Geology topics

Robert E. Wilson

Publications and source records attributed to Robert E. Wilson.

At least 19 recordsLinked to original sources

USGS2026

Family life is critical for migration and survival in a long-lived social bird

Extended parental care is common among birds and particularly well known among long-lived migratory species. Yet, factors influencing the duration of parental care are poorly understood, and empirical evidence for the functional importance of family life for offspring development is scarce. Using unique tracking and genetic data of 55 adult and juvenile migratory Bewick’s swans, among which 18 parent-offspring pairs and 13 sibling pairs, we quantify variation in family bond duration and identify the cause and consequences of their dissolution. Families generally broke up during the second half of the first northward migration of the offspring, when offspring were nearly one year old. Earlier separation occurred on the wintering grounds in response to disturbance ( n = 10 juveniles) and led to delayed migration and, critically, lower survival (40 vs. 86%). Our results provide rare empirical evidence that family bonds, as a pathway for social learning, are not just important, but vital to the migration and survival of young family-living birds.

Behavioral Ecology and Sociobiology↗

USGS2026

Colonization of southern flying squirrels (Glaucomys volans) to urban Nebraska: Range expansion or human assisted translocation?

Southern flying squirrels ( Glaucomys volans; Linnaeus 1758) were first observed in Lincoln, Nebraska, in 2018, 80 km north of their described range. Given that southern flying squirrels are a species of concern within Nebraska, determining the origin of this new population (natural expansion or pet-trade) garnered interest from state biologists. Further, the recent colonization of Lincoln by southern flying squirrels presents a unique opportunity to investigate the genetic implications of a founding event on a small arboreal mammal. The Lincoln population had genetic characteristics suggestive of a single-event colonization with fewer rare alleles and lower genetic diversity than potential source populations and a high genetic variation between populations. Sample size and absence of other geographically close populations in our data set make it difficult to ascertain the origin of the Lincoln population. Based on shared co-ancestry and membership assignment clustering algorithms, the Lincoln population had greater genetic associations with an individual sampled from the native south-eastern Nebraska population relative to other studied locations, suggesting that Lincoln was colonized by a native population.

Nebraska↗

USGS2025

Too hot for comfort: Elevated temperatures influence gene expression and exceed thermal tolerance of bigmouth shiners, Ericymba dorsalis

Environmental and associated ecosystem change may affect the persistence of fish species based on their ability to adapt to changing conditions, including decreasing flows and rising water temperatures. Exceeding the thermal tolerances of stream fish will likely result in a loss of ability to maintain metabolic processes. We evaluated the critical thermal maximum (CTmax) of bigmouth shiner ( Ericymba dorsalis ) and analysed the expression of heat shock protein 70 messenger RNA (mRNA) (HSP70) to quantify a thermal stress response over a gradient of temperatures (25°C–31°C). E. dorsalis HSP70 mRNA expression was upregulated in response to temperatures >25°C, indicating a stress response. This study supports the existence of a thermal stress threshold for E. dorsalis . The frequency at which this threshold is exceeded may increase under forecasted future climate scenarios for Nebraska.

Nebraska↗

USGS2025

Hybridization and asymmetrical introgression between the vulnerable Gray‐Headed Chickadee and a more abundant congener, the Boreal Chickadee: Implications for conservation

Hybridization is a common process among bird species that can precipitate a mix of positive or negative species outcomes. Particularly for rare populations, detrimental effects of hybridization on demographic growth rates and genetic integrity are of serious concern. In Alaska and a small region of northwestern Canada, the endemic subspecies of Gray-headed Chickadee ( Poecile cinctus lathami ) has declined in recent decades from being locally common to being extremely rare. The more widespread Boreal Chickadee ( P. hudsonicus ) has become increasingly abundant in areas of sympatry. These changes in abundance may have led to hybridization between Gray-headed Chickadees and Boreal Chickadees. We used a series of analyses to test for signatures of introgression at mitochondrial DNA and nuclear DNA using historical museum samples of both species collected between 1875 and 1979 as well as contemporary Boreal Chickadee samples. In addition, we modeled Gray-headed Chickadee and Boreal Chickadee demographic histories to better understand patterns of effective population size changes and gene flow over time. Introgression of Gray-headed Chickadee nuclear DNA was detected in contemporary and historical Boreal Chickadee populations, and two first-generation hybrid backcrosses were observed in the historical Boreal Chickadee samples. Lack of mitochondrial DNA introgression or backcrossing into the Gray-headed Chickadee historical samples may be an artifact of mate scarcity during the period before local abundances of Boreal Chickadee exceeded Gray-headed Chickadees. Demographic modeling with nuclear loci estimated a low level of symmetric gene flow between Gray-headed Chickadees and Boreal Chickadees since the time of divergence. Our study suggests that hybridization may be linked to Gray-headed Chickadee declines and represents a case study of how museum collections can be used to infer introgression in a population too scarce to directly investigate.

