Social and genetic connectivity despite ecological variation in a killer whale network.

Philopatric kin-based societies encourage a narrow breadth of conservative behaviours owing to individuals primarily learning from close kin, promoting behavioural homogeneity. However, weaker social ties beyond kin, and across a behaviourally diverse social landscape, could be sufficient to induce variation and a greater ecological niche breadth. We investigated a network of 457 photo-identified killer whales from Norway (548 encounters in 2008-2021) with diet data available (46 mixed-diet individuals feeding on both fish and mammals, and 411 exclusive fish-eaters) to quantify patterns of association within and between diet groups, and to identify underlying correlates. We genotyped a subset of 106 whales to assess patterns of genetic differentiation. Our results suggested kinship as main driver of social bonds within and among cohesive social units, while diet was most likely a consequence reflective of cultural diffusion, rather than a driver. Flexible associations within and between ecologically diverse social units led to a highly connected network, reducing social and genetic differentiation between diet groups. Our study points to a role of social connectivity, in combination with individual behavioural variation, in influencing population ecology in killer whales.

Dietary plasticity and broad North Atlantic origins inferred from bulk and amino acid-specific δ15N and δ13C favour killer whale range expansions into Arctic waters.

Killer whales (Orcinus orca) occur seasonally in the eastern Canadian Arctic (ECA), where their range expansion associated with declining sea ice have raised questions about the impacts of increasing killer whale predation pressure on Arctic-endemic prey. We assessed diet and distribution of ECA killer whales using bulk and compound-specific stable isotope analysis (CSIA) of amino acids (AA) of 54 skin biopsies collected from 2009 to 2020 around Baffin Island, Canada. Bulk ECA killer whale skin δ15N and δ13C values did not overlap with potential Arctic prey after adjustment for trophic discrimination, and instead reflected foraging history in the North Atlantic prior to their arrival in the ECA. Adjusted killer whale stable isotope (SI) values primarily overlapped with several species of North Atlantic baleen whales or tuna. Amino acid (AA)-specific δ15N values indicated the ECA killer whales fed primarily on marine mammals, having similar glutamic acid δ15N-phenylalanine δ15N (δ15NGlx-Phe) and threonine δ15N (δ15NThr) as mammal-eating killer whales from the eastern North Pacific (ENP) that served as a comparative framework. However, one ECA whale grouped with the fish-eating ENP ecotype based δ15NThr. Distinctive essential AA δ13C of ECA killer whale groups, along with bulk SI similarity to killer whales from different regions of the North Atlantic, indicates different populations converge in Arctic waters from a broad source area. Generalist diet and long-distance dispersal capacity favour range expansions, and integration of these insights will be critical for assessing ecological impacts of increasing killer whale predation pressure on Arctic-endemic species.

Assessment of persistent organic pollutants in killer whales (Orcinus orca) of the Canadian Arctic: Implications for subsistence consumption and conservation strategies.

Killer whales (Orcinus orca) historically restricted to certain Arctic regions due to extensive sea ice have recently been documented farther north and for longer durations in the Canadian Arctic. These apex predators accumulate high levels of persistent organic pollutants (POPs). The objective of this study was to evaluate the concentrations and profiles of POPs in killer whales of the Canadian Arctic, thus determining potential risks for Inuit communities if consumed. Biopsies were collected from 33 killer whales across areas of the Canadian Arctic between 2009 and 2021. Significant variability in POP concentrations was observed among whales. The cumulative POP concentrations ranged from 12 to >2270 mg/kg lw, representing ∼200-fold increase from the least to the most contaminated individual. The rank order of concentrations of the top five contaminant classes was ∑DDT, ∑PCB, ∑CHL, ∑Toxaphene, and Dieldrin. Several emerging Arctic contaminants were detected, including chlorpyrifos, endosulfan, pentachloroanisole, and polychlorinated naphthalenes, although at relatively lower concentrations than legacy POPs. Considering the elevated blubber POP levels in killer whales, recommended daily consumption thresholds, established based on human tolerable daily intake (TDI) values, were notably restricted for ∑PCB (<0.14 g), ∑DDT (<6.9 g), ∑CHL (<13 g), dieldrin (<8 g) and heptachlor epoxide (<5 g). Killer whales in the Canadian Arctic exhibited higher POP concentrations than other commonly hunted species such as polar bears, ringed seals, and Arctic char. We acknowledge that a more holistic risk assessment of diet is required to assess the cumulative impacts of contaminant mixtures as well as nutritional quality of tissues commonly consumed by northern communities.

Are periodontitis and dental caries associated? A systematic review with meta-analyses.

