The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Charles R Brown - One of the best experts on this subject based on the ideXlab platform.
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immune responses of a native and an invasive bird to buggy creek virus togaviridae alphavirus and its arthropod vector the swallow bug oeciacus vicarius
PLOS ONE, 2013Co-Authors: Carol A Fassbinderorth, Virginia A Barak, Charles R BrownAbstract:: Invasive species often display different patterns of parasite burden and virulence compared to their native counterparts. These differences may be the result of variability in host-parasite co-evolutionary relationships, the occurrence of novel host-parasite encounters, or possibly innate differences in physiological responses to infection between invasive and native hosts. Here we examine the adaptive, humoral immune responses of a resistant, native bird and a susceptible, invasive bird to an arbovirus (Buggy Creek virus; Togaviridae: Alphavirus) and its ectoparasitic arthropod vector (the swallow bug; Oeciacus vicarius). Swallow bugs parasitize the native, colonially nesting cliff swallow (Petrochelidon pyrrhonota) and the introduced house Sparrow (Passer domesticus) that occupies nests in cliff swallow colonies. We measured levels of BCRV-specific and swallow bug-specific IgY levels before nesting (prior to swallow bug exposure) and after nesting (after swallow bug exposure) in house Sparrows and cliff swallows in western Nebraska. Levels of BCRV-specific IgY increased significantly following nesting in the house Sparrow but not in the cliff swallow. Additionally, house Sparrows displayed consistently higher levels of swallow bug-specific antibodies both before and after nesting compared to cliff swallows. The higher levels of BCRV and swallow bug specific antibodies detected in house Sparrows may be reflective of significant differences in both antiviral and anti-ectoparasite immune responses that exist between these two avian species. To our knowledge, this is the first study to compare the macro- and microparasite-specific immune responses of an invasive and a native avian host exposed to the same parasites.
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Factors potentially influencing the likelihood of ≥ 1 house Sparrow nestling in a nest becoming infected with Buggy Creek virus in Sparrows nesting in unused cliff swallow nests in western Nebraska.
2013Co-Authors: Valerie A. O'brien, Charles R BrownAbstract:Factors potentially influencing the likelihood of ≥ 1 house Sparrow nestling in a nest becoming infected with Buggy Creek virus in Sparrows nesting in unused cliff swallow nests in western Nebraska.
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Immune responses of a native and an invasive bird to Buggy Creek virus (Togaviridae: Alphavirus) and its arthropod vector, the swallow bug (Oeciacus vicarius). PLoS One 8
2013Co-Authors: Carol A. Fassbinder-orth, Virginia A Barak, Charles R BrownAbstract:Invasive species often display different patterns of parasite burden and virulence compared to their native counterparts. These differences may be the result of variability in host-parasite co-evolutionary relationships, the occurrence of novel host-parasite encounters, or possibly innate differences in physiological responses to infection between invasive and native hosts. Here we examine the adaptive, humoral immune responses of a resistant, native bird and a susceptible, invasive bird to an arbovirus (Buggy Creek virus; Togaviridae: Alphavirus) and its ectoparasitic arthropod vector (the swallow bug; Oeciacus vicarius). Swallow bugs parasitize the native, colonially nesting cliff swallow (Petrochelidon pyrrhonota) and the introduced house Sparrow (Passer domesticus) that occupies nests in cliff swallow colonies. We measured levels of BCRV-specific and swallow bug-specific IgY levels before nesting (prior to swallow bug exposure) and after nesting (after swallow bug exposure) in house Sparrows and cliff swallows in western Nebraska. Levels of BCRV-specific IgY increased significantly following nesting in the house Sparrow but not in the cliff swallow. Additionally, house Sparrows displayed consistently higher levels of swallow bug-specific antibodies both before and after nesting compared to cliff swallows. The higher levels of BCRV and swallow bug specific antibodies detected in house Sparrows may be reflective of significant differences in both antiviral and anti-ectoparasite immune responses that exist between these two avian species. To our knowledge, this is the first study to compare the macro- and microparasite-specific immune responses of an invasive and a native avian hos
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BCRV ELISA.
