1
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Dobson JL, Pike TW, Gonzalez-Rodriguez J, Soulsbury CD. Identifying and locating carotenoids in supra-orbital combs of male black grouse (Lyurus tetrix) using Raman and transmission electron microscopy: A histological study using rehydrated tissue samples. J Morphol 2023; 284:e21652. [PMID: 37990765 DOI: 10.1002/jmor.21652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 09/28/2023] [Accepted: 10/02/2023] [Indexed: 11/23/2023]
Abstract
Colourful signals have long been implicated as indicators of individual quality in animals. Bare-skin signals are an understudied aspect of avian colouration compared with plumage studies, despite displaying rapid changes in size and colour in response to different environmental or physiological stressors. Even fewer studies have focused on the underlying histology of these structures and the importance this plays in the resulting skin colour. Using the Black Grouse (Lyrurus tetrix), we identified the underlying structure of individual dermal spikes, which make up the red supra-orbital comb (a known integumentary signal of male quality), and highlight visual structural differences between combs of different sizes. In addition, we used Raman spectroscopy to indicate the presence of carotenoids within the tissue, something that had previously only been inferred through characteristic reflectance patterns. An increased understanding of the structural basis of colour of featherless parts of the skin opens up exciting new avenues for interpreting the information content of integumentary signals.
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Affiliation(s)
- Jessica L Dobson
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln, Brayford Pool, UK
| | - Thomas W Pike
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln, Brayford Pool, UK
| | - Jose Gonzalez-Rodriguez
- Joseph Banks Laboratories, School of Chemistry, University of Lincoln, Lincoln, Brayford Pool, UK
| | - Carl D Soulsbury
- Department of Life Sciences, School of Life and Environmental Sciences, University of Lincoln, Lincoln, Brayford Pool, UK
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2
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Fernández-Eslava B, Alonso D, Alonso-Alvarez C. An age-related decline in the expression of a red carotenoid-based ornament in wild birds. Evolution 2021; 75:3142-3153. [PMID: 34643274 DOI: 10.1111/evo.14378] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 09/21/2021] [Accepted: 09/27/2021] [Indexed: 01/02/2023]
Abstract
The past decades have provided valuable information on how animals age in the wild. However, examples of male reproductive senescence are scarce. In particular, few studies have described an age-related decline in the expression of conspicuous traits influencing mating success. Red ornaments could be good candidates to detect this decline because their expression may depend on the availability of pigments (carotenoids) related to oxidative stress, the latter frequently linked to senescence. Furthermore, it has been argued that efficient mitochondrial metabolism is key to express red carotenoid-based ornaments, and mitochondrial dysfunction is usually associated with senescence. We studied the age-linked expression of a red carotenoid-based trait: the yellow-to-red plumage coloration of male common crossbills (Loxia curvirostra). This coloration has recently been experimentally related to mitochondrial function. Here, we analyzed longitudinal plumage coloration data obtained throughout 28 years in free-living birds. We detected an initial increase in redness during the first 2 years of life and a subsequent decline. The relationship between color and age was unrelated to within-individual body mass variability. As far as we know, this is the first demonstration of an age-related ketocarotenoid-based color decrease detected by simultaneously testing within- and between-individual variability in wild animals.
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Affiliation(s)
- B Fernández-Eslava
- Department of Environmental Biology, Universidad de Navarra, Pamplona, Spain
| | - D Alonso
- Department of Ornithology, Aranzadi Sciences Society, Donostia-S. Sebastián, Spain
| | - C Alonso-Alvarez
- Department of Evolutionary Ecology, Spanish National Research Council (CSIC), Madrid, Spain
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3
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Cain KE, Griffith SC, Kruuk LEB. Sex and morph differences in age-dependent trait changes in a polymorphic songbird. J Evol Biol 2021; 34:1691-1703. [PMID: 34528324 DOI: 10.1111/jeb.13930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 08/30/2021] [Accepted: 08/31/2021] [Indexed: 11/27/2022]
Abstract
There is growing evidence of important variation in how animals age, in particular in how the expression of traits changes with age among different species and populations. However, less is known about variation within populations, which may include variation in ageing patterns between different types of individuals (e.g. sexes or distinct polymorphisms) and between different types of traits (e.g. general traits versus those used in social signalling contexts). We used 6 years of longitudinal data to examine age-related changes in trait expression in a captive population of Gouldian finches (Erythrura gouldiae), a socially monogamous songbird with genetically determined colour morphs that differ in behaviour and physiology. We contrasted ageing patterns of different types of traits (social signalling vs. size-related) in both sexes and in two colour morphs, using a mixed model approach to account for both within- and between-individual effects. We found pronounced sex differences in how social signalling traits change with age, showing a quadratic pattern in males, but not changing with age in females. In contrast, we observed no sex-specific ageing patterns in size traits. We also found subtle morph differences in how size-related traits changed with age, with black morphs stable or increasing with age while red morphs showing a decline with age. Finally, we found an interesting sex by morph interaction in one important social signal (headband width). These results highlight the importance of using within-individual approaches to understand ageing patterns across types of individuals (sex, morph, etc.) and the need for further research on the ageing patterns of traits that may experience different selective pressures.
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Affiliation(s)
- Kristal E Cain
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.,School of Biological Science, University of Auckland, Auckland, New Zealand
| | - Simon C Griffith
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Loeske E B Kruuk
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
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4
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Physiological costs and age constraints of a sexual ornament: an experimental study in a wild bird. Behav Ecol 2021. [DOI: 10.1093/beheco/araa143] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Abstract
Sexual ornaments are often considered honest signals of quality because potential costs or constraints prevent their display by low-quality individuals. Testing for potential physiological costs of ornaments is difficult, as this requires experimentally forcing individuals to produce and display elaborate ornaments. We use this approach to test whether a sexually selected trait is physiologically costly to male superb fairy-wrens (Malurus cyaneus). Male fairy-wrens molt from brown to blue breeding plumage at different times of the year, and females strongly prefer the few males that are blue early, during winter. We used short-acting testosterone implants to stimulate males to produce “early-blue” plumage and assessed costs during and after molt using a panel of physiological indices. Testosterone-implanted, T-males molted in winter and produced blue plumage 6 weeks before control-implanted, C-males. T-males molted while in lower body condition, tended to have lower fat reserves, and were more likely to be parasitized by lice. However, we detected no negative effects on immune function, blood parasites, exposure to stressors, or survival. Juvenile males never naturally display early-blue plumage, but we found no evidence for increased costs paid by juvenile T-males. Instead, juvenile T-males molted later than adult T-males, suggesting that age presents an absolute constraint on ornament exaggeration that cannot be fully overcome by testosterone treatment. Together, these small costs and large, age-related constraints may enforce signal honesty, and explain female preference for early-blue males.
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5
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Harris S, Kervinen M, Lebigre C, Pike TW, Soulsbury CD. Full spectra coloration and condition-dependent signaling in a skin-based carotenoid sexual ornament. Behav Ecol 2020. [DOI: 10.1093/beheco/araa031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Carotenoid-based traits commonly act as condition-dependent signals of quality to both males and females. Such colors are typically quantified using summary metrics (e.g., redness) derived by partitioning measured reflectance spectra into blocks. However, perceived coloration is a product of the whole spectrum. Recently, new methods have quantified a range of environmental factors and their impact on reflection data at narrow wavebands across the whole spectrum. Using this approach, we modeled the reflectance of red integumentary eye combs displayed by male black grouse (Lyrurus tetrix) as a function of ornament size and variables related to male quality. We investigated the strength and direction of effect sizes of variables at each waveband. The strongest effect on the spectra came from eye comb size, with a negative effect in the red part of the spectrum and a positive effect in ultraviolet reflectance. Plasma carotenoid concentration and body mass were also related to reflectance variance in differing directions across the entire spectra. Comparisons of yearlings and adults showed that the effects were similar but stronger on adult reflectance spectra. These findings suggest that reflectance in different parts of the spectrum is indicative of differing components of quality. This method also allows a more accurate understanding of how biologically relevant variables may interact to produce perceived coloration and multicomponent signals and where the strongest biological effects are found.
