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McKee JL, Tompkins EM, Estela FA, Anderson DJ. Age effects on Nazca booby foraging performance are largely constant across variation in the marine environment: Results from a 5-year study in Galápagos. Ecol Evol 2023; 13:e10138. [PMID: 37304365 PMCID: PMC10253949 DOI: 10.1002/ece3.10138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/06/2023] [Accepted: 05/12/2023] [Indexed: 06/13/2023] Open
Abstract
Foraging outcomes dictate the nutritional resources available to an organism and may vary with intrinsic factors, like age. Thus, understanding how age affects foraging performance, alone or in interaction with extrinsic factors (like environmental quality), improves our understanding of aging processes in the wild. We examined how foraging traits, measured across five breeding seasons, change with age, environmental variation, and their interaction in Nazca boobies (Sula granti), a pelagic seabird in Galápagos. We evaluated the hypotheses that (1) foraging performance is better in middle-aged birds than in young ones, and that (2) foraging performance is better in middle-aged birds than in old ones. Furthermore, favorable environmental conditions will either (3) attenuate age differences in foraging performance (by relieving constraints on young, inexperienced and old, senescent age classes), or (4) accentuate age differences (if middle-aged birds can exploit abundant resources better than other age classes can). Incubating birds tagged with GPS loggers (N = 815) provided data on foraging performance (e.g., total distance traveled, mass gained) to evaluate interactions between age and environmental variation (e.g., sea surface temperature). Poor environmental conditions associated with the cool phase of the El Niño-Southern Oscillation increased foraging effort, including foraging distance and duration, for example. Across age classes, foraging boobies responded similarly to environmental variation except for female mass gain rate: age-related declines in mass gain rate were reduced under favorable environmental conditions. Birds of different ages also searched in somewhat distinct areas in the poor conditions of 2016, but not in other years. In several foraging traits, including foraging duration and distance, female boobies showed predicted early-life improvement and late-life decline, following the established pattern for reproductive traits in this species. Thus, deficits in resource acquisition (this study) may contribute to the poor survival and reproductive outcomes previously observed in old Nazca boobies, particularly in females.
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Affiliation(s)
- Jennifer L. McKee
- Department of BiologyWake Forest UniversityWinston‐SalemNorth CarolinaUSA
| | - Emily M. Tompkins
- Department of BiologyWake Forest UniversityWinston‐SalemNorth CarolinaUSA
| | - Felipe A. Estela
- Department of BiologyWake Forest UniversityWinston‐SalemNorth CarolinaUSA
- Departamento de Ciencias Naturales y MatemáticasPontificia Universidad Javeriana – CaliValle del CaucaColombia
| | - David J. Anderson
- Department of BiologyWake Forest UniversityWinston‐SalemNorth CarolinaUSA
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2
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Vrtílek M, Žák J, Reichard M. Evidence for reproductive senescence across ray-finned fishes: A review. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.982915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The origin, incidence, and consequences of reproductive senescence vary greatly across the tree of life. In vertebrates, research on reproductive senescence has been mainly focused on mammals and birds, demonstrating that its variation is largely linked to critical life history traits, such as growth patterns, juvenile, and adult mortality, and reproductive strategy. Fishes represent half of the vertebrate taxonomic diversity and display remarkable variation in life history. Based on a thorough literature review, we summarize current evidence on reproductive senescence in ray-finned fishes (Actinopterygii). While survival and physiological senescence are acknowledged in fish, their potential age-related reproductive decline has often been disregarded due to the prevalence of indeterminate growth. We demonstrate that age-related reproductive decline is reported across fish phylogeny, environments, and traits. An important point of our review is that the incidence of reproductive senescence in a species depends on both the number of studies for that species and the coverage of its maximum lifespan by the study. Reproductive senescence was documented for one-third of the studied fish species, with females suffering an age-related decline in reproductive traits less often than males or both parents combined. Neither parental care nor migratory strategy corresponded with the occurrence of reproductive senescence in fish. The traits that were affected by reproductive senescence most often were sex-specific, with pre-mating and mating categories of traits declining in females and sperm quality and quantity in males. We also demonstrate that reproductive senescence can be buffered by indeterminate growth. We provide rich evidence of reproductive senescence across ray-finned fishes, but we highlight the need for better data on age-related reproduction in fishes.
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Rebol EJ, Anderson DJ. Sex-specific aging in bite force in a wild vertebrate. Exp Gerontol 2021; 159:111661. [PMID: 34923056 DOI: 10.1016/j.exger.2021.111661] [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: 11/16/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 11/18/2022]
Abstract
The manifold differences between the sexes provide wide scope for sex differences in senescence. However, detecting physiological decline in old age and evaluating any sex difference in aging in a wild population can be challenging. This applies especially to long-lived species that require marking around birth in order to recognize elderly individuals, perhaps decades later. Here, we used bite force of known-age, long-lived Nazca boobies (Sula granti, a seabird) as a functional measure of muscle strength; surprisingly, only a single study has evaluated the possibility of senescent decline in muscle strength in a wild vertebrate. The male-biased adult sex ratio of this population constrains breeding opportunities across the lifespan for males, so we predicted that slower accumulation of reproductive costs would delay senescent decline in bite force in males compared to females, matching observed patterns in some non-muscle traits in this species. Data were collected from 349 adults using a force transducer at the start of the breeding season in November 2017 on Isla Española, Galápagos. Both sexes achieved less bite force in late life. The decline began at a later age in males, providing evidence of sex-specific schedules of decline in muscle function in a wild vertebrate.
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Affiliation(s)
- Erynn J Rebol
- Dept. of Biology, Wake Forest University, Winston-Salem, NC 27106, USA.
| | - David J Anderson
- Dept. of Biology, Wake Forest University, Winston-Salem, NC 27106, USA
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Saraux C, Chiaradia A. Age‐related breeding success in little penguins: a result of selection and ontogenetic changes in foraging and phenology. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Claire Saraux
- DEPE UMR7178 IPHC CNRS‐Université de Strasbourg 23 rue du Loess 67037 Strasbourg France
| | - Andre Chiaradia
- Conservation Department Phillip Island Nature Parks PO Box 97 Cowes Victoria 3922 Australia
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Tompkins EM, Anderson DJ. Breeding responses to environmental variation are age- and trait-dependent in female Nazca boobies. Ecology 2021; 102:e03457. [PMID: 34166542 DOI: 10.1002/ecy.3457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 12/04/2020] [Accepted: 04/05/2021] [Indexed: 12/17/2022]
Abstract
Age and environment are important determinants of reproductive parameters in long-lived organisms. These factors may interact to determine breeding responses to environmental change, yet few studies have examined the environmental dependence of aging patterns across the entire life span. We do so, using a 20-yr longitudinal data set of reproductive phenotypes in long-lived female Nazca boobies (Sula granti), a monogamous seabird breeding in the eastern tropical Pacific. Young and old females may suffer from inexperience and senescence, respectively, and/or practice reproductive restraint. Breeding performance (for breeding participation, breeding date, clutch size, egg volume, and offspring production) was expected to be lower in these age classes, particularly under environmental challenge, in comparison with middle-aged breeders. Sea surface temperature anomalies (SSTA) represented interannual variation in the El Niño-Southern Oscillation (ENSO) and were one proxy for environmental quality (a population count of clutch initiations was a second). Although only females lay eggs, both sexes care for eggs and nestlings, and the male partner's age, alone or in interaction with female age, was evaluated as a predictor of breeding performance. Middle-aged females performed better than young and old birds for all reproductive traits. Pairing with a young male delayed breeding (particularly for old females) and reduced clutch size, and pairing with an old male reduced offspring production. Challenging environments increased age effects on breeding probability and breeding date across young to middle ages and for offspring production across middle to old ages. However, important exceptions to the predicted patterns for clutch size and fledging success across young to middle ages suggested that trade-offs between fitness components may complicate patterns of trait expression across the life span. Relationships between breeding participation, environment, and individual quality and/or experience in young females may also contribute to unexpected patterns for clutch size and fledging success, traits expressed only in breeders. Finally, independent of age, breeding responses of female Nazca boobies to the ENSO did not follow expectations derived from oceanic forcing of primary productivity. During El Niño-like conditions, egg-laying traits (clutch size, breeding date) improved, but offspring production declined, whereas La Niña-like conditions were "poor" environments throughout the breeding cycle.
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Affiliation(s)
- Emily M Tompkins
- Biology Department, Wake Forest University, Winston-Salem, North Carolina, USA
| | - David J Anderson
- Biology Department, Wake Forest University, Winston-Salem, North Carolina, USA
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6
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Forsythe AB, Day T, Nelson WA. Demystifying individual heterogeneity. Ecol Lett 2021; 24:2282-2297. [PMID: 34288328 DOI: 10.1111/ele.13843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 06/07/2021] [Accepted: 06/14/2021] [Indexed: 12/01/2022]
Abstract
Among-individual variation in vital rates, such as mortality and birth rates, exists in nearly all populations. Recent studies suggest that this individual heterogeneity produces substantial life-history and fitness differences among individuals, which in turn scale up to influence population dynamics. However, our ability to understand the consequences of individual heterogeneity is limited by inconsistencies across conceptual frameworks in the field. Studies of individual heterogeneity remain filled with contradicting and ambiguous terminology that introduces risks of misunderstandings, conflicting models and unreliable conclusions. Here, we synthesise the existing literature into a single and comparatively straightforward framework with explicit terminology and definitions. This work introduces a distinction between potential vital rates and realised vital rates to develop a coherent framework that maps directly onto mathematical models of individual heterogeneity. We suggest the terms "fixed condition" and "dynamic condition" be used to distinguish potential vital rates that are permanent from those that can change throughout an individual's life. To illustrate, we connect the framework to quantitative genetics models and to common classes of statistical models used to infer individual heterogeneity. We also develop a population projection matrix model that provides an example of how our definitions are translated into precise quantitative terms.
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Affiliation(s)
- Amy B Forsythe
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada
| | - Troy Day
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada.,Department of Mathematics and Statistics, Queen's University, Kingston, ON, Canada
| | - William A Nelson
- Department of Biology, Biosciences Complex, Queen's University, Kingston, ON, Canada
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Howard JL, Tompkins EM, Anderson DJ. Effects of age, sex, and ENSO phase on foraging and flight performance in Nazca boobies. Ecol Evol 2021; 11:4084-4100. [PMID: 33976796 PMCID: PMC8093656 DOI: 10.1002/ece3.7308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/15/2021] [Accepted: 01/28/2021] [Indexed: 12/02/2022] Open
Abstract
Age-related changes in survival and reproduction are common in seabirds; however, the underlying causes remain elusive. A lack of experience for young individuals, and a decline in foraging performance for old birds, could underlie age-related variation in reproduction because reproductive success is connected closely to provisioning offspring. For seabirds, flapping flight during foraging trips is physiologically costly; inexperience or senescent decline in performance of this demanding activity might cap delivery of food to the nest, providing a proximate explanation for poor breeding success in young and old age, respectively. We evaluated the hypothesis that young and old Nazca boobies (Sula granti), a Galápagos seabird, demonstrate deficits in foraging outcomes and flight performance. We tagged incubating male and female adults across the life span with both accelerometer and GPS loggers during the incubation periods of two breeding seasons (years), during the 2015 El Niño and the following weak La Niña. We tested the ability of age, sex, and environment to explain variation in foraging outcomes (e.g., mass gained) and flight variables (e.g., wingbeat frequency). Consistent with senescence, old birds gained less mass while foraging than middle-aged individuals, a marginal effect, and achieved a slower airspeed late in a foraging trip. Contrary to expectations, young birds showed no deficit in foraging outcomes or flight performance, except for airspeed (contingent on environment). Young birds flew slower than middle-aged birds in 2015, but faster than middle-aged birds in 2016. Wingbeat frequency, flap-glide ratio, and body displacement (approximating wingbeat strength) failed to predict airspeed and were unaffected by age. Sex influenced nearly all aspects of performance. Environment affected flight performance and foraging outcomes. Boobies' foraging outcomes were better during the extreme 2015 El Niño than during the 2016 weak La Niña, a surprising result given the negative effects tropical seabirds often experience during extreme El Niños.
