Population genetic structure and phylogeography of common eiders (Somateria mollissima)

Thesis (Ph.D.) University of Alaska Fairbanks, 2006Population genetic structure of Common Eiders (Somateria mollissima) was assessed at increasing spatial scales (microgeographic [<1 km] to throughout their circumpolar distribution), using molecular markers with varying modes of inheritance and rates of evolution. Population genetic subdivision was observed at all spatial scales; however, the degree of structure differed among marker types. Relatively lower levels of spatial genetic structuring were observed at bi-parentally inherited markers, and high levels of structuring were observed at a maternally inherited locus. Differences in the degree of subdivision between marker types may be attributable to the breeding biology of eiders. Pair formation occurs on the wintering grounds; where several populations of eiders interact. Female eiders exhibit high natal and breeding philopatry; whereas, males accompany females back to breeding sites and may disperse long distances between breeding seasons. Significant structuring observed at microgeographic scales indicates that eiders may nest in kin groups. Though the underlying mechanism enabling female eiders to discriminate kin is unknown, waterfowl may achieve kin recognition indirectly through association during brood rearing. Genetic signatures of philopatry among Common Eider populations do vary among Alaskan populations. No genetic structuring at mitochondrial DNA (mtDNA) was observed among islands in the Beaufort Sea in close geographic proximity (1-49 km apart). However, high structuring was observed among island groups, suggesting females are philopatric to island groups rather than individual islands. In contrast, moderate levels of genetic partitioning for mtDNA were observed among Yukon-Kuskokwim Delta (YKD) colonies (9-63 km apart); therefore, female eiders may be philopatric to individual colonies. MtDNA haplotypes representing Aleutian and YKD populations are more genetically similar to Canadian and Scandinavian populations than northern Alaska populations, indicating that southern Alaskan populations were colonized from central Canadian refugia. Data indicate that the North Slope may have been a refugium for eiders but contributed little to the post-glacial colonization of North America and Scandinavia. Finally, philopatry and winter site fidelity observed in waterfowl have predictable effects on population genetic structure. Researchers characterizing populations using molecular techniques could under- or over-estimate the degree of population genetic differentiation if estimates are based on a single marker type.1. Do waterfowl nest in kin groups? Evidence from the common eider (Somateria mollissima) breeding in the Beaufort Sea, Alaska -- 2. Population genetic structure of common eiders (Somateria mollissima) breeding in the Beaufort Sea, Alaska -- 3. Genetic characterization of common eiders (Somateria mollissima) breeding on the Yukon-Kuskokwim Delta, Alaska -- 4. Multilocus phylogeography and population structure of common eiders breeding in North America and Scandinavia -- 5. Detection of sex-linkage in "autosomal" microsatellite locus and its implication on an estimator of population differentiation -- Conclusions -- Literature cited

Species-specific responses to landscape features shaped genomic structure within Alaska galliformes

Aim: Connectivity is vital to the resiliency of populations to environmental change and stochastic events, especially for cold-adapted species as Arctic and alpine tundra habitats retract as the climate warms. We examined the influence of past and current landscapes on genomic connectivity in cold-adapted galliformes as a critical first step to assess the vulnerability of Alaska ptarmigan and grouse to environmental change. We hypothesize that the mosaic of physical features and habitat within Alaska promoted the formation of genetic structure across species. Location: Alaska, United States of America. Taxa: Ptarmigan and Grouse (Galliformes: Tetraoninae). Methods: We collected double digest restriction-site- associated DNA sequence data from six ptarmigan and grouse species (N = 13–145/ species) sampled across multiple ecosystems up to ~10 degrees of latitude. Spatial genomic structure was analysed using methods that reflect different temporal scales: (1) principal components analysis to identify major trends in the distribution of genomic variation; (2) maximum likelihood clustering analyses to test for the presence of multiple genomic groupings; (3) shared co-ancestry analyses to assess contemporary relationships and (4) effective migration surfaces to identify regions that deviate from a null model of isolation by distance. Results: Levels of genomic structure varied across species (ΦST =0.009–0.042). Three general patterns of structure emerged: (1) east-west partition located near the Yukon-Tanana uplands; (2) north-south split coinciding with the Alaska Range and (3) northern group near the Brooks Range. Species-specific patterns were observed; not all landscape features were barriers to gene flow for all ptarmigan and grouse and temporal contrasts were detected at the Brooks Range. Main conclusions: Within Alaska galliformes, patterns of genomic structure coincide with physiographic features and highlight the importance of physical and ecological barriers in shaping how genomic diversity is arrayed across the landscape. Lack of concordance in spatial patterns indicates that species behaviour and habitat affinities play key roles in driving the contrasting patterns of genomic structure

Record fledging count from a seven-egg clutch in the Cooper’s Hawk (\u3ci\u3eAccipiter cooperii\u3c/i\u3e)