AIM: The epidemiological relationship between periodontitis and caries remains controversial, and evidence synthesis is currently lacking. Therefore, this systematic review was designed to answer the following PECO question: 'In human adults (P), do subjects suffering from periodontitis (E) have higher presence/number of untreated carious lesions and caries experience (O) than subjects not suffering from periodontitis (C)?'. MATERIALS AND METHODS: Observational studies that met specific inclusion criteria established to answer to the PECO question were included. Two review authors independently searched for eligible studies, screened the titles and abstracts, carried out the full text analysis, extracted the data and performed the risk of bias assessment. In case of disagreement, a third review author took the final decision during ad hoc consensus meetings. Data synthesis was carried out through random-effects meta-analyses. RESULTS: A total of 18 studies on 21 cohorts, involving 135,018 participants, were included. Meta-analyses showed a significant association between periodontitis and the presence of at least one tooth with either untreated carious lesions (odds ratio [OR] = 1.63; 95% confidence interval [CI]: 1.32-2.01; p <.00; I2 = 83.0%) or caries experience (decayed and filled teeth ≥ 1) (OR = 1.27; 95% CI: 1.01-1.59; p = .038; I2 = 90.0%). Moreover, subjects with periodontitis exhibited a higher number of surfaces (difference in means [MD] = 0.86; 95% CI: 0.46-1.27; p <.001; I2 = 0.0%) and teeth (MD = 0.35; 95% CI: 0.28-0.42; p <.001; I2 = 69.6%) with untreated carious lesions, as well as a higher number of teeth with caries experience (standardized difference in means [SMD] = 1.46; 95% CI: 0.15-2.78; p = .029; I2 = 98.9%) compared with those without periodontitis. Sensitivity analyses focusing on severe periodontitis as exposure mostly showed consistent results. Estimates for caries experience were only slightly attenuated in adjusted models compared with crude models. Subgroup analyses by caries location also indicated that periodontitis was associated only with root caries, while it was not with caries affecting the anatomical crown. CONCLUSIONS: Periodontitis was found to be associated with the presence and number of treated/untreated root carious lesions. Therefore, caries-specific preventive measures (e.g., fluorides) should be considered for individuals with periodontitis.

Association of exposure factors and their causal relationship with oral cancer: A Mendelian randomization study.

OBJECTIVES: There is a strong association among risk factors for oral cancer (ORCA), such as smoking, alcohol consumption, fiber intake, and red meat intake. The apparent synergistic effects reported in previous observational studies may also underestimate the independent effects. Our study aims to further explore the potential etiology and causality of oral cancer. MATERIALS AND METHODS: This study used the genome-wide associations study database (GWAS) in European populations for Mendelian randomization (MR) analysis to explore exposure factors associated with ORCA and detect the genetic causality between these exposures and ORCA risk. RESULTS: Our results demonstrated that in univariate MR analysis, the five exposure factors (celery intake, average weekly beer and cider intake, spirits intake, and pork intake) were risk factors, and oily fish intake was a safety factor, but in multivariate MR analysis, pork intake had the greatest impact on oral cancer when the five food/drink intakes were simultaneously consumed. CONCLUSIONS: The causal relationship between the five exposure factors (oily fish intake, celery intake, pork intake, average weekly beer and cider intake, and spirits intake) and oral cancer was analyzed. The causal effects of pork on oral cancer may be underestimated. CLINICAL RELEVANCE: Prevention of oral cancer requires better education about lifestyle-related risk factors, and improved awareness and tools for early diagnosis. Our study provides some risk factors that cannot be ignored for the cause prevention of oral cancer, such as pork intake, and its role in oral cancer prevention and control.

GUIDE: A GUI for automated quantum chemistry calculations.

The accuracy of quantum mechanics (QM) simulations depends heavily on the quality of initial input files. Despite the popularity of QM simulation packages, achieving precise results still heavily relies on the user's proficiency in preparing the QM simulation systems. In this work, we present an easy-to-use tool called GUIDE, a YASARA plugin to assist researchers in quantum chemistry workflow automation using ORCA and MOPAC simulation packages. GUIDE lets users compute complex QM calculation workflows via an automated graphical window system. It allows for a more integrated and streamlined research process, as researchers can easily access all the necessary tools within one software without switching between multiple programs. This tool can save time and increase efficiency in computational chemistry methods. GUIDE is written in Python and is freely available for download at https://github.com/YAMACS-SML/GUIDE. The plugin is released under a GPL-3.0 license and is supported on Windows and Linux.

Temporal dynamics of mother-offspring relationships in Bigg's killer whales: opportunities for kin-directed help by post-reproductive females.

Age-related changes in the patterns of local relatedness (kinship dynamics) can be a significant selective force shaping the evolution of life history and social behaviour. In humans and some species of toothed whales, average female relatedness increases with age, which can select for a prolonged post-reproductive lifespan in older females due to both costs of reproductive conflict and benefits of late-life helping of kin. Killer whales (Orcinus orca) provide a valuable system for exploring social dynamics related to such costs and benefits in a mammal with an extended post-reproductive female lifespan. We use more than 40 years of demographic and association data on the mammal-eating Bigg's killer whale to quantify how mother-offspring social relationships change with offspring age and identify opportunities for late-life helping and the potential for an intergenerational reproductive conflict. Our results suggest a high degree of male philopatry and female-biased budding dispersal in Bigg's killer whales, with some variability in the dispersal rate for both sexes. These patterns of dispersal provide opportunities for late-life helping particularly between mothers and their adult sons, while partly mitigating the costs of mother-daughter reproductive conflict. Our results provide an important step towards understanding why and how menopause has evolved in Bigg's killer whales.