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Affiliation(s)
- Sarah Harris
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, UK
| | - Matti Kervinen
- Finnish Wildlife Agency, Kiekkoti, Kuopio, Finland
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Christophe Lebigre
- IFREMER, Unité Sciences et Technologies Halieutiques, Centre Bretagne, Plouzané, France
| | - Thomas W Pike
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, UK
| | - Carl D Soulsbury
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, UK
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6
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Bretman A, Fricke C. Exposure to males, but not receipt of sex peptide, accelerates functional ageing in female fruit flies. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13339] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Amanda Bretman
- School of Biology, Faculty of Biological Sciences University of Leeds Leeds UK
| | - Claudia Fricke
- Institute for Evolution and Biodiversity University of Muenster Muenster Germany
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8
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Soulsbury CD, Lipponen A, Wood K, Mein CA, Hoffman JI, Lebigre C. Age- and quality-dependent DNA methylation correlate with melanin-based coloration in a wild bird. Ecol Evol 2018; 8:6547-6557. [PMID: 30038756 PMCID: PMC6053554 DOI: 10.1002/ece3.4132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/16/2018] [Accepted: 03/29/2018] [Indexed: 12/11/2022] Open
Abstract
Secondary sexual trait expression can be influenced by fixed individual factors (such as genetic quality) as well as by dynamic factors (such as age and environmentally induced gene expression) that may be associated with variation in condition or quality. In particular, melanin-based traits are known to relate to condition and there is a well-characterized genetic pathway underpinning their expression. However, the mechanisms linking variable trait expression to genetic quality remain unclear. One plausible mechanism is that genetic quality could influence trait expression via differential methylation and differential gene expression. We therefore conducted a pilot study examining DNA methylation at a candidate gene (agouti-related neuropeptide: AgRP) in the black grouse Lyrurus tetrix. We specifically tested whether CpG methylation covaries with age and multilocus heterozygosity (a proxy of genetic quality) and from there whether the expression of a melanin-based ornament (ultraviolet-blue chroma) correlates with DNA methylation. Consistent with expectations, we found clear evidence for age- and heterozygosity-specific patterns of DNA methylation, with two CpG sites showing the greatest DNA methylation in highly heterozygous males at their peak age of reproduction. Furthermore, DNA methylation at three CpG sites was significantly positively correlated with ultraviolet-blue chroma. Ours is the first study to our knowledge to document age- and quality-dependent variation in DNA methylation and to show that dynamic sexual trait expression across the lifespan of an organism is associated with patterns of DNA methylation. Although we cannot demonstrate causality, our work provides empirical support for a mechanism that could potentially link key individual factors to variation in sexual trait expression in a wild vertebrate.
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Affiliation(s)
| | - Anssi Lipponen
- Department of Biological and Environmental ScienceUniversity of JyväskyläFinland
- A. I. Virtanen Institute for Molecular SciencesUniversity of Eastern FinlandKuopioFinland
| | - Kristie Wood
- The Genome Centre, Barts and The London School of Medicine and DentistryQueen Mary University of LondonLondonUK
| | - Charles A. Mein
- The Genome Centre, Barts and The London School of Medicine and DentistryQueen Mary University of LondonLondonUK
| | - Joseph I. Hoffman
- Department of Animal BehaviourUniversity of BielefeldBielefeldGermany
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9
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Gaillard JM, Lemaître JF. The Williams' legacy: A critical reappraisal of his nine predictions about the evolution of senescence. Evolution 2017; 71:2768-2785. [DOI: 10.1111/evo.13379] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 09/25/2017] [Accepted: 09/30/2017] [Indexed: 12/16/2022]
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10
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Stabilising selection on immune response in male black grouse Lyrurus tetrix. Oecologia 2017; 186:405-414. [PMID: 29177843 PMCID: PMC5799332 DOI: 10.1007/s00442-017-4014-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 11/14/2017] [Indexed: 12/20/2022]
Abstract
Illnesses caused by a variety of micro- and macro- organisms can negatively affect individuals’ fitness, leading to the expectation that immunity is under positive selection. However, immune responses are costly and individuals must trade-off their immune response with other fitness components (e.g. survival or reproductive success) meaning that individuals with intermediate response may have the greatest overall fitness. Such a process might be particularly acute in species with strong sexual selection because the condition-dependence of male secondary sexual-traits might lead to striking phenotypic differences amongst males of different immune response levels. We tested whether there is selection on immune response by survival and reproduction in yearling and adult male black grouse (Lyrurus tetrix) following an immune challenge with a novel antigen and tested the hypothesis that sexual signals and body mass are honest signals of the immune response. We show that yearling males with highest immune response to these challenges had higher survival, but the reverse was true for adults. Adults with higher responses had highest mass loss and adult males with intermediate immune response had highest mating success. Tail length was related to baseline response in adults and more weakly in yearlings. Our findings reveal the complex fitness consequences of mounting an immune response across age classes. Such major differences in the direction and magnitude of selection in multiple fitness components is an alternative route underpinning the stabilising selection of immune responses with an intermediate immune response being optimal.
