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Simons MJP, Sebire M, Verhulst S, Groothuis TGG. Androgen Elevation Accelerates Reproductive Senescence in Three-Spined Stickleback. Front Cell Dev Biol 2022; 9:752352. [PMID: 34977010 PMCID: PMC8718761 DOI: 10.3389/fcell.2021.752352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Costs of reproduction shape the life-history evolution of investment in current and future reproduction and thereby aging. Androgens have been proposed to regulate the physiology governing these investments. Furthermore, androgens are hypothesized to play a central role in carotenoid-dependent sexual signaling, regulating how much carotenoids are diverted to ornamentation and away from somatic maintenance, increasing oxidative stress, and accelerating aging. We investigated these relationships in male three-spined stickleback in which we elevated 11-ketotestosterone and supplied vitamin E, an antioxidant, in a 2 × 2 design. Androgen elevation shortened the time stickleback maintained reproductive activities. We suspect that this effect is caused by 11-ketotestosterone stimulating investment in current reproduction, but we detected no evidence for this in our measurements of reproductive effort: nest building, body composition, and breeding coloration. Carotenoid-dependent coloration was even slightly decreased by 11-ketotestosterone elevation and was left unaffected by vitamin E. Red coloration correlated with life expectancy and reproductive capacity in a quadratic manner, suggesting overinvestment of the individuals exhibiting the reddest bellies. In contrast, blue iris color showed a negative relationship with survival, suggesting physiological costs of producing this aspect of nuptial coloration. In conclusion, our results support the hypothesis that androgens regulate investment in current versus future reproduction, yet the precise mechanisms remain elusive. The quadratic relationships between sexual signal expression and aspects of quality have wider consequences for how we view sexual selection on ornamentation and its relationship with aging.
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Affiliation(s)
- Mirre J P Simons
- School of Biosciences, University of Sheffield, Sheffield, United Kingdom
| | - Marion Sebire
- The Centre for Environment, Fisheries and Aquaculture Science, Weymouth, United Kingdom
| | - Simon Verhulst
- Behavioural Biology, Centre for Behaviour and Neuroscience, University of Groningen, Groningen, Netherlands
| | - Ton G G Groothuis
- Behavioural Biology, Centre for Behaviour and Neuroscience, University of Groningen, Groningen, Netherlands
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2
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Abror As Sidiqi A, Sarmin, Mona Airin C, Astuti P. The Effect of Zinc, Shell, and Fishbone Supplementations on Comb Width and Length of Bangkok Rooster. BIO WEB OF CONFERENCES 2022. [DOI: 10.1051/bioconf/20224901003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Bangkok rooster is a prestigious ornamental bird in Indonesia. Zinc and shell have an aromatase blocker effect that results in testosterone elevations. Additionally, fishbone contains rich protein for optimum biological functions. Serum testosterone regulates comb size in the chicken. This study aimed to investigate the effect of natural aromatase blockers and protein in the comb of Bangkok roosters. This experiment divided thirteen Bangkok roosters into control and treatment groups with zinc, fishbone-shell, and fishbone supplementations. The weekly comb lengthening and widening were intervals between week 0 and the measurement week in this study. The results suggested that fishbone and fishbone-shell supplementations escalated the comb lengthening. Fishbone–shell treatment significantly increased the comb lengthening in the second and fourth weeks (p < 0.05). The significant elongation change in the fishbone group only appeared in the second week (p < 0.05). Otherwise, the treatments produced lower comb widening in the roosters. Fishbone and fishbone-shell supplementation significantly caused a lower widening in every measurement week (p < 0.05). This study uncovered the effects of zinc, shell, and fishbone supplementations on reproductive phenotype in Bangkok roosters.
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Argaez V, Solano-Zavaleta I, Zúñiga-Vega JJ. Do ectoparasites affect survival of three species of lizards of the genus Sceloporus? ZOOLOGY 2019; 138:125723. [PMID: 31756648 DOI: 10.1016/j.zool.2019.125723] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/25/2019] [Accepted: 10/27/2019] [Indexed: 12/22/2022]
Abstract
The short-term effects that ectoparasites cause to their hosts, such as local wounds and secondary infections that occur within a few hours or days after infection, are well documented in a wide variety of taxa, whereas long-term negative effects on the fitness of hosts, which result from chronic infections and are evident after several months, are less understood. Lizards are hosts of distinct species of mites and ticks that cause short-term negative effects such as ulcers, sores and local inflammation. However, the negative effects that these ectoparasites may have on the long-term survival of lizards have not been evaluated. In this study, we collected two years of capture-mark-recapture data and implemented a multi-model inference framework to examine if high ectoparasite loads have negative effects on the long-term survival probability of three lizard species of the genus Sceloporus (S. grammicus, S. megalepidurus, and S. torquatus). In addition, we considered that the potential negative effect of ectoparasites on survival may vary depending on sex, body condition, reproductive season, or climatic season. Contrary to our expectations, our results did not support the hypothesis that high ectoparasite loads reduce the survival probability of these lizards. In S. grammicus and S. megalepidurus we found no evidence of an effect of ectoparasite load on host survival. In S. torquatus ectoparasites influenced survival probability, but the effect was opposite to what we predicted: survival increased substantially as ectoparasite load increased. This unexpected result might be explained by mites discriminating between hosts and attaching more frequently to lizards in better health status, or by high-quality lizards having greater chances of contracting ectoparasites, because these individuals move around large areas and frequently engage in social interactions.