Orcas remember what to copy: a deferred and interference-resistant imitation study.

Response facilitation has often been portrayed as a "low level" category of social learning, because the demonstrator's action, which is already in the observer's repertoire, automatically triggers that same action, rather than induces the learning of a new action. One way to rule out response facilitation consists of introducing a delay between the demonstrator's behavior and the observer's response to let their possible effects wear off. However, this may not rule out "delayed response facilitation" in which the subject could be continuously "mentally rehearsing" the demonstrated actions during the waiting period. We used a do-as-the-other-did paradigm in two orcas to study whether they displayed cognitive control regarding their production of familiar actions by (1) introducing a delay ranging from 60 to 150 s between observing and producing the actions and (2) interspersing distractor (non-target) actions performed by the demonstrator and by the subjects during the delay period. These two manipulations were aimed at preventing the mental rehearsal of the observed actions during the delay period. Both orcas copied the model's target actions on command after various delay periods, and crucially, despite the presence of distractor actions. These findings suggest that orcas are capable of selectively retrieving a representation of an observed action to generate a delayed matching response. Moreover, these results lend further support to the proposal that the subjects' performance relied not only on a mental representation of the specific actions that were requested to copy, but also flexibly on the abstract and domain general rule requested by the specific "copy command". Our findings strengthen the view that orcas and other cetaceans are capable of flexible and controlled social learning.

Quantitative fatty acid signature analysis reveals a high level of dietary specialization in killer whales across the North Atlantic.

Quantifying the diet composition of apex marine predators such as killer whales (Orcinus orca) is critical to assessing their food web impacts. Yet, with few exceptions, the feeding ecology of these apex predators remains poorly understood. Here, we use our newly validated quantitative fatty acid signature analysis (QFASA) approach on nearly 200 killer whales and over 900 potential prey to model their diets across the 5000 km span of the North Atlantic. Diet estimates show that killer whales mainly consume other whales in the western North Atlantic (Canadian Arctic, Eastern Canada), seals in the mid-North Atlantic (Greenland), and fish in the eastern North Atlantic (Iceland, Faroe Islands, Norway). Nonetheless, diet estimates also varied widely among individuals within most regions. This level of inter-individual feeding variation should be considered for future ecological studies focusing on killer whales in the North Atlantic and other oceans. These estimates reveal remarkable population- and individual-level variation in the trophic ecology of these killer whales, which can help to assess how their predation impacts community and ecosystem dynamics in changing North Atlantic marine ecosystems. This new approach provides researchers with an invaluable tool to study the feeding ecology of oceanic top predators.

Connaître en détails la composition du régime alimentaire des grands prédateurs marins tels que les orques (Orcinus orca) est primordial afin d'évaluer leurs impacts sur les écosystèmes. Pourtant, à quelques exceptions près, l'écologie alimentaire de ces super-prédateurs reste mal comprise. Ici, nous utilisons notre nouvelle approche d'analyse quantitative des signatures d'acides gras (QFASA) sur près de 200 orques et plus de 900 proies potentielles pour modéliser leur régime alimentaire à travers l'Atlantique Nord. Les estimations de leurs régimes alimentaires montrent que les orques consomment principalement d'autres baleines dans l'ouest de l'Atlantique Nord (Arctique canadien, Est du Canada), des phoques dans le milieu de l'Atlantique Nord (Groenland) et des poissons dans l'est de l'Atlantique Nord (Islande, îles Féroé, Norvège). Néanmoins, ces estimations varient considérablement d'un individu à l'autre dans la plupart des régions. Cette variation alimentaire importante entre les individus doit être prise en compte dans les futures études écologiques qui s'intéressent aux orques de l'Atlantique Nord et d'ailleurs. Ces estimations révèlent des variations remarquables dans l'écologie trophique des orques tant au niveau des population que de l'individu, ce qui peut aider à évaluer l'impact de leur prédation sur la dynamique des communautés et des écosystèmes dans un contexte de changements climatiques en l'Atlantique Nord. Cette nouvelle approche fournit aux chercheurs un outil inestimable pour étudier l'écologie alimentaire des super-prédateurs océaniques.

Varying Diet Composition Causes Striking Differences in Legacy and Emerging Contaminant Concentrations in Killer Whales across the North Atlantic.

Lipophilic persistent organic pollutants (POPs) tend to biomagnify in food chains, resulting in higher concentrations in species such as killer whales (Orcinus orca) feeding on marine mammals compