor. These findings are consistent with the hypothesis that VTG functions as an anti-oxidant to counteract oxidative stress associated with vitellogenesis. The relationship between bSO and VTG was strongest in post-ovulatory females, indicating that its function may be largely anti-oxidant at this time. In conclusion, VTG may be under selection to offset oxidative costs of reproduction in egg-producing species.
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Affiliation(s)
- Willow R Lindsay
- Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Christopher R Friesen
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
| | - Carina Sihlbom
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Jörgen Bergström
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Evelin Berger
- Proteomics Core Facility of Sahlgrenska Academy, University of Gothenburg, SE 405 30 Gothenburg, Sweden
| | - Mark R Wilson
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia
| | - Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, SE 405 30 Gothenburg, Sweden
- School of Chemistry and Molecular Bioscience and Molecular Horizons Research Institute, The University of Wollongong, Wollongong, NSW 2522, Australia
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9
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Friesen CR, Rollings N, Wilson M, Whittington CM, Shine R, Olsson M. Covariation in superoxide, sperm telomere length and sperm velocity in a polymorphic reptile. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02855-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Olsson M, Geraghty NJ, Wapstra E, Wilson M. Telomere length varies substantially between blood cell types in a reptile. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192136. [PMID: 32742684 PMCID: PMC7353983 DOI: 10.1098/rsos.192136] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/12/2020] [Indexed: 05/19/2023]
Abstract
Telomeres are repeat sequences of non-coding DNA-protein molecules that cap or intersperse metazoan chromosomes. Interest in telomeres has increased exponentially in recent years, to now include their ongoing dynamics and evolution within natural populations where individuals vary in telomere attributes. Phylogenetic analyses show profound differences in telomere length across non-model taxa. However, telomeres may also differ in length within individuals and between tissues. The latter becomes a potential source of error when researchers use different tissues for extracting DNA for telomere analysis and scientific inference. A commonly used tissue type for assessing telomere length is blood, a tissue that itself varies in terms of nuclear content among taxa, in particular to what degree their thrombocytes and red blood cells (RBCs) contain nuclei or not. Specifically, when RBCs lack nuclei, leucocytes become the main source of telomeric DNA. RBCs and leucocytes differ in lifespan and how long they have been exposed to 'senescence' and erosion effects. We report on a study in which cells in whole blood from individual Australian painted dragon lizards (Ctenophorus pictus) were identified using flow cytometry and their telomere length simultaneously measured. Lymphocyte telomeres were on average 270% longer than RBC telomeres, and in azurophils (a reptilian monocyte), telomeres were more than 388% longer than those in RBCs. If this variation in telomere length among different blood cell types is a widespread phenomenon, and DNA for comparative telomere analyses are sourced from whole blood, evolutionary inference of telomere traits among taxa may be seriously complicated by the blood cell type comprising the main source of DNA.