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Affiliation(s)
- Víctor Argaez
- Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México. Ciudad Universitaria, 04510, Ciudad de México, Mexico.
| | - Israel Solano-Zavaleta
- Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México. Ciudad Universitaria, 04510, Ciudad de México, Mexico.
| | - J Jaime Zúñiga-Vega
- Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México. Ciudad Universitaria, 04510, Ciudad de México, Mexico.
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5
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Intra-sexual competition modulates calling behavior and its association with secondary sexual traits. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2169-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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6
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Redmond LJ, Murphy MT, Cooper NW, O'Reilly KM. Testosterone secretion in a socially monogamous but sexually promiscuous migratory passerine. Gen Comp Endocrinol 2016; 228:24-32. [PMID: 26808965 DOI: 10.1016/j.ygcen.2016.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 01/19/2016] [Accepted: 01/21/2016] [Indexed: 11/30/2022]
Abstract
The steroid hormone testosterone (T) influences a multitude of traits critical to reproduction in vertebrates. In birds, high male T supports territory establishment and mate attraction, but is thought to interfere with parental care. Interspecific comparisons indicate that migratory species with short, synchronous breeding seasons have the highest peak T, and that the seasonal profile of T exhibits a rapid decline with the onset of incubation by females. We describe the T profile of the migratory, socially monogamous, and biparental Eastern Kingbird (Tyrannus tyrannus) from the high desert of eastern Oregon, USA, where breeding occurs within a short 2-3 month period. Eastern Kingbirds are socially monogamous but exhibit high rates of extra-pair paternity as ∼60% of broods contain extra-pair young. We therefore evaluate whether Eastern Kingbirds exhibit the "typical" T profile expected for a synchronously breeding migratory species, or whether T is maintained at a more constant level as would be predicted for a species with opportunities for mating that extend over a majority of the breeding season. Our samples were divided into six periods of the reproductive cycle from territory establishment to the feeding of fledglings. T did not change across stages of the nest cycle. Instead, T declined with sampling date and nest density, and increased with the number of fertile females in the population. Male kingbirds advertise their presence through song for most of the breeding season, and we suggest that T is maintained throughout most of the breeding season because male fitness is equally dependent on within- and extra-pair reproductive success.
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Affiliation(s)
- Lucas J Redmond
- Department of Biology, PO Box 751, Portland State University, Portland, OR 97201, USA.
| | - Michael T Murphy
- Department of Biology, PO Box 751, Portland State University, Portland, OR 97201, USA
| | - Nathan W Cooper
- Department of Biology, PO Box 751, Portland State University, Portland, OR 97201, USA
| | - Kathleen M O'Reilly
- Department of Biology, University of Portland, 5000 N. Willamette Blvd., Portland, OR 97203, USA
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Foo YZ, Nakagawa S, Rhodes G, Simmons LW. The effects of sex hormones on immune function: a meta-analysis. Biol Rev Camb Philos Soc 2016; 92:551-571. [DOI: 10.1111/brv.12243] [Citation(s) in RCA: 220] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 10/30/2015] [Accepted: 11/06/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Yong Zhi Foo
- ARC Centre of Excellence in Cognition and its Disorders, School of Psychology, University of Western Australia; 35 Stirling Hwy Crawley Western Australia 6009 Australia
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia; 35 Stirling Hwy Crawley Western Australia 6009 Australia
| | - Shinichi Nakagawa
- Department of Zoology; University of Otago; 340 Great King Street Dunedin 9016 New Zealand
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales; UNSW Sydney NSW 2052 Australia
| | - Gillian Rhodes
- ARC Centre of Excellence in Cognition and its Disorders, School of Psychology, University of Western Australia; 35 Stirling Hwy Crawley Western Australia 6009 Australia
| | - Leigh W. Simmons
- ARC Centre of Excellence in Cognition and its Disorders, School of Psychology, University of Western Australia; 35 Stirling Hwy Crawley Western Australia 6009 Australia
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia; 35 Stirling Hwy Crawley Western Australia 6009 Australia
