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Kevin J. Mcgraw - One of the best experts on this subject based on the ideXlab platform.
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Can House Finches (Carpodacus mexicanus) use non-visual cues to discriminate the carotenoid content of foods?
Journal of Ornithology, 2012Co-Authors: Mathieu Giraudeau, Matthew B. Toomey, Kevin J. McgrawAbstract:Carotenoid pigments are involved in different physiological processes (e.g., immunoenhancement, antioxidant activity) in addition to coloring plumage and integuments. As animals cannot synthesize these pigments de novo, it has been proposed that carotenoids constitute a limiting resource that birds may specifically seek in their food. Confirming this hypothesis, it was recently found that birds can discriminate between carotenoid-enriched diets and control diets, even if both have the same color, suggesting that there may be underlying non-visual (e.g., olfactory, taste) mechanisms for detecting carotenoid presence or enrichment in foods. In this study, we performed two experiments with male House Finches ( Carpodacus mexicanus ) to test if this species is able to discriminate between (1) carotenoid-enriched and plain sunflower seeds (while controlling for food coloration), and (2) plain seeds scented with β-ionone, which is a carotenoid-degradation product that is common in many fruits and is one of the most powerful flavor-active organic compounds, or a sham odorant. We found that finches did not show significant food preferences in either experiment, indicating that they did not use odor or flavor cues associated with carotenoids to discriminate between foods. However, our results do not rule out the possibilities that other flavors or odors can be used in discrimination or that finches may learn to discriminate flavors and odors over longer periods of time or at other times of year through post-ingestive feedback mechanisms. Können Hausgimpel ( Carpodacus mexicanus ) andere als optische Informationen verwenden, um den Karotinoid-Gehalt ihrer Nahrung einzuschätzen? Über die Farbgebung von Gefieder und Haut hinaus sind Karotinoid-Farbstoffe an diversen physiologischen Prozessen beteiligt (Stärkung des Immunsystems, Antioxidantien-Aktivität). Da Tiere diese Farbstoffe nicht selbst synthetisieren können, wurde bereits die Idee präsentiert, Karotinoide stellten einen Ressource-Faktor dar, den Vögel gezielt in ihrer Nahrung suchen. Als Bestätigung dieser Hypothese wurde kürzlich herausgefunden, dass Vögel zwischen Karotinoid-angereicherter und Kontroll-Nahrung unterscheiden können, auch wenn beide die gleiche Farbe haben. Dies legt nahe, dass es außer optischen noch andere Informationen geben muss (z. B. Geruch, Geschmack), die als Mechanismen dienen können, das Vorhandensein von, und den Gehalt an, Karotinioden in der Nahrung festzustellen. In unserer Untersuchung führten wir ein Zwei-Stufen-Experiment mit männlichen Hausgimpeln ( Carpodacus mexicanus ) durch, um zu testen, ob diese Art unterscheiden kann zwischen (1) Karotinoid-angereicherten und reinen Sonnenblumensamen (bei gleicher Farbe), und (2) reinen, mit β-Iononen parfürmierten Samenkörnern und solchen mit einem anderen, ähnlichen Duft (β-Ionone sind ein in vielen Früchten vorkommendes Abbauprodukt von Karotinoiden und eine der am stärksten duftenden organischen Verbindungen überhaupt). Wir stellten fest, dass die Finken in den Experimenten keinerlei signifikante Bevorzugung einer der Nahrungsstoffe zeigten, was darauf hinwies, dass sie in der Wahl ihrer Nahrung keine mit Karotinoiden zusammenhängende Geschmacks- oder Geruchs-Informationen benutzten. Andererseits schließen unsere Ergebnisse aber auch nicht die Möglichkeit aus, dass in der Unterscheidung von Nahrungsstoffen ein anderer Geruch oder Geschmack benutzt wurde, oder dass die Finken die Unterscheidung anhand von Geruch oder Geschmack über einen längeren Zeitraum oder zu anderen Jahreszeiten über Rückkopplungsmechanismen in der Verdauung lernen.
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Carotenoids in bird testes: links to body carotenoid supplies, plumage coloration, body mass and testes mass in house finches (Carpodacus mexicanus).
