Seasonal migration distance varies with natal dispersal and predicts parasitic infection in song sparrows

Kelly, Tosha R.; MacGillivray, Heather L.; Sarquis‐Adamson, Yanina; Watson, Matthew J.; Hobson, Keith A.; MacDougall‐Shackleton, Elizabeth A.

doi:10.1007/s00265-016-2191-2

Cited by 32 publications

(35 citation statements)

References 41 publications

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“…We measured mass to the nearest 0.1 g using a spring‐loaded scale, measured tarsus length and unflattened wing length to the nearest 0.1 mm using dial calipers, and determined sex based on the presence (male) or absence (female) of a cloacal protuberance. We used previous years’ banding records to categorize birds to age class (i.e., second‐year, hereafter SY, or after‐second‐year, hereafter ASY; see Kelly et al., for details). We clipped a sample of claw tissue for stable‐isotope analysis of overwinter latitude (details below), outfitted the bird with a numbered USFWS aluminum leg band and a unique combination of three colored plastic leg bands if not already banded, and released the bird at the site of capture.…”

Section: Methodsmentioning

confidence: 99%

“…We estimated the latitude at which each individual had overwintered using stable isotope analysis of deuterium (∂ 2 H) content of winter‐grown claw tissue. Details of this analysis are provided elsewhere (Kelly et al., , Lymburner et al. (2016), but in brief, we took advantage of a latitudinal gradient in the ∂ 2 H content of growing‐season precipitation across North America.…”

Section: Methodsmentioning

confidence: 99%

“…Rates of claw growth in white‐throated sparrows ( Zonotrichia albicollis ), which are closely related and ecologically similar to song sparrows, indicate that this sample should correspond to tissue grown during the winter months (Kelly et al., ). Claw samples were stored, cleaned of surface oils, and prepared as described elsewhere (Kelly et al., ), then analyzed for nonexchangeable hydrogen at Environment Canada's Stable Isotope Laboratory (Saskatoon, Canada), using online continuous‐flow isotope ratio mass spectrometry on a Micromass Isoprime mass spectrometer (Micro‐mass UK, Manchester, UK) interfaced with a Eurovector elemental analyzer (Milan, Italy). Isotopic measurements were performed on H 2 gas derived from high‐temperature (1350°C) flash pyrolysis of claw samples and keratin standards.…”

Section: Methodsmentioning

confidence: 99%

“…Here, we test the hypothesis that the immune phenotype of migratory song sparrows ( Melospiza melodia ) reflects individual and seasonal variation in the risk of encountering familiar versus unfamiliar pathogens. Individuals in the study population vary markedly in latitudinal migration distance, as inferred from stable hydrogen isotope analysis (Kelly et al., , Lymburner, Kelly, Hobson, MacDougall‐Shackleton, & MacDougall‐Shackleton (2016), and in natal philopatry, as inferred from genetic assignment tests (Kelly et al., ). Migration distance varies consistently among individuals across years in this study system (repeatability = 0.41) and is associated with natal dispersal such that individuals that migrate longer distances are also more likely to have immigrated from outside the local breeding population (Kelly et al., ).…”

Section: Introductionmentioning

confidence: 99%

“…Individuals in the study population vary markedly in latitudinal migration distance, as inferred from stable hydrogen isotope analysis (Kelly et al., , Lymburner, Kelly, Hobson, MacDougall‐Shackleton, & MacDougall‐Shackleton (2016), and in natal philopatry, as inferred from genetic assignment tests (Kelly et al., ). Migration distance varies consistently among individuals across years in this study system (repeatability = 0.41) and is associated with natal dispersal such that individuals that migrate longer distances are also more likely to have immigrated from outside the local breeding population (Kelly et al., ). We predicted that longer distance migrants and dispersing individuals would rely more heavily on innate immune defenses, reflecting their increased exposure to novel pathogens.…”