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Mougeot F, Lendvai ÁZ, Martínez-Padilla J, Pérez-Rodríguez L, Giraudeau M, Casas F, Moore IT, Redpath S. Parasites, mate attractiveness and female feather corticosterone levels in a socially monogamous bird. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-2048-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Wenzel MA, James MC, Douglas A, Piertney SB. Genome-wide association and genome partitioning reveal novel genomic regions underlying variation in gastrointestinal nematode burden in a wild bird. Mol Ecol 2015; 24:4175-92. [PMID: 26179597 DOI: 10.1111/mec.13313] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 06/23/2015] [Accepted: 07/03/2015] [Indexed: 02/06/2023]
Abstract
Identifying the genetic architecture underlying complex phenotypes is a notoriously difficult problem that often impedes progress in understanding adaptive eco-evolutionary processes in natural populations. Host-parasite interactions are fundamentally important drivers of evolutionary processes, but a lack of understanding of the genes involved in the host's response to chronic parasite insult makes it particularly difficult to understand the mechanisms of host life history trade-offs and the adaptive dynamics involved. Here, we examine the genetic basis of gastrointestinal nematode (Trichostrongylus tenuis) burden in 695 red grouse (Lagopus lagopus scotica) individuals genotyped at 384 genome-wide SNPs. We first use genome-wide association to identify individual SNPs associated with nematode burden. We then partition genome-wide heritability to identify chromosomes with greater heritability than expected from gene content, due to harbouring a multitude of additive SNPs with individually undetectable effects. We identified five SNPs on five chromosomes that accounted for differences of up to 556 worms per bird, but together explained at best 4.9% of the phenotypic variance. These SNPs were closely linked to genes representing a range of physiological processes including the immune system, protein degradation and energy metabolism. Genome partitioning indicated genome-wide heritability of up to 29% and three chromosomes with excess heritability of up to 4.3% (total 8.9%). These results implicate SNPs and novel genomic regions underlying nematode burden in this system and suggest that this phenotype is somewhere between being based on few large-effect genes (oligogenic) and based on a large number of genes with small individual but large combined effects (polygenic).
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Affiliation(s)
- Marius A Wenzel
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Marianne C James
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Alex Douglas
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
| | - Stuart B Piertney
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, AB24 2TZ, UK
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10
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Alvarado LC, Muller MN, Emery Thompson M, Klimek M, Nenko I, Jasienska G. The Paternal Provisioning Hypothesis: effects of workload and testosterone production on men's musculature. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 158:19-35. [PMID: 26123405 DOI: 10.1002/ajpa.22771] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 05/11/2015] [Accepted: 05/14/2015] [Indexed: 01/30/2023]
Abstract
OBJECTIVES Testosterone supports male reproduction through a broad range of behavioral and physiological effects, including the maintenance of sexually dimorphic muscle used in male-male competition. Although it is often assumed that a persistent relationship exists between men's testosterone production and musculature, most studies either fail to find evidence for such a relationship, or document very weak associations. In nonhuman primates, by contrast, correlations between testosterone and muscle mass are higher. Here, we propose the "Paternal Provisioning Hypothesis," which predicts that men's skeletal muscle is less dependent on the effects of androgens than that of other primates, and more sensitive to the physical demands of men's work. This permits human fathers to downregulate testosterone, which has negative impacts on pair-bonding and parenting effort, but without sacrificing the strength and musculature necessary to provision mates and offspring. METHODS We tested predictions of the Paternal Provisioning Hypothesis by assessing parental status, salivary testosterone levels, anthropometry, and strength among 122 men (ages 18-78) at the Mogielica Human Ecology Study Site in rural Poland. We chose this population because men practice subsistence agriculture, regularly engaging in physically demanding labor. Grip and chest strength were assessed using a dynamometer, and upper-body musculature was estimated from arm muscle circumference. RESULTS In this population, testosterone showed no association with measures of strength or musculature, and was lower in older men and pair-bonded fathers. Marital and parental status and workload, by contrast, were positive predictors of muscle mass and strength measures. DISCUSSION These findings offer support for the Paternal Provisioning Hypothesis.
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Affiliation(s)
| | - Martin N Muller
- Department of Anthropology, University of New Mexico, Albuquerque, 87131, NM
| | | | - Magdalena Klimek
- Department of Environmental Health, Jagiellonian University, 31-007, Kraków, Poland
| | - Ilona Nenko
- Department of Environmental Health, Jagiellonian University, 31-007, Kraków, Poland
| | - Grazyna Jasienska
- Department of Environmental Health, Jagiellonian University, 31-007, Kraków, Poland
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11
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Martínez-Padilla J, Pérez-Rodríguez L, Mougeot F, Ludwig S, Redpath SM. Intra-sexual competition alters the relationship between testosterone and ornament expression in a wild territorial bird. Horm Behav 2014; 65:435-44. [PMID: 24698833 DOI: 10.1016/j.yhbeh.2014.03.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 03/18/2014] [Accepted: 03/22/2014] [Indexed: 01/21/2023]
Abstract
In a reliable signalling system, individual quality is expected to mediate the costs associated with ornamental displays, with relatively lower costs being paid by individuals of higher quality. These relative costs should depend not only on individual quality, but also on levels of intra-sexual competition. We explored the current and delayed effects that testosterone implants have on bird ornamentation in populations with contrasted population densities, as a proxy for intra-sexual competition. In a replicated experiment, we manipulated testosterone in 196 yearling male red grouse Lagopus lagopus scoticus in autumn in populations of high and low levels of intra-sexual competition. Males were assigned to one of three exogenous testosterone (T) treatments: empty implants (T0), small T implants (T1) or larger T implants (T2). We monitored subsequent changes in testosterone levels, ornament size and carotenoid-based colouration, carotenoid levels and body condition from autumn to spring. Testosterone implants increased testosterone levels, comb redness and comb size, and decreased body condition but these effects depended on levels of intra-sexual competition. Specifically, T2-implanted birds increased testosterone levels and comb size more, and reduced body condition more, in populations where intra-sexual competition was low. In the following spring, testosterone levels of T2-treated birds kept increasing in populations where intra-sexual competition was high but not in populations where intra-sexual competition was low. Our results highlight that levels of intra-sexual competition alter the relationship between testosterone levels and ornament expression, influencing their condition-dependence; they also indicate that the outcome of standard hormone manipulation conducted in free-living animals vary depending on the population context.
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Affiliation(s)
- J Martínez-Padilla
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, José Gutiérrez Abascal, 2, 23005, Madrid, Spain.
| | - L Pérez-Rodríguez
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo, s/n, 3005 Ciudad Real, Spain; Department of Evolutionary Ecology, Estación Biológica de Doñana, (EBD-CSIC), Avda. Americo Vespucio, s/n, 41092 Seville, Spain
| | - F Mougeot
- Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC, UCLM, JCCM), Ronda de Toledo, s/n, 3005 Ciudad Real, Spain; Estación Experimental de Zonas Áridas (CSIC), Ctra. de Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain
| | - S Ludwig
- Game & Wildlife Conservation Trust, Eggleston Hall, Barnard Castle, DL12 0AG UK
| | - S M Redpath
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
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Martínez-Padilla J, Pérez-Rodríguez L, Mougeot F, Ludwig SC, Redpath SM. Experimentally elevated levels of testosterone at independence reduce fitness in a territorial bird. Ecology 2014; 95:1033-44. [DOI: 10.1890/12-1905.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Bonier F, Eikenaar C, Martin PR, Moore IT. Extrapair Paternity Rates Vary with Latitude and Elevation in Emberizid Sparrows. Am Nat 2014; 183:54-61. [DOI: 10.1086/674130] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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14
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Alvarado LC. Do evolutionary life-history trade-offs influence prostate cancer risk? a review of population variation in testosterone levels and prostate cancer disparities. Evol Appl 2013; 6:117-33. [PMID: 23396824 PMCID: PMC3567477 DOI: 10.1111/eva.12036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 10/31/2012] [Accepted: 11/05/2012] [Indexed: 12/20/2022] Open
Abstract
An accumulation of evidence suggests that increased exposure to androgens is associated with prostate cancer risk. The unrestricted energy budget that is typical of Western diets represents a novel departure from the conditions in which men's steroid physiology evolved and is capable of supporting distinctly elevated testosterone levels. Although nutritional constraints likely underlie divergent patterns of testosterone secretion between Westernized and non-Western men, considerable variability exists in men's testosterone levels and prostate cancer rates within Westernized populations. Here, I use evolutionary life history theory as a framework to examine prostate cancer risk. Life history theory posits trade-offs between investment in early reproduction and long-term survival. One corollary of life history theory is the 'challenge hypothesis', which predicts that males augment testosterone levels in response to intrasexual competition occurring within reproductive contexts. Understanding men's evolved steroid physiology may contribute toward understanding susceptibility to prostate cancer. Among well-nourished populations of Westerners, men's testosterone levels already represent an outlier of cross-cultural variation. I hypothesize that Westernized men in aggressive social environments, characterized by intense male-male competition, will further augment testosterone production aggravating prostate cancer risk.