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2012Co-Authors: Melissah Rowe, Elizabeth A Tourville, Kevin J. McgrawAbstract:Carotenoid pigments can be allocated to different parts of the body to serve specific functions. In contrast to other body tissues, studies of carotenoid resources in the testes of animals are relatively scarce. We used high-performance liquid chromatography to determine the types and concentrations of carotenoids in the testes of house finches (Carpodacus mexicanus). Additionally, we examined the relationships between testes carotenoid concentrations and carotenoid pools in other body tissues, as well as body mass, testes mass and plumage coloration. We detected low concentrations of several carotenoids - lutein (the predominant carotenoid), zeaxanthin, anhydrolutein, β-cryptoxanthin, β-carotene and an unknown carotene - in the testes of wild house finches. We also found that testes lutein levels were significantly and positively associated with circulating lutein levels, while the concentration of zeaxanthin in testes was positively associated with zeaxanthin levels in liver, though in this instance the relationship was much weaker and only marginally significant. Furthermore, lutein levels in testes were significantly negatively associated with testes mass. Finally, plumage coloration was not associated with either the concentration of carotenoids in the testes or relative testes mass. These results suggest that testes carotenoids are reflective of the pool of circulating carotenoids in house finches, and that plumage coloration is unlikely to signal either the carotenoid content of testes tissue or a male's capacity for sperm production.
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MATE ATTENTIVENESS, SEASONAL TIMING OF BREEDING AND LONG-TERM PAIR BONDING IN THE HOUSE FINCH (Carpodacus mexicanus)
2012Co-Authors: Kevin J. Mcgraw, Geoffrey E. HillAbstract:In seasonally breeding birds, natural selection favors individualsthat begin breeding earlier in a year because they produce more or higher quality offspring than those that begin breeding later. Among the factors that in � uence the timing of breeding, which include the age, health, competitive ability, or mate quality of individuals,is the longevity of the pair bond, with birds that remain mated across years initiating breeding earlier in the season than newly formed pairs. The behavioural interactions between pair members that may facilitate long-term pair bonding and early breeding onset have infrequently been studied, however. Here we report the relationship between male-female af � liative behaviour, pair-bond duration, and breeding date in house � nches (Carpodacus mexicanus), a short-lived,socially monogamous passerine species in which the duration of pair bonds is highly variable within and among seasons. Finches that initiated breeding earliest in the season were those that had bred with one another in previous years. Early breeding males from returning pairs maintained signi � cantly closer contact with their mate during the � rst egg-laying period of the year than did males from late-breeding, newly formed pairs. Similarly, early-breeding females from returning pairs followed their mate more closely in nest-vicinity � ights during the fertile period than 3) Corresponding author’
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734 Plumage color as a dynamic trait: carotenoid
2012Co-Authors: Kevin J. Mcgraw, Geoffrey EAbstract:pigmentation of male house finches (Carpodacus mexicanus) fades during the breeding seaso
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Food color preferences against a dark, textured background vary in relation to sex and age in house finches (Carpodacus mexicanus)
Behaviour, 2012Co-Authors: Hirbod Behbahaninia, Matthew B. Toomey, Michael W. Butler, Kevin J. McgrawAbstract:Many animals consume colorful foods, because bright coloration either enhances conspicuousness of food items or signals nutritional rewards. A comparatively under-studied aspect of food color preferences is the role of the background environment in shaping food detectability and choices. Previous work with house finches (Carpodacus mexicanus), for example, showed that individuals preferred red and green food items and avoided yellow ones. However, this study of desert, ground-feeding birds was done with seeds presented against an artificial white background that is unlikely to reflect natural conditions. Therefore, we performed a similar experiment, but quantified selection of colorful foods using a different visual environment that better mimicked natural conditions. We mixed dark, inedible distractor pellets (i.e., analogous to natural desert sand and rocks) with sunflower kernels that were colored red, green, yellow, or orange to test for differences in foraging patterns by sex, age, and expression of male plumage coloration in non-molting house finches. This food presentation resulted in yellow seeds having a significantly greater chromatic, but not achromatic, contrast with the background than red or green seeds. Under these conditions, all birds consumed yellow, and to a lesser extent red, seeds most often, and both adult males and females had a strong preference for yellow kernels; adult males also tended to prefer green kernels, but females tended not to prefer green kernels. Juveniles showed no significant preferences for any seed color, and adult male plumage coloration was not related to seed color preference. Therefore, in contrast to studies using different foraging environments, house finches tended to prefer yellow seeds, supporting models that suggest that visual background and contrast may be more important than color per se in visually mediated foraging decisions of birds. Moreover, the fact that adult males and females differed in food color preference has not been reported previously in songbirds.
Matthew B. Toomey - One of the best experts on this subject based on the ideXlab platform.
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Can House Finches (Carpodacus mexicanus) use non-visual cues to discriminate the carotenoid content of foods?
