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Thomas W Custer - One of the best experts on this subject based on the ideXlab platform.
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annual variation in polychlorinated biphenyl pcb exposure in Tree Swallow tachycineta bicolor eggs and nestlings at great lakes restoration initiative glri study sites
Environmental Monitoring and Assessment, 2018Co-Authors: Christine M Custer, Thomas W Custer, Paul M Dummer, Diana R Goldberg, Christian J FransonAbstract:Tree Swallow (Tachycineta bicolor) eggs and nestlings were collected from 16 sites across the Great Lakes to quantify normal annual variation in total polychlorinated biphenyl (PCB) exposure and to validate the sample size choice in earlier work. A sample size of five eggs or five nestlings per site was adequate to quantify exposure to PCBs in Tree Swallows given the current exposure levels and variation. There was no difference in PCB exposure in two randomly selected sets of five eggs collected in the same year, but analyzed in different years. Additionally, there was only modest annual variation in exposure, with between 69% (nestlings) and 73% (eggs) of sites having no differences between years. There was a tendency, both statistically and qualitatively, for there to be less exposure in the second year compared to the first year.
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erod activity chromosomal damage and oxidative stress in response to contaminants exposure in Tree Swallow tachycineta bicolor nestlings from great lakes areas of concern
Ecotoxicology, 2017Co-Authors: Thomas W Custer, Christine M Custer, Paul M Dummer, Richard A. Erickson, Emilie Bigorgne, Elias M Oziolor, Natalie K Karounarenier, Sandra L Schultz, Kevin Aagaard, Cole W MatsonAbstract:Tree Swallow, Tachycineta bicolor, nestlings were collected from 60 sites in the Great Lakes, which included multiple sites within 27 Areas of Concern (AOCs) and six sites not listed as AOCs from 2010 to 2014. Nestlings, approximately 12 days-of-age, were evaluated for ethoxyresorufin-O-dealkylase (EROD) activity, chromosomal damage, and six measures of oxidative stress. Data on each of these biomarkers were divided into four equal numbered groups from the highest to lowest values and the groups were compared to contaminant concentrations using multivariate analysis. Contaminant concentrations, from the same nestlings, included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and 17 elements. Alkylated polycyclic aromatic hydrocarbons (aPAHs) and parent PAHs (pPAHs) were measured in pooled nestling dietary samples. Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and pesticides were measured in sibling eggs. Concentrations of aPAHs, pPAHs, chlordane, dieldrin, heptachlor, and PCBs, in that order, were the major contributors to the significant differences between the lowest and highest EROD activities; PFCs, PBDEs, the remaining pesticides, and all elements were of secondary importance. The four categories of chromosomal damage did not separate out well based on the contaminants measured. Concentrations of aPAHs, pPAHs, heptachlor, PCBs, chlordane, and dieldrin were the major contributors to the significant differences between the lowest and highest activities of two oxidative stress measures, total sulfhydryl (TSH) activity and protein bound sulfhydryl (PBSH) activity. The four categories of thiobarbituric acid reacting substances (TBARS), oxidized glutathione (GSSG), reduced glutathione (GSH), and the ratio of GSSG/GSH did not separate well based on the contaminants measured.
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organic contamination in Tree Swallow tachycineta bicolor nestlings at united states and binational great lakes areas of concern
Environmental Toxicology and Chemistry, 2017Co-Authors: Thomas W Custer, Christine M Custer, Christian J Franson, Paul M Dummer, Diana R Goldberg, Richard A. EricksonAbstract:Contaminant exposure of Tree Swallows, Tachycineta bicolor, nesting in 27 Areas of Concern (AOC) in the Great Lakes' basin was assessed from 2010 to 2014 to assist managers and regulators in their assessments of Great Lakes AOCs. Contaminant concentrations in nestlings from AOCs were compared to nestlings from nearby non-AOC sites. Polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) concentrations in Tree Swallow nestling carcasses at 30% and 33% of AOCs were below the mean concentration for non-AOCs. Polycyclic aromatic hydrocarbon (PAH) concentrations in nestling stomach contents and perfluorinated compound (PFC) concentrations in nestling plasma at 67% and 64% of AOCs were below the mean concentration for non-AOCs. Concentrations of PCBs in nestling carcasses were elevated at some AOCs, but were modest compared to highly PCB-contaminated sites where reproductive effects have been documented. Concentrations of PAHs in diet were sufficiently elevated at some AOCs to elicit a measurable physiological response. Among AOCs, the PFC compound perfluorooctane sulfonate concentrations in plasma were the highest on the River Raisin, MI (geometric mean 330 ng/ml), but well below an estimated toxicity reference value (1,700 ng/ml). Both PAH and PCB concentrations in nestling stomach contents, and PCBs in carcasses, were significantly correlated with concentrations in sediment reported in another study, thereby reinforcing the utility of using Tree Swallows to assess bioavailability of sediment contamination. This article is protected by copyright. All rights reserved
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Contaminant exposure of birds nesting in Green Bay, Wisconsin, USA.