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15
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Vergara P, Redpath SM, Martínez-Padilla J, Mougeot F. Environmental conditions influence red grouse ornamentation at a population level. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01974.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pablo Vergara
- School of Biological Sciences; University of Aberdeen; Tillydrone Av.; Aberdeen; AB24 2TZ; UK
| | - Stephen M. Redpath
- School of Biological Sciences; University of Aberdeen & The James Hutton Institute; Aberdeen Centre for Environmental Sustainability (ACES); Tillydrone Av.; Aberdeen; AB24 2TZ; UK
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16
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Vergara P, Martínez-Padilla J. Social context decouples the relationship between a sexual ornament and testosterone levels in a male wild bird. Horm Behav 2012; 62:407-12. [PMID: 22841824 DOI: 10.1016/j.yhbeh.2012.07.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/16/2012] [Accepted: 07/18/2012] [Indexed: 11/19/2022]
Abstract
In order to maximise fitness individuals should adjust their level of signalling according to their surrounding social environment. However, field experiments showing such adjustment of current signalling associated to changes in social context are lacking. Here, we manipulated levels of male aggressive- and dominance-related displays in a wild bird in our treated area by increasing testosterone levels using implants in a subset of males. We then compared the expression of sexual signals (i.e. comb size) between non-treated red grouse Lagopus lagopus scoticus males from control and treatment areas. We further explored the potential endocrinological mechanism linking social environment and signal expression by analysing testosterone levels in all males. Our treatment successfully increased overall aggressive- and dominance-related behaviours in the treatment area. Furthermore, testosterone-implanted birds increased their comb size as repeatedly shown in previous studies in male red grouse. Interestingly, untreated males living in the treatment area decreased their comb size, whilst increasing testosterone levels. Since comb size is a signal of dominance, untreated males from the treatment area may have perceived themselves as subordinate individuals and decreased their signalling levels to avoid confrontations with testosterone-treated, dominant individuals. In conclusion, our findings show that social context has the potential to regulate sexual signalling and testosterone levels. Our results highlight the role of social context when exploring the link between testosterone and behaviour, as it may reverse the relationship between both traits. Our results suggest that social context affects signalling and testosterone independently.
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Affiliation(s)
- Pablo Vergara
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
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17
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Martinez-Padilla J, Vergara P, Mougeot F, Redpath SM. Parasitized mates increase infection risk for partners. Am Nat 2012; 179:811-20. [PMID: 22617268 DOI: 10.1086/665664] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Individuals can gain fitness benefits and costs through their mates. However, studies on sexual selection have tended to focus on genetic benefits. A potentially widespread cost of pairing with a parasitized mate is that doing so will increase an individual's parasite abundance. Such a cost has been overlooked in systems in which parasites are indirectly transmitted. We manipulated the abundance of the nematode parasite Trichostrongylus tenuis, an indirectly transmitted parasite, within pairs of wild red grouse Lagopus lagopus scoticus in spring. Parasite levels were correlated within pairs before the experiment. We removed parasites from males, females, or both members of the pair and evaluated individual parasite uptake over the subsequent breeding period. At the end of the breeding season, an individual's parasite abundance was greater when its mate had not been initially purged of parasites. This cost appeared to be greater for males. We discuss the implications of our results in relation to the costs that parasites may have on sexual selection processes.
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Affiliation(s)
- Jesus Martinez-Padilla
- Department of Evolutionary Ecology, Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Científicas (CSIC), José Gutiérrez Abascal 2, 28006 Madrid, Spain.
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18
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Testosterone dynamics during encounter: role of emotional factors. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2012; 198:485-94. [DOI: 10.1007/s00359-012-0726-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/27/2012] [Accepted: 04/06/2012] [Indexed: 10/28/2022]
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Vergara P, Mougeot F, Martínez-Padilla J, Leckie F, Redpath SM. The condition dependence of a secondary sexual trait is stronger under high parasite infection level. Behav Ecol 2012. [DOI: 10.1093/beheco/arr216] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Tonra CM, Marra PP, Holberton RL. Early elevation of testosterone advances migratory preparation in a songbird. ACTA ACUST UNITED AC 2011; 214:2761-7. [PMID: 21795574 DOI: 10.1242/jeb.054734] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The timing of events associated with spring migration can be an important determinant of fitness for migratory birds. The need to prepare and maintain physical condition for migration is one demand that must be met for early arrival on breeding areas, and this demand is compounded by the energetic demands of the physiological transition to breeding. Here, we examined whether migratory birds, specifically males, can adequately meet both of these demands by elevating the sex steroid testosterone early during migratory preparation. To test this, we used a captive experiment in which we photostimulated male dark-eyed juncos (Junco hyemalis) and manipulated circulating testosterone. We predicted males with elevated testosterone would prepare to migrate and breed faster than control males or males where the ability of testosterone to bind with receptors, or be converted to estradiol, was inhibited (testosterone inhibited). We measured migratory preparation using mass, food intake, fat deposits and nocturnal activity (Zugunruhe). To estimate breeding preparation, we measured the diameter of the cloacal protuberance (CP). We found that males in the testosterone treatment group began migratory preparation approximately 10 days before controls. There was no difference in the magnitude of peak migratory condition between testosterone-implanted birds and controls. Males implanted with testosterone also reached the onset of breeding preparation faster and had larger peak CP diameter compared with controls. Testosterone-inhibited birds showed no signs of migratory preparation and only a weak increase in CP diameter. These results demonstrate that early elevation of testosterone during migratory preparation could incur benefits for males in terms of the ability to depart earlier from non-breeding areas and arrive in a more advanced breeding condition. This experiment demonstrates that there may be important physiological underpinnings to known winter to breeding season carry-over effects in migratory birds.
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Affiliation(s)
- Christopher M Tonra
- Laboratory of Avian Biology, School of Biology and Ecology, University of Maine, Orono, ME 04469, USA.