Journal of Ornithology, 2012Co-Authors: Mathieu Giraudeau, Matthew B. Toomey, Kevin J. McgrawAbstract:Carotenoid pigments are involved in different physiological processes (e.g., immunoenhancement, antioxidant activity) in addition to coloring plumage and integuments. As animals cannot synthesize these pigments de novo, it has been proposed that carotenoids constitute a limiting resource that birds may specifically seek in their food. Confirming this hypothesis, it was recently found that birds can discriminate between carotenoid-enriched diets and control diets, even if both have the same color, suggesting that there may be underlying non-visual (e.g., olfactory, taste) mechanisms for detecting carotenoid presence or enrichment in foods. In this study, we performed two experiments with male House Finches ( Carpodacus mexicanus ) to test if this species is able to discriminate between (1) carotenoid-enriched and plain sunflower seeds (while controlling for food coloration), and (2) plain seeds scented with β-ionone, which is a carotenoid-degradation product that is common in many fruits and is one of the most powerful flavor-active organic compounds, or a sham odorant. We found that finches did not show significant food preferences in either experiment, indicating that they did not use odor or flavor cues associated with carotenoids to discriminate between foods. However, our results do not rule out the possibilities that other flavors or odors can be used in discrimination or that finches may learn to discriminate flavors and odors over longer periods of time or at other times of year through post-ingestive feedback mechanisms. Können Hausgimpel ( Carpodacus mexicanus ) andere als optische Informationen verwenden, um den Karotinoid-Gehalt ihrer Nahrung einzuschätzen? Über die Farbgebung von Gefieder und Haut hinaus sind Karotinoid-Farbstoffe an diversen physiologischen Prozessen beteiligt (Stärkung des Immunsystems, Antioxidantien-Aktivität). Da Tiere diese Farbstoffe nicht selbst synthetisieren können, wurde bereits die Idee präsentiert, Karotinoide stellten einen Ressource-Faktor dar, den Vögel gezielt in ihrer Nahrung suchen. Als Bestätigung dieser Hypothese wurde kürzlich herausgefunden, dass Vögel zwischen Karotinoid-angereicherter und Kontroll-Nahrung unterscheiden können, auch wenn beide die gleiche Farbe haben. Dies legt nahe, dass es außer optischen noch andere Informationen geben muss (z. B. Geruch, Geschmack), die als Mechanismen dienen können, das Vorhandensein von, und den Gehalt an, Karotinioden in der Nahrung festzustellen. In unserer Untersuchung führten wir ein Zwei-Stufen-Experiment mit männlichen Hausgimpeln ( Carpodacus mexicanus ) durch, um zu testen, ob diese Art unterscheiden kann zwischen (1) Karotinoid-angereicherten und reinen Sonnenblumensamen (bei gleicher Farbe), und (2) reinen, mit β-Iononen parfürmierten Samenkörnern und solchen mit einem anderen, ähnlichen Duft (β-Ionone sind ein in vielen Früchten vorkommendes Abbauprodukt von Karotinoiden und eine der am stärksten duftenden organischen Verbindungen überhaupt). Wir stellten fest, dass die Finken in den Experimenten keinerlei signifikante Bevorzugung einer der Nahrungsstoffe zeigten, was darauf hinwies, dass sie in der Wahl ihrer Nahrung keine mit Karotinoiden zusammenhängende Geschmacks- oder Geruchs-Informationen benutzten. Andererseits schließen unsere Ergebnisse aber auch nicht die Möglichkeit aus, dass in der Unterscheidung von Nahrungsstoffen ein anderer Geruch oder Geschmack benutzt wurde, oder dass die Finken die Unterscheidung anhand von Geruch oder Geschmack über einen längeren Zeitraum oder zu anderen Jahreszeiten über Rückkopplungsmechanismen in der Verdauung lernen.
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Food color preferences against a dark, textured background vary in relation to sex and age in house finches (Carpodacus mexicanus)
Behaviour, 2012Co-Authors: Hirbod Behbahaninia, Matthew B. Toomey, Michael W. Butler, Kevin J. McgrawAbstract:Many animals consume colorful foods, because bright coloration either enhances conspicuousness of food items or signals nutritional rewards. A comparatively under-studied aspect of food color preferences is the role of the background environment in shaping food detectability and choices. Previous work with house finches (Carpodacus mexicanus), for example, showed that individuals preferred red and green food items and avoided yellow ones. However, this study of desert, ground-feeding birds was done with seeds presented against an artificial white background that is unlikely to reflect natural conditions. Therefore, we performed a similar experiment, but quantified selection of colorful foods using a different visual environment that better mimicked natural conditions. We mixed dark, inedible distractor pellets (i.e., analogous to natural desert sand and rocks) with sunflower kernels that were colored red, green, yellow, or orange to test for differences in foraging patterns by sex, age, and expression of male plumage coloration in non-molting house finches. This food presentation resulted in yellow seeds having a significantly greater chromatic, but not achromatic, contrast with the background than red or green seeds. Under these conditions, all birds consumed yellow, and to a lesser extent red, seeds most often, and both adult males and females had a strong preference for yellow kernels; adult males also tended to prefer green kernels, but females tended not to prefer green kernels. Juveniles showed no significant preferences for any seed color, and adult male plumage coloration was not related to seed color preference. Therefore, in contrast to studies using different foraging environments, house finches tended to prefer yellow seeds, supporting models that suggest that visual background and contrast may be more important than color per se in visually mediated foraging decisions of birds. Moreover, the fact that adult males and females differed in food color preference has not been reported previously in songbirds.
