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  • 1. Abalaka, J. L.
    et al.
    Ottosson, Ulf
    Tende, Talatu
    Larson, Keith W.
    Rock Firefinch Lagonosticta sanguinodorsalis in the Mandara Mountains, north-east Nigeria: a new subspecies?2010In: African Bird Club Bulletin, ISSN 1352-481X, Vol. 17, no 2, p. 210-211Article in journal (Refereed)
    Abstract [fr]

    L’Amarante des rochers Lagonosticta sanguinodorsalis dans les Monts Mandara, Nigeria du sud-est: une nouvelle sous-espèce ? Nous fournissons une description d’un mâle et d’une femelle, ainsi que desphotos d’un mâle, d’un amarante capturé dans les Monts Mandara, au nord-est du Nigeria. Le plumage et le cri de cet amarante sont identiques à ceux de l’Amarante des rochers Lagonosticta sanguinodorsalis, une espèce précédemment rapportée de la zone, excepté que le mâle n’a pas la couronne grise typique de l’espèce. Des travaux supplémentaires sur le terrain sont nécessaires pour déterminer s’il agit d’un individu aberrant ou d’une population de l’Amarante des rochers morphologiquement distincte.

  • 2. Collis, Ken
    et al.
    Roby, Daniel D.
    Larson, Keith W.
    Department of Fisheries and Wildlife, 104 Nash Hall, Oregon State University, Corvallis, OR, 97331, USA; Evolutionary Ecology, Lund University, Sølvegatan 37, 223 62 Lund, Sweden.
    Adrean, Lindsay J.
    Nelson, S. Kim
    Evans, Allen F.
    Hostetter, Nathan
    Battaglia, Dan
    Lyons, Donald E.
    Marcella, Tim
    Patterson, Allison
    Trends in Caspian Tern Nesting and Diet in San Francisco Bay: Conservation Implications for Terns and Salmonids2012In: Waterbirds (De Leon Springs, Fla.), ISSN 1524-4695, E-ISSN 1938-5390, Vol. 35, no 1, p. 25-34Article in journal (Refereed)
    Abstract [en]

    Colony size, nesting ecology and diet of Caspian Terns (Hydroprogne caspia) were investigated in the San Francisco Bay area (SFBA) during 2003-2009 to assess the potential for conservation of the tern breeding population and possible negative effects of predation on survival of juvenile salmonids (Oncorhyn-chusspp.). Numbers of breeding Caspian Terns declined 36% from 2003 to 2009, mostly due to abandonment of the Knight Island colony and decline of the Brooks Island colony, the two largest colonies in the SFBA. Concurrently, nesting success declined 69% associated with colony site characteristics such as (a) quality and quantity of nesting substrate, (b) vulnerability to nest predators, (c) displacement by other colonial waterbirds and (d) human disturbance. Marine fishes were the predominant prey in tern diets from the SFBA; however, diet composition varied among colonies. Juvenile salmonids comprised 22.9% of the diet of terns nesting in the North Bay, 5.3% of diet of terns nesting in the Central Bay, and 0.1% in the South Bay. Construction or restoration of nesting islands in the South Bay may help maintain and restore breeding Caspian Terns without enhancing mortality of salmonid stocks of conservation concern.

  • 3. De Ruyck, Chris
    et al.
    Hobson, Keith A.
    Koper, Nicola
    Larson, Keith W.
    Wassenaar, Leonard I.
    An Appraisal of the Use of Hydrogen-Isotope Methods to Delineate Origins of Migratory Saw-whet Owls in North America2013In: The Condor, ISSN 00105422, 1938-5129, Vol. 115, no 2, p. 366-374Article in journal (Refereed)
  • 4. Fritsch, Peter W.
    et al.
    Schiller, Anja M.
    Larson, Keith W.
    Department of Animal Ecology, Lund University, Sölvegatan 37, Lund 22362, Sweden .
    Taxonomic Implications of Morphological Variation in Cercis canadensis (Fabaceae) from Mexico and Adjacent Parts of Texas2009In: Systematic Botany, ISSN 0363-6445, E-ISSN 1548-2324, Vol. 34, no 3, p. 510-520Article in journal (Refereed)
    Abstract [en]

