| 1. |
- Gunnarsson, Gunnar, 1976-, et al.
(författare)
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Disease dynamics and bird migration : linking mallards Anas platyrhynchos and subtype diversity of the influenza A virus in time and space
- 2012
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Ingår i: PLOS ONE. - 1932-6203. ; 7:4, s. e35679-
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Tidskriftsartikel (refereegranskat)abstract
- The mallard Anas platyrhynchos is a reservoir species for influenza A virus in the northern hemisphere, with particularly high prevalence rates prior to as well as during its prolonged autumn migration. It has been proposed that the virus is brought from the breeding grounds and transmitted to conspecifics during subsequent staging during migration, and so a better understanding of the natal origin of staging ducks is vital to deciphering the dynamics of viral movement pathways. Ottenby is an important stopover site in southeast Sweden almost halfway downstream in the major Northwest European flyway, and is used by millions of waterfowl each year. Here, mallards were captured and sampled for influenza A virus infection, and positive samples were subtyped in order to study possible links to the natal area, which were determined by a novel approach combining banding recovery data and isotopic measurements (δ2H) of feathers grown on breeding grounds. Geographic assignments showed that the core natal areas of studied mallards were in Estonia, southern and central Finland, and northwestern Russia. This study demonstrates a clear temporal succession of latitudes of natal origin during the course of autumn migration. We also demonstrate a corresponding and concomitant shift in virus subtypes. Acknowledging that these two different patterns were based in part upon different data, a likely interpretation worth further testing is that the early arriving birds with more proximate origins have different influenza A subtypes than the more distantly originating late autumn birds. If true, this knowledge would allow novel insight into the origins and transmission of the influenza A virus among migratory hosts previously unavailable through conventional approaches.
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| 4. |
- De Ruyck, Chris, et al.
(författare)
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n Appraisal of the use of Hydrogen-Isotope Methods to Delineate Origins of Migratory Saw-Whet Owls in North America
- 2013
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Ingår i: The Condor: ornithological applications. - : Oxford University Press (OUP). - 0010-5422 .- 1938-5129. ; 115:2, s. 366-374
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Tidskriftsartikel (refereegranskat)abstract
- Northern Saw-whet Owls (Aegolius acadicus) breed throughout the boreal forest of North America, but little is known about their population trends or distribution within this region. Analysis of stable hydrogen isotopes (delta H-2) in feathers can delineate origins of a variety of avian migrants, but raptors are reported to have high infra-feather isotopic variance and mean delta H-2 values higher than predicted from delta H-2 isoscapes specific to raptor feathers, making assignment of geographic origin sometimes difficult. We examined the applicability of delta H-2 analysis of saw-whet owl feathers to delineating origins of migrants and to assessing differences in the migratory behavior of adult and young owls by using multiple generations of feathers from owls captured during fall migration at the Delta Marsh Bird Observatory, Manitoba, 2006-2007. Values of delta H-2 in saw-whet owl feathers were higher than predicted from a delta H-2 isoscape specific to raptor feathers and from patterns of movements inferred from analysis of band recoveries. This effect was pronounced in adults, while values of delta H-2 in feathers of hatching-year owls fell primarily within the range predicted for the boreal forest northwest of Delta Marsh. Significant differences in delta H-2 values among feather generations suggest that physiological or behavioral differences between adults and young give rise to greater H-2 enrichment in adult feathers. These results indicate that current delta H-2 isoscapes for feathers cannot be used to track adult saw-whet owls reliably and further research into the mechanisms of H-2 enrichment in owl feathers is required.
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| 5. |
- Hobson, Keith A., et al.