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The effects of dietary carotenoid intake on carotenoid accumulation in the retina of a wild bird, the house finch (Carpodacus mexicanus)
Archives of biochemistry and biophysics, 2010Co-Authors: Matthew B. Toomey, Kevin J. McgrawAbstract:Abstract Carotenoid pigments accumulate in the retinas of many animals, including humans, where they play an important role in visual health and performance. Recently, birds have emerged as a model system for studying the mechanisms and functions of carotenoid accumulation in the retina. However, these studies have been limited to a small number of domesticated species, and the effects of dietary carotenoid access on retinal carotenoid accumulation have not been investigated in any wild animal species. The purpose of our studies was to examine how variation in dietary carotenoid types and levels affect retinal accumulation in house finches ( Carpodacus mexicanus ), a common and colorful North American songbird. We carried out three 8-week studies with wild-caught captive birds: (1) we tracked the rate of retinal carotenoid depletion, compared to other body tissues, on a very low-carotenoid diet, (2) we supplemented birds with two common dietary carotenoids (lutein + zeaxanthin) and measured the effect on retinal accumulation, and (3) we separately supplemented birds with high levels of zeaxanthin – an important dietary precursor for retinal carotenoids – or astaxanthin – a dominant retinal carotenoid not commonly found in the diet (i.e. a metabolic derivative). We found that carotenoids depleted slowly from the retina compared to other tissues, with a significant (∼50%) decline observed only after 8 weeks on a very low-carotenoid diet. Supplementation with lutein + zeaxanthin or zeaxanthin alone significantly increased only retinal galloxanthin and e-carotene levels, while other carotenoid types in the retina remained unaffected. Concentrations of retinal astaxanthin were unaffected by direct dietary supplementation with astaxanthin. These results suggest highly specific mechanisms of retinal carotenoid metabolism and accumulation, as well as differential rates of turnover among retinal carotenoid types, all of which have important implications for visual health maintenance and interventions.
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Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus).
Journal of Experimental Biology, 2010Co-Authors: Matthew B. Toomey, Michael W. Butler, Kevin J. McgrawAbstract:doi:10.1242/jeb.041004 Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus
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Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus).
The Journal of experimental biology, 2010Co-Authors: Matthew B. Toomey, Michael W. Butler, Kevin J. McgrawAbstract:The costs of developing, maintaining, and activating the immune system have been cited as an important force shaping life-history evolution in animals. Immunological defenses require energy, nutrients and time that might otherwise be devoted to other life-history traits like sexual displays or reproduction. Carotenoid pigments in animals provide a unique opportunity to track the costs of immune activation, because they are diet-derived, modulate the immune system, and are used to develop colorful signals of quality. Carotenoids also accumulate in the retinas of birds, where they tune spectral sensitivity and provide photoprotection. If carotenoid accumulation in the retina follows the patterns of other tissues, then immune activation may deplete retinal carotenoid levels and impact visual health and function. To test this hypothesis, we challenged molting wild-caught captive house finches (Carpodacus mexicanus) with weekly injections of lipopolysaccharide (LPS) and phytohaemagglutinin (PHA) over the course of 8 weeks. Immunostimulated adult males and females produced significant antibody responses and molted more slowly than uninjected control birds. After 8 weeks, immune-challenged birds had significantly lower levels of specific retinal carotenoid types (galloxanthin and zeaxanthin), but there were no significant differences in the plasma, liver or feather carotenoid levels between the treatment groups. These results indicate that immune-system activation can specifically deplete retinal carotenoids, which may compromise visual health and performance and represent an additional somatic and behavioral cost of immunity.
Andre A Dhondt - One of the best experts on this subject based on the ideXlab platform.
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Pathogenicity and immunogenicity of three Mycoplasma gallisepticum isolates in house finches (Carpodacus mexicanus).