Environmental Toxicology and Chemistry, 2014Co-Authors: Thomas W Custer, J. Christian Franson, Paul Michael Howell Dummer, Christine M Custer, Michael JonesAbstract:In earlier studies, elevated concentrations of polychlorinated biphenyl (PCB) and p,p'-dichlorodiphenyldichloroethylene (DDE) were reported in double-crested cormorant (Phalacrocorax auritus) eggs and Tree Swallow (Tachycineta bicolor) eggs and nestlings collected from lower Green Bay (WI, USA) in 1994 and 1995 and black-crowned night-heron (Nycticorax nycticorax) eggs collected in 1991. Comparable samples collected in 2010 and 2011 indicated that concentrations of PCBs were 35%, 62%, 70%, and 88% lower than in the early 1990s in Tree Swallow eggs, Tree Swallow nestlings, double-crested cormorant eggs, and black-crowned night-heron eggs, respectively; concentrations of DDE were 47%, 43%, 51%, and 80% lower, respectively. These declines are consistent with regional contaminant trends in other species. Concentrations of PCBs were higher in herring gull (Larus argentatus) than in black-crowned night-heron eggs collected from Green Bay in 2010; PCB concentrations in double-crested cormorant and Tree Swallow eggs were intermediate. The estimated toxicity of the PCB mixture in eggs of the insectivorous Tree Swallow was the equal to or greater than toxicity in the 3 piscivorous bird species. A multivariate analysis indicated that the composition percentage of lower-numbered PCB congeners was greater in eggs of the insectivorous Tree Swallow than in eggs of the 3 piscivorous species nesting in Green Bay. Dioxin and furan concentrations and the toxicity of these chemicals were also higher in Tree Swallows than these other waterbird species nesting in Green Bay. Environ Toxicol Chem 2014;33:1832–1839. Published 2014 Wiley Periodicals, Inc. Published 2014 Wiley Periodicals, Inc. This article is a US Government work and, as such, is in the public domain in the USA.
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Mercury and other element exposure in Tree Swallows nesting at low pH and neutral pH lakes in northern Wisconsin USA.
Environmental pollution (Barking Essex : 1987), 2012Co-Authors: Thomas W Custer, Christine M Custer, Paul M Dummer, Wayne E. Thogmartin, Ronald Rossmann, Kevin P. Kenow, Michael W. MeyerAbstract:The primary objective of this study was to determine whether Tree Swallows (Tachycineta bicolor) demonstrate similar responses to lake pH and mercury (Hg) contamination in northern Wisconsin as do common loons (Gavia immer). Similar to common loons, Hg concentrations in the blood of Tree Swallow nestlings were higher, Hg concentrations in eggs tended to be higher, and egg size tended to be smaller at low (
Christine M Custer - One of the best experts on this subject based on the ideXlab platform.
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annual variation in polychlorinated biphenyl pcb exposure in Tree Swallow tachycineta bicolor eggs and nestlings at great lakes restoration initiative glri study sites
Environmental Monitoring and Assessment, 2018Co-Authors: Christine M Custer, Thomas W Custer, Paul M Dummer, Diana R Goldberg, Christian J FransonAbstract:Tree Swallow (Tachycineta bicolor) eggs and nestlings were collected from 16 sites across the Great Lakes to quantify normal annual variation in total polychlorinated biphenyl (PCB) exposure and to validate the sample size choice in earlier work. A sample size of five eggs or five nestlings per site was adequate to quantify exposure to PCBs in Tree Swallows given the current exposure levels and variation. There was no difference in PCB exposure in two randomly selected sets of five eggs collected in the same year, but analyzed in different years. Additionally, there was only modest annual variation in exposure, with between 69% (nestlings) and 73% (eggs) of sites having no differences between years. There was a tendency, both statistically and qualitatively, for there to be less exposure in the second year compared to the first year.