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VERGARA P, MARTINEZ-PADILLA J, MOUGEOT F, LECKIE F, REDPATH SM. Environmental heterogeneity influences the reliability of secondary sexual traits as condition indicators. J Evol Biol 2011; 25:20-8. [DOI: 10.1111/j.1420-9101.2011.02399.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Vergara P, Martínez-Padilla J, Redpath SM, Mougeot F. The ornament–condition relationship varies with parasite abundance at population level in a female bird. Naturwissenschaften 2011; 98:897-902. [DOI: 10.1007/s00114-011-0833-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 07/31/2011] [Accepted: 08/03/2011] [Indexed: 10/17/2022]
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Bunnefeld N, Reuman DC, Baines D, Milner-Gulland EJ. Impact of unintentional selective harvesting on the population dynamics of red grouse. J Anim Ecol 2011; 80:1258-68. [PMID: 21595686 DOI: 10.1111/j.1365-2656.2011.01862.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
1. The effect of selective exploitation of certain age, stage or sex classes (e.g., trophy hunting) on population dynamics is relatively well studied in fisheries and sexually dimorphic mammals. 2. Harvesting of terrestrial species with no morphological differences visible between the different age and sex classes (monomorphic species) is usually assumed to be nonselective because monomorphicity makes intentionally selective harvesting pointless and impractical. But harvesting of the red grouse (Lagopus lagopus scoticus), a monomorphic species, was recently shown to be unintentionally selective. This study uses a sex- and age-specific model to explore the previously unresearched effects of unintentional harvesting selectivity. 3. We examine the effects of selectivity on red grouse dynamics by considering models with and without selectivity. Our models include territoriality and parasitism, two mechanisms known to be important for grouse dynamics. 4. We show that the unintentional selectivity of harvesting that occurs in red grouse decreases population yield compared with unselective harvesting at high harvest rates. Selectivity also dramatically increases extinction risk at high harvest rates. 5. Selective harvesting strengthens the 3- to 13-year red grouse population cycle, suggesting that the selectivity of harvesting is a previously unappreciated factor contributing to the cycle. 6. The additional extinction risk introduced by harvesting selectivity provides a quantitative justification for typically implemented 20-40% harvest rates, which are below the maximum sustainable yield that could be taken, given the observed population growth rates of red grouse. 7. This study shows the possible broad importance of investigating in future research whether unintentionally selective harvesting occurs on other species.
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Affiliation(s)
- Nils Bunnefeld
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, SL5 7PY, UK.
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24
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López-Rull I, Celis P, Salaberria C, Puerta M, Gil D. Post-fledging recruitment in relation to nestling plasma testosterone and immunocompetence in the spotless starling. Funct Ecol 2010. [DOI: 10.1111/j.1365-2435.2010.01783.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Horton BM, Yoon J, Ghalambor CK, Moore IT, Scott Sillett T. Seasonal and population variation in male testosterone levels in breeding orange-crowned warblers (Vermivora celata). Gen Comp Endocrinol 2010; 168:333-9. [PMID: 20420840 DOI: 10.1016/j.ygcen.2010.04.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 04/07/2010] [Accepted: 04/20/2010] [Indexed: 11/29/2022]
Abstract
Comparative hormone studies can reveal how physiology underlies life history variation. Here, we examined seasonal variation in plasma testosterone concentration between populations of male orange-crowned warblers (Vermivora celata) breeding in Fairbanks, Alaska (V. c. celata) and on Santa Catalina Island, California (V. c. sordida). These populations face different ecological constraints and exhibit different life histories. Alaska birds have a short breeding season, low annual adult survival, and high reproductive rates. In contrast, Catalina Island birds exhibit high adult survival and low reproductive rates despite having a long breeding season. We examined seasonal variation in male testosterone concentrations as a potential mechanism underlying differences in male reproductive strategies between populations. From 2006 to 2008, we sampled males during the pre-incubation, incubation, and nestling stages. Alaska males exhibited a seasonal testosterone pattern typical of northern passerines: testosterone levels were high during pre-incubation and declined during incubation to low levels during nestling provisioning. Testosterone concentrations in Catalina Island males, however, did not vary consistently with breeding stage, remained elevated throughout the breeding season, and were higher than in Alaska males during the nestling stage. We hypothesize that in Alaska, where short seasons and high adult mortality limit breeding opportunities, the seasonal testosterone pattern facilitates high mating effort prior to incubation, but high parental investment during the nestling stage. On Catalina Island, elevated testosterone levels may reflect the extended mating opportunities and high population density facing males in this population. Our results suggest that population variation in seasonal testosterone patterns in orange-crowned warblers may be a function of differences in life history strategy and the social environment.
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Affiliation(s)
- Brent M Horton
- Smithsonian Migratory Bird Center, National Zoological Park, PO Box 37012 MRC 5503, Washington, DC 20013-7012, USA.