    Taxonomic treatments recognize three varieties of Cercis canadensis: with variety canadensis, widespread throughout the eastern United States, and varieties texensis and mexicana, found east and west of the Pecos River in Texas, respectively. The distribution of Cercis continues southward into northeastern Mexico, but complex variation in leaf shape has confounded straightforward application of varietal names to the Mexican plants. To clarify the taxonomy of Cercis in Mexico, we conducted a morphometric analysis with 281 herbarium specimens, including a representative set of samples from Texas. Correlation and principal component analysis of 12 characters recovered two groups that correspond to the presence versus absence of branchlet pubescence. These groups are geographically distinct at the northern and southern extremes of the focus area but exhibit a large central region of overlap. No other discontinuities in character states were discovered to corroborate this division. Leaf shape varies continuously from ovate-acuminate at the northern and southern extremes to subreniform in the central region, suggesting clinal adaptation to the mesic versus xeric environments in which the plants occur. Based on our data, we apply the varietal epithets mexicana and, provisionally, texensis to Mexican C. canadensis with pubescent and glabrous branchlets, respectively, the latter based on geographic proximity to plants in Texas in the absence of definitive evidence on the phenotypic distinction between varieties canadensis and texensis.

  • 5. Hobson, Keith A.
    et al.
    Van Wilgenburg, Steven L.
    Larson, Keith W.
    Environment Canada, Saskatoon, Saskatchewan, Canada.
    Wassenaar, Leonard I.
    A feather hydrogen isoscape for Mexico2009In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 102, no 3, p. 167-174Article in journal (Refereed)
    Abstract [en]

    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]Dgw; precipitation proxy), sex, amount of precipitation, and the coefficient of variation in amount of precipitation. Overall, [delta]Dgw was a poor predictor of sparrow [delta]Df 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]Dgw and [delta]Df was found for female sparrows in the Atlantic drainage basin (r2 = 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.

  • 6. Hobson, Keith A.
    et al.
    Van Wilgenburg, Steven L.
    Wassenaar, Leonard I.
    Larson, Keith W.
    Department of Zoology, Lund University, Lund, Scania, Sweden.
    Linking Hydrogen (δ2H) Isotopes in Feathers and Precipitation: sources of Variance and Consequences for Assignment to Isoscapes2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 4, article id e35137Article in journal (Refereed)
    Abstract [en]

    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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  • 7. Karczmarski, Leszek
    et al.
    Wursig, Bernd
    Gailey, Glenn
    Larson, Keith W.
    Midway Atoll National Wildlife Refuge, Pacific Remote Islands NWR Complex, U.S. Fish and Wildlife Service, Honolulu, USA.
    Vanderlip, Cynthia
    Spinner dolphins in a remote Hawaiian atoll: social grouping and population structure2005In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 16, no 4, p. 675-685Article in journal (Refereed)
    Abstract [en]

    Spinner dolphins (Stenella longirostris) commonly use inshore island and atoll habitats for daytime rest and social interactions and forage over deep waters at night. In Hawaii, they occur throughout the archipelago. We applied photoidentification mark-recapture techniques to study the population structure of spinner dolphins associated with remote Midway Atoll, far-western Hawaii. At Midway, spinner dolphins live in stable bisexually bonded societies of long-term associates, with strong geographic fidelity, no obvious fission-fusion, and limited contacts with other populations. Their large cohesive groups change little over time and are behaviorally/socially discrete from other spinner dolphin groups. This social pattern differs considerably from the fluid fission-fusion model proposed previously for spinner dolphins associated with a large island habitat in the main Hawaiian Archipelago. These differences correspond to geographic separation and habitat variation. While in the main islands there are several daytime resting places available at each island habitat; in far-western Hawaii, areas of suitable habitat are limited and separated by large stretches of open pelagic waters with potentially high risk of shark predation. We hypothesize that with deepwater food resources in close proximity and other atolls relatively far away for easy (day-to-day) access, it is energetically more beneficial in the remote Hawaiian atolls to remain “at home” than to travel to other atolls, so there is stability instead of variability; there is no fission-fusion effect. Thus, the geographic isolation and small size of remote atolls trigger a process in which the fluidity of the fission-fusion spinner dolphin society is replaced with long-term group fidelity and social stability.