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erod activity chromosomal damage and oxidative stress in response to contaminants exposure in Tree Swallow tachycineta bicolor nestlings from great lakes areas of concern
Ecotoxicology, 2017Co-Authors: Thomas W Custer, Christine M Custer, Paul M Dummer, Richard A. Erickson, Emilie Bigorgne, Elias M Oziolor, Natalie K Karounarenier, Sandra L Schultz, Kevin Aagaard, Cole W MatsonAbstract:Tree Swallow, Tachycineta bicolor, nestlings were collected from 60 sites in the Great Lakes, which included multiple sites within 27 Areas of Concern (AOCs) and six sites not listed as AOCs from 2010 to 2014. Nestlings, approximately 12 days-of-age, were evaluated for ethoxyresorufin-O-dealkylase (EROD) activity, chromosomal damage, and six measures of oxidative stress. Data on each of these biomarkers were divided into four equal numbered groups from the highest to lowest values and the groups were compared to contaminant concentrations using multivariate analysis. Contaminant concentrations, from the same nestlings, included polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and 17 elements. Alkylated polycyclic aromatic hydrocarbons (aPAHs) and parent PAHs (pPAHs) were measured in pooled nestling dietary samples. Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and pesticides were measured in sibling eggs. Concentrations of aPAHs, pPAHs, chlordane, dieldrin, heptachlor, and PCBs, in that order, were the major contributors to the significant differences between the lowest and highest EROD activities; PFCs, PBDEs, the remaining pesticides, and all elements were of secondary importance. The four categories of chromosomal damage did not separate out well based on the contaminants measured. Concentrations of aPAHs, pPAHs, heptachlor, PCBs, chlordane, and dieldrin were the major contributors to the significant differences between the lowest and highest activities of two oxidative stress measures, total sulfhydryl (TSH) activity and protein bound sulfhydryl (PBSH) activity. The four categories of thiobarbituric acid reacting substances (TBARS), oxidized glutathione (GSSG), reduced glutathione (GSH), and the ratio of GSSG/GSH did not separate well based on the contaminants measured.
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organic contamination in Tree Swallow tachycineta bicolor nestlings at united states and binational great lakes areas of concern
Environmental Toxicology and Chemistry, 2017Co-Authors: Thomas W Custer, Christine M Custer, Christian J Franson, Paul M Dummer, Diana R Goldberg, Richard A. EricksonAbstract:Contaminant exposure of Tree Swallows, Tachycineta bicolor, nesting in 27 Areas of Concern (AOC) in the Great Lakes' basin was assessed from 2010 to 2014 to assist managers and regulators in their assessments of Great Lakes AOCs. Contaminant concentrations in nestlings from AOCs were compared to nestlings from nearby non-AOC sites. Polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) concentrations in Tree Swallow nestling carcasses at 30% and 33% of AOCs were below the mean concentration for non-AOCs. Polycyclic aromatic hydrocarbon (PAH) concentrations in nestling stomach contents and perfluorinated compound (PFC) concentrations in nestling plasma at 67% and 64% of AOCs were below the mean concentration for non-AOCs. Concentrations of PCBs in nestling carcasses were elevated at some AOCs, but were modest compared to highly PCB-contaminated sites where reproductive effects have been documented. Concentrations of PAHs in diet were sufficiently elevated at some AOCs to elicit a measurable physiological response. Among AOCs, the PFC compound perfluorooctane sulfonate concentrations in plasma were the highest on the River Raisin, MI (geometric mean 330 ng/ml), but well below an estimated toxicity reference value (1,700 ng/ml). Both PAH and PCB concentrations in nestling stomach contents, and PCBs in carcasses, were significantly correlated with concentrations in sediment reported in another study, thereby reinforcing the utility of using Tree Swallows to assess bioavailability of sediment contamination. This article is protected by copyright. All rights reserved
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Contaminant exposure of birds nesting in Green Bay, Wisconsin, USA.
