The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
James N Mills - One of the best experts on this subject based on the ideXlab platform.
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transmission ecology of sin nombre hantavirus in naturally infected north american deermouse populations in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Jonathan S Towner, Amy J Kuenzi, Richard J Douglass, Pierre E Rollin, Lance A Waller, James N MillsAbstract:Sin Nombre hantavirus (SNV), hosted by the North American deermouse (Peromyscus maniculatus), causes hantavirus pulmonary syndrome (HPS) in North America. Most transmission studies in the host were conducted under artificial conditions, or extrapolated information from mark-recapture data. Previous studies using experimentally infected deermice were unable to demonstrate SNV transmission. We explored SNV transmission in Outdoor Enclosures using naturally infected deermice. Deermice acquiring SNV in Enclosures had detectable viral RNA in blood throughout the acute phase of infection and acquired significantly more new wounds (indicating aggressive encounters) than uninfected deermice. Naturally-infected wild deermice had a highly variable antibody response to infection, and levels of viral RNA sustained in blood varied as much as 100-fold, even in individuals infected with identical strains of virus. Deermice that infected other susceptible individuals tended to have a higher viral RNA load than those that did not infect other deermice. Our study is a first step in exploring the transmission ecology of SNV infection in deermice and provides new knowledge about the factors contributing to the increase of the prevalence of a zoonotic pathogen in its reservoir host and to changes in the risk of HPS to human populations. The techniques pioneered in this study have implications for a wide range of zoonotic disease studies.
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population density and seasonality effects on sin nombre virus transmission in north american deermice peromyscus maniculatus in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Amy J Kuenzi, Richard J Douglass, Lance A Waller, James N Mills, Arlene Alvarado, Brian R AmmanAbstract:Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using Outdoor Enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007–2008, predetermined numbers of infected and uninfected adult wild deermice were released into Enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality.
Karoun H Bagamian - One of the best experts on this subject based on the ideXlab platform.
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transmission ecology of sin nombre hantavirus in naturally infected north american deermouse populations in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Jonathan S Towner, Amy J Kuenzi, Richard J Douglass, Pierre E Rollin, Lance A Waller, James N MillsAbstract:Sin Nombre hantavirus (SNV), hosted by the North American deermouse (Peromyscus maniculatus), causes hantavirus pulmonary syndrome (HPS) in North America. Most transmission studies in the host were conducted under artificial conditions, or extrapolated information from mark-recapture data. Previous studies using experimentally infected deermice were unable to demonstrate SNV transmission. We explored SNV transmission in Outdoor Enclosures using naturally infected deermice. Deermice acquiring SNV in Enclosures had detectable viral RNA in blood throughout the acute phase of infection and acquired significantly more new wounds (indicating aggressive encounters) than uninfected deermice. Naturally-infected wild deermice had a highly variable antibody response to infection, and levels of viral RNA sustained in blood varied as much as 100-fold, even in individuals infected with identical strains of virus. Deermice that infected other susceptible individuals tended to have a higher viral RNA load than those that did not infect other deermice. Our study is a first step in exploring the transmission ecology of SNV infection in deermice and provides new knowledge about the factors contributing to the increase of the prevalence of a zoonotic pathogen in its reservoir host and to changes in the risk of HPS to human populations. The techniques pioneered in this study have implications for a wide range of zoonotic disease studies.
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population density and seasonality effects on sin nombre virus transmission in north american deermice peromyscus maniculatus in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Amy J Kuenzi, Richard J Douglass, Lance A Waller, James N Mills, Arlene Alvarado, Brian R AmmanAbstract:Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using Outdoor Enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007–2008, predetermined numbers of infected and uninfected adult wild deermice were released into Enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality.
