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Ben C. Sheldon - One of the best experts on this subject based on the ideXlab platform.
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The epidemiology underlying age-related avian malaria infection in a long-lived host: the Mute Swan Cygnus olor
Journal of Avian Biology, 2013Co-Authors: Matthew J.a. Wood, Christopher M. Perrins, Dylan Z. Childs, Alicia S Davies, Olof Hellgren, Charlie K. Cornwallis, Ben C. SheldonAbstract:Quantifying the factors that predict parasite outbreak and persistence is a major challenge for both applied and fundamental biology. Key to understanding parasite prevalence and disease outbreaks is determining at what age individuals show signs of infection, and whether or not they recover. Age-dependent patterns of the infection of a host population by parasites can indicate among-individual heterogeneities in their susceptibility to, or rate of recovery from, parasite infections. Here, we present a cross-sectional study of avian malaria in a long-lived bird species, the Mute Swan Cygnus olor, examining age-related patterns of parasite prevalence and modelling patterns of infection and recovery. One-hundred and fifteen Swans, ranging from one to nineteen years old, were screened for infection with Plasmodium, Haemoproteus and Leucocytozoon parasites. Infections with three cytochrome-b lineages of Haemoproteus were found (pooled prevalence 67%), namely WW1 (26%), which is common in passerine birds, and two new lineages closely related to WW1: MUTSW1 (25%) and MUTSW2 (16%). We found evidence for age-related infection in one lineage, MUTSW1. Catalytic models examining patterns of infection and recovery in the population suggested that infections in this population were not life-long – recovery of individuals was included in the best fitting models. These findings support the results of recent studies that suggest hosts can clear infections, although patterns of infection-related mortality in older birds remain to be studied in more detail.
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quantitative genetics of age at reproduction in wild Swans support for antagonistic pleiotropy models of senescence
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Why do individuals stop reproducing after a certain age, and how is this age determined? The antagonistic pleiotropy theory for the evolution of senescence predicts that increased early-life performance should be accompanied by earlier (or faster) senescence. Hence, an individual that has started to breed early should also lose its reproductive capacities early. We investigate here the relationship between age at first reproduction (AFR) and age at last reproduction (ALR) in a free-ranging Mute Swan (Cygnus olor) population monitored for 36 years. Using multivariate analyses on the longitudinal data, we show that both traits are strongly selected in opposite directions. Analysis of the phenotypic covariance between these characters shows that individuals vary in their inherent quality, such that some individuals have earlier AFR and later ALR than expected. Quantitative genetic pedigree analyses show that both traits possess additive genetic variance but also that AFR and ALR are positively genetically correlated. Hence, although both traits display heritable variation and are under opposing directional selection, their evolution is constrained by a strong evolutionary tradeoff. These results are consistent with the theory that increased early-life performance comes with faster senescence because of genetic tradeoffs.
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age dependent genetic variance in a life history trait in the Mute Swan
Proceedings of The Royal Society B: Biological Sciences, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Genetic variance in characters under natural selection in natural populations determines the way those populations respond to that selection. Whether populations show temporal and/or spatial constancy in patterns of genetic variance and covariance is regularly considered, as this will determine whether selection responses are constant over space and time. Much less often considered is whether characters show differing amounts of genetic variance over the life-history of individuals. Such age-specific variation, if present, has important potential consequences for the force of natural selection and for understanding the causes of variation in quantitative characters. Using data from a long-term study of the Mute Swan Cygnus olor, we report the partitioning of phenotypic variance in timing of breeding (subject to strong natural selection) into component parts over 12 different age classes. We show that the additive genetic variance and heritability of this trait are strongly age-dependent, with higher additive genetic variance present in young and, particularly, old birds, but little evidence of any genetic variance for birds of intermediate ages. These results demonstrate that age can have a very important influence on the components of variation of characters in natural populations, and consequently that separate age classes cannot be assumed to be equivalent, either with respect to their evolutionary potential or response.