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11
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Tarwater CE, Arcese P. Age and years to death disparately influence reproductive allocation in a short‐lived bird. Ecology 2017; 98:2248-2254. [DOI: 10.1002/ecy.1851] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/20/2017] [Accepted: 03/31/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Corey E. Tarwater
- Department of Forest and Conservation Sciences University of British Columbia Vancouver 2424 Main Mall Vancouver British Columbia V6T 1Z4 Canada
| | - Peter Arcese
- Department of Forest and Conservation Sciences University of British Columbia Vancouver 2424 Main Mall Vancouver British Columbia V6T 1Z4 Canada
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12
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Lemaître JF, Gaillard JM. Reproductive senescence: new perspectives in the wild. Biol Rev Camb Philos Soc 2017; 92:2182-2199. [PMID: 28374548 DOI: 10.1111/brv.12328] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 02/23/2017] [Accepted: 03/03/2017] [Indexed: 11/26/2022]
Abstract
According to recent empirical studies, reproductive senescence, the decline in reproductive success with increasing age, seems to be nearly ubiquitous in the wild. However, a clear understanding of the evolutionary causes and consequences of reproductive senescence is still lacking and requires new and integrative approaches. After identifying the sequential and complex nature of female reproductive senescence, we show that the relative contributions of physiological decline and alterations in the efficiency of parental care to reproductive senescence remain unknown and need to be assessed in the light of current evolutionary theories of ageing. We demonstrate that, although reproductive senescence is generally studied only from the female viewpoint, age-specific female reproductive success strongly depends on male-female interactions. Thus, a reduction in male fertilization efficiency with increasing age has detrimental consequences for female fitness. Lastly, we call for investigations of the role of environmental conditions on reproductive senescence, which could provide salient insights into the underlying sex-specific mechanisms of reproductive success. We suggest that embracing such directions should allow building new bridges between reproductive senescence and the study of sperm competition, parental care, mate choice and environmental conditions.
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Affiliation(s)
- Jean-François Lemaître
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
| | - Jean-Michel Gaillard
- Univ Lyon, Université Lyon 1; CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR5558, F-69622, Villeurbanne, France
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13
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Bourret A, Bélisle M, Pelletier F, Garant D. Evolutionary potential of morphological traits across different life-history stages. J Evol Biol 2017; 30:616-626. [PMID: 28000316 DOI: 10.1111/jeb.13031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 12/15/2016] [Indexed: 02/05/2023]
Affiliation(s)
- A. Bourret
- Département de Biologie; Université de Sherbrooke; Sherbrooke QC Canada
| | - M. Bélisle
- Département de Biologie; Université de Sherbrooke; Sherbrooke QC Canada
| | - F. Pelletier
- Département de Biologie; Université de Sherbrooke; Sherbrooke QC Canada
| | - D. Garant
- Département de Biologie; Université de Sherbrooke; Sherbrooke QC Canada
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14
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No behavioural response to kin competition in a lekking species. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2154-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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15
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Simons MJP, Briga M, Verhulst S. Stabilizing survival selection on presenescent expression of a sexual ornament followed by a terminal decline. J Evol Biol 2016; 29:1368-78. [PMID: 27061923 PMCID: PMC4957616 DOI: 10.1111/jeb.12877] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 03/02/2016] [Accepted: 04/05/2016] [Indexed: 11/27/2022]
Abstract
Senescence is a decrease in functional capacity, increasing mortality rate with age. Sexual signals indicate functional capacity, because costs of ornamentation ensure signal honesty, and are therefore expected to senesce, tracking physiological deterioration and mortality. For sexual traits, mixed associations with age and positive associations with life expectancy have been reported. However, whether these associations are caused by selective disappearance and/or within-individual senescence of sexual signals, respectively, is not known. We previously reported that zebra finches with redder bills had greater life expectancy, based on a single bill colour measurement per individual. We here extend this analysis using longitudinal data and show that this finding is attributable to terminal declines in bill redness in the year before death, with no detectable change in presenescent redness. Additionally, there was a quadratic relationship between presenescent bill colouration and survival: individuals with intermediate bill redness have maximum survival prospects. This may reflect that redder individuals overinvest in colouration and/or associated physiological changes, while below-average bill redness probably reflects poorer phenotypic quality. Together, this pattern suggests that bill colouration is defended against physiological deterioration, because of mate attraction benefits, or that physiological deterioration is not a gradual process, but accelerates sharply prior to death. We discuss these possibilities in the context of the reliability theory of ageing and sexual selection.