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transmission ecology of sin nombre hantavirus in deer mouse populations in Outdoor Enclosures
2012Co-Authors: Karoun H BagamianAbstract:Since the inception of the multidisciplinary field of disease ecology in 1979, ecologists and public health researchers have been exploring natural disease systems and attempting to build predictive models of disease. Disease models of directly transmitted pathogens often predict that increased host population densities result in increased levels of disease in an environment, but mark-recapture data from multiple well-studied rodent-virus host-pathogen systems have reported conflicting results. Concurrently, these field studies have identified the importance of seasonality, host physiology and population processes on infection dynamics. Traditionally, transmission information is often deduced from disease prevalence data, or determined in highly artificial laboratory settings-both of which do not adequately illustrate the natural progression of disease through a host population, and often separate ecological factors from within-host pathological and immunological factors. In this dissertation, I address these discrepancies and explore questions about the role of host population density, seasonality, and host aggression on disease transmission by conducting manipulative field transmission experiments using deer mice ( Peromyscus maniculatus) naturally infected with Sin Nombre hantavirus (SNV) in Outdoor Enclosures. This project is largely interdisciplinary and uses ecological, molecular, and immunological approaches to understand SNV infection and transmission in a natural host-pathogen system. The results of this study indicate that seasonality and host heterogeneities in behavior and viral infection load may have a stronger influence on disease transmission dynamics than host population density. This project reports the first successful SNV transmission experiment in a closed deer-mouse population. Also, in the process of this research, a new sub-specialty of disease ecology-transmission ecology-defined as the study of within- and between-host infection dynamics and their relationship to transmission-related host population processes and environmental conditions in an effort to better understand natural disease systems-was developed.
Jana A Eccard - One of the best experts on this subject based on the ideXlab platform.
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breeding state and season affect interspecific interaction types indirect resource competition and direct interference
Oecologia, 2011Co-Authors: Jana A Eccard, Barbara A Caspers, Hannu YlonenAbstract:Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction in 14 experimental populations of bank voles Myodes glareolus in large Outdoor Enclosures with and without a dominant competitor, the field vole Microtus agrestis. We further compared vole behaviour using staged dyadic encounters in neutral arenas in both seasons. Survival of the non-breeding overwintering bank voles was not affected by competition. In the spring, the numbers of male bank voles, but not of females, were reduced significantly in the competition populations. Bank vole home ranges expanded with vole density in the presence of competitors, indicating food limitation. A comparison of behaviour between seasons based on an analysis of similarity revealed an avoidance of costly aggression against opponents, independent of species. Interactions were more aggressive during the summer than during the winter, and heterospecific encounters were more aggressive than conspecific encounters. Based on these results, we suggest that interaction types and their respective mechanisms are not either–or categories and may change over the seasons. During the winter, energy constraints and thermoregulatory needs decrease direct aggression, but food constraints increase indirect resource competition. Direct interference appears in the summer, probably triggered by each individual’s reproductive and hormonal state and the defence of offspring against conspecific and heterospecific intruders. Both interaction forms overlap in the spring, possibly contributing to spring declines in the numbers of subordinate species.
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long term fitness benefits of polyandry in a small mammal the bank vole clethrionomys glareolus
Proceedings of The Royal Society B: Biological Sciences, 2008Co-Authors: Ines Klemme, Hannu Ylonen, Jana A EccardAbstract:Polyandry, i.e. mating with multiple males within one reproductive event, is a common female mating strategy but its adaptive function is often unclear. We tested whether polyandrous females gain genetic benefits by comparing fitness traits of monandrous (mated twice with a single male) and polyandrous (mated twice with two different males) female bank voles Clethrionomys glareolus. We raised the offspring in the laboratory until adulthood and measured their body size, before releasing them to Outdoor Enclosures to overwinter. At the onset of the breeding season in the following spring, we found that offspring of polyandrous females performed significantly better at reproduction than those of monandrous females. This was mainly due to sons of polyandrous females producing significantly more offspring than those of monandrous females. No significant differences were found for offspring body mass or winter survival between the two treatments. Our results appear to provide evidence that bank vole females gain long-term benefits from polyandry.
