Admixture is the exchange of genetic variation between differentiated demes, resulting in ancestry within a population coalescing in multiple ancestral source populations. Low‐latitude killer whales ( Orcinus orca ) populations typically have higher genetic diversity than those in more densely populated, high productivity and high‐latitude regions. This has been hypothesized to be due to episodic admixture between populations...

Aim During glacial periods, highly mobile species often shifted to warmer, ice‐free regions known as refugia, which frequently maintained higher genetic diversity than newly colonised areas after glacial retreat. We analyse complete mitogenome sequences from 11 killer whale samples in Nemuro Strait to test the hypothesis that waters around Japan may have preserved a refugial population of killer whales that retained historical...

Reference genomes from representative species across families provide the critical infrastructure for research and conservation. The Cetacean Genomes Project (CGP) began in early 2020 to facilitate the generation of near error-free, chromosome-resolved reference genomes for all cetacean species. Towards that goal, and using the methods, goals and genome assembly quality standards of the Vertebrate Genomes Project (VGP), we gen...

Chromosomal inversions can play an important role in divergence and reproductive isolation by building and maintaining distinct allelic combinations between evolutionary lineages. Alternatively, they can take the form of balanced polymorphisms that segregate within populations until one arrangement becomes fixed. Many questions remain about how inversion polymorphisms arise, how they are maintained over the long term, and ulti...

The Arctic is the fastest‐warming region on the planet, and the lengthening ice‐free season is opening Arctic waters to sub‐Arctic species such as the killer whale ( Orcinus orca ). As apex predators, killer whales can cause significant ecosystem‐scale changes. Setting conservation priorities for killer whales and their Arctic prey species requires knowledge of their evolutionary history and demographic trajectory. Using whole...

Establishment of microbial communities in neonatal calves is vital for their growth and overall health. While this process has received considerable attention for bacteria, our knowledge on temporal progression of anaerobic gut fungi (AGF) in calves is lacking. Here, we examined AGF communities in faecal samples from six dairy cattle collected at 24 different time points during the pre‐weaning (days 1–48), weaning (days 48–60)...

Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale ( Orcinus orca ) demographic history is reflected in genome‐wide heterozygosity and ROH l...

Practical biodiversity conservation relies on delineation of biologically meaningful units. Manta and devil rays (Mobulidae) are threatened worldwide, yet morphological similarities and a succession of recent taxonomic changes impede the development of an effective conservation strategy. Here, we generate genome‐wide single nucleotide polymorphism (SNP) data from a geographically and taxonomically representative set of manta a...

Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree‐like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to...

Recent exploration into the interactions and relationship between hosts and their microbiota has revealed a connection between many aspects of the host's biology, health and associated micro‐organisms. Whereas amplicon sequencing has traditionally been used to characterize the microbiome, the increasing number of published population genomics data sets offers an underexploited opportunity to study microbial profiles from the h...

Mitochondrial DNA has been heavily utilized in phylogeography studies for several decades. However, underlying patterns of demography and phylogeography may be misrepresented due to coalescence stochasticity, selection, variation in mutation rates and cultural hitchhiking (linkage of genetic variation to culturally‐transmitted traits affecting fitness). Cultural hitchhiking has been suggested as an explanation for low genetic...

Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely distributed of marine mammals, the killer whale ( Orcinus orca ), using a global data set of over...

Invasive plants provide ample opportunity to study evolutionary shifts that occur after introduction to novel environments. However, although genetic characters pre‐dating introduction can be important determinants of later success, large‐scale investigations of historical genetic structure have not been feasible. Common ragweed ( A mbrosia artemisiifolia L .) is an invasive weed native to N orth A merica that is known for its...

Epidermal skin samples from eastern North Atlantic killer whales, Orcinus orca , were analyzed for carbon and nitrogen stable isotope ratios. From those, comparisons within a data set of 17 samples collected from Tysfjord, Norway, in November suggested that diet is relatively specialized during this time period at this location. There were significant differences between a small set of samples from Iceland and those collected...