Veterinary microbiology, 2011Co-Authors: Jessica L. Grodio, David H Ley, Keila V. Dhondt, Andre A Dhondt, Dana M. Hawley, Erik E. Osnas, Karel A. SchatAbstract:Mycoplasma gallisepticum (MG) has become a common cause of conjunctivitis in free-living house finches (Carpodacus mexicanus) since its emergence in the early 1990s. To date, temporal and spatial genotypic variation in MG has been documented, but phenotypic variation in pathogenicity and immunogenicity has not been examined. House finches were inoculated with MG isolates Virginia (VA)1994, California (CA)2006, or North Carolina (NC)2006, which were cultured from free-living house finches with conjunctivitis in 1994, 2006, and 2006, respectively. Infection with NC2006 resulted in the most severe eye lesions, highest pathogen loads, and highest levels of pathogen-specific lachrymal and serum antibodies. Infection with CA2006 caused the least severe eye lesions, lowest pathogen load, and lowest levels of antibodies. A small number of birds in each group developed protracted, severe disease in spite of robust antibody responses, suggesting that immunopathology may contribute to the lesions. Immunoblot analyses indicated that isolates are antigenically similar; thus, there may be partial cross-protection if a house finch encounters two or more strains of MG throughout the course of its lifetime. This study provides evidence that MG strains or strain variants circulating in house finch populations vary in their ability to cause disease, induce antibody responses, and persist in the host.
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Mycoplasma sturni from a California House Finch with Conjunctivitis Did Not Cause Disease in Experimentally Infected House Finches
Journal of Wildlife Diseases, 2010Co-Authors: Nancy Anderson, Keila V. Dhondt, Andre A DhondtAbstract:Mycoplasma gallisepticum conjunctivitis emerged in 1994 as a disease of free-ranging House Finches (Carpodacus mexicanus) in North America and has also been isolated from other songbirds with conjunctivitis. A key feature for the successful study of natural and experimental disease has been the apparent, very-high correlation between characteristic eye lesions and M. gallisepticum. Mycoplasma sturni was originally isolated from an adult European Starling (Sturnus vulgaris) with bilateral conjunctivitis and has since been reported in a relatively small number of other avian species, but not in House Finches. We identified as M. sturni a mycoplasma isolate from a California House Finch with conjunctivitis. However, experimental infection of House Finches with the M. sturni isolate failed to reproduce the disease. Therefore, M. gallisepticum remains the primary known cause of conjunctivitis in House Finches.
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Reconciling molecular signatures across markers: Mitochondrial DNA confirms founder effect in invasive North American house finches (Carpodacus mexicanus)
Conservation Genetics, 2008Co-Authors: Dana M. Hawley, James Briggs, Andre A Dhondt, Irby J LovetteAbstract:Well-characterized species introductions provide opportunities to compare the genetic signatures of known founder effects across classes of molecular markers. The release of small numbers of house finches (Carpodacus mexicanus) into the eastern United States in the 1940s led to substantial interest in the effects of this introduction on genetic diversity in this now abundant species, an issue that has been highlighted by a recent Mycoplasma disease epidemic that most intensively affects the introduced and potentially genetically depauperate house finch populations. Previous studies comparing genetic diversity levels in native and introduced house finch populations produced seemingly disparate results: comparisons based on amplified fragment length polymorphism, RFLP mtDNA, and allozyme markers found essentially equivalent levels of diversity in eastern and western populations, whereas microsatellite markers showed clear reductions in diversity in the introduced populations. Here we employ sequence variation at the ND2 mtDNA locus to further compare levels of diversity between the four native and five introduced house finch populations that were previously examined in the microsatellite study. We found substantially lower ND2 haplotype richness and diversity across all introduced populations of house finches. The majority of sequence variation (78%) was detected within subpopulations, with the remainder (22%) explained by the historical status of each population (native or introduced). Our results are consistent with previous microsatellite evidence for a founder effect during the introduction of eastern house finches, and suggest that the mtDNA founder effect was particularly severe, likely owing to a male-biased sex ratio at the time of introduction coupled with the lower effective population size of clonally inherited markers. We discuss how the inconsistencies between past studies of house finch diversity can inform the usefulness of distinct marker sets for detecting molecular signatures of founder events.
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Mycoplasma gallisepticum infection in house finches (Carpodacus mexicanus) affects mosquito blood feeding patterns.
The American journal of tropical medicine and hygiene, 2007Co-Authors: Jonathan M. Darbro, Andre A Dhondt, Francoise Vermeylen, Laura C. HarringtonAbstract:Disease-induced lethargy can diminish host capacity to repel or kill biting mosquitoes. We exposed house finches (Carpodacus mexicanus) to mosquitoes (Culex pipiens pipiens), repeated the experiment after inoculating finches with Mycoplasma gallisepticum, and then repeated the experiment with the same birds after curing their infections. We videotaped avian behaviors before and during mosquito exposure, identifying hosts through blood meal DNA fingerprinting. Results revealed heterogeneity in mosquito preference regardless of infection. Mosquitoes choosing between two healthy finches were more likely to feed upon the same individual bird consistently. When one bird was sick, mosquitoes exhibited no preference. Sick birds made fewer total defensive behaviors than healthy birds, but only foot stomps were associated with reduced mosquito feeding success. Our results suggest that Mycoplasma and other avian infections that alter bird defensive behavior may influence mosquito feeding patterns and transmission of arthropod-borne pathogens such as West Nile virus.