Section: Introductionmentioning

confidence: 99%

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Immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird

et al. 2017

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A central tenet of ecoimmunology is that an organism's environment shapes its optimal investment in immunity. For example, the benefits of acquired (relatively pathogen specific) versus innate (nonspecific) immune defenses are thought to vary with the risk of encountering familiar versus unfamiliar pathogens. Because pathogen communities vary geographically, individuals that travel farther during seasonal migration or natal dispersal are predicted to have higher exposure to novel pathogens, and lower exposure to familiar pathogens, potentially favoring investment in innate immunity. During the breeding season, migratory animals’ exposure to familiar pathogens should increase, potentially favoring investment in acquired immunity. We hypothesized that song sparrows Melospiza melodia adjust their constitutive immune profiles in response to risk of encountering novel versus familiar pathogens. We predicted that individuals migrating longer distances (inferred from stable hydrogen isotope analysis of claws) and less philopatric individuals (inferred from microsatellite assignment testing) would rely more heavily on acquired than innate defenses. We also predicted that reliance on acquired defenses would increase throughout the early breeding season. Consistent with trade‐offs between acquired and innate defenses, levels of immunoglobulin Y (acquired) varied negatively with macrophage phagocytosis activity (innate). Levels of acquired relative to innate immunity did not vary significantly with migration distance or philopatry, but increased throughout the early breeding season. Macrophage phagocytosis was not significantly repeatable between years. Song sparrows appear to shift from innate defenses immediately after migration to acquired defenses with increasing time at the breeding grounds. These patterns highlight the plasticity of constitutive immune defenses in migratory animals.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird

et al. 2017

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Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme

Byrd,

Talbott,

Smiley

et al. 2024

Ecology and Evolution

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Numerous factors influence the timing of spring migration in birds, yet the relative importance of intrinsic and extrinsic variables on migration initiation remains unclear. To test for interactions among weather, migration distance, parasitism, and physiology in determining spring departure date, we used the Dark‐eyed Junco (Junco hyemalis) as a model migratory species known to harbor diverse and common haemosporidian parasites. Prior to spring migration departure from their wintering grounds in Indiana, USA, we quantified the intrinsic variables of fat, body condition (i.e., mass ~ tarsus residuals), physiological stress (i.e., ratio of heterophils to lymphocytes), cellular immunity (i.e., leukocyte composition and total count), migration distance (i.e., distance to the breeding grounds) using stable isotopes of hydrogen from feathers, and haemosporidian parasite intensity. We then attached nanotags to determine the timing of spring migration departure date using the Motus Wildlife Tracking System. We used additive Cox proportional hazard mixed models to test how risk of spring migratory departure was predicted by the combined intrinsic measures, along with meteorological predictors on the evening of departure (i.e., average wind speed and direction, relative humidity, and temperature). Model comparisons found that the best predictor of spring departure date was average nightly wind direction and a principal component combining relative humidity and temperature. Juncos were more likely to depart for spring migration on nights with largely southwestern winds and on warmer and drier evenings (relative to cooler and more humid evenings). Our results indicate that weather conditions at take‐off are more critical to departure decisions than the measured physiological and parasitism variables.

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“Balancing” balancing selection? Assortative mating at the major histocompatibility complex despite molecular signatures of balancing selection

Slade

Watson

MacDougall‐Shackleton

2019

Ecology and Evolution

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In vertebrate animals, genes of the major histocompatibility complex (MHC) determine the set of pathogens to which an individual's adaptive immune system can respond. MHC genes are extraordinarily polymorphic, often showing elevated nonsynonymous relative to synonymous sequence variation and sharing presumably ancient polymorphisms between lineages. These patterns likely reflect pathogen‐mediated balancing selection, for example, rare‐allele or heterozygote advantage. Such selection is often reinforced by disassortative mating at MHC. We characterized exon 2 of MHC class II, corresponding to the hypervariable peptide‐binding region, in song sparrows ( Melospiza melodia ). We compared nonsynonymous to synonymous sequence variation in order to identify positively selected sites; assessed evidence for trans‐species polymorphisms indicating ancient balancing selection; and compared MHC similarity of socially mated pairs to expectations under random mating. Six codons showed elevated ratios of nonsynonymous to synonymous variation, consistent with balancing selection, and we characterized several alleles similar to those occurring in at least four other avian families. Despite this evidence for historical balancing selection, mated pairs were significantly more similar at MHC than were randomly generated pairings. Nonrandom mating at MHC thus appears to partially counteract, not reinforce, pathogen‐mediated balancing selection in this system. We suggest that in systems where individual fitness does not increase monotonically with MHC diversity, assortative mating may help to avoid excessive offspring heterozygosity that could otherwise arise from long‐standing balancing selection.

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Seasonal migration distance varies with natal dispersal and predicts parasitic infection in song sparrows

Cited by 32 publications

References 41 publications

Immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird

Immune profiles vary seasonally, but are not significantly related to migration distance or natal dispersal, in a migratory songbird

Determinants of spring migration departure dates in a New World sparrow: Weather variables reign supreme

“Balancing” balancing selection? Assortative mating at the major histocompatibility complex despite molecular signatures of balancing selection

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