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Effects of competition and season on survival and maturation of young bank vole females
Evolutionary Ecology, 2002Co-Authors: Jana A Eccard, Taina J. Horne, Ines Klemme, Hannu YlonenAbstract:In territorial microtines intra-specific density dependent processes can limit the maturation of individuals during the summer of their birth. This may have demographic consequences by affecting the number and the age distribution of breeding individuals in the population. Little is known about this process on a community level, though populations of many northern microtine species fluctuate in synchrony and are known to interfere socially with each other. We experimentally studied the influence of the field vole Microtus agrestis on maturation, breeding, space use and survival of weanling bank voles, Clethrionomys glareolus . Two additive competition experiments on bank vole populations were conducted in large Outdoor Enclosures, half of them additionally housing a field vole population. In a mid-summer experiment low population density and absence of older breeding females minimised intra-specific competition. Survival was not affected by the presence of field voles. Season had a significant effect on both the probability of maturation and breeding of the weanlings. Competition with field voles significantly delayed breeding, and coupled with seasonal effects decreased the probability of breeding. In a late-summer experiment breeding and survival of bank vole weanlings were studied for three weeks as part of a high density breeding bank vole population. Weanlings did not mature at all nor were their space use and survival affected by the presence of field voles. Our results show that competition with other species can also have an impact on breeding of immatures. In an extreme seasonal environment, even a short delay of breeding may decrease survival chances of offspring. Seasonal and competition effects together may thus limit the contribution of year born females to reproductive output of the population. Other studies have shown that adult breeding bank voles suffer lower survival in the presence of field voles, but this study showed no survival effects on the weanlings. Thus it might be beneficial for weanlings to stay immature especially in the end of the breeding season and postpone reproduction to the next breeding season if densities of competing species are high.
Hannu Ylonen - One of the best experts on this subject based on the ideXlab platform.
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breeding state and season affect interspecific interaction types indirect resource competition and direct interference
Oecologia, 2011Co-Authors: Jana A Eccard, Barbara A Caspers, Hannu YlonenAbstract:Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction in 14 experimental populations of bank voles Myodes glareolus in large Outdoor Enclosures with and without a dominant competitor, the field vole Microtus agrestis. We further compared vole behaviour using staged dyadic encounters in neutral arenas in both seasons. Survival of the non-breeding overwintering bank voles was not affected by competition. In the spring, the numbers of male bank voles, but not of females, were reduced significantly in the competition populations. Bank vole home ranges expanded with vole density in the presence of competitors, indicating food limitation. A comparison of behaviour between seasons based on an analysis of similarity revealed an avoidance of costly aggression against opponents, independent of species. Interactions were more aggressive during the summer than during the winter, and heterospecific encounters were more aggressive than conspecific encounters. Based on these results, we suggest that interaction types and their respective mechanisms are not either–or categories and may change over the seasons. During the winter, energy constraints and thermoregulatory needs decrease direct aggression, but food constraints increase indirect resource competition. Direct interference appears in the summer, probably triggered by each individual’s reproductive and hormonal state and the defence of offspring against conspecific and heterospecific intruders. Both interaction forms overlap in the spring, possibly contributing to spring declines in the numbers of subordinate species.
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long term fitness benefits of polyandry in a small mammal the bank vole clethrionomys glareolus
Proceedings of The Royal Society B: Biological Sciences, 2008Co-Authors: Ines Klemme, Hannu Ylonen, Jana A EccardAbstract:Polyandry, i.e. mating with multiple males within one reproductive event, is a common female mating strategy but its adaptive function is often unclear. We tested whether polyandrous females gain genetic benefits by comparing fitness traits of monandrous (mated twice with a single male) and polyandrous (mated twice with two different males) female bank voles Clethrionomys glareolus. We raised the offspring in the laboratory until adulthood and measured their body size, before releasing them to Outdoor Enclosures to overwinter. At the onset of the breeding season in the following spring, we found that offspring of polyandrous females performed significantly better at reproduction than those of monandrous females. This was mainly due to sons of polyandrous females producing significantly more offspring than those of monandrous females. No significant differences were found for offspring body mass or winter survival between the two treatments. Our results appear to provide evidence that bank vole females gain long-term benefits from polyandry.