2013Co-Authors: Carol A. Fassbinder-orth, Virginia A Barak, Charles R BrownAbstract:Values shown represent mean (+ SEM) values for BCRV specific IgY levels in each group. House Sparrow Control samples collected from house Sparrows at Council Bluffs, Iowa (no known cliff swallow colonies in the area) in August, 2011. All other blood samples collected from house Sparrows and cliff swallows at swallow colony sites in western Nebraska in 2011. Letters above bars denote statistical differences among groups (P
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group size and nest spacing affect buggy creek virus togaviridae alphavirus infection in nestling house Sparrows
PLOS ONE, 2011Co-Authors: Valerie A Obrien, Charles R BrownAbstract:The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house Sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house Sparrows are seriously affected by BCRV. For house Sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling Sparrows increased with Sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house Sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in Sparrows as cliff swallows at a site increased reflects the “dilution effect,” in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host.
Shuping Zhang - One of the best experts on this subject based on the ideXlab platform.
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differences in the reproductive hormone rhythm of tree Sparrows passer montanus from urban and rural sites in beijing the effect of anthropogenic light sources
General and Comparative Endocrinology, 2014Co-Authors: Shuping Zhang, Xiaoyu Chen, Jingruo ZhangAbstract:The pervasiveness of anthropogenic light in urban environments has increased the exposure to light of many animals. Since photoperiod is a regulator of the timing of reproduction in most temperate region birds, such light sources could potentially change the timing of reproduction. We compared the luteinizing hormone (LH), testosterone (T), and estradiol (E2) levels of tree Sparrow (Passer montanus) populations sampled at two urban and two rural sites in China, and also performed a controlled photoperiod experiment to determine the influence of artificial light on the endocrine rhythm of these populations. LH levels of urban tree Sparrows increased earlier than those of rural ones, but rural populations had higher LH peaks. A linear mixed model (LMM) indicates that increased exposure to light at night (LAN) significantly influenced the LH, T and E2 concentrations of free-living tree Sparrows in urban environments compared to their rural counterparts. The results of the controlled photoperiod experiment showed that tree Sparrows that were exposed to 6 lux of light during the dark phase of the artificial photoperiod began to secrete LH earlier, and had lower peak LH levels, than control birds. A LMM indicates that LAN had a significant effect on LH levels in this experiment. Although urban tree Sparrows began to secrete LH earlier than their rural counterparts, we found no corresponding advance in T or E2 secretion. On the contrary, peak T and E2 levels of urban birds were lower than those of rural birds. These results suggest that although anthropogenic light sources appear to advance the onset of LH secretion in urban tree Sparrow populations, they also lower peak LH, and consequently levels of T and E2. A possible explanation for these observations is that greater exposure to anthropogenic light in urban environments stimulates LH secretion and may influence photosensitivity, but further experimental work is required to test this hypothesis.
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variation in baseline corticosterone levels of tree Sparrow passer montanus populations along an urban gradient in beijing china
Journal of Ornithology, 2011Co-Authors: Shuping Zhang, Fumin Lei, Shenglin Liu, Cong Chen, Peizhe WangAbstract:Rapid urbanization is a major anthropogenic pressure on bird species that rely on vegetation for food and shelter. Since the baseline corticosterone concentration (BCC) in some bird species has been found to increase slightly in response to environmental challenges, we hypothesized that urbanization could also induce an increase in BCC. To test this hypothesis, we compared the BCC of Tree Sparrow (Passer montanus) populations in five urban and two rural habitats and analyzed the relationship between BCC and the degree of urbanization. Here, we show that the BCCs of Tree Sparrow populations were strongly and positively correlated with the degree of urbanization of the habitat. Average BCC of Tree Sparrows from high-rise residential areas and a university campus were significantly higher than those from rural areas, suggesting that Tree Sparrows living in highly urbanized areas have greater environmental challenges than those in rural areas. However, the average BCC of birds from an urban park was not significantly different to that of birds at rural sites and also differed significantly from that of birds at two of the other urban sites. These results suggest that urbanization could pose environmental challenges for Tree Sparrows, a species that appears relatively well-adapted to human-modified environments. The marked variation in BCC between different urban sites indicates that conclusions drawn from data collected at single sites must be interpreted with caution.