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Affiliation(s)
- Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
- The School of Earth, Atmospheric and Life Sciences, University of Wollongong, Australia
- Author for correspondence: Mats Olsson e-mail:
| | - Nicholas J. Geraghty
- The School of Earth, Atmospheric and Life Sciences, University of Wollongong, Australia
| | - Erik Wapstra
- School of Natural Sciences, University of Tasmania, Hobart, Australia
| | - Mark Wilson
- School of Chemistry and Molecular Bioscience, Illawarra Health and Medical Research Institute, University of Wollongong, Australia
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11
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Bury S, Cierniak A, Jakóbik J, Sadowska ET, Cichoń M, Bauchinger U. Cellular Turnover: A Potential Metabolic Rate-Driven Mechanism to Mitigate Accumulation of DNA Damage. Physiol Biochem Zool 2020; 93:90-96. [PMID: 32011970 DOI: 10.1086/707506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Oxidative stress, the imbalance of reactive oxygen species and antioxidant capacity, may cause damage to biomolecules pivotal for cellular processes (e.g., DNA). This may impair physiological performance and, therefore, drive life-history variation and aging rate. Because aerobic metabolism is supposed to be the main source of such oxidative risk, the rate of oxygen consumption should be positively associated with the level of damage and/or antioxidants. Empirical support for such relationships remains unclear, and recent considerations suggest even a negative relationship between metabolic rate and oxidative stress. We investigated the relationship between standard metabolic rate (SMR), antioxidants, and damage in blood plasma and erythrocytes for 35 grass snakes (Natrix natrix). Reactive oxygen metabolites (dROMs) and nonenzymatic antioxidants were assessed in plasma, while two measures of DNA damage and the capacity to neutralize H2O2 were measured in erythrocytes. Plasma antioxidants showed no correlation to SMR, and the level of dROMs was positively related to SMR. A negative relationship between antioxidant capacity and SMR was found in erythrocytes, but no association of SMR with either measure of DNA damage was detected. No increase in DNA damage, despite lower antioxidant capacity at high SMR, indicates an upregulation in other defense mechanisms (e.g., damage repair and/or removal). Indeed, we observed a higher frequency of immature red blood cells in individuals with higher SMR, which indicates that highly metabolic individuals had increased erythrocyte turnover, a mechanism of damage removal. Such DNA protection through upregulated cellular turnover might explain the negligible senescence observed in some ectotherm taxa.
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12
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Lindsay WR, Andersson S, Bererhi B, Höglund J, Johnsen A, Kvarnemo C, Leder EH, Lifjeld JT, Ninnes CE, Olsson M, Parker GA, Pizzari T, Qvarnström A, Safran RJ, Svensson O, Edwards SV. Endless forms of sexual selection. PeerJ 2019; 7:e7988. [PMID: 31720113 PMCID: PMC6839514 DOI: 10.7717/peerj.7988] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 10/04/2019] [Indexed: 12/11/2022] Open
Abstract
In recent years, the field of sexual selection has exploded, with advances in theoretical and empirical research complementing each other in exciting ways. This perspective piece is the product of a “stock-taking” workshop on sexual selection and sexual conflict. Our aim is to identify and deliberate on outstanding questions and to stimulate discussion rather than provide a comprehensive overview of the entire field. These questions are organized into four thematic sections we deem essential to the field. First we focus on the evolution of mate choice and mating systems. Variation in mate quality can generate both competition and choice in the opposite sex, with implications for the evolution of mating systems. Limitations on mate choice may dictate the importance of direct vs. indirect benefits in mating decisions and consequently, mating systems, especially with regard to polyandry. Second, we focus on how sender and receiver mechanisms shape signal design. Mediation of honest signal content likely depends on integration of temporally variable social and physiological costs that are challenging to measure. We view the neuroethology of sensory and cognitive receiver biases as the main key to signal form and the ‘aesthetic sense’ proposed by Darwin. Since a receiver bias is sufficient to both initiate and drive ornament or armament exaggeration, without a genetically correlated or even coevolving receiver, this may be the appropriate ‘null model’ of sexual selection. Thirdly, we focus on the genetic architecture of sexually selected traits. Despite advances in modern molecular techniques, the number and identity of genes underlying performance, display and secondary sexual traits remains largely unknown. In-depth investigations into the genetic basis of sexual dimorphism in the context of long-term field studies will reveal constraints and trajectories of sexually selected trait evolution. Finally, we focus on sexual selection and conflict as drivers of speciation. Population divergence and speciation are often influenced by an interplay between sexual and natural selection. The extent to which sexual selection promotes or counteracts population divergence may vary depending on the genetic architecture of traits as well as the covariance between mating competition and local adaptation. Additionally, post-copulatory processes, such as selection against heterospecific sperm, may influence the importance of sexual selection in speciation. We propose that efforts to resolve these four themes can catalyze conceptual progress in the field of sexual selection, and we offer potential avenues of research to advance this progress.