(författare)
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A feather hydrogen isoscape for Mexico
- 2009
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Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742. ; 102:2, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- Developing useful biological isoscapes for areas of the world is a priority. This is the case for Mexico that hosts a large percentage of North America's Neotropical migrant birds. Here we investigated the use of House Sparrow (Passer domesticus) feathers to create a spatially explicit feather deuterium isoscape for that country using samples (n=461) that were collected across Mexico. Considerable and useful spatial hydrogen isotopic structure was observed, suggesting that isotopes may be a potential forensic tool for evaluating origins of Mexican derived fauna and. ora. The most positive feather delta D values occurred in the northeast and most negative in the south-central part of the country, roughly matching delta D patterns observed in groundwater. A weak negative isotopic relationship was found with altitude in both the Pacific and Atlantic drainage systems. The most parsimonious model describing isotopic spatial variation in feathers between 300 and 3000 m a.s.l. included groundwater delta D (delta D-gw; precipitation proxy), sex, amount of precipitation, and the coefficient of variation in amount of precipitation. Overall, delta D-gw was a poor predictor of sparrow delta D-f values for all of Mexico. However, this relationship was considerably strengthened when we considered sex separately, removed the Baja peninsula from our sample, and considered the Atlantic and Pacific drainage basins separately. The strongest relationship between delta D-gw and delta D-f was found for female sparrows in the Atlantic drainage basin (r(2)=0.464). We recommend that researchers interested in inferring origins of migratory birds and other animals in Mexico create species specific isotopic basemaps that may be guided by the isotopic patterns we have observed for House Sparrows and groundwater. (C) 2009 Published by Elsevier B.V.
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| 6. |
- Hobson, Keith A., et al.
(författare)
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A feather hydrogen isoscape for Mexico
- 2009
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Ingår i: Journal of Geochemical Exploration. - : Elsevier BV. - 0375-6742 .- 1879-1689. ; 102:3, s. 167-174
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Tidskriftsartikel (refereegranskat)abstract
- Developing useful biological isoscapes for areas of the world is a priority. This is the case for Mexico that hosts a large percentage of North America's Neotropical migrant birds. Here we investigated the use of House Sparrow (Passer domesticus) feathers to create a spatially explicit feather deuterium isoscape for that country using samples (n=461) that were collected across Mexico. Considerable and useful spatial hydrogen isotopic structure was observed, suggesting that isotopes may be a potential forensic tool for evaluating origins of Mexican derived fauna and flora. The most positive feather delta D values occurred in the northeast and most negative in the south-central part of the country, roughly matching delta D patterns observed in groundwater. A weak negative isotopic relationship was found with altitude in both the Pacific and Atlantic drainage systems. The most parsimonious model describing isotopic spatial variation in feathers between 300 and 3000 m a.s.l. included groundwater delta D (delta D-gw; precipitation proxy), sex, amount of precipitation, and the coefficient of variation in amount of precipitation. Overall, delta D-gw was a poor predictor of sparrow delta D-f values for all of Mexico. However, this relationship was considerably strengthened when we considered sex separately, removed the Baja peninsula from our sample, and considered the Atlantic and Pacific drainage basins separately. The strongest relationship between delta D-gw and delta D-f was found for female sparrows in the Atlantic drainage basin (r(2)=0.464). We recommend that researchers interested in inferring origins of migratory birds and other animals in Mexico create species specific isotopic basemaps that may be guided by the isotopic patterns we have observed for House Sparrows and groundwater. (C) 2009 Published by Elsevier B.V.
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| 7. |
- Hobson, Keith A., et al.
(författare)
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Linking Hydrogen (δ2H) Isotopes in Feathers and Precipitation : sources of Variance and Consequences for Assignment to Isoscapes
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Tracking small migrant organisms worldwide has been hampered by technological and recovery limitations and sampling bias inherent in exogenous markers. Naturally occurring stable isotopes of H (δ2H) in feathers provide an alternative intrinsic marker of animal origin due to the predictable spatial linkage to underlying hydrologically driven flow of H isotopes into foodwebs. This approach can assess the likelihood that a migrant animal originated from a given location(s) within a continent but requires a robust algorithm linking H isotopes in tissues of interest to an appropriate hydrological isotopic spatio-temporal pattern, such as weighted-annual rainfall. However, a number of factors contribute to or alter expected isotopic patterns in animals. We present results of an extensive investigation into taxonomic and environmental factors influencing feather δ2H patterns across North America. Stable isotope data were measured from 544 feathers from 40 species and 140 known locations. For δ2H, the most parsimonious model explaining 83% of the isotopic variance was found with amount-weighted growing-season precipitation δ2H, foraging substrate and migratory strategy. This extensive H isotopic analysis of known-origin feathers of songbirds in North America and elsewhere reconfirmed the strong coupling between tissue δ2H and global hydrologic δ2H patterns, and accounting for variance associated with foraging substrate and migratory strategy, can be used in conservation and research for the purpose of assigning birds and other species to their approximate origin.