Ecology and Evolution↗

USGS2025

Adoption of non‐related goslings and intergenerational family cohesion among Greenland White‐fronted Geese (Anser albifrons flavirostris)

Greenland White-fronted Geese Anser albifrons flavirostris exhibit prolonged parent–offspring and sibling–sibling associations, suggesting fitness advantages to such behaviour, so we used reduced representation genome sequence data to determine the degree to which marked flock members observed associating in apparent parent–offspring and sibling–sibling relationships in the field were genetically related. Among 50 bled, marked and released geese, we genetically identified members of 11 different family groups, confirming all observed male parent–offspring relationships as genetically predicted, but only 10 out of 12 (83%) possible female parent–offspring relationships (i.e. two offspring were not genetically related to the adult female in their family groups observed in the field); these two ‘adopted’ offspring were responsible for four (15%) of the cases where observed ‘siblings’ were not genetically related to other family-member first-winter birds with which they associated. One multigenerational family consisted of three genetically confirmed grandmother–mother–sibling offspring relationships, not previously reported in arctic-nesting geese, as well as one of the two ‘adopted’ first-winter geese.

Wexford Slobs↗

USGS2024

The complete genome sequence of Splendidofilaria pectoralis (Onchocercidae, Rhabditida, Chromadorea, Nematoda)

We present the complete genome sequence of Splendidofilaria pectoralis, a nematode parasite of grouse (Aves: Galliformes: Tetraonini). Illumina paired-end reads were assembled by a de novo method followed by a finishing step. The raw and assembled data are publicly available via GenBank: Sequence Read Archive (SRR28509439) and assembled genome (JBFSWT000000000).

Biodiversity Genomes↗

USGS2024

Wintering grounds leave their mark: Where birds winter influences genomic structure in Arctic nesting common eiders

Information about the distribution of genomic variation within and between nesting locations of waterfowl can aid in defining populations and conservation plans and inform harvest management. Identification of locations where shifts in allelic diversity occur is particularly important for Arctic nesting species nesting, a region currently experiencing rapid change associated with climate and other factors. Here, we build upon previous investigations on spatial patterns of genetic variation in a largely migratory, circumpolar breeding sea duck, the common eider ( Somateria mollissima ) through inclusion of additional sample locations and genomic markers. We analyzed double-digest restriction site-associated DNA sequences from 309 common eiders to estimate genetic variation within, and differentiation among, 21 nesting locations across North America. Our results corroborate previous evidence of four genetic groups that coincide with colonies that share similar winter areas. We found deeper genomic differences between common eiders wintering in the west (Pacific Ocean) versus the east (Atlantic Ocean and Hudson Bay). We also identified subtle structure, not previously recognized, within Hudson Bay nesting common eiders. Our findings add to evidence linking wintering areas and genomic differentiation in waterfowl, offering further insights for management of this culturally important sea duck species.

Conservation Genetics↗

USGS2024

Where east meets west: Phylogeography of the high Arctic North American brant goose