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Mougeot F, Martínez-Padilla J, Bortolotti GR, Webster LMI, Piertney SB. Physiological stress links parasites to carotenoid-based colour signals. J Evol Biol 2010; 23:643-50. [PMID: 20074170 DOI: 10.1111/j.1420-9101.2009.01926.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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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. J Exp Biol 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] [Abstract] [MESH Headings] [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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LISLEVAND T, FIGUEROLA J, SZÉKELY T. Evolution of sexual size dimorphism in grouse and allies (Aves: Phasianidae) in relation to mating competition, fecundity demands and resource division. J Evol Biol 2009; 22:1895-905. [DOI: 10.1111/j.1420-9101.2009.01802.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bortolotti GR, Mougeot F, Martinez-Padilla J, Webster LMI, Piertney SB. Physiological stress mediates the honesty of social signals. PLoS One 2009; 4:e4983. [PMID: 19319197 PMCID: PMC2656621 DOI: 10.1371/journal.pone.0004983] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 02/24/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Extravagant ornaments used as social signals evolved to advertise their bearers' quality. The Immunocompetence Handicap Hypothesis proposes that testosterone-dependent ornaments reliably signal health and parasite resistance; however, empirical studies have shown mixed support. Alternatively, immune function and parasite resistance may be indirectly or directly related to glucocorticoid stress hormones. We propose that an understanding of the interplay between the individual and its environment, particularly how they cope with stressors, is crucial for understanding the honesty of social signals. METHODOLOGY/PRINCIPAL FINDINGS We analyzed corticosterone deposited in growing feathers as an integrated measure of hypothalamic-pituitary-adrenal activity in a wild territorial bird, the red grouse Lagopus lagopus scoticus. We manipulated two key, interrelated components, parasites and testosterone, which influence both ornamentation and fitness. Birds were initially purged of parasites, and later challenged with parasites or not, while at the same time being given testosterone or control implants, using a factorial experimental design. At the treatment level, testosterone enhanced ornamentation, while parasites reduced it, but only in males not implanted with testosterone. Among individuals, the degree to which both parasites and testosterone had an effect was strongly dependent on the amount of corticosterone in the feather grown during the experiment. The more stressors birds had experienced (i.e., higher corticosterone), the more parasites developed, and the less testosterone enhanced ornamentation. CONCLUSIONS/SIGNIFICANCE With this unique focus on the individual, and a novel, integrative, measure of response to stressors, we show that ornamentation is ultimately a product of the cumulative physiological response to environmental challenges. These findings lead toward a more realistic concept of honesty in signaling as well as a broader discussion of the concept of stress.
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Affiliation(s)
- Gary R Bortolotti
- Department of Biology, University of Saskatchewan, Saskatoon, Canada.
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Mougeot F, Martínez-Padilla J, Webster LMI, Blount JD, Pérez-Rodríguez L, Piertney SB. Honest sexual signalling mediated by parasite and testosterone effects on oxidative balance. Proc Biol Sci 2009; 276:1093-100. [PMID: 19129122 PMCID: PMC2679075 DOI: 10.1098/rspb.2008.1570] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 11/13/2008] [Indexed: 11/21/2022] Open
Abstract
Extravagant ornaments evolved to advertise their bearers' quality, the honesty of the signal being ensured by the cost paid to produce or maintain it. The oxidation handicap hypothesis (OHH) proposes that a main cost of testosterone-dependent ornamentation is oxidative stress, a condition whereby the production of reactive oxygen and nitrogen species (ROS/RNS) overwhelms the capacity of antioxidant defences. ROS/RNS are unstable, very reactive by-products of normal metabolic processes that can cause extensive damage to key biomolecules (cellular proteins, lipids and DNA). Oxidative stress has been implicated in the aetiology of many diseases and could link ornamentation and genetic variation in fitness-related traits. We tested the OHH in a free-living bird, the red grouse. We show that elevated testosterone enhanced ornamentation and increased circulating antioxidant levels, but caused oxidative damage. Males with smaller ornaments suffered more oxidative damage than those with larger ornaments when forced to increase testosterone levels, consistent with a handicap mechanism. Parasites depleted antioxidant defences, caused oxidative damage and reduced ornament expression. Oxidative damage extent and the ability of males to increase antioxidant defences also explained the impacts of testosterone and parasites on ornamentation within treatment groups. Because oxidative stress is intimately linked to immune function, parasite resistance and fitness, it provides a reliable currency in the trade-off between individual health and ornamentation. The costs induced by oxidative stress can apply to a wide range of signals, which are testosterone-dependent or coloured by pigments with antioxidant properties.
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Affiliation(s)
- Francois Mougeot
- Estación Experimental de Zonas Aridas, CSIC, c. General Segura 1, 04001 Almeria, Spain.