  • 8.
    Larson, Keith
    et al.
    Department of Animal Ecology, Lund University, Lund, Sweden; Klamath Bird Observatory, Ashland, USA.
    Hobson, Keith
    Assignment to breeding and wintering grounds using stable isotopes: a comment on lessons learned by Rocque et al.2009In: Journal of Ornithology, ISSN 2193-7192, E-ISSN 2193-7206, Vol. 150, no 3, p. 709-712Article in journal (Refereed)
  • 9.
    Larson, Keith W.
    Lund University.
    Hybrid zone dynamics, assortative mating, and migratory programmes in a willow warbler migratory divide2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis I will compare and contrast the two willow warbler subspecies (Phylloscopus trochilus trochilus and P. t. acredula) with differing migratory phenotypes (or "migratype") in the context of their migratory divide and hybrid zone in central Sweden. Their migratory programs differ in the direction and distance traveled during migration. The "northern" willow warblers migrate south-southeast through the Balkan Peninsula to winter in eastern Africa. The "southern" willow warbler migrates southwest through the Iberian Peninsula to winter in western Africa. In this thesis I will also explore the consequences of hybridization for these two very closely related subspecies where they meet in central Sweden. In the first paper I investigate the role of population abundance in determining the location of the hybrid zone. Specifically, is there a region of low abundance associated with the hybrid zone? Further, is the hybrid zone located on an environmental gradient which might suggest that breeding ground environmental conditions are responsible for the lower abundance? This lower abundance may reflect the unsuitability of habitats along the environmental gradient for either parental or hybrid offspring. In my second paper, I ask if there are population specific differences in their wintering moult ecology that can be elucidated from diet derived stable isotope patterns in their winter moulted primary flight feathers? The third paper addresses the important question, does assortative mating lead to reproductive isolation or do these very similar subspecies hybridize and produce offspring? In my fourth paper, I ask does local adaptation to environmental conditions, such as temperature extremes and the short growing season, in mountain populations of willow warblers explain the apparent distribution of the “northern-allele” for the AFLP derived genetic marker WW1? Finally, in the fifth paper, I conduct a detailed analysis of phenotypic traits at 50 sites across the hybrid zone, including 35 sites visited more than once. Here I ask, does lower abundances in the west of the hybrid zone predict the zone to be wider in the west than in the east? Further, using data from repeated visits to sites across the zone, we predict low repeatabilities for migratory associated traits that would suggest that high annual turn-over in migratypes occupying the zone. For future efforts to understand hybrid zone dynamics, it will be essential to develop genetic markers that allow one to separate each parental migratypes, hybrids, and back-crosses. Once genetic markers allow the identification of hybrid offspring, orientation experiments should be conducted to elucidate migratory directional preferences that would support our hypothesis that hybrids take an intermediate migratory direction to their parental migratypes. This intermediate direction could be a significant cost to hybrid fitness, as this route would require they cross the Mediterranean Sea and Sahara Desert at their widest points.

  • 10.
    Larson, Keith W.
    et al.
    Willamette University, 900 State Street, Salem, Oregon 97301 USA.
    Craig, David P.
    Digiscoping Vouchers for Diet Studies in Bill-load Holding Birds2006In: Waterbirds (De Leon Springs, Fla.), ISSN 1524-4695, E-ISSN 1938-5390, Vol. 29, no 2, p. 198-202Article in journal (Refereed)
    Abstract [en]

    We conducted an observer-based diet study of Caspian Terns (Sterna caspia) incorporating digiscoping to collect digital photographic vouchers of fish. Observer-based diet studies pose several problems, ranging from differential experience and abilities of observers to the lack of vouchers for confirming identification. One solution to these problems is to recover fish either directly from birds (i.e., trapping, shooting) or ones dropped on the colony. This may not, however, be desirable or achieve adequate sample sizes. Some species are difficult to capture or methods may cause significant disturbance and/or nest abandonment. To overcome these problems, we used a relatively inexpensive new photographic technique known as digiscoping. By holding a high-resolution point-and-shoot digital camera up to the eyepiece of a spotting scope or pair of binoculars, we could take digital photographic vouchers of fish as terns brought them into the colony. During the study, we made 16,423 observations, identifying 92% of the fish to the family (3%), genus (15%), or species (74%) level. We supported these observations with over 2,500 digital photograph vouchers. Vouchers confirmed identification of all fish taxa and allowed for later identification, by us or qualified fisheries biologists, of several species unidentifiable in the field. The ability to have independent experts confirm observations and identify previously unidentifiable observations greatly expanded our understanding of the range of fish taken by Caspian Terns.