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Pathogen resistance and immunocompetence covary with social status in house finches (Carpodacus mexicanus)
Functional Ecology, 2007Co-Authors: Dana M. Hawley, C. S. Jennelle, Keila V. Sydenstricker, Andre A DhondtAbstract:1. Social status has striking effects on individual physiology, but the extent to which it influences pathogen resistance has rarely been explored. Here we examine how social status within groups of wintering house finches (Carpodacus mexicanus) relates to immunocompetence and susceptibility to an infectious disease. 2. We assayed cellular and humoral components of the immune response, then quantified symptom severity in response to experimental infection with Mycoplasma gallisepticum, a naturally occurring bacterial pathogen that causes periodic epidemics in social aggregations of house finches across North America. 3. Socially dominant house finches mounted stronger immune responses to phytohaemagglutinin but weaker antibody titres to sheep red blood cells. Dominant males, but not females, showed significantly lower symptom severity and proportion of time symptomatic when inoculated with M. gallisepticum. 4. Individual condition was not associated with social status before or after infection, but infection with M. gallisepticum created disparities in resource access across social status. Infected dominant birds of both sexes fed for significantly more time intervals than infected subordinate birds following infection. 5. Changes in resource access may partly underlie observed relationships between social status and disease severity, but the detected sex-specific interactions suggest a role for endocrine-immune relationships that warrant further study. Overall, our results indicate that social behaviour can influence both immunocompetence and resistance to an infectious disease of broad impact in the wild, highlighting the importance of considering the social context of individuals in studies of disease in natural populations.
Dana M. Hawley - One of the best experts on this subject based on the ideXlab platform.
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Multi-locus class II major histocompatibility complex (MHC) diversity and house finch disease resistance.
2013Co-Authors: Dana M. Hawley, Robert C. FleischerAbstract:MHC class II diversity as measured by single strand nuclear polymorphism predicts the severity of house finch (Carpodacus mexicanus) conjunctivitis in response to experimental infection with Mycoplasma gallisepticum (MG). All bars indicate one standard error around the mean.
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Pathogenicity and immunogenicity of three Mycoplasma gallisepticum isolates in house finches (Carpodacus mexicanus).
Veterinary microbiology, 2011Co-Authors: Jessica L. Grodio, David H Ley, Keila V. Dhondt, Andre A Dhondt, Dana M. Hawley, Erik E. Osnas, Karel A. SchatAbstract:Mycoplasma gallisepticum (MG) has become a common cause of conjunctivitis in free-living house finches (Carpodacus mexicanus) since its emergence in the early 1990s. To date, temporal and spatial genotypic variation in MG has been documented, but phenotypic variation in pathogenicity and immunogenicity has not been examined. House finches were inoculated with MG isolates Virginia (VA)1994, California (CA)2006, or North Carolina (NC)2006, which were cultured from free-living house finches with conjunctivitis in 1994, 2006, and 2006, respectively. Infection with NC2006 resulted in the most severe eye lesions, highest pathogen loads, and highest levels of pathogen-specific lachrymal and serum antibodies. Infection with CA2006 caused the least severe eye lesions, lowest pathogen load, and lowest levels of antibodies. A small number of birds in each group developed protracted, severe disease in spite of robust antibody responses, suggesting that immunopathology may contribute to the lesions. Immunoblot analyses indicated that isolates are antigenically similar; thus, there may be partial cross-protection if a house finch encounters two or more strains of MG throughout the course of its lifetime. This study provides evidence that MG strains or strain variants circulating in house finch populations vary in their ability to cause disease, induce antibody responses, and persist in the host.