Environmental Toxicology and Chemistry, 2014Co-Authors: Thomas W Custer, J. Christian Franson, Paul Michael Howell Dummer, Christine M Custer, Michael JonesAbstract:In earlier studies, elevated concentrations of polychlorinated biphenyl (PCB) and p,p'-dichlorodiphenyldichloroethylene (DDE) were reported in double-crested cormorant (Phalacrocorax auritus) eggs and Tree Swallow (Tachycineta bicolor) eggs and nestlings collected from lower Green Bay (WI, USA) in 1994 and 1995 and black-crowned night-heron (Nycticorax nycticorax) eggs collected in 1991. Comparable samples collected in 2010 and 2011 indicated that concentrations of PCBs were 35%, 62%, 70%, and 88% lower than in the early 1990s in Tree Swallow eggs, Tree Swallow nestlings, double-crested cormorant eggs, and black-crowned night-heron eggs, respectively; concentrations of DDE were 47%, 43%, 51%, and 80% lower, respectively. These declines are consistent with regional contaminant trends in other species. Concentrations of PCBs were higher in herring gull (Larus argentatus) than in black-crowned night-heron eggs collected from Green Bay in 2010; PCB concentrations in double-crested cormorant and Tree Swallow eggs were intermediate. The estimated toxicity of the PCB mixture in eggs of the insectivorous Tree Swallow was the equal to or greater than toxicity in the 3 piscivorous bird species. A multivariate analysis indicated that the composition percentage of lower-numbered PCB congeners was greater in eggs of the insectivorous Tree Swallow than in eggs of the 3 piscivorous species nesting in Green Bay. Dioxin and furan concentrations and the toxicity of these chemicals were also higher in Tree Swallows than these other waterbird species nesting in Green Bay. Environ Toxicol Chem 2014;33:1832–1839. Published 2014 Wiley Periodicals, Inc. Published 2014 Wiley Periodicals, Inc. This article is a US Government work and, as such, is in the public domain in the USA.
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Mercury and other element exposure in Tree Swallows nesting at low pH and neutral pH lakes in northern Wisconsin USA.
Environmental pollution (Barking Essex : 1987), 2012Co-Authors: Thomas W Custer, Christine M Custer, Paul M Dummer, Wayne E. Thogmartin, Ronald Rossmann, Kevin P. Kenow, Michael W. MeyerAbstract:The primary objective of this study was to determine whether Tree Swallows (Tachycineta bicolor) demonstrate similar responses to lake pH and mercury (Hg) contamination in northern Wisconsin as do common loons (Gavia immer). Similar to common loons, Hg concentrations in the blood of Tree Swallow nestlings were higher, Hg concentrations in eggs tended to be higher, and egg size tended to be smaller at low (
John P Giesy - One of the best experts on this subject based on the ideXlab platform.
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Tree Swallow tachycineta bicolor exposure to polychlorinated biphenyls at the kalamazoo river superfund site michigan usa
Environmental Toxicology and Chemistry, 2006Co-Authors: Arianne M Neigh, Matthew J Zwiernik, Patrick W Bradley, Cyrus S Park, Alan L Blankenship, Paul D. Jones, John L. Newsted, John P GiesyAbstract:In 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The Tree Swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species. A top-down methodology was used to evaluate the bioaccumulation of PCBs, including non-ortho and mono-ortho congeners, in Tree Swallow eggs, nestlings, and adults at the Kalamazoo River area of concern (KRAOC) and at an upstream reference site. Generally, a sixfold difference in tissue concentrations of total PCBs was observed between the two sites with concentrations in eggs and nestlings at the KRAOC ranging from 0.95 to 15 mg PCB/g wet weight. Concentrations of 2,3,7,8- tetrachlorodibenzo-p-dioxin equivalents (TEQsWHO2Avian) for PCBs, based on bird-specific World Health Organization toxic equiv- alence factors, were 10- to 30-fold greater in the KRAOC than at the reference location. Egg and nestling TEQsWHO2Avian ranged from 0.21 to 2.4 ng TEQ/g wet weight at the KRAOC. Hazard quotients calculated from literature-derived toxicity reference values were below 1.0 at both the target and the reference site based on the no-observed-adverse-effect level and the lowest-observed- adverse-effect level.