  • 11.
    Larson, Keith W.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kundisch, Sieglinde
    Attempted predation of Northern Hawk-owl Surnia ullula by Common Kestrel Falco tinnunculus?2014In: Ornis Svecica, ISSN 1102-6812, Vol. 24, no 3-4, p. 165-166Article in journal (Refereed)
  • 12.
    Larson, Keith W.
    et al.
    Department of Biology, Lund University, Lund, Sweden.
    Kundisch, Sieglinde
    Department of Biology, Lund University, Lund, Sweden.
    Willow warbler Phylloscopus trochilus nesting in a juniper during a peak lemming year2012In: Ornis Svecica, ISSN 1102-6812, Vol. 22, no 3-4, p. 141-143Article in journal (Refereed)
  • 13.
    Larson, Keith W.
    et al.
    Department of Biology, Centre for Animal Movement Research, Lund University, Lund, Sweden.
    Liedvogel, Miriam
    Addison, BriAnne
    Kleven, Oddmund
    Laskemoen, Terje
    Lifjeld, Jan T.
    Lundberg, Max
    Åkesson, Susanne
    Bensch, Staffan
    Allelic Variation in a Willow Warbler Genomic Region Is Associated with Climate Clines2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 5, article id e95252Article in journal (Refereed)
    Abstract [en]

    Local adaptation is an important process contributing to population differentiation which can occur in continuous or isolated populations connected by various amounts of gene flow. The willow warbler (Phylloscopus trochilus) is one of the most common songbirds in Fennoscandia. It has a continuous breeding distribution where it is found in all forested habitats from sea level to the tree line and therefore constitutes an ideal species for the study of locally adapted genes associated with environmental gradients. Previous studies in this species identified a genetic marker (AFLP-WW1) that showed a steep north-south cline in central Sweden with one allele associated with coastal lowland habitats and the other with mountainous habitats. It was further demonstrated that this marker is embedded in a highly differentiated chromosome region that spans several megabases. In the present study, we sampled 2,355 individuals at 128 sites across all of Fennoscandia to study the geographic and climatic variables associated with the allele frequency distributions of WW1. Our results demonstrate that 1) allele frequency patterns significantly differ between mountain and lowland populations, 2) these allele differences coincide with extreme temperature conditions and the short growing season in the mountains, and milder conditions in coastal areas, and 3) the northern-allele or "altitude variant" of WW1 occurs in willow warblers that occupy mountainous habitat regardless of subspecies. Finally these results suggest that climate may exert selection on the genomic region associated with these alleles and would allow us to develop testable predictions for the distribution of the genetic marker based on climate change scenarios.

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  • 14.
    Larson, Keith W.
    et al.
    Dept of Biology, Centre for Animal Movement Research, Lund University, Lund, Sweden.
    Liedvogel, Miriam
    Bensch, Staffan
    Åkesson, Susanne
    Wassenaar, Leonard I.
    Hobson, Keith A.
    Inferring the ecology of willow warblers during their winter moult by sequential stable isotope analyses of remiges2013In: Journal of Avian Biology, ISSN 0908-8857, E-ISSN 1600-048X, Vol. 44, no 6, p. 561-566Article in journal (Refereed)
    Abstract [en]

    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.

  • 15.
    Larson, Keith W.
    et al.
    Klamath Bird Observatory, PO Box 758, Ashland, OR 97520, USA.
    Martinez Leyva, Jesus Eduardo
    Wintering Black Terns Foraging Among Manta Rays in Coastal Guerrero, Mexico2007In: Waterbirds (De Leon Springs, Fla.), ISSN 1524-4695, E-ISSN 1938-5390, Vol. 30, no 3, p. 448-449Article in journal (Refereed)
    Abstract [en]

    Winter observations of Black Terns (Chlidonias niger) in Mexico are rare. On 19 January 2007, we observed over 3,000 Black Terns foraging among hundreds of breaching manta rays one kilometer offshore on the coast of Guerrero, Mexico.