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8
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Cooper EB, Bonnet T, Osmond HL, Cockburn A, Kruuk LEB. Aging and Senescence across Reproductive Traits and Survival in Superb Fairy-Wrens ( Malurus cyaneus). Am Nat 2020; 197:111-127. [PMID: 33417527 DOI: 10.1086/711755] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractWhy do senescence rates of fitness-related traits often vary dramatically? By considering the full aging trajectories of multiple traits, we can better understand how a species' life history shapes the evolution of senescence within a population. Here, we examined age-related changes in sex-specific survival, reproduction, and several components of reproduction using a long-term study of a cooperatively breeding songbird, the superb fairy-wren (Malurus cyaneus). We compared aging patterns between traits by estimating standardized rates of maturation, age of onset of senescence, and rates of senescence while controlling for confounding factors reflecting individual variability in life history. We found striking differences in aging and senescence patterns between survival and reproduction as well as between reproductive traits. In both sexes, survival started to decline from maturity onward. In contrast, all reproductive traits showed improvements into early adulthood, and many showed little or no evidence of senescence. In females, despite senescence in clutch size, number of offspring surviving to independence did not decline in late life, possibly due to improvements in maternal care with age. Superb fairy-wrens have exceptionally high levels of extragroup paternity, and while male within-group reproductive success did not change with age, extragroup reproductive success showed a dramatic increase in early ages, followed by a senescent decline, suggesting that male reproductive aging is driven by sexual selection. We discuss how the superb fairy-wrens' complex life history may contribute to the disparate aging patterns across different traits.
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Thorley J, Duncan C, Sharp SP, Gaynor D, Manser MB, Clutton-Brock T. Sex-independent senescence in a cooperatively breeding mammal. J Anim Ecol 2020; 89:1080-1093. [PMID: 31943191 DOI: 10.1111/1365-2656.13173] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/28/2019] [Indexed: 11/30/2022]
Abstract
Researchers studying mammals have frequently interpreted earlier or faster rates of ageing in males as resulting from polygyny and the associated higher costs of reproductive competition. Yet, few studies conducted on wild populations have compared sex-specific senescence trajectories outside of polygynous species, making it difficult to make generalized inferences on the role of reproductive competition in driving senescence, particularly when other differences between males and females might also contribute to sex-specific changes in performance across lifespan. Here, we examine age-related variation in body mass, reproductive output and survival in dominant male and female meerkats, Suricata suricatta. Meerkats are socially monogamous cooperative breeders where a single dominant pair virtually monopolizes reproduction in each group and subordinate group members help to rear offspring produced by breeders. In contrast to many polygynous societies, we find that neither the onset nor the rate of senescence in body mass or reproductive output shows clear differences between males and females. Both sexes also display similar patterns of age-related survival across lifespan, but unlike most wild vertebrates, survival senescence (increases in annual mortality with rising age) was absent in dominants of both sexes, and as a result, the fitness costs of senescence were entirely attributable to declines in reproductive output from mid- to late-life. We suggest that the potential for intrasexual competition to increase rates of senescence in females-who are hormonally masculinized and frequently aggressive-is offset by their ability to maintain longer tenures of dominance than males, and that these processes when combined lead to similar patterns of senescence in both sexes. Our results stress the need to consider the form and intensity of sexual competition as well as other sex-specific features of life history when investigating the operation of senescence in wild populations.
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Affiliation(s)
- Jack Thorley
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa
| | - Christopher Duncan
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa
| | - Stuart P Sharp
- Lancaster Environment Centre, Lancaster University, Lancashire, UK
| | - David Gaynor
- Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa
| | - Marta B Manser
- Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa.,Animal Behaviour, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Tim Clutton-Brock
- Department of Zoology, University of Cambridge, Cambridge, UK.,Kalahari Research Centre, Kuruman River Reserve, South Africa.,Mammal Research Institute, University of Pretoria, Pretoria, South Africa
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10
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Jehan C, Chogne M, Rigaud T, Moret Y. Sex-specific patterns of senescence in artificial insect populations varying in sex-ratio to manipulate reproductive effort. BMC Evol Biol 2020; 20:18. [PMID: 32013878 PMCID: PMC6998128 DOI: 10.1186/s12862-020-1586-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/24/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The disposable soma theory of ageing assumes that organisms optimally trade-off limited resources between reproduction and longevity to maximize fitness. Early reproduction should especially trade-off against late reproduction and longevity because of reduced investment into somatic protection, including immunity. Moreover, as optimal reproductive strategies of males and females differ, sexually dimorphic patterns of senescence may evolve. In particular, as males gain fitness through mating success, sexual competition should be a major factor accelerating male senescence. In a single experiment, we examined these possibilities by establishing artificial populations of the mealworm beetle, Tenebrio molitor, in which we manipulated the sex-ratio to generate variable levels of investment into reproductive effort and sexual competition in males and females. RESULTS As predicted, variation in sex-ratio affected male and female reproductive efforts, with contrasted sex-specific trade-offs between lifetime reproduction, survival and immunity. High effort of reproduction accelerated mortality in females, without affecting immunity, but high early reproductive success was observed only in balanced sex-ratio condition. Male reproduction was costly on longevity and immunity, mainly because of their investment into copulations rather than in sexual competition. CONCLUSIONS Our results suggest that T. molitor males, like females, maximize fitness through enhanced longevity, partly explaining their comparable longevity.
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Affiliation(s)
- Charly Jehan
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France.
| | - Manon Chogne
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France
| | - Thierry Rigaud
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France
| | - Yannick Moret
- UMR CNRS 6282 BioGéoSciences, Équipe Écologie Évolutive, Université Bourgogne-Franche Comté, Dijon, France.
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Barbraud C. Senescence in nature: New insights from a long-term seabird study. J Anim Ecol 2019; 88:968-970. [PMID: 31274204 DOI: 10.1111/1365-2656.13026] [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: 01/31/2019] [Accepted: 02/18/2019] [Indexed: 11/26/2022]
Abstract
In Focus: Tompkins, E. M., & Anderson, D. J. (2019). Sex-specific patterns of senescencein Nazca boobies linked to mating system. Journal of Animal Ecology, 88, 986-1000. https://doi.org/10.1111/1365-2656.12944. Sex-specific differences in senescence and environmental impacts on senescence in both sexes remain poorly understood. Tompkins and Anderson (2019) studied senescence in survival (hereafter called actuarial senescence) and in reproduction (hereafter called reproductive senescence) in Nazca boobies using 33 years of individual-based capture-recapture data. Senescence patterns (life-history traits, ages at onset, senescence rates) differed between sexes and were affected by environmental conditions (food availability) faced by individuals during their younger ages. Patterns of sex differences in senescence may result from the mating dynamics due to the population's male-biased sex ratio.
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Affiliation(s)
- Christophe Barbraud
- Centre d'Etudes Biologiques de Chizé, UMR7372 - CNRS & Université La Rochelle, Villiers en Bois, France
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