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Bioaccumulation of polychlorinated biphenyls from sediments to aquatic insects and Tree Swallow eggs and nestlings in Saginaw Bay, Michigan, USA
Environmental Toxicology and Chemistry, 1998Co-Authors: Kenneth L. Froese, D. A. Verbrugge, Gerald T. Ankley, Gerald J. Niemi, Christen P. Larsen, John P GiesyAbstract:Sediments in the Saginaw Bay region of the Great Lakes contain concentrations and polychlorinated biphenyls (PCBs) that may adversely affect biotic species in various trophic levels. In this study the authors collected and analyzed sediments, benthic invertebrates, Tree Swallow eggs, and nestlings to evaluate linkages between PCBs in sediments and at various trophic levels in the Saginaw River, Michigan, USA. Their results indicate that patterns of relative concentrations of PCB congeners change with trophic level, specifically from sediment to invertebrates and from Tree Swallow eggs to nestlings. However, if biota-sediment accumulation factor (BSAF) values are based on only the non- and mono-ortho-substituted PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEq), calculated BSAF values are close to those predicted by fugacity theory. The use of site-specific BSAF values and reference doses for toxic effects in wildlife can be used to derive sediment quality criteria (SQC) that are protective of wildlife at the top of the sediment-based food chain. The threshold concentration of TEq in sediments that would protect sensitive avian species at the same trophic level as Tree Swallows was calculated to be 1.5 {times} 10{sup {minus}1} TEq/g total organic carbon. Based on this value and the BSAF determined for Tree Swallow nestlings,more » the hazard quotient for sediments in this area was determined to be 0.7. This indicates that current concentrations of TEq due to PCB congeners in the sediments should be below the threshold for adverse effects on Tree Swallows. The uncertainty in the concentrations of PCB congeners in the sediments was approximately a factor of 2, which determined the degree of resolution that could be obtained from the observations made in this study.« less
Mary Ann Ottinger - One of the best experts on this subject based on the ideXlab platform.
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effects of in ovo exposure to 3 3 4 4 tetrachlorobiphenyl pcb 77 on heart development in Tree Swallow tachycineta bicolor
Environmental Toxicology and Chemistry, 2018Co-Authors: Tiffany Carro, Mary K. Walker, Karen M. Dean, Mary Ann OttingerAbstract:Tree Swallow (Tachycineta bicolor) eggs from 2 uncontaminated sites, the Patuxent Research Refuge (Laurel, MD, USA) and the Cobleskill Reservoir (Cobleskill, NY, USA) were dosed with polychlorinated biphenyl (PCB) 77 to evaluate effects on the developing cardiovascular system. To ensure embryonic viability, treatments were administered into the air cell at embryonic day 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1000 ng/g egg. Eggs were dosed in the field with 0.2 μL/egg, returned to the nest, collected at embryonic day 13, hatched in the laboratory, and necropsied. The PCB 77-treated hatchlings were compared with uninjected, vehicle-injected, and environmentally exposed hatchlings collected from a PCB-contaminated Upper Hudson River (NY, USA) site. The PCB 77-treated embryos showed no effects on hatching success or hatchling mortality, heart index, or morphological measures of 4 distinct heart layers (heart width, length, septal thickness, total and ventricular cavity area) compared with controls. Hatchlings that had received PCB 77 exhibited increased incidence of a cardiomyopathy and absence of the ventricular heart wall compact layer (Chi square test; p < 0.001); environmentally exposed embryos showed no apparent effects. The compact layer is essential in development and overall heart function for ventricular cardiomyocyte proliferation and normal heart contraction. The finding that in ovo exposure to PCB 77 resulted in distinct cardiomyopathy has implications for long-term individual fitness. Environ Toxicol Chem 2018;37:116-125. © 2017 SETAC.
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Effects of in ovo exposure to 3,3',4,4'-tetrachlorobiphenyl (PCB 77) on heart development in Tree Swallow (Tachycineta bicolor).
Environmental Toxicology and Chemistry, 2017Co-Authors: Tiffany Carro, Mary K. Walker, Karen M. Dean, Mary Ann OttingerAbstract:: Tree Swallow (Tachycineta bicolor) eggs from 2 uncontaminated sites, the Patuxent Research Refuge (Laurel, MD, USA) and the Cobleskill Reservoir (Cobleskill, NY, USA) were dosed with polychlorinated biphenyl (PCB) 77 to evaluate effects on the developing cardiovascular system. To ensure embryonic viability, treatments were administered into the air cell at embryonic day 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1000 ng/g egg. Eggs were dosed in the field with 0.2 μL/egg, returned to the nest, collected at embryonic day 13, hatched in the laboratory, and necropsied. The PCB 77-treated hatchlings were compared with uninjected, vehicle-injected, and environmentally exposed hatchlings collected from a PCB-contaminated Upper Hudson River (NY, USA) site. The PCB 77-treated embryos showed no effects on hatching success or hatchling mortality, heart index, or morphological measures of 4 distinct heart layers (heart width, length, septal thickness, total and ventricular cavity area) compared with controls. Hatchlings that had received PCB 77 exhibited increased incidence of a cardiomyopathy and absence of the ventricular heart wall compact layer (Chi square test; p
Daniel R. Ardia - One of the best experts on this subject based on the ideXlab platform.