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Reconciling molecular signatures across markers: Mitochondrial DNA confirms founder effect in invasive North American house finches (Carpodacus mexicanus)
Conservation Genetics, 2008Co-Authors: Dana M. Hawley, James Briggs, Andre A Dhondt, Irby J LovetteAbstract:Well-characterized species introductions provide opportunities to compare the genetic signatures of known founder effects across classes of molecular markers. The release of small numbers of house finches (Carpodacus mexicanus) into the eastern United States in the 1940s led to substantial interest in the effects of this introduction on genetic diversity in this now abundant species, an issue that has been highlighted by a recent Mycoplasma disease epidemic that most intensively affects the introduced and potentially genetically depauperate house finch populations. Previous studies comparing genetic diversity levels in native and introduced house finch populations produced seemingly disparate results: comparisons based on amplified fragment length polymorphism, RFLP mtDNA, and allozyme markers found essentially equivalent levels of diversity in eastern and western populations, whereas microsatellite markers showed clear reductions in diversity in the introduced populations. Here we employ sequence variation at the ND2 mtDNA locus to further compare levels of diversity between the four native and five introduced house finch populations that were previously examined in the microsatellite study. We found substantially lower ND2 haplotype richness and diversity across all introduced populations of house finches. The majority of sequence variation (78%) was detected within subpopulations, with the remainder (22%) explained by the historical status of each population (native or introduced). Our results are consistent with previous microsatellite evidence for a founder effect during the introduction of eastern house finches, and suggest that the mtDNA founder effect was particularly severe, likely owing to a male-biased sex ratio at the time of introduction coupled with the lower effective population size of clonally inherited markers. We discuss how the inconsistencies between past studies of house finch diversity can inform the usefulness of distinct marker sets for detecting molecular signatures of founder events.
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Pathogen resistance and immunocompetence covary with social status in house finches (Carpodacus mexicanus)
Functional Ecology, 2007Co-Authors: Dana M. Hawley, C. S. Jennelle, Keila V. Sydenstricker, Andre A DhondtAbstract:1. Social status has striking effects on individual physiology, but the extent to which it influences pathogen resistance has rarely been explored. Here we examine how social status within groups of wintering house finches (Carpodacus mexicanus) relates to immunocompetence and susceptibility to an infectious disease. 2. We assayed cellular and humoral components of the immune response, then quantified symptom severity in response to experimental infection with Mycoplasma gallisepticum, a naturally occurring bacterial pathogen that causes periodic epidemics in social aggregations of house finches across North America. 3. Socially dominant house finches mounted stronger immune responses to phytohaemagglutinin but weaker antibody titres to sheep red blood cells. Dominant males, but not females, showed significantly lower symptom severity and proportion of time symptomatic when inoculated with M. gallisepticum. 4. Individual condition was not associated with social status before or after infection, but infection with M. gallisepticum created disparities in resource access across social status. Infected dominant birds of both sexes fed for significantly more time intervals than infected subordinate birds following infection. 5. Changes in resource access may partly underlie observed relationships between social status and disease severity, but the detected sex-specific interactions suggest a role for endocrine-immune relationships that warrant further study. Overall, our results indicate that social behaviour can influence both immunocompetence and resistance to an infectious disease of broad impact in the wild, highlighting the importance of considering the social context of individuals in studies of disease in natural populations.
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Transmission-relevant behaviours shift with pathogen infection in wild house finches (Carpodacus mexicanus)
Canadian Journal of Zoology, 2007Co-Authors: Dana M. Hawley, A. K. Davis, Andre A DhondtAbstract:Host individuals who are infected with a pathogen may alter their behaviour in ways that influence transmission. We observed a marked population of house finches (Carpodacus mexicanus(Muller, 1776)) in Ithaca, New York, to test whether individuals change their behaviour at feeding stations when infected with a prevalent bacterial pathogen, Myco- plasma gallisepticum (MG). We found that house finches with conjunctival lesions consistent with MG infection fed for longer bouts of time than individuals without conjunctivitis. Furthermore, the same individuals that were observed both with and without conjunctivitis during 3 years of study were more likely to feed alone and associated in significantly smaller flocks when conjunctivitis signs were present. These results suggest house finches alter their foraging and social behaviour at feeding stations when visibly infected with MG. Since MG transmission is thought to primarily occur at feeders, these changes in host behaviour likely have important consequences for MG transmission dynamics. Resume ´ : Les hotes individuels qui sont infectes par un agent pathogene peuvent modifier leur comportement de maniere aen affecter la transmission. Nous avons observeune population de roselins familiers (Carpodacus mexicanus(Muller, 1776)) a Ithaca, New York, afin de verifier si les individus changent leur comportement dans les mangeoires lorsqu'ils sont infectes avec une bacterie pathogene commune, Mycoplasma gallisepticum(MG). Les roselins familiers portant des lesions ala conjonctive compatibles avec une infection a MG ont des episodes alimentaires plus longs que les individus sans conjonctivite. De plus, les memes individus, qui ont eteobserves au cours des 3 annees de l'etude avec et sans con- jonctivite, ont plus tendance ase nourrir en solitaires ou en groupes significativement plus petits lorsqu'ils possedent des symptomes de conjonctivite. Ces resultats indiquent que les roselins familiers modifient leurs comportements alimentaires et sociaux dans les mangeoires lorsqu'ils sont manifestement infectes au MG. Puisque l'on croit que la transmission de MG se fait principalement aux mangeoires, ces changements de comportement de l'hote ont vraisemblablement des conse ´- quences importantes sur la dynamique de la transmission de MG. (Traduit par la Redaction)
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Pathogenicity and immunogenicity of three Mycoplasma gallisepticum isolates in house finches (Carpodacus mexicanus).