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Affiliation(s)
- M J P Simons
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - M Briga
- Behavioural Biology, Centre for Life Sciences, University of Groningen, Groningen, The Netherlands
| | - S Verhulst
- Behavioural Biology, Centre for Life Sciences, University of Groningen, Groningen, The Netherlands
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16
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Kervinen M, Lebigre C, Soulsbury CD. Simultaneous age‐dependent and age‐independent sexual selection in the lekking black grouse(Lyrurus tetrix). J Anim Ecol 2016; 85:715-25. [DOI: 10.1111/1365-2656.12496] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 12/11/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Matti Kervinen
- Department of Biological and Environmental Science University of Jyväskylä P. O. Box 35 Jyväskylä FI‐40014 Finland
| | - Christophe Lebigre
- Earth and Life Institute Place de la Croix du Sud 4 Carnoy building B‐1348 Louvain‐la‐Neuve Belgium
| | - Carl D. Soulsbury
- Joseph Banks Laboratories School of Life Sciences University of Lincoln Lincoln LN6 7TS UK
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17
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Lopez‐Idiaquez D, Vergara P, Fargallo JA, Martinez‐Padilla J. Old males reduce melanin-pigmented traits and increase reproductive outcome under worse environmental conditions in common kestrels. Ecol Evol 2016; 6:1224-35. [PMID: 26941948 PMCID: PMC4761766 DOI: 10.1002/ece3.1910] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/01/2015] [Indexed: 12/31/2022] Open
Abstract
Secondary sexual traits displayed by males and females may have evolved as a signal of individual quality. However, both individual quality and investment on producing or maintaining enhanced sexual traits change as individuals age. At the same time, the costs associated to produce sexual traits might be attenuated or increased if environmental conditions are benign or worse respectively. Accordingly, environmental conditions are expected to shape the association between the expression of sexual traits and their reproductive outcome as individuals age. Nonetheless, little is known about the environmental influence on the co-variation between sexual traits and reproductive outcome throughout the life of individuals. We studied the age-dependency of the number and size of back spots, a melanin-based and sexual trait in adults of common kestrels (Falco tinnunculus). We analysed the age-dependence of reproductive traits and the environmental influence, defined as vole abundance, using a 10-year individual-based dataset. We broke down age-related changes of reproductive traits into within- and between-individual variation to assess their contribution to population-level patterns. Our results showed a within-individual decrease in the number, but not the size, of back spots in males. The size of back spots was positively correlated with food availability in males. Reproductive performance of males increased as they aged, in agreement with the life-history theory but depending of vole abundance. Remarkably, we found that having fewer back spots was positively associated with clutch size only for old individuals under low-food conditions. We suggest that environmental variation may shape the association between the expression of a sexual signal and reproductive outcome. We speculate that the reliability of sexual traits is higher when environmental conditions are poor only for old individuals. Within an evolutionary context, we suggest that the expression of sexual traits might be constrained by environmental conditions at later stages of life.