Cooper’s Hawks (Accipiter cooperii) typically lay 3–5 eggs per clutch, rarely 6 eggs, and there are 2 accounts of 7-egg clutches and 1 record of a maximum 8-egg clutch for the species. Brood sizes of 3–5 young are common and the previous maximum brood count is 6 young. However, in 2019, we found an urban nest in Stevens Point, Wisconsin, with 7 eggs that resulted in a record high of 7 fledglings. We genetically confirmed that the attending male sired all the offspring and the attending female laid all 7 eggs. Larger body size of the tending adults may have been a factor in the exceptional reproduction reported here. El gavila´n Accipiter cooperii t´ıpicamente pone 3–5 huevos por puesta, rara vez 6. Hay 2 reportes de puestas de 7 huevos y 1 registro ma´ximo de una puesta de 8 huevos para esta especie. Los tama˜nos de nidada de 3–5 polluelos son comunes y la nidada ma´xima es de 6 polluelos. Sin embargo, en 2019 encontramos un nido urbano en Stevens Point, Wisconsin, con 7 huevos que result ´o en un r´ecord ma´ximo de 7 polluelos emancipados. Confirmamos gen´eticamente que el macho que los cuidaba era el padre de todos los polluelos y que la hembra que los cuidaba puso los 7 huevos. El tama˜no corporal de los adultos a cargo podr´ıa ser un factor en el evento de reproducci´on extraordinario que reportamos aqu´ı

Development of On-Shore Behavior Among Polar Bears (\u3ci\u3eUrsus maritimus\u3c/i\u3e) in the Southern Beaufort Sea: Inherited or Learned?

Polar bears (Ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. Polar bears of the southern Beaufort Sea (SB) have historically spent most of the year on the sea ice. However, recent reports from Alaska indicate that the proportion of the SB subpopulation observed on‐shore during late summer and early fall has increased. Our objective was to investigate whether this on‐shore behavior has developed through genetic inheritance, asocial learning, or through social learning. From 2010 to 2013, genetic data were collected from SB polar bears in the fall via hair snags and remote biopsy darting on‐shore and in the spring from captures and remote biopsy darting on the sea ice. Bears were categorized as either on‐shore or off‐shore individuals based on their presence on‐shore during the fall. Levels of genetic relatedness, first‐order relatives, mother–offspring pairs, and father–offspring pairs were determined and compared within and between the two categories: on‐shore versus off‐shore. Results suggested transmission of on‐shore behavior through either genetic inheritance or social learning as there was a higher than expected number of first‐order relatives exhibiting on‐shore behavior. Genetic relatedness and parentage data analyses were in concurrence with this finding, but further revealed mother–offspring social learning as the primary mechanism responsible for the development of on‐shore behavior. Recognizing that on‐shore behavior among polar bears was predominantly transmitted via social learning from mothers to their offspring has implications for future management and conservation as sea ice continues to decline

Phylogenomics reveals ancient and contemporary gene flow contributing to the evolutionary history of sea ducks (Tribe Mergini)

Insight into complex evolutionary histories continues to build through broad comparative phylogenomic and population genomic studies. In particular, there is a need to understand the extent and scale that gene flow contributes to standing genomic diversity and the role introgression has played in evolutionary processes such as hybrid speciation. Here, we investigate the evolutionary history of the Mergini tribe (sea ducks) by coupling multi-species comparisons with phylogenomic analyses of thousands of nuclear ddRAD-seq loci, including Z-sex chromosome and autosomal linked loci, and the mitogenome assayed across all extant sea duck species in North America. All sea duck species are strongly structured across all sampled marker types (pair-wise species ΦST \u3e 0.2), with clear genetic assignments of individuals to their respective species, and phylogenetic relationships recapitulate known relationships. Despite strong species integrity, we identify at least 18 putative hybrids; with all but one being late generational backcrosses. Most interesting, we provide the first evidence that an ancestral gene flow event between long-tailed ducks (Clangula hyemalis) and true Eiders (Somateria spp.) not only moved genetic material into the former species, but likely generated a novel species — the Steller’s eider (Polysticta stelleri) — via hybrid speciation. Despite generally low contemporary levels of gene flow, we conclude that hybridization has and continues to be an important process that shifts novel genetic variation between species within the tribe Mergini. Finally, we outline methods that permit researchers to contrast genomic patterns of contemporary versus ancestral gene flow when attempting to reconstruct potentially complex evolutionary histories

Gull plumages are, and are not, what they appear to human vision

Clear correlations between human and bird visual assessments of color have been documented, and are often assumed, despite fundamental differences in human and avian visual physiology and morphology. Analyses of plumage colors with avian perceptual models have shown widespread hidden inter-sexual and inter-specific color variation among passerines perceived as monochromatic to humans, highlighting the uncertainty of human vision to predict potentially relevant variation in color. Herein, we use reflectance data from 13 Larus gull species as an exemplar data set to study concordance between human vision and avian visual modeling of feather colors near, or below, the human threshold for discrimination. We found little evidence among gulls for sexual dichromatism hidden from human vision, but did find inter-specific color variation among gulls that is not seen by humans. Neither of these results were predictable a priori, and we reassert that reflectance measurements of actual feather colors, analyzed with avian relevant visual models, represent best practice when studying bird coloration

Spatio-temporal variation in European starling reproductive success at multiple small spatial scales

Funding Information This work received funding from the Natural Environment Research Council, Fair Isle Bird Observatory Trust and the Royal Society. Acknowledgments We thank Jessica Walkup, Jeroen Minderman, and many volunteers for help with data collection; Deryk and Hollie Shaw and Fair Isle Bird Observatory staff for help and support; Xavier Lambin and Justin Travis for comments on the manuscript and NERC (DB); and Fair Isle Bird Observatory Trust (DB) and the Royal Society (JMR) for funding.Peer reviewedPublisher PD