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the effects of nest size and insulation on thermal properties of Tree Swallow nests
Journal of Avian Biology, 2013Co-Authors: Rebecca L Windsor, Jessica L Fegely, Daniel R. ArdiaAbstract:The nest environment can have important influences on incubation behavior and nestling development in birds. Nest thermal properties, particularly nest composition and size, can have a major influence on heat loss. To examine the role of nest size and insulation on clutch cooling rates, we collected Tree Swallow Tachycineta bicolor nests and measured the cooling rate of eggs in a controlled thermal environment. We also examined the thermal benefits of nest feathers by comparing the cooling rates of nests with and without feathers. Nests with more feather insulation and heavier, deeper cupped nests cooled at slower rates. In addition, nests with feathers cooled at much slower rates than did the same nests without feathers. Our results show that nest insulation and size play important roles in nest cooling rates, which may ultimately affect incubation costs and thus reproductive performance.
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Subtle Edge-of-Range Genetic Structuring in Transcontinentally Distributed North American Tree Swallows
The Condor, 2009Co-Authors: Laura M. Stenzler, Daniel R. Ardia, Christopher A. Makarewich, Aurélie Coulon, Irby J. Lovette, David W. WinklerAbstract:Abstract. Understanding how genetic variation in the Tree Swallow (Tachycineta bicolor) is geographically structured is informative because this broadly distributed North American bird is increasingly used as a model for studies of mating systems, life-history traits, and physiology. We explored patterns of phylogeographic differentiation across the Tree Swallow's breeding range by using nine microsatellite loci and a mitochondrial DNA sequence marker. Contrary to this species' high population-level variation in life-history traits and other ecologically important characteristics, we found no genetic structuring across the majority of its distribution, spanning Tennessee, New York, and Alaska, but we found that birds from California form a distinct yet subtly differentiated genetic cluster. The Tree Swallow can be characterized as a species with both continent-wide genetic panmixia and slight differentiation at one edge of its breeding distribution. This pattern of genetic variation has implications for u...
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experimental heating reveals nest temperature affects nestling condition in Tree Swallows tachycineta bicolor
Biology Letters, 2008Co-Authors: Jonathan H Perez, Daniel R. Ardia, Elise K Chad, Ethan D. ClotfelterAbstract:Investment in one life-history stage can have delayed effects on subsequent life-history stages within a single reproductive bout. We experimentally heated Tree Swallow (Tachycineta bicolor) nests ...
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variation in heritability of immune function in the Tree Swallow
Evolutionary Ecology, 2006Co-Authors: Daniel R. Ardia, Elizabeth RiceAbstract:Heritability is an important component of the ability of a trait to respond to natural selection; variation in heritability can lead to differences in how a trait responds to selection pressures. Here we test whether an important physiological trait, immune function, varies by comparing heritability estimates through cross-fostering brood manipulation at three wide-spread sites in the Tree Swallow (Tachycineta bicolor): Alaska, New York and Tennessee. In two of three sites, there was no additive genetic component to nestling immune response to the mitogen phytohaemagglutinin, while immune response had a heritable component in Tennessee. Bootstrapping revealed significant differences in estimated heritability. This conclusion was supported by mother–offspring regressions; in Tennessee breeding females mounting strong immune responses tended to have offspring with strong immune responses, while in New York and Alaska, there was no relationship between the immune responses of mothers and offspring. These results suggest that studies investigating the roles of common origin and rearing environment should consider yearly or spatial variation within a species.
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geographic variation in the trade off between nestling growth rate and body condition in the Tree Swallow
The Condor, 2006Co-Authors: Daniel R. ArdiaAbstract:Abstract Nestlings can exhibit considerable variation in developmental patterns both within and among locations due to differences in environmental conditions and parental investment. I investigated trade-offs between nestling growth rate and residual body mass (body condition) at three locations across the range of the Tree Swallow (Tachycineta bicolor). Nestlings at the northern extreme of the range in Alaska had slower growth rates, lower body mass, and higher residual body mass than nestlings in New York and Tennessee. High insect availability was correlated with increased growth rates of nestlings in New York and Tennessee, but not in Alaska. Conversely, nestlings in Alaska showed increased residual body mass with high insect availability, but nestlings in New York and Tennessee did not. The trade-off between growth rate and residual body mass varied among sites, with fast-growing nestlings in Tennessee maintaining a higher residual body mass than those in Alaska. These results suggest that factors a...