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Effects of competition and season on survival and maturation of young bank vole females
Evolutionary Ecology, 2002Co-Authors: Jana A Eccard, Taina J. Horne, Ines Klemme, Hannu YlonenAbstract:In territorial microtines intra-specific density dependent processes can limit the maturation of individuals during the summer of their birth. This may have demographic consequences by affecting the number and the age distribution of breeding individuals in the population. Little is known about this process on a community level, though populations of many northern microtine species fluctuate in synchrony and are known to interfere socially with each other. We experimentally studied the influence of the field vole Microtus agrestis on maturation, breeding, space use and survival of weanling bank voles, Clethrionomys glareolus . Two additive competition experiments on bank vole populations were conducted in large Outdoor Enclosures, half of them additionally housing a field vole population. In a mid-summer experiment low population density and absence of older breeding females minimised intra-specific competition. Survival was not affected by the presence of field voles. Season had a significant effect on both the probability of maturation and breeding of the weanlings. Competition with field voles significantly delayed breeding, and coupled with seasonal effects decreased the probability of breeding. In a late-summer experiment breeding and survival of bank vole weanlings were studied for three weeks as part of a high density breeding bank vole population. Weanlings did not mature at all nor were their space use and survival affected by the presence of field voles. Our results show that competition with other species can also have an impact on breeding of immatures. In an extreme seasonal environment, even a short delay of breeding may decrease survival chances of offspring. Seasonal and competition effects together may thus limit the contribution of year born females to reproductive output of the population. Other studies have shown that adult breeding bank voles suffer lower survival in the presence of field voles, but this study showed no survival effects on the weanlings. Thus it might be beneficial for weanlings to stay immature especially in the end of the breeding season and postpone reproduction to the next breeding season if densities of competing species are high.
Lance A Waller - One of the best experts on this subject based on the ideXlab platform.
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transmission ecology of sin nombre hantavirus in naturally infected north american deermouse populations in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Jonathan S Towner, Amy J Kuenzi, Richard J Douglass, Pierre E Rollin, Lance A Waller, James N MillsAbstract:Sin Nombre hantavirus (SNV), hosted by the North American deermouse (Peromyscus maniculatus), causes hantavirus pulmonary syndrome (HPS) in North America. Most transmission studies in the host were conducted under artificial conditions, or extrapolated information from mark-recapture data. Previous studies using experimentally infected deermice were unable to demonstrate SNV transmission. We explored SNV transmission in Outdoor Enclosures using naturally infected deermice. Deermice acquiring SNV in Enclosures had detectable viral RNA in blood throughout the acute phase of infection and acquired significantly more new wounds (indicating aggressive encounters) than uninfected deermice. Naturally-infected wild deermice had a highly variable antibody response to infection, and levels of viral RNA sustained in blood varied as much as 100-fold, even in individuals infected with identical strains of virus. Deermice that infected other susceptible individuals tended to have a higher viral RNA load than those that did not infect other deermice. Our study is a first step in exploring the transmission ecology of SNV infection in deermice and provides new knowledge about the factors contributing to the increase of the prevalence of a zoonotic pathogen in its reservoir host and to changes in the risk of HPS to human populations. The techniques pioneered in this study have implications for a wide range of zoonotic disease studies.
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population density and seasonality effects on sin nombre virus transmission in north american deermice peromyscus maniculatus in Outdoor Enclosures
PLOS ONE, 2012Co-Authors: Karoun H Bagamian, Amy J Kuenzi, Richard J Douglass, Lance A Waller, James N Mills, Arlene Alvarado, Brian R AmmanAbstract:Surveys of wildlife host-pathogen systems often document clear seasonal variation in transmission; conclusions concerning the relationship between host population density and transmission vary. In the field, effects of seasonality and population density on natural disease cycles are challenging to measure independently, but laboratory experiments may poorly reflect what happens in nature. Outdoor manipulative experiments are an alternative that controls for some variables in a relatively natural environment. Using Outdoor Enclosures, we tested effects of North American deermouse (Peromyscus maniculatus) population density and season on transmission dynamics of Sin Nombre hantavirus. In early summer, mid-summer, late summer, and fall 2007–2008, predetermined numbers of infected and uninfected adult wild deermice were released into Enclosures and trapped weekly or bi-weekly. We documented 18 transmission events and observed significant seasonal effects on transmission, wounding frequency, and host breeding condition. Apparent differences in transmission incidence or wounding frequency between high- and low-density treatments were not statistically significant. However, high host density was associated with a lower proportion of males with scrotal testes. Seasonality may have a stronger influence on disease transmission dynamics than host population density, and density effects cannot be considered independent of seasonality.