Genetic variation in Arctic species is often influenced by vicariance during the Pleistocene, as ice sheets fragmented the landscape and displaced populations to low- and high-latitude refugia. The formation of secondary contact or suture zones during periods of ice sheet retraction has important consequences on genetic diversity by facilitating genetic connectivity between formerly isolated populations. Brant geese ( Branta bernicla ) are a maritime migratory waterfowl (Anseriformes) species that almost exclusively uses coastal habitats. Within North America, brant geese are characterized by two phenotypically distinct subspecies that utilize disjunct breeding and wintering areas in the northern Pacific and Atlantic. In the Western High Arctic of Canada, brant geese consist of individuals with an intermediate phenotype that are rarely observed nesting outside this region. We examined the genetic structure of brant geese populations from each subspecies and areas consisting of intermediate phenotypes using mitochondrial DNA (mtDNA) control region sequence data and microsatellite loci. We found a strong east–west partition in both marker types consistent with refugial populations. Within subspecies, structure was also observed at mtDNA while microsatellite data suggested the presence of only two distinct genetic clusters. The Western High Arctic (WHA) appears to be a secondary contact zone for both Atlantic and Pacific lineages as mtDNA and nuclear genotypes were assigned to both subspecies, and admixed individuals were observed in this region. The mtDNA sequence data outside WHA suggests no or very restricted intermixing between Atlantic and Pacific wintering populations which is consistent with published banding and telemetry data. Our study indicates that, although brant geese in the WHA are not a genetically distinct lineage, this region may act as a reservoir of genetic diversity and may be an area of high conservation value given the potential of low reproductive output in this species.

Ecology and Evolution↗

USGS2024

Diversity, distribution, and methodological considerations of haemosporidian infections among Galliformes in Alaska

Using samples spanning 10-degrees of latitude in Alaska, we provide the first comparative assessment of avian haemosporidia distribution of Arctic Alaska with subarctic host populations for four species of grouse and three species of ptarmigan (Galliformes). We found a high overall prevalence for at least one haemospordian genus (88%; N = 351/400), with spruce grouse ( Canachites canadensis ) showing the highest prevalence (100%; N = 54/54). Haemoproteus and Plasmodium lineages were only observed within grouse, while Leucocytozoon species were found within both grouse and ptarmigan. Further, different Leucocytozoon lineages were obtained from blood and tissue samples from the same individual, potentially due to the differential timing and duration of blood and tissue stages. Using different primer sets, we were able to identify different Leucocytozoon lineages within 55% (N = 44/80) of sequenced individuals, thereby detecting coinfections that may have otherwise gone undetected. The commonly used Haemoproteus / Plasmodium primers amplified Leucocytozoon for 90% (N = 103/115) of the products sequenced, highlighting the potential value of alternate primers to identify intra-genus coinfections and the importance of obtaining sequence information rather than relying solely on PCR amplification to assess parasite diversity. Overall, this dataset provides baseline information on parasite lineage distributions to assess the range expansion associated with climate change into Arctic regions and underscores methodological considerations for future studies.

Alaska↗

USGS2023

Movement and genomic methods reveal mechanisms promoting connectivity in a declining shorebird: The lesser yellowlegs

Integrating tracking technology and molecular approaches provides a comprehensive picture of contemporary and evolutionary mechanisms promoting connectivity. We used mitochondrial DNA and double digest restriction-site associated DNA (ddRAD) sequencing combined with satellite telemetry to investigate the connectivity of geographically disparate breeding populations of a declining boreal shorebird, the lesser yellowlegs ( Tringa flavipes ). We were able to track 33 individuals on their round-trip migrations to Central and South America and back to the boreal wetlands of North America. Nearly all (93%) adults captured on the breeding grounds returned to within 5 km of the original capture site, with a median dispersal distance of 629 m. While our telemetry data revealed limited breeding dispersal in adults, genetic data uncovered significant interconnectedness across the species’ range. Very little genetic structure was estimated at ddRAD autosomal ( Φ ST = 0.001), Z-linked ( Φ ST = 0.001), and mtDNA loci ( Φ ST = 0.020), and maximum likelihood-based clustering methods placed all individuals in a single cluster regardless of capture location, indicating the species is panmictic. Our data indicate that large-scale juvenile dispersal is the main mechanism maintaining connectivity in this species, resulting in the absence of genomic structure.

Diversity↗

USGS2022

As the goose flies: Migration routes and timing influence patterns of genetic diversity in a circumpolar migratory herbivore

