T.M. Burg’s research while affiliated with University of Lethbridge and other places

A small colony of black-browed albatrosses (Thalassarche melanophris, 21–65 breeding pairs) was discovered in 2003 on Albatross Islet, Tierra del Fuego, Chile. The formation of new breeding sites is important from an ecological and evolutionary perspective. This colony is particularly significant because it is the only one recorded for the species in a land-locked area. As its population dynamics could be shaped by stochastic and other factors affecting small populations, understanding the variables influencing its persistence, such as source of breeders, is crucial. Here, we used genetic markers (mitochondrial control region) to determine the origin of individuals at this new breeding site. Our results show that the new colony is an even mix of birds from Chilean colonies to the south and west (52%) and Falklands/Malvinas birds to the east (48%). Understanding the unique characteristics of this colony provides valuable insights for the conservation of black-browed albatrosses given increasing anthropogenic and environmental changes.

Many species-at-risk reach the edge of their range as disjunct and isolated populations. These peripheral populations may harbour unique genetic diversity crucial for future range shifts, or they may lack genetic diversity due to isolation or small population size. As such it is important to assess the genetic diversity and differentiation of these populations. We used 1,838 SNPs to evaluate the differentiation and genetic diversity in six Canadian (peripheral) and eight US (core) populations of wood-poppy (Stylophorum diphyllum), a perennial wildflower that is endangered at the northern limit of its range. We also compared these 14 populations to seeds from two commercial seed providers to determine if commercial sources are introgressing into wild populations. We found strong differentiation between core and peripheral populations, low levels of gene flow among both core and peripheral populations, and low to moderate levels of genetic diversity across the range with a decrease in heterozygosity in peripheral populations. We also noted that the commercial populations were genetically distinct from all natural sampled populations, with no evidence of introgression between commercial seeds and either Canadian or US populations. Our study indicates that peripheral and core populations form unique conservation units and therefore the conservation and recovery of the wood-poppy in Canada is necessary to conserve the full range of genetic diversity within the species.

Incidental mortality in fisheries is a major driver of population declines for albatrosses and petrels globally. However, accurate identification of species can be difficult due to the poor condition of bycaught birds and/or visual similarities between closely related species. We assessed three genetic markers for their ability to distinguish the 36 albatross and petrel species listed in Annex 1 to the Agreement on the Conservation of Albatrosses and Petrels (ACAP) and in Australia's Threat Abatement Plan (TAP) for the bycatch of seabirds during oceanic longline fishing operations. We generated 275 new sequences, from 29 species, to improve the coverage of reference databases for these listed species. The combined use of the selected Cytochrome b and Control Region markers enabled the identification of 31 of 36 listed seabirds to species level and four to sister species. One petrel species could not be evaluated as no reference sequences were available. We tested these markers on 59 feathers from bycaught seabirds and compared these to onboard visual identification. We successfully assigned all procellariiforms to species (n = 58), whereas only two seabirds were correctly identified to species visually onboard, highlighting the difficulty of visual species assignment and the need for alternative methods. We assessed the utility of our two chosen markers for the assignment of all procellariiform species, with 74% of species with reference sequences identified to species or sister species level. However, a precautionary approach is needed for application beyond our listed species due to unvalidated reference sequences. The approach described here provides a streamlined framework for the molecular identification of seabird bycatch. This approach is recommended for use in fisheries within and outside Australian waters to improve the resolution of bycatch reporting and to corroborate logbook entries, observer reports and audits of images captured by electronic monitoring systems as well as help inform conservation efforts.

The southern oceans are home to a large variety of organisms, including many endemic species. High levels of endemism are due in part to non-physical barriers limiting gene flow in marine species. The sooty albatross Phoebetria fusca is an endangered seabird breeding on seven island groups in Atlantic and Indian Oceans. We sequenced the mitochondrial control region (55 birds) and genotyped 10 microsatellite markers (88 birds) to examine the population genetics of sooty albatrosses from Tristan da Cunha and Gough Island (Atlantic Ocean), and Marion Island, Île de la Possession (Crozet) and Amsterdam Island (Indian Ocean), which together support > 99% of the global population. We also analysed the bill sulcus colouration and quantified stable isotope composition of body feathers of breeding adults from Gough and Marion Islands. Both genetic markers identified two clusters separating sooty albatrosses breeding in the Atlantic and Indian Ocean basins. Standardized colour analysis also separated populations in the two ocean basins and revealed the sulcus of sooty albatrosses on Gough Island is significantly more yellow than individuals on Marion Island. Stable isotope analysis of body feathers showed significantly higher δ¹³C values from Marion sooty albatrosses compared to Gough conspecifics, indicating different moulting areas. Sooty albatrosses breeding on islands in the two ocean basins differ from each other in their genetics, morphology and ecological preferences. Accordingly, it is recommended that separate conservation management plans be implemented for sooty albatrosses breeding in each ocean basin to prevent the loss of evolutionarily significant units.