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Affiliation(s)
- Willow R Lindsay
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - Staffan Andersson
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - Badreddine Bererhi
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - Jacob Höglund
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Arild Johnsen
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Charlotta Kvarnemo
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - Erica H Leder
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Jan T Lifjeld
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Calum E Ninnes
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden.,Department of Entomology and Nematology, University of Florida, Gainesville, FL, United States of America
| | - Mats Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Göteborg, Sweden
| | - Geoff A Parker
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Tommaso Pizzari
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford, United Kingdom
| | - Anna Qvarnström
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Rebecca J Safran
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, United States of America
| | - Ola Svensson
- School of Natural Sciences, Technology and Environmental Studies, Södertörn University, Huddinge, Sweden
| | - Scott V Edwards
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA, United States of America.,Gothenburg Centre for Advanced Studies in Science and Technology, Chalmers University of Technology, Göteborg, Sweden
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13
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McLennan D, Recknagel H, Elmer KR, Monaghan P. Distinct telomere differences within a reproductively bimodal common lizard population. Funct Ecol 2019; 33:1917-1927. [PMID: 31762528 PMCID: PMC6853248 DOI: 10.1111/1365-2435.13408] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 06/18/2019] [Accepted: 07/03/2019] [Indexed: 12/21/2022]
Abstract
Different strategies of reproductive mode, either oviparity (egg-laying) or viviparity (live-bearing), will be associated with a range of other life-history differences that are expected to affect patterns of ageing and longevity. It is usually difficult to compare the effects of alternative reproductive modes because of evolutionary and ecological divergence. However, the very rare exemplars of reproductive bimodality, in which different modes exist within a single species, offer an opportunity for robust and controlled comparisons.One trait of interest that could be associated with life history, ageing and longevity is the length of the telomeres, which form protective caps at the chromosome ends and are generally considered a good indicator of cellular health. The shortening of these telomeres has been linked to stressful conditions; therefore, it is possible that differing reproductive costs will influence patterns of telomere loss. This is important because a number of studies have linked a shorter telomere length to reduced survival.Here, we have studied maternal and offspring telomere dynamics in the common lizard (Zootoca vivipara). Our study has focused on a population where oviparous and viviparous individuals co-occur in the same habitat and occasionally interbreed to form admixed individuals.While viviparity confers many advantages for offspring, it might also incur substantial costs for the mother, for example require more energy. Therefore, we predicted that viviparous mothers would have relatively shorter telomeres than oviparous mothers, with admixed mothers having intermediate telomere lengths. There is thought to be a heritable component to telomere length; therefore, we also hypothesized that offspring would follow the same pattern as the mothers.Contrary to our predictions, the viviparous mothers and offspring had the longest telomeres, and the oviparous mothers and offspring had the shortest telomeres. The differing telomere lengths may have evolved as an effect of the life-history divergence between the reproductive modes, for example due to the increased growth rate that viviparous individuals may undergo to reach a similar size at reproduction. A free http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13408/suppinfo can be found within the Supporting Information of this article.
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Affiliation(s)
- Darryl McLennan
- Institute of Biodiversity, Animal Health and Comparative MedicineUniversity of GlasgowGlasgowUK
- Department of Fish Ecology and EvolutionEAWAGKastanienbaumSwitzerland
| | - Hans Recknagel
- Institute of Biodiversity, Animal Health and Comparative MedicineUniversity of GlasgowGlasgowUK
| | - Kathryn R. Elmer
- Institute of Biodiversity, Animal Health and Comparative MedicineUniversity of GlasgowGlasgowUK
| | - Pat Monaghan
- Institute of Biodiversity, Animal Health and Comparative MedicineUniversity of GlasgowGlasgowUK
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14
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Friesen CR, de Graaf SP, Olsson M. The relationship of body condition, superoxide dismutase, and superoxide with sperm performance. Behav Ecol 2019. [DOI: 10.1093/beheco/arz086] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Abstract
Sperm competition theory predicts a negative correlation between somatic investment and traits that aid in pre- and postcopulatory sexual selection. Sperm performance is critical for postcopulatory success but sperm are susceptible to damage by free radicals such as superoxide radicals generated during mitochondrial respiration (mtSOx). Males can ameliorate damage to spermatozoa by investing in the production of antioxidants, like superoxide dismutase (SOD), which may act as a mechanistic link to pre- and postcopulatory trade-offs. Some male Australian, color-polymorphic painted dragon lizards (Ctenophorus pictus) possess a yellow throat patch (bib) that females prefer over nonbibbed males and are also more likely to win male–male contests indicating that males with bibs may be better at monopolizing females. We tested whether the sperm performance in nonbibbed males was superior to that of bibbed males. We show that overall sperm performance was not different between the bib-morphs, however, higher mtSOx levels were negatively correlated with sperm performance in bibbed males, but not of nonbibbed males. Blood cell mtSOx levels are negatively correlated with SOD activity in the plasma in all males early in the breeding season but SOD was lower in bibbed males. Nonbibbed males maintain a positive correlation between body condition and SOD activity over time while bibbed males do not. Together, these data suggest physiological associations between body condition, SOD activity, and sperm performance are linked to the expression of a yellow gular patch, which may be related to intrinsic differences in the metabolism of bibbed versus nonbibbed males.
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Affiliation(s)
- Christopher R Friesen
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Ross St. Camperdown, NSW Australia, Australia
| | - Simon P de Graaf
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Ross St. Camperdown, NSW Australia, Australia
| | - Mats Olsson
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, Australia
- Department of Biological & Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
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15
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Rollings N, Friesen CR, Whittington CM, Johansson R, Shine R, Olsson M. Sex- And tissue-specific differences in telomere length in a reptile. Ecol Evol 2019; 9:6211-6219. [PMID: 31236215 PMCID: PMC6580261 DOI: 10.1002/ece3.5164] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 03/19/2019] [Accepted: 03/22/2019] [Indexed: 12/25/2022] Open
Abstract
The usage of telomere length (TL) in blood as a proxy for the TL of other tissues relies on the assumption that telomere dynamics across all tissues are similar. However, telomere attrition can be caused by reactive oxygen species (ROS) which may vary with metabolic rate, which itself varies across organs depending upon the life history strategy of an organism. Thus, we chose to measure the telomeres of various cell types in juvenile painted dragon lizards, Ctenophorus pictus, given their unusual life history strategy. Individuals typically only experience a single mating season. We measured the TL of male and female dragons using qPCR and observed that TL varied with tissue type and sex. Telomeres of blood cells were longer than those of liver, heart, brain, and spleen, and females had longer telomeres than males. Brain telomeres in males were approximately half the length of those in females. Telomeric attrition in the male brain may be due to the need for rapid learning of reproductive tactics (territory patrol and defense, mate-finding). Significant correlations between the TL of tissue types suggest that blood TL may be a useful proxy for the TL of other tissues. Our comparison of organ-specific telomere dynamics, the first in a reptile, suggests that the usage of blood TL as a proxy requires careful consideration of the life history strategy of the organism.
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Affiliation(s)
- Nicky Rollings
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
| | | | - Camilla M. Whittington
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
- Sydney School of Veterinary ScienceUniversity of SydneySydneyNew South WalesAustralia
| | - Rasmus Johansson
- Department of Biological & Environmental SciencesUniversity of GothenburgGothenburgSweden
| | - Richard Shine
- School of Life and Environmental SciencesUniversity of SydneySydneyNew South WalesAustralia
- Department of Biological SciencesMacquarie UniversitySydneyNew South WalesAustralia
| | - Mats Olsson
- Department of Biological & Environmental SciencesUniversity of GothenburgGothenburgSweden
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