  • 16.
    Larson, Keith W.
    et al.
    Klamath Bird Observatory, Ashland, Oregon, USA; Department of Biology, Lund university, Lund, Sweden.
    Smith, Joseph A. M.
    Merker, Samuel A.
    Reitsma, Leonard R.
    Plasticity in the Swainson's Thrush (Catharus ustulatus) First Pre-basic Molt2013In: North American Bird Bander, Vol. 38, no 1, p. 28-30Article in journal (Refereed)
  • 17. Liedvogel, Miriam
    et al.
    Larson, Keith W.
    Center for Animal Movement Research (CAnMove), Department of Biology, Lund University, 22362 Lund, Sweden.
    Lundberg, Max
    Gursoy, Arzu
    Wassenaar, Leonard I.
    Hobson, Keith A.
    Bensch, Staffan
    Åkesson, Susanne
    No evidence for assortative mating within a willow warbler migratory divide2014In: Frontiers in Zoology, ISSN 1742-9994, E-ISSN 1742-9994, Vol. 11, article id 52Article in journal (Refereed)
    Abstract [en]

    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 (δ 15N) 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.

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  • 18. Lundberg, Max
    et al.
    Boss, John
    Canbäck, Björn
    Liedvogel, Miriam
    Larson, Keith W.
    Grahn, Mats
    Åkesson, Susanne
    Bensch, Staffan
    Wright, Anthony
    Characterisation of a transcriptome to find sequence differences between two differentially migrating subspecies of the willow warbler Phylloscopus trochilus2013In: BMC Genomics, ISSN 1471-2164, E-ISSN 1471-2164, Vol. 14, no 1, p. 1-11, article id 330Article in journal (Refereed)
    Abstract [en]

    Background: Animal migration requires adaptations in morphological, physiological and behavioural traits. Several of these traits have been shown to possess a strong heritable component in birds, but little is known about their genetic architecture. Here we used 454 sequencing of brain-derived transcriptomes from two differentially migrating subspecies of the willow warbler Phylloscopus trochilus to detect genes potentially underlying traits associated with migration. Results: The transcriptome sequencing resulted in 1.8 million reads following filtering steps. Most of the reads (84%) were successfully mapped to the genome of the zebra finch Taeniopygia gutatta. The mapped reads were situated within at least 12,101 predicted zebra finch genes, with the greatest sequencing depth in exons. Reads that were mapped to intergenic regions were generally located close to predicted genes and possibly located in uncharacterized untranslated regions (UTRs). Out of 85,000 single nucleotide polymorphisms (SNPs) with a minimum sequencing depth of eight reads from each of two subspecies-specific pools, only 55 showed high differentiation, confirming previous studies showing that most of the genetic variation is shared between the subspecies. Validation of a subset of the most highly differentiated SNPs using Sanger sequencing demonstrated that several of them also were differentiated between an independent set of individuals of each subspecies. These SNPs were clustered in two chromosome regions that are likely to be influenced by divergent selection between the subspecies and that could potentially be associated with adaptations to their different migratory strategies. Conclusions: Our study represents the first large-scale sequencing analysis aiming at detecting genes underlying migratory phenotypes in birds and provides new candidates for genes potentially involved in migration.

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  • 19. Molina, Kathy C.
    et al.
    Garrett, Kimball L.
    Larson, Keith W.
    Klamath Bird Observatory, P. O. Box 758, Ashland. Oregon 97520; Department of Integrative Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
    Craig, David P.
    The Winter Distribution of the Western Gull-billed Tern (Gelochelidon nilotica vanrossemi)2009In: Western Birds, ISSN 0160-1121, Vol. 40, no 1, p. 2-20Article in journal (Other academic)
    Abstract [en]

    We surveyed 73 sites along the Gulf of California and Pacific coasts of mainland Mexico during five nonbreeding seasons from December 1999 to January 2007 to clarify the winter status and distribution of the western North American subspecies of the Gull-billed Tern (Gelochelidon nilotica vanrossemi), a taxon of conservation concern. We located birds at 44 of the 73 sites, (60%) with the largest numbers found around coastal lagoons with extensive tidal flats in southern Sonora, Sinaloa, and extreme northern Nayarit. Local concentrations were also noted at other sites from the Colorado River delta of extreme northwestern Sonora south to Guerrero. Resightings of birds banded as chicks at California breeding colonies establish the first evidence of connectivity to specific wintering sites in Mexico as far south as southern Sonora and possibly into Nayarit.