Migration schedules and the timing of other annual events (e.g., pair formation and molt) can affect the distribution of genetic diversity as much as where these events occur. The greater white-fronted goose ( Anser albifrons ) is a circumpolar goose species, exhibiting temporal and spatial variation of events among populations during the annual cycle. Previous range-wide genetic assessments of the nuclear genome based on eight microsatellite loci suggest a single, largely panmictic population despite up to five subspecies currently recognized based on phenotypic differences. We used double digest restriction-site associated DNA (ddRAD-seq) and mitochondrial DNA (mtDNA) sequence data to re-evaluate estimates of spatial genomic structure and to characterize how past and present processes have shaped the patterns of genetic diversity and connectivity across the Arctic and subarctic. We uncovered previously undetected inter-population differentiation with genetic clusters corresponding to sampling locales associated with current management groups. We further observed subtle genetic clustering within each management unit that can be at least partially explained by the timing and directionality of migration events along with other behaviors during the annual cycle. The Tule Goose ( A. a. elgasi ) and Greenland subspecies ( A. a. flavirostris ) showed the highest level of divergence among all sampling locales investigated. The recovery of previously undetected broad and fine-scale spatial structure suggests that the strong cultural transmission of migratory behavior restricts gene flow across portions of the species’ range. Our data further highlight the importance of re-evaluating previous assessments conducted based on a small number of highly variable genetic markers in phenotypically diverse species.

Circumpolar Arctic↗

USGS2022

Low levels of hybridization between sympatric cold-water-adapted Arctic cod and Polar cod in the Beaufort Sea confirm genetic distinctiveness

As marine ecosystems respond to climate change and other stressors, it is necessary to evaluate current and past hybridization events to gain insight on the outcomes and drivers of such events. Ancestral introgression within the gadids has been suggested to allow cod to inhabit a variety of habitats. Little attention has been given to contemporary hybridization, especially within cold-water-adapted cod ( Boreogadus saida Lepechin, 1774 and Arctogadus glacialis Peters, 1872). We used whole-genome, restriction-site associated, and mitochondrial sequence data to explore the degree and direction of hybridization between these species where previous hybridization had not been reported. Although nearly identical morphologically at certain life stages, we detected very distinct nuclear and mitochondrial lineages. We detected one potential hybrid with a Arctogadus mitochondrial haplotype and Boreogadus nuclear genotype, but no early generational hybrids. The presence of a late generation hybrid suggests that at least some hybrids survive to maturity and reproduce. However, a historical introgression event could not be excluded. Contemporary gene flow appears asymmetrical from Arctogadus into Boreogadus , which may be due to overlap in timing of spawning, environmental heterogeneity, or differences in population size. This study provides important baseline information for the degree of potential hybridization between these species within Alaska marine environments.

Beaufort Sea, Chukchi Sea↗

USGS2022

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 (Φ ST =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.

Alaska↗

USGS2022

Detection of Splendidofilaria sp. (Onchocercidae:Splendidofilariinae) Microfilaria within Alaskan ground-dwelling birds in the grouse subfamily tetraoninae using taqman probe-based real-time PCR

Grouse and ptarmigan (Galliformes) harbor fairly diverse helminth faunas that can impact the host's health, including filarial nematodes in the genus Splendidofilaria . As host and parasite distributions are predicted to shift in response to recent climate change, novel parasites may be introduced into a region and impose additional stressors on bird populations. Limited information is available on the prevalence of filariasis in Alaska galliforms. To date, no molecular surveys have been completed. Past studies relied on examining blood smears or total body necropsies, which are time-consuming and may not detect filarial parasites with low prevalence in hosts. Therefore, we developed a TaqMan probe-based real-time PCR assay targeting the cytochrome c oxidase 1 gene ( COI ) of Splendidofilaria to decrease processing times and increase sensitivity as well as provide baseline data on the diversity of filariid infections in galliform species in Alaska. We screened a combined total of 708 galliform samples (678 unique individual birds) from different tissues (blood, muscle, and lung) for the presence of filarial DNA across the state of Alaska. Real-time PCR screening revealed an overall prevalence of filarial infection of 9.5% across species: Bonasa umbellus (0%, n = 23), Dendragapus fuliginosus (0%, n = 8), Falcipennis canadensis (26.8%, n = 198), Lagopus lagopus (2.6%, n = 274), Lagopus leucura (0%, n = 23), Lagopus muta (3%, n = 166), and Tympanuchus phasianellus (12.5%, n = 16). We observed microfilarial infections throughout most of Alaska except in Arctic regions and the Aleutian Islands where viable vectors may not be present.

Journal of Parasitology↗

USGS2022

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.