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Affiliation(s)
- David Lopez‐Idiaquez
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
- Department of EcologyInstituto de Investigación en Recursos Cinegéticos – IRECRonda de Toledos/n. 13005Ciudad RealSpain
| | - Pablo Vergara
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
| | - Juan Antonio Fargallo
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
| | - Jesús Martinez‐Padilla
- Department of Evolutionary EcologyMuseo Nacional de Ciencias NaturalesMadridJosé Gutiérrez Abascal2. 23006MadridSpain
- Research Unit of Biodiversity (OU, CSIC, PA)Oviedo University33600MieresSpain
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18
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Soulsbury CD, Kervinen M, Lebigre C. Curse of the black spot: spotting negatively correlates with fitness in black grouse Lyrurus tetrix. Behav Ecol 2016. [DOI: 10.1093/beheco/arw057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Nieminen E, Kervinen M, Lebigre C, Soulsbury C. Flexible timing of reproductive effort as an alternative mating tactic in black grouse (Lyrurus tetrix) males. BEHAVIOUR 2016. [DOI: 10.1163/1568539x-00003374] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Alternative reproductive tactics often take the form of dichotomous behavioural phenotypes. Focusing attention on such obvious dichotomy means that flexible patterns of behaviour within tactics is largely ignored. Using a long-term dataset of black grouse (Lyrurus tetrix) lek behaviours, we tested whether there were fine-scale differences in reproductive effort (lek attendance, fighting rates) and whether these were related to age and phenotype. Yearling males increased their lek attendance and fighting rate to a peak when adult male effort was declining. Adults and yearlings allocated reproductive effort according to their body mass but this was unrelated to differences in timing of effort. In adult males, different patterns of lek attendance were associated with different costs of reproduction, measured by mass loss or gain. Overall, our work demonstrates that individuals can use flexible patterns of reproductive effort both in terms of their own condition, their age and the likely costs of behaviours.
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Affiliation(s)
- E. Nieminen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
| | - M. Kervinen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland
| | - C. Lebigre
- Earth and Life Institute, Place de la Croix du Sud 4, Carnoy Building, B-1348 Louvain-la-Neuve, Belgium
| | - C.D. Soulsbury
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Lincoln LN6 7TS, UK
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20
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Hayward AD, Moorad J, Regan CE, Berenos C, Pilkington JG, Pemberton JM, Nussey DH. Asynchrony of senescence among phenotypic traits in a wild mammal population. Exp Gerontol 2015; 71:56-68. [PMID: 26277618 PMCID: PMC4661475 DOI: 10.1016/j.exger.2015.08.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/14/2015] [Accepted: 08/04/2015] [Indexed: 01/10/2023]
Abstract
The degree to which changes in lifespan are coupled to changes in senescence in different physiological systems and phenotypic traits is a central question in biogerontology. It is underpinned by deeper biological questions about whether or not senescence is a synchronised process, or whether levels of synchrony depend on species or environmental context. Understanding how natural selection shapes patterns of synchrony in senescence across physiological systems and phenotypic traits demands the longitudinal study of many phenotypes under natural conditions. Here, we examine the patterns of age-related variation in late adulthood in a wild population of Soay sheep (Ovis aries) that have been the subject of individual-based monitoring for thirty years. We examined twenty different phenotypic traits in both males and females, encompassing vital rates (survival and fecundity), maternal reproductive performance (offspring birth weight, birth date and survival), male rutting behaviour, home range measures, parasite burdens, and body mass. We initially quantified age-related variation in each trait having controlled for annual variation in the environment, among-individual variation and selective disappearance effects. We then standardised our age-specific trait means and tested whether age trajectories could be meaningfully grouped according to sex or the type of trait. Whilst most traits showed age-related declines in later life, we found striking levels of asynchrony both within and between the sexes. Of particular note, female fecundity and reproductive performance declined with age, but male annual reproductive success did not. We also discovered that whilst home range size and quality decline with age in females, home range size increases with age in males. Our findings highlight the complexity of phenotypic ageing under natural conditions and, along with emerging data from other wild populations and laboratory models, suggest that the long-standing hypothesis within evolutionary biology that fitness-related traits should senesce in a synchronous manner is seriously flawed.
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Affiliation(s)
- Adam D Hayward
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Jacob Moorad
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Charlotte E Regan
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Camillo Berenos
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Jill G Pilkington
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Josephine M Pemberton
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Daniel H Nussey
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, United Kingdom.
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