  • 20. Schiller, Anja M.
    et al.
    Larson, Keith W.
    Fox Sparrow foraging on a king bolete mushroom2006In: Northwest Naturalist: a journal of vertebrate biology, ISSN 1051-1733, Vol. 87, no 3, p. 252-252Article in journal (Refereed)
  • 21. Schiller, Anja M.
    et al.
    Larson, Keith W.
    Klamath Bird Observatory, Ashland, Oregon.
    Alexander, John D.
    A White-crowned Sparrow with three legs2007In: Western Birds, ISSN 0160-1121, Vol. 38, no 3, p. 222-223Article in journal (Refereed)
  • 22. Wassenaar, Leonard I.
    et al.
    Van Wilgenburg, Steve L.
    Larson, Keith W.
    Klamath Bird Observatory, PO Box 758, Ashland, OR, 97520, USA; Department of Animal Ecology, University of Lund, Lund, Sweden.
    Hobson, Keith A.
    A groundwater isoscape (δD, δ18O) for Mexico2009In: Journal of Geochemical Exploration, ISSN 0375-6742, E-ISSN 1879-1689, Vol. 102, no 3, p. 123-136Article in journal (Refereed)
    Abstract [en]

    Numerous studies have shown that precipitation isocapes drive δD and δ18O patterns in surficial waters and in terrestrial food webs. While the GNIP (Global Network for Isotopes in Precipitation) dataset provided a key foundation for linking precipitation-terrestrial isoscapes globally, it has insufficient spatial coverage in many countries like Mexico. To overcome this limitation, we hypothesized that shallow phreatic groundwaters in Mexico could be used as an isotopic integrator of long-term seasonally weighted precipitation inputs to the landscape to aid in calibrating spatial H and O isotope datasets for terrestrial, biological and hydrological research. Groundwater was sampled from 234 sites in Mexico at ~ 50 km latitudinal spacing to obtain high spatial resolution and country-wide coverage for the construction of a groundwater isoscape. Our data revealed that shallow groundwater infiltration in Mexico appears largely unaffected by evaporation and reflects seasonally weighted precipitation inputs. These precipitation inputs are primarily biased to summertime when highest rainfall occurs, but a small degree of post-precipitation evaporation revealed a lower d-excess zone that corresponded to the interior semi-arid ecozone. We developed a predictive general linear model (GLM) for hydrogen and oxygen isotopic spatial patterns in Mexican groundwater and then compared the results to a validation subset of our field data, as well external data reported in the literature. The GLM used elevation, latitude, drainage basin (Atlantic vs. Pacific), and rainfall as the most relevant predictive variables. The GLM explained 81% of the overall isotopic variance observed in groundwater, 68% of the variance within our validation subset, and 77% of the variance in the external data set. Our predictive GLM is sufficiently accurate to allow for future ecological, hydrological and forensic isoscape applications in Mexico, and may be an approach that is applicable to other countries and regions where GNIP stations are lacking.

  • 23. Wellenreuther, Maren
    et al.
    Larson, Keith W.
    Evolutionary Ecology Unit, Department of Biology, Ecology Building, Lund University, SE-223 62 Lund, Sweden.
    Svensson, Erik I.
    Climatic niche divergence or conservatism?: Environmental niches and range limits in ecologically similar damselflies2012In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 93, no 6, p. 1353-1366Article in journal (Refereed)
    Abstract [en]

    The factors that determine species' range limits are of central interest to biologists. One particularly interesting group comprises odonates (dragonflies and damselflies), which show large differences in secondary sexual traits and respond quickly to climatic factors, but often have minor interspecific niche differences, challenging models of niche-based species coexistence. We quantified the environmental niches at two geographic scales to understand the ecological causes of northern range limits and the coexistence of two congeneric damselflies (Calopteryx splendens and C. virgo). Using environmental niche modeling, we quantified niche divergence first across the whole geographic range in Fennoscandia, and second only in the sympatric part of this range. We found evidence for interspecific divergence along the environmental axes of temperature and precipitation across the northern range in Fennoscandia, suggesting that adaptation to colder and wetter climate might have allowed C. virgo to expand farther north than C. splendens. However, in the sympatric zone in southern Fennoscandia we found only negligible and nonsignificant niche differences. Minor niche differences in sympatry lead to frequent encounters and intense interspecific sexual interactions at the local scale of populations. Nevertheless, niche differences across Fennoscandia suggest that species differences in physiological tolerances limit range expansions northward, and that current and future climate could have large effects on the distributional ranges of these and ecologically similar insects.

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