Veterinary microbiology, 2011Co-Authors: Jessica L. Grodio, David H Ley, Keila V. Dhondt, Andre A Dhondt, Dana M. Hawley, Erik E. Osnas, Karel A. SchatAbstract:Mycoplasma gallisepticum (MG) has become a common cause of conjunctivitis in free-living house finches (Carpodacus mexicanus) since its emergence in the early 1990s. To date, temporal and spatial genotypic variation in MG has been documented, but phenotypic variation in pathogenicity and immunogenicity has not been examined. House finches were inoculated with MG isolates Virginia (VA)1994, California (CA)2006, or North Carolina (NC)2006, which were cultured from free-living house finches with conjunctivitis in 1994, 2006, and 2006, respectively. Infection with NC2006 resulted in the most severe eye lesions, highest pathogen loads, and highest levels of pathogen-specific lachrymal and serum antibodies. Infection with CA2006 caused the least severe eye lesions, lowest pathogen load, and lowest levels of antibodies. A small number of birds in each group developed protracted, severe disease in spite of robust antibody responses, suggesting that immunopathology may contribute to the lesions. Immunoblot analyses indicated that isolates are antigenically similar; thus, there may be partial cross-protection if a house finch encounters two or more strains of MG throughout the course of its lifetime. This study provides evidence that MG strains or strain variants circulating in house finch populations vary in their ability to cause disease, induce antibody responses, and persist in the host.
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Production of house finch (Carpodacus mexicanus) IgA specific anti-sera and its application in immunohistochemistry and in ELISA for detection of Mycoplasma gallisepticum-specific IgA.
Veterinary immunology and immunopathology, 2009Co-Authors: Jessica L. Grodio, Elizabeth L Buckles, Karel A. SchatAbstract:The IgA antibody response plays a vital role in mucosal immunity because it functions to neutralize pathogens at the mucosal surface and thus impedes attachment to underlying tissues. Although the importance of IgA in the mucosal immunity of galliform birds has been established, studies examining IgA-based immunity in passerine birds are lacking, perhaps due in part to the absence of reagents that can detect passerine IgA. A 469 base pair region of the house finch (Carpodacus mexicanus) IgA heavy chain was PCR-amplified from spleen cDNA and sequenced. The predicted amino acid sequence was found to share 55% and 46% identity with the IgA heavy chain of mallard (Anas platyrhynchos) and chicken (Gallus gallus), respectively. The heavy chain fragment was produced using a bacterial expression system and purified. Rabbit anti-sera were generated against the recombinant protein. The anti-sera reacted with a single house finch serum protein ( approximately 50-55kDa) in Western blot. The anti-sera were used to identify plasma cells in the Harderian gland and conjunctiva of house finches with conjunctivitis associated with Mycoplasma gallisepticum infection. The anti-sera were also utilized in an ELISA to detect M. gallisepticum-specific IgA antibodies in lachrymal samples of infected finches.
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Production of house finch (Carpodacus mexicanus) IgA specific anti-sera and its application in immunohistochemistry and in ELISA for detection of Mycoplasma gallisepticum-specific IgA
Veterinary Immunology and Immunopathology, 2009Co-Authors: Jessica L. Grodio, Elizabeth L Buckles, Karel A. SchatAbstract:Abstract The IgA antibody response plays a vital role in mucosal immunity because it functions to neutralize pathogens at the mucosal surface and thus impedes attachment to underlying tissues. Although the importance of IgA in the mucosal immunity of galliform birds has been established, studies examining IgA-based immunity in passerine birds are lacking, perhaps due in part to the absence of reagents that can detect passerine IgA. A 469 base pair region of the house finch (Carpodacus mexicanus) IgA heavy chain was PCR-amplified from spleen cDNA and sequenced. The predicted amino acid sequence was found to share 55% and 46% identity with the IgA heavy chain of mallard (Anas platyrhynchos) and chicken (Gallus gallus), respectively. The heavy chain fragment was produced using a bacterial expression system and purified. Rabbit anti-sera were generated against the recombinant protein. The anti-sera reacted with a single house finch serum protein (∼50–55 kDa) in Western blot. The anti-sera were used to identify plasma cells in the Harderian gland and conjunctiva of house finches with conjunctivitis associated with Mycoplasma gallisepticum infection. The anti-sera were also utilized in an ELISA to detect M. gallisepticum-specific IgA antibodies in lachrymal samples of infected finches.