Animals are strongly connected to the environments they live in and may become adapted to local environments. Examining genetic–environment associations of key indicator species, like seabirds, provides greater insights into the forces that drive evolution in marine systems. Here we examined a RADseq dataset of 19,213 SNPs for 99 rhinoceros auklets (Cerorhinca monocerata) from five western Pacific and 10 eastern Pacific breeding colonies. We used partial redundancy analyses to identify candidate adaptive loci and to quantify the effects of environmental variation on population genetic structure. We identified 262 candidate adaptive loci, which accounted for 3.0% of the observed genetic variation among western Pacific and eastern Pacific breeding colonies. Genetic variation was more strongly associated with pH and maximum current velocity, than maximum sea surface temperature. Genetic–environment associations explain genetic differences between western and eastern Pacific populations; however, genetic variation within the western and eastern Pacific Ocean populations appears to follow a pattern of isolation‐by‐distance. This study represents a first to quantify the relationship between environmental and genetic variation for this widely distributed marine species and provides greater insights into the evolutionary forces that act on marine species.

Understanding how both contemporary and historical physical barriers influence gene flow is key to reconstructing evolutionary histories and can allow us to predict species' resilience to changing environmental conditions. During the last glacial maximum (LGM), many high latitude North American bird species were forced into glacial refugia, including mountain bluebirds (Silia currucoides). Within their current breeding range, mountain bluebirds still experience a wide variety of environmental conditions and barriers that may disrupt gene flow and isolate populations. Using single nucleotide polymorphisms (SNPs) obtained through restriction site‐associated DNA sequencing, we detected at least four genetically distinct mountain bluebird populations. Based on this structure, we determined that isolation‐by‐distance, the northern Rocky Mountains, and discontinuous habitat are responsible for the low connectivity and the overall history of each population going back to the last glacial maximum. Finally, we identified five candidate genes under balancing selection and three loci under diversifying selection. This study provides the first look at connectivity and gene flow across the range of these high‐altitude and high latitude songbirds.

Differences in life history can cause co-distributed species to display discordant population genetic patterns. In high-latitude animals, evolutionary processes may be especially influenced by long-distance seasonal migration, a widespread adaptation to seasonality. Although migratory movements are intuitively linked to dispersal, their evolutionary genetic consequences remain poorly understood. Using ∼1700 genomes from 35 co-distributed boreal-breeding bird species, we reveal that most long-distance migrants exhibit spatial genetic structure, revealing evolutionary effects of philopatry rather than dispersal. We further demonstrate that migration distance and genetic diversity are strongly positively correlated in our study species. This striking relationship suggests that the adaptive seasonal shifts in biogeography that long-distance migratory species undergo each year lends them enhanced population stability that preserves genetic diversity relative to shorter-distance migrants that winter at higher latitudes. Our results suggest that the major impact of long-distance seasonal migration on population genetic evolution occurs through promotion of demographic stability, rather than facilitation of dispersal.

Species reintroductions have the potential to cause genetic bottleneck events resulting in increased genetic drift, increased inbreeding, and reduced genetic diversity creating negative fitness consequences for populations. Roosevelt elk (Cervus canadensis roosevelti Erxleben, 1777) are “at risk” in British Columbia (BC), Canada. Once widespread along the west coast, Roosevelt elk were likely extirpated from the mainland by 1900 and experienced a substantial population bottleneck on Vancouver Island at that time, and again in the 1950s. Reintroduced to the mainland from Vancouver Island in the 1980s, this re-established population became the source for subsequent mainland translocations. To understand the effects of reintroduction strategy on genetic diversity, we analyzed genetic variation in 355 Roosevelt elk from Vancouver Island and mainland BC. Using mitochondrial DNA and 10 microsatellite loci, molecular analyses showed overall reduced genetic diversity relative to other extant elk populations, genetic isolation of the southern Vancouver Island population, and increased genetic drift among reintroduced herds. Four reintroduced populations were found to have increased levels of inbreeding. Results of this study contribute to our knowledge of reintroduction biology and can be used to guide continued conservation and management of at-risk species.