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effect of urbanization on the abundance and distribution of tree Sparrows passer montanus in beijing
Chinese Birds, 2010Co-Authors: Shuping Zhang, Guangmei ZhengAbstract:With rapid urbanization occurring throughout China, the existence of Tree Sparrows (Passer montanus) in big cities is likely to be affected by a decrease in habitat and food availability. Can the urban Tree Sparrow adapt to these changes? To elucidate this question, we studied the effect of urbanization on the abundance and distribution of Tree Sparrows in Beijing. We found the abundance of the Tree Sparrow negatively correlated with an urbanization score. Sparrow abundance was very low in residential areas with high-rise buildings, commercial centers and main roads, while their numbers were significantly higher in parks, university campuses, low building residential and suburban areas. Environmental factors within the 50 m and 200 m scales were most suitable in predicting the distribution of Tree Sparrows during winter, while factors with in 50 m and 400 m scales are suitable during the breeding season. During winter, the number of conifer trees and pedestrians were the major factors at the 50 m scale, while the area of high-rise buildings and vegetation become the predominant factors on a 200 m scale. Alternatively, during the breeding season the area of low buildings and the number of conifers and pedestrians were the main factors on the 50 m scale while the area of high-rise buildings and vegetation remained the most important factors on the 400 m scale. These results indicate that highly urbanized areas are not suitable habitats for the Tree Sparrow, although this species can adapt to human environments. Food and nest sites for urban birds should be considered in urban planning of big cities in developing countries.
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habitat use of urban tree Sparrows in the process of urbanization beijing as a case study
Frontiers of Biology in China, 2008Co-Authors: Shuping Zhang, Guangmei ZhengAbstract:The Tree Sparrow (Passer montanus) is a dominant species in urban bird communities. With the development of urbanization, the habitats and sources of food for Tree Sparrows are decreasing. Can the urban Tree Sparrow adapt to changes in the urban environment? To answer this question, we studied the habitat use of Tree Sparrows in eight types of urban areas in Beijing. The results show that the number of both breeding and wintering Tree Sparrows decreased with increasing urbanization. The habitat use of Tree Sparrows, analyzed using stepwise discriminant analysis, was positively correlated with the number of brick bungalows, coniferous and broad-leaved trees and air conditioners. It was negatively correlated with the area of high buildings and hardened roads, pedestrian and automobile flux. This indicates that the Tree Sparrow had not adapted to rapid urbanization even though it is a generally adaptable species. Urban planning should take birds such as the Tree Sparrow into consideration.
Ryan S Brady - One of the best experts on this subject based on the ideXlab platform.
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mercury in swamp Sparrows melospiza georgiana from wetland habitats in wisconsin
Ecotoxicology, 2011Co-Authors: Sean M Strom, Ryan S BradyAbstract:Wetlands play a major role in the export of methylmercury (MeHg) to a watershed. The large contribution of wetlands to watersheds in northern Wisconsin, coupled with the acidic environment of this area, makes these habitats especially vulnerable to mercury (Hg) accumulation by biota. The purpose of this study was to compare Hg accumulation between northern Wisconsin wetlands and southern Wisconsin wetlands using the swamp Sparrow (Melospiza georgiana) as a representative species. The swamp Sparrow was selected as a representative passerine species in which to examine Hg in these habitats, because during their breeding season, they feed at a higher trophic level than many of their counterparts. During the breeding seasons of 2007 and 2008, blood samples were collected from swamp Sparrows inhabiting wetlands in both northern and southern Wisconsin and analyzed for total Hg. The mean concentration of total Hg in swamp Sparrows from northern wetlands was 0.135 ± 0.064 μg/ml while the mean concentration of total Hg in swamp Sparrows from southern wetlands was 0.187 ± 0.106 μg/ml. Results revealed no significant difference (P = 0.17) between Hg accumulation in swamp Sparrows from less-acidic wetlands in southern Wisconsin and Hg in swamp Sparrows from acidic wetlands in northern Wisconsin. The results are contrary to those observed in other species such as common loon, tree swallow and river otter where higher accumulation has been observed in individuals from acidic habitats. Reasons for the lack of this accumulation pattern in swamp Sparrows are unclear and warrant further study.