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31
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Chapman DS, Cornell SJ, Kunin WE. Interactions between harvesting, noise and territoriality in a model of red grouse population cycles. J Anim Ecol 2009; 78:476-84. [DOI: 10.1111/j.1365-2656.2008.01496.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Kempenaers B, Peters A, Foerster K. Sources of individual variation in plasma testosterone levels. Philos Trans R Soc Lond B Biol Sci 2008; 363:1711-23. [PMID: 18048297 PMCID: PMC2367619 DOI: 10.1098/rstb.2007.0001] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The steroid hormone testosterone (T) plays a central role in the regulation of breeding in males, because many physiological, morphological and behavioural traits related to reproduction are T dependent. Moreover, in many seasonally breeding vertebrates, male plasma T levels typically show a pronounced peak during the breeding season. While such population-level patterns are fairly well worked out, the sources and the implications of the large variability in individual T levels within the seasonal cycle remain surprisingly little understood. Understanding the potential sources of individual variation in T levels is important for behavioural and evolutionary ecologists, for at least two reasons. First, in 'honest signalling' theory, T is hypothesized to play a critical role as the assumed factor that enforces honesty of the expression of sexually selected quality indicators. Second, T is often considered a key mediator of central life-history trade-offs, such as investment in survival versus reproduction or in mating versus parental care. Here, we discuss the patterns of within- and between-individual variation in male plasma T levels in free-living populations of birds. We argue that it is unclear whether this variability mainly reflects differences in underlying individual quality (intrinsic factors such as genetic or maternal effects) or in the environment (extrinsic factors including time of day, individual territorial status and past experience). Research in avian behavioural endocrinology has mainly focused on the effects of extrinsic factors, while other sources of variance are often ignored. We suggest that studies that use an integrative approach and investigate the relative importance of all potential sources of variation are essential for the interpretation of data on individual plasma T levels.
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Affiliation(s)
- Bart Kempenaers
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology, PO Box 1564, 82305 Seewiesen, Germany.
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Nooker JK, Sandercock BK. Phenotypic correlates and survival consequences of male mating success in lek-mating greater prairie-chickens (Tympanuchus cupido). Behav Ecol Sociobiol 2008. [DOI: 10.1007/s00265-008-0566-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Karubian J, Sillett TS, Webster MS. The effects of delayed plumage maturation on aggression and survival in male red-backed fairy-wrens. Behav Ecol 2008. [DOI: 10.1093/beheco/arm159] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Muñoz A, Aparicio JM, Bonal R. Male barn swallows use different resource allocation rules to produce ornamental tail feathers. Behav Ecol 2008. [DOI: 10.1093/beheco/arm148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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MOUGEOT F, PÉREZ-RODRÍGUEZ L, MARTÍNEZ-PADILLA J, LECKIE F, REDPATH SM. Parasites, testosterone and honest carotenoid-based signalling of health. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01302.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Mougeot F. Ornamental comb colour predicts T-cell-mediated immunity in male red grouse Lagopus lagopus scoticus. Naturwissenschaften 2007; 95:125-32. [PMID: 17898979 DOI: 10.1007/s00114-007-0303-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 08/28/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022]
Abstract
Sexual ornaments might reliably indicate the ability to cope with parasites and diseases, and a better ability to mount a primary inflammatory response to a novel challenge. Carotenoid-based ornaments are amongst the commonest sexual signals of birds and often influence mate choice. Because carotenoids are immuno-stimulants, signallers may trade-off allocating these to ornamental colouration or using them for immune responses, so carotenoid-based ornaments might be particularly useful as honest indicators of immuno-compentence. Tetraonid birds, such as the red grouse Lagopus lagopus scoticus, exhibit supra-orbital yellow-red combs, a conspicuous ornament which functions in intra- and inter-sexual selection. The colour of combs is due to epidermal pigmentation by carotenoids, while their size is testosterone-dependent. In this study, I investigated whether comb characteristics, and in particular, comb colour, indicated immuno-competence in free-living male red grouse. I assessed T-cell-mediated immunity using a standardised challenge with phytohaemagglutinin. Red grouse combs reflect in the red and in the ultraviolet spectrum of light, which is not visible to humans but that grouse most likely see, so I measured comb colour across the whole bird visible spectrum (300-700 nm) using a reflectance spectrometer. I found that males with bigger and redder combs, but with less ultraviolet reflectance, had greater T-cell-mediated immune response. Comb colour predicted T-cell-mediated immune response better than comb size, indicating that the carotenoid-based colouration of this ornament might reliably signal this aspect of male quality.
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Affiliation(s)
- Francois Mougeot
- School of Biological Sciences, University of Aberdeen, Zoology Building, Aberdeen AB24 2TZ, UK.
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Mougeot F, Martínez-Padilla J, Pérez-Rodríguez L, Bortolotti GR. Carotenoid-based colouration and ultraviolet reflectance of the sexual ornaments of grouse. Behav Ecol Sociobiol 2006. [DOI: 10.1007/s00265-006-0304-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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