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| 9. |
- Larson, Keith W., 1968-, et al.
(författare)
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Inferring the ecology of willow warblers during their winter moult by sequential stable isotope analyses of remiges
- 2013
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Ingår i: Journal of Avian Biology. - 0908-8857 .- 1600-048X. ; 44:6, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- We present a comparison of feather stable isotope (δ13C, δ15N) patterns representing the habitat and diet conditions for two subspecies of willow warblers Phylloscopus trochilus that breed in parapatry, but winter in different regions of sub-Saharan Africa. Previous analyses have shown that on average winter moulted innermost primaries (P1) show subspecific differences in δ15N values, although individuals show substantial variation for both δ13C and δ15N within the subspecies. We examined whether corresponding variation in the timing of the winter moult, as reflected by consistent intra-wing correlations for individual's δ13C and δ15N values, could explain some of the previously observed isotopic variation. Further, differential subspecific adaptations to winter precipitation patterns across Africa might result in a variable degree of site fidelity or itinerancy during moult. We found no consistent trend in isotopic values from innermost to outermost primaries, thus inter-individual variation in the timing of moult does not explain the subspecific isotopic variation for P1. Patterns in wing feather δ13C and δ15N values indicated that 41% of the individuals from both subspecies shifted their diet or habitats during winter moult. Importantly, despite well-documented itinerancy in willow warblers during the winter, 59% of the individuals had feather isotope values consistent with stable use of habitats or diets during winter moult. Repeatability analyses suggest that individuals of both subspecies initiate moult in similar habitats from year-to-year while feeding on isotopically similar diets.
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| 10. |
- Liedvogel, Miriam, et al.
(författare)
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No evidence for assortative mating within a willow warbler migratory divide
- 2014
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Ingår i: Frontiers in Zoology. - : Springer Science and Business Media LLC. - 1742-9994. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: In contact zones, genetic mixing of two taxa can be restricted by prezygotic (e.g. assortative mating) or postzygotic (lower fitness of hybrid offspring) barriers, or a combination of the two. A hybrid zone between two willow warbler subspecies (Phylloscopus trochilus trochilus, P. t. acredula) with distinctive migratory strategies occurs in central Sweden. These subspecies exhibit differences in migratory direction and distance, resulting in geographically distinct wintering areas in Africa. The subspecies may have diverged from a common refuge after the last ice age, and neutral genetic markers are homogeneous across their range. By contrast, several phenotypic traits and genetic markers of two chromosomal regions previously identified show steep clines across the divide. The evolutionary forces that maintain this migratory divide remain unknown. Here we use plumage colour, morphology, genetic markers and feather stable nitrogen-isotopes (delta N-15) to assess if assortative mating between migratory phenotypes could be acting as a possible mechanism for keeping the two forms genetically separate and maintaining the migratory divide. We colour-ringed a willow warbler breeding population in the central part of the hybrid zone and observed the breeding population to assess phenotypic and genotypic traits of social pairs. Results: Our data suggest that wintering area and genetic ancestry had an effect on male arrival time to the breeding grounds which could contribute to assortment. However, evidence for assortative mating could not be detected based on a comparison of plumage colour, morphology and delta N-15 between social mates. Conclusion: This finding was strengthened by analyses of subspecies-specific genetic markers, which allowed us to identify the presence of a large proportion of potential hybrids and backcrosses at the study site. Our results supported the hypothesis that pre-mating isolation in willow warblers is weak, resulting in extensive hybridisation across the migratory divide.
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