Valerie A Obrien - One of the best experts on this subject based on the ideXlab platform.
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group size and nest spacing affect buggy creek virus togaviridae alphavirus infection in nestling house Sparrows
PLOS ONE, 2011Co-Authors: Valerie A Obrien, Charles R BrownAbstract:The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house Sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house Sparrows are seriously affected by BCRV. For house Sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling Sparrows increased with Sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house Sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in Sparrows as cliff swallows at a site increased reflects the “dilution effect,” in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host.
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an enzootic vector borne virus is amplified at epizootic levels by an invasive avian host
Proceedings of The Royal Society B: Biological Sciences, 2011Co-Authors: Valerie A Obrien, Ginger Young, Nicholas Komar, Amy T Moore, William K Reisen, Charles R BrownAbstract:Determining the effect of an invasive species on enzootic pathogen dynamics is critical for understanding both human epidemics and wildlife epizootics. Theoretical models suggest that when a naive species enters an established host–parasite system, the new host may either reduce (‘dilute’) or increase (‘spillback’) pathogen transmission to native hosts. There are few empirical data to evaluate these possibilities, especially for animal pathogens. Buggy Creek virus (BCRV) is an arthropod-borne alphavirus that is enzootically transmitted by the swallow bug (Oeciacus vicarius) to colonially nesting cliff swallows (Petrochelidon pyrrhonota). In western Nebraska, introduced house Sparrows (Passer domesticus) invaded cliff swallow colonies approximately 40 years ago and were exposed to BCRV. We evaluated how the addition of house Sparrows to this host–parasite system affected the prevalence and amplification of a bird-associated BCRV lineage. The infection prevalence in house Sparrows was eight times that of cliff swallows. Nestling house Sparrows in mixed-species colonies were significantly less likely to be infected than Sparrows in single-species colonies. Infected house Sparrows circulated BCRV at higher viraemia titres than cliff swallows. BCRV detected in bug vectors at a site was positively associated with virus prevalence in house Sparrows but not with virus prevalence in cliff swallows. The addition of a highly susceptible invasive host species has led to perennial BCRV epizootics at cliff swallow colony sites. The native cliff swallow host confers a dilution advantage to invasive Sparrow hosts in mixed colonies, while at the same sites house Sparrows may increase the likelihood that swallows become infected.
Carol A Fassbinderorth - One of the best experts on this subject based on the ideXlab platform.
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immune responses of a native and an invasive bird to buggy creek virus togaviridae alphavirus and its arthropod vector the swallow bug oeciacus vicarius
PLOS ONE, 2013Co-Authors: Carol A Fassbinderorth, Virginia A Barak, Charles R BrownAbstract:: Invasive species often display different patterns of parasite burden and virulence compared to their native counterparts. These differences may be the result of variability in host-parasite co-evolutionary relationships, the occurrence of novel host-parasite encounters, or possibly innate differences in physiological responses to infection between invasive and native hosts. Here we examine the adaptive, humoral immune responses of a resistant, native bird and a susceptible, invasive bird to an arbovirus (Buggy Creek virus; Togaviridae: Alphavirus) and its ectoparasitic arthropod vector (the swallow bug; Oeciacus vicarius). Swallow bugs parasitize the native, colonially nesting cliff swallow (Petrochelidon pyrrhonota) and the introduced house Sparrow (Passer domesticus) that occupies nests in cliff swallow colonies. We measured levels of BCRV-specific and swallow bug-specific IgY levels before nesting (prior to swallow bug exposure) and after nesting (after swallow bug exposure) in house Sparrows and cliff swallows in western Nebraska. Levels of BCRV-specific IgY increased significantly following nesting in the house Sparrow but not in the cliff swallow. Additionally, house Sparrows displayed consistently higher levels of swallow bug-specific antibodies both before and after nesting compared to cliff swallows. The higher levels of BCRV and swallow bug specific antibodies detected in house Sparrows may be reflective of significant differences in both antiviral and anti-ectoparasite immune responses that exist between these two avian species. To our knowledge, this is the first study to compare the macro- and microparasite-specific immune responses of an invasive and a native avian host exposed to the same parasites.