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evolutionary response to selection on clutch size in a long term study of the Mute Swan
The American Naturalist, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Abstract: Life‐history traits in wild populations are often regarded as being subject to directional selection, and the existence of substantial variation and microevolutionary stasis of these characters is therefore a problem in need of explanation. Avian clutch size is an archetypal life‐history trait in this context, and many studies have sought to test explanations for stasis in clutch size. Surprisingly, there are many fewer studies that used long‐term data to ask how selection acts on clutch size, particularly in a multivariate framework. In this article, we report selection, inheritance, and evolution of clutch size over 25 years in a colony of Mute Swans using a multivariate quantitative genetic framework to control for correlations with breeding time. We show that clutch size is influenced by both additive genetic and permanent environmental effects and that selection acts on clutch size in combination with breeding time. Natural selection on clutch size is strongly directional, favoring larger c...
Christopher M. Perrins - One of the best experts on this subject based on the ideXlab platform.
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The epidemiology underlying age-related avian malaria infection in a long-lived host: the Mute Swan Cygnus olor
Journal of Avian Biology, 2013Co-Authors: Matthew J.a. Wood, Christopher M. Perrins, Dylan Z. Childs, Alicia S Davies, Olof Hellgren, Charlie K. Cornwallis, Ben C. SheldonAbstract:Quantifying the factors that predict parasite outbreak and persistence is a major challenge for both applied and fundamental biology. Key to understanding parasite prevalence and disease outbreaks is determining at what age individuals show signs of infection, and whether or not they recover. Age-dependent patterns of the infection of a host population by parasites can indicate among-individual heterogeneities in their susceptibility to, or rate of recovery from, parasite infections. Here, we present a cross-sectional study of avian malaria in a long-lived bird species, the Mute Swan Cygnus olor, examining age-related patterns of parasite prevalence and modelling patterns of infection and recovery. One-hundred and fifteen Swans, ranging from one to nineteen years old, were screened for infection with Plasmodium, Haemoproteus and Leucocytozoon parasites. Infections with three cytochrome-b lineages of Haemoproteus were found (pooled prevalence 67%), namely WW1 (26%), which is common in passerine birds, and two new lineages closely related to WW1: MUTSW1 (25%) and MUTSW2 (16%). We found evidence for age-related infection in one lineage, MUTSW1. Catalytic models examining patterns of infection and recovery in the population suggested that infections in this population were not life-long – recovery of individuals was included in the best fitting models. These findings support the results of recent studies that suggest hosts can clear infections, although patterns of infection-related mortality in older birds remain to be studied in more detail.
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quantitative genetics of age at reproduction in wild Swans support for antagonistic pleiotropy models of senescence
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Why do individuals stop reproducing after a certain age, and how is this age determined? The antagonistic pleiotropy theory for the evolution of senescence predicts that increased early-life performance should be accompanied by earlier (or faster) senescence. Hence, an individual that has started to breed early should also lose its reproductive capacities early. We investigate here the relationship between age at first reproduction (AFR) and age at last reproduction (ALR) in a free-ranging Mute Swan (Cygnus olor) population monitored for 36 years. Using multivariate analyses on the longitudinal data, we show that both traits are strongly selected in opposite directions. Analysis of the phenotypic covariance between these characters shows that individuals vary in their inherent quality, such that some individuals have earlier AFR and later ALR than expected. Quantitative genetic pedigree analyses show that both traits possess additive genetic variance but also that AFR and ALR are positively genetically correlated. Hence, although both traits display heritable variation and are under opposing directional selection, their evolution is constrained by a strong evolutionary tradeoff. These results are consistent with the theory that increased early-life performance comes with faster senescence because of genetic tradeoffs.
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age dependent genetic variance in a life history trait in the Mute Swan
Proceedings of The Royal Society B: Biological Sciences, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Genetic variance in characters under natural selection in natural populations determines the way those populations respond to that selection. Whether populations show temporal and/or spatial constancy in patterns of genetic variance and covariance is regularly considered, as this will determine whether selection responses are constant over space and time. Much less often considered is whether characters show differing amounts of genetic variance over the life-history of individuals. Such age-specific variation, if present, has important potential consequences for the force of natural selection and for understanding the causes of variation in quantitative characters. Using data from a long-term study of the Mute Swan Cygnus olor, we report the partitioning of phenotypic variance in timing of breeding (subject to strong natural selection) into component parts over 12 different age classes. We show that the additive genetic variance and heritability of this trait are strongly age-dependent, with higher additive genetic variance present in young and, particularly, old birds, but little evidence of any genetic variance for birds of intermediate ages. These results demonstrate that age can have a very important influence on the components of variation of characters in natural populations, and consequently that separate age classes cannot be assumed to be equivalent, either with respect to their evolutionary potential or response.