Annales Zoologici Fennici↗

USGS2021

Implications of historical and contemporary processes on genetic differentiation of a declining boreal songbird: The rusty blackbird

The arrangement of habitat features via historical or contemporary events can strongly influence genomic and demographic connectivity, and in turn affect levels of genetic diversity and resilience of populations to environmental perturbation. The rusty blackbird ( Euphagus carolinus ) is a forested wetland habitat specialist whose population size has declined sharply (78%) over recent decades. The species breeds across the expansive North American boreal forest region, which contains a mosaic of habitat conditions resulting from active natural disturbance regimes and glacial history. We used landscape genomics to evaluate how past and present landscape features have shaped patterns of genetic diversity and connectivity across the species’ breeding range. Based on reduced-representation genomic and mitochondrial DNA, genetic structure followed four broad patterns influenced by both historical and contemporary forces: (1) an east–west partition consistent with vicariance during the last glacial maximum; (2) a potential secondary contact zone between eastern and western lineages at James Bay, Ontario; (3) insular differentiation of birds on Newfoundland; and (4) restricted regional gene flow among locales within western and eastern North America. The presence of genomic structure and therefore restricted dispersal among populations may limit the species’ capacity to respond to rapid environmental change.

Diversity↗

USGS2020

High site fidelity does not equate to population genetic structure for common goldeneye and Barrow's goldeneye in North America

Delineation of population structure provides valuable information for conservation and management of species, as levels of demographic and genetic connectivity not only affect population dynamics but also have important implications for adaptability and resiliency of populations and species. Here, we measure population genetic structure and connectivity across the ranges of two sister species of sea ducks: Barrow's goldeneye Bucephala islandica and common goldeneye B. clangula . We use two different marker types: 7–8 nuclear microsatellite loci assayed across 229 samples and 3678 double digest restriction‐site associated DNA sequencing (ddRAD‐seq) loci assayed across 61 samples. First, both datasets found no evidence of genetic structure within common or Barrow's goldeneye, including between North American and European samples of common goldeneye. These results are in contrast with previous mitochondrial DNA, band recovery and telemetry data which suggest that goldeneyes are structured across their range. We posit that the discordance between autosomal genetic markers and other data types suggests that males, possibly subadult males, may be maintaining genetic connectivity across each species' respective ranges. Next, although mate choice consequences resulting from inter‐specific brood parasitism was hypothesized to cause some level of gene flow between goldeneye species, we only identified a single F1 hybrid with no further evidence of contemporary or historical gene flow. Despite ddRAD‐seq demographic analyses which recovered an optimum evolutionary model of split‐with‐migration (i.e. secondary contact), estimates of gene flow were <<1 migrant per generation in both directions. Together, we conclude that either strong ecological barriers or assortative mating are likely playing a role in preventing further backcrossing. Finally, demographic analyses estimated a relatively deep divergence time between Barrow's goldeneye and common goldeneye of ~1.6 million years before present and suggests that the genomes of both species have been under similar evolutionary constraints.

Journal of Avian Biology↗

USGS2020

Mitochondrial genome diversity and population mitogenomics of Polar cod (Boreogadus saida) and Arctic dwelling gadoids

High-latitude fish typically exhibit a narrow thermal tolerance window, which may pose challenges when coping with temperatures that shift outside of a species’ range of tolerance. Due to its role in aerobic metabolism and energy balance, the mitochondrial genome is likely critical for the acclimation and adaptation to differing temperature regimes in marine ectotherms. As oceans continue to warm, there is growing need to understand the ability of organisms to respond to changing environmental conditions given evidence that some species, in particular cold-water species, may already be experiencing difficulties. To assess how Arctic gadids in Alaska have responded to differential thermal preferences in the past and how regions are interconnected, we sequenced complete mitochondrial genomes for four Arctic gadids to determine the distribution of mitochondrial diversity and population-level structure as well as to detect signatures of selection acting on the mitochondrial genome. We found little population-level structure within all four species with the clear exception of Gulf of Alaska saffron cod ( Eleginus gracilis ). Northern localities exhibited higher levels of genetic diversity and primarily northern lineages were observed within polar cod ( Boreogadus saida ) and saffron cod, likely reflecting asymmetrical dispersal and potentially admixture of distinct lineages via ocean currents. The main evolutionary force shaping the evolution of the mitogenome appears to be purifying selection, but we also identified potential positive selection of candidate amino acid replacements primarily in complex I (ND genes) in polar cod. The high levels of mitochondrial diversity observed in our study and large population size may provide this species with the ability to respond evolutionarily (i.e. long-term) to a changing environment.

Alaska↗