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evolutionary response to selection on clutch size in a long term study of the Mute Swan
The American Naturalist, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Abstract: Life‐history traits in wild populations are often regarded as being subject to directional selection, and the existence of substantial variation and microevolutionary stasis of these characters is therefore a problem in need of explanation. Avian clutch size is an archetypal life‐history trait in this context, and many studies have sought to test explanations for stasis in clutch size. Surprisingly, there are many fewer studies that used long‐term data to ask how selection acts on clutch size, particularly in a multivariate framework. In this article, we report selection, inheritance, and evolution of clutch size over 25 years in a colony of Mute Swans using a multivariate quantitative genetic framework to control for correlations with breeding time. We show that clutch size is influenced by both additive genetic and permanent environmental effects and that selection acts on clutch size in combination with breeding time. Natural selection on clutch size is strongly directional, favoring larger c...
Anne Charmantier - One of the best experts on this subject based on the ideXlab platform.
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quantitative genetics of age at reproduction in wild Swans support for antagonistic pleiotropy models of senescence
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Why do individuals stop reproducing after a certain age, and how is this age determined? The antagonistic pleiotropy theory for the evolution of senescence predicts that increased early-life performance should be accompanied by earlier (or faster) senescence. Hence, an individual that has started to breed early should also lose its reproductive capacities early. We investigate here the relationship between age at first reproduction (AFR) and age at last reproduction (ALR) in a free-ranging Mute Swan (Cygnus olor) population monitored for 36 years. Using multivariate analyses on the longitudinal data, we show that both traits are strongly selected in opposite directions. Analysis of the phenotypic covariance between these characters shows that individuals vary in their inherent quality, such that some individuals have earlier AFR and later ALR than expected. Quantitative genetic pedigree analyses show that both traits possess additive genetic variance but also that AFR and ALR are positively genetically correlated. Hence, although both traits display heritable variation and are under opposing directional selection, their evolution is constrained by a strong evolutionary tradeoff. These results are consistent with the theory that increased early-life performance comes with faster senescence because of genetic tradeoffs.
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age dependent genetic variance in a life history trait in the Mute Swan
Proceedings of The Royal Society B: Biological Sciences, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Genetic variance in characters under natural selection in natural populations determines the way those populations respond to that selection. Whether populations show temporal and/or spatial constancy in patterns of genetic variance and covariance is regularly considered, as this will determine whether selection responses are constant over space and time. Much less often considered is whether characters show differing amounts of genetic variance over the life-history of individuals. Such age-specific variation, if present, has important potential consequences for the force of natural selection and for understanding the causes of variation in quantitative characters. Using data from a long-term study of the Mute Swan Cygnus olor, we report the partitioning of phenotypic variance in timing of breeding (subject to strong natural selection) into component parts over 12 different age classes. We show that the additive genetic variance and heritability of this trait are strongly age-dependent, with higher additive genetic variance present in young and, particularly, old birds, but little evidence of any genetic variance for birds of intermediate ages. These results demonstrate that age can have a very important influence on the components of variation of characters in natural populations, and consequently that separate age classes cannot be assumed to be equivalent, either with respect to their evolutionary potential or response.
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evolutionary response to selection on clutch size in a long term study of the Mute Swan
The American Naturalist, 2006Co-Authors: Anne Charmantier, Robin H. Mccleery, Christopher M. Perrins, Ben C. SheldonAbstract:Abstract: Life‐history traits in wild populations are often regarded as being subject to directional selection, and the existence of substantial variation and microevolutionary stasis of these characters is therefore a problem in need of explanation. Avian clutch size is an archetypal life‐history trait in this context, and many studies have sought to test explanations for stasis in clutch size. Surprisingly, there are many fewer studies that used long‐term data to ask how selection acts on clutch size, particularly in a multivariate framework. In this article, we report selection, inheritance, and evolution of clutch size over 25 years in a colony of Mute Swans using a multivariate quantitative genetic framework to control for correlations with breeding time. We show that clutch size is influenced by both additive genetic and permanent environmental effects and that selection acts on clutch size in combination with breeding time. Natural selection on clutch size is strongly directional, favoring larger c...
Kevin A. Wood - One of the best experts on this subject based on the ideXlab platform.
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regulation of lead fishing weights results in Mute Swan population recovery
Biological Conservation, 2019Co-Authors: Kevin A. Wood, Martin J Brown, Ruth L Cromie, Geoff M Hilton, Conor Mackenzie, Julia L Newth, Deborah J Pain, C M Perrins, Eileen C ReesAbstract:Abstract Legal regulation of human activities is a key mechanism for alleviating anthropogenic impacts on wildlife populations. Conservationists frequently request the regulation of toxic substances such as lead, which can be harmful to animals even at low levels of exposure. However, without assessments of the effectiveness of legislation, such regulations may be undermined or revoked and opportunities to make amendments to improve the legislation may be missed. Here we carried out a population-level study of the effectiveness of regulating the use of lead. We show that the increase in population size of a charismatic waterbird (the Mute Swan Cygnus olor) in Great Britain over 39 years was best explained by the regulation of lead fishing weights, rather than by changes in food supplies, habitat quality, or winter temperature. The proportion of individuals dying of lead poisoning dropped following regulation, from 0.34 to 0.06, suggesting that higher survival rates were the demographic driver of increased population size. Legal restriction therefore succeeded in alleviating, although not eliminating, the impact of poisoning on Mute Swans. Restrictions on the use of toxic substances, and their release into the environment, would provide an effective conservation mechanism for reducing negative effects of human activities on wildlife populations. At a time when many policy makers prefer to rely on voluntary actions or market forces to achieve change, our study highlights that legal regulations on human activities can be an effective means of alleviating anthropogenic impacts on wildlife.
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Water velocity limits the temporal extent of herbivore effects on aquatic plants in a lowland river
Hydrobiologia, 2018Co-Authors: Kevin A. Wood, Richard A. Stillman, Ralph T. Clarke, Francis Daunt, Matthew T. O’hareAbstract:The role of herbivores in regulating aquatic plant dynamics has received growing recognition from researchers and managers. However, the evidence for herbivore impacts on aquatic plants is largely based on short-term exclosure studies conducted within a single plant growing season. Thus, it is unclear how long herbivore impacts on aquatic plant abundance can persist for. We addressed this knowledge gap by testing whether Mute Swan ( Cygnus olor ) grazing on lowland river macrophytes could be detected in the following growing season. Furthermore, we investigated the role of seasonal changes in water current speed in limiting the temporal extent of grazing. We found no relationship between Swan biomass density in 1 year and aquatic plant cover or biomass in the following spring. No such carry-over effects were detected despite observing high Swan biomass densities in the previous year from which we inferred grazing impacts on macrophytes. Seasonal increases in water velocity were associated with reduced grazing pressure as Swans abandoned river habitat. Furthermore, our study highlights the role of seasonal changes in water velocity in determining the length of the Mute Swan grazing season in shallow lowland rivers and thus in limiting the temporal extent of herbivore impacts on aquatic plant abundance.
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the role of season and social grouping on habitat use by Mute Swans cygnus olor in a lowland river catchment
Bird Study, 2013Co-Authors: Kevin A. Wood, Richard A. Stillman, Francis Daunt, Terry Coombs, Claire Mcdonald, Matthew T OhareAbstract:Capsule The Mute Swan, a large generalist herbivore, showed patterns of habitat use influenced by social grouping and season. Territorial Swans showed strong preferences for river and lake habitat in all seasons, while the non-territorial birds known to cause grazing conflicts preferred river in summer–autumn and pasture in winter–spring. Aims To quantify the habitat preferences across different seasons of two types of Mute Swan social group, territorial and non-territorial, and assess the implications for the grazing conflict between Swans and valuable plant communities. Methods Repeated surveys of the River Frome catchment, Dorset, UK, over a two-year period allowed us to record the numbers of Swans in each habitat type. An electivity index was used to calculate habitat preference scores for territorial and non-territorial Swans across different seasons. Results We found strong seasonal switches in habitat use for both territorial and non-territorial Swans, but preferences for some habitats differed bet...
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Understanding plant community responses to combinations of biotic and abiotic factors in different phases of the plant growth cycle.
PLOS ONE, 2012Co-Authors: Kevin A. Wood, Richard A. Stillman, Ralph T. Clarke, Francis Daunt, Matthew T. O'hareAbstract:Understanding plant community responses to combinations of biotic and abiotic factors is critical for predicting ecosystem response to environmental change. However, studies of plant community regulation have seldom considered how responses to such factors vary with the different phases of the plant growth cycle. To address this deficit we studied an aquatic plant community in an ecosystem subject to gradients in Mute Swan (Cygnus olor) herbivory, riparian shading, water temperature and distance downstream of the river source. We quantified abundance, species richness, evenness, flowering and dominance in relation to biotic and abiotic factors during the growth-, peak-, and recession-phases of the plant growth cycle. We show that the relative importance of biotic and abiotic factors varied between plant community properties and between different phases of the plant growth cycle. Herbivory became more important during the later phases of peak abundance and recession due to an influx of Swans from adjacent pasture fields. Shading by riparian vegetation also had a greater depressing effect on biomass in later seasons, probably due to increased leaf abundance reducing light intensity reaching the aquatic plants. The effect of temperature on community diversity varied between upstream and downstream sites by altering the relative competitiveness of species at these sites. These results highlight the importance of seasonal patterns in the regulation of plant community structure and function by multiple factors.
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Understanding Plant Community Responses to Combinations of Biotic and Abiotic Factors in Different Phases of the Plant Growth Cycle
2012Co-Authors: Kevin A. Wood, Richard A. Stillman, Ralph T. Clarke, Francis Daunt, Matthew T. O’hareAbstract:Understanding plant community responses to combinations of biotic and abiotic factors is critical for predicting ecosystem response to environmental change. However, studies of plant community regulation have seldom considered how responses to such factors vary with the different phases of the plant growth cycle. To address this deficit we studied an aquatic plant community in an ecosystem subject to gradients in Mute Swan (Cygnus olor) herbivory, riparian shading, water temperature and distance downstream of the river source. We quantified abundance, species richness, evenness, flowering and dominance in relation to biotic and abiotic factors during the growth-, peak-, and recession-phases of the plant growth cycle. We show that the relative importance of biotic and abiotic factors varied between plant community properties and between different phases of the plant growth cycle. Herbivory became more important during the later phases of peak abundance and recession due to an influx of Swans from adjacent pasture fields. Shading by riparian vegetation also had a greater depressing effect on biomass in later seasons, probably due to increased leaf abundance reducing light intensity reaching the aquatic plants. The effect of temperature on community diversity varied between upstream and downstream sites by altering the relative competitiveness of species at these sites. These results highlight the importance of seasona
Bc Sheldon - One of the best experts on this subject based on the ideXlab platform.
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The epidemiology underlying age-related avian malaria infection in a long-lived host: The Mute Swan Cygnus olor
'Wiley', 2013Co-Authors: Mj Wood, Charlie K. Cornwallis, C M Perrins, Dz Childs, As Davies, Hellgren O, Bc SheldonAbstract:Quantifying the factors that predict parasite outbreak and persistence is a major challenge for both applied and fundamental biology. Key to understanding parasite prevalence and disease outbreaks is determining at what age individuals show signs of infection, and whether or not they recover. Age-dependent patterns of the infection of a host population by parasites can indicate among-individual heterogeneities in their susceptibility to, or rate of recovery from, parasite infections. Here, we present a cross-sectional study of avian malaria in a long-lived bird species, the Mute Swan Cygnus olor, examining age-related patterns of parasite prevalence and modelling patterns of infection and recovery. One-hundred and fifteen Swans, ranging from one to nineteen years old, were screened for infection with Plasmodium, Haemoproteus and Leucocytozoon parasites. Infections with three cytochrome-b lineages of Haemoproteus were found (pooled prevalence 67%), namely WW1 (26%), which is common in passerine birds, and two new lineages closely related to WW1: MUTSW1 (25%) and MUTSW2 (16%). We found evidence for age-related infection in one lineage, MUTSW1. Catalytic models examining patterns of infection and recovery in the population suggested that infections in this population were not life-long - recovery of individuals was included in the best fitting models. These findings support the results of recent studies that suggest hosts can clear infections, although patterns of infection-related mortality in older birds remain to be studied in more detail. © 2013 The Author. Journal of Avian Biology © 2013 Nordic Society Oikos
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The epidemiology underlying age-related avian malaria infection in a long-lived host: the Mute Swan Cygnus olor
'Wiley', 2013Co-Authors: Mj Wood, Charlie K. Cornwallis, C M Perrins, Dz Childs, As Davies, Hellgren O, Bc SheldonAbstract:Quantifying the factors that predict parasite outbreak and persistence is a major challenge for both applied and fundamental biology. Key to understanding parasite prevalence and disease outbreaks is determining at what age individuals show signs of infection, and whether or not they recover. Age-dependent patterns of the infection of a host population by parasites can indicate among-individual heterogeneities in their susceptibility to, or rate of recovery from, parasite infections. Here, we present a cross-sectional study of avian malaria in a long-lived bird species, the Mute Swan Cygnus olor, examining age-related patterns of parasite prevalence and modelling patterns of infection and recovery. One-hundred and fifteen Swans, ranging from one to nineteen years old, were screened for infection with Plasmodium, Haemoproteus and Leucocytozoon parasites. Infections with three cytochrome-b lineages of Haemoproteus were found (pooled prevalence 67%), namely WW1 (26%), which is common in passerine birds, and two new lineages closely related to WW1: MUTSW1 (25%) and MUTSW2 (16%). We found evidence for age-related infection in one lineage, MUTSW1. Catalytic models examining patterns of infection and recovery in the population suggested that infections in this population were not life-long - recovery of individuals was included in the best fitting models. These findings support the results of recent studies that suggest hosts can clear infections, although patterns of infection-related mortality in older birds remain to be studied in more detail. © 2013 The Authors
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Age-dependent genetic variance in a life-history trait in the Mute Swan
'The Royal Society', 2006Co-Authors: Charmantier A, Perrins C, Rh Mccleery, Bc SheldonAbstract:Genetic variance in characters under natural selection in natural populations determines the way those populations respond to that selection. Whether populations show temporal and/or spatial constancy in patterns of genetic variance and covariance is regularly considered, as this will determine whether selection responses are constant over space and time. Much less often considered is whether characters show differing amounts of genetic variance over the life-history of individuals. Such age-specific variation, if present, has important potential consequences for the force of natural selection and for understanding the causes of variation in quantitative characters. Using data from a long-term study of the Mute Swan Cygnus olor, we report the partitioning of phenotypic variance in timing of breeding (subject to strong natural selection) into component parts over 12 different age classes. We show that the additive genetic variance and heritability of this trait are strongly age-dependent, with higher additive genetic variance present in young and, particularly, old birds, but little evidence of any genetic variance for birds of intermediate ages. These results demonstrate that age can have a very important influence on the components of variation of characters in natural populations, and consequently that separate age classes cannot be assumed to be equivalent, either with respect to their evolutionary potential or response. © 2005 The Royal Society
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Data depth, data completeness, and their influence on quantitative genetic estimation in two contrasting bird populations.
2006Co-Authors: Jl Quinn, Charmantier A, Garant D, Bc SheldonAbstract:Evolutionary biologists increasingly use pedigree-based quantitative genetic methods to address questions about the evolutionary dynamics of traits in wild populations. In many cases, phenotypic data may have been collected only for recent parts of the study. How does this influence the performance of the models used to analyse these data? Here we explore how data depth (number of years) and completeness (number of observations) influence estimates of genetic variance and covariance within the context of an existing pedigree. Using long-term data from the great tit Parus major and the Mute Swan Cygnus olor, species with different life-histories, we examined the effect of manipulating the amount of data included on quantitative genetic parameter estimates. Manipulating data depth and completeness had little influence on estimated genetic variances, heritabilities, or genetic correlations, but (as expected) did influence confidence in these estimates. Estimated breeding values in the great tit were not influenced by data depth but were in the Mute Swan, probably because of differences in pedigree structure. Our analyses suggest the 'rule of thumb' that data from 3 years and a minimum of 100 individuals per year are needed to estimate genetic parameters with acceptable confidence, and that using pedigree data is worthwhile, even if phenotypes are only available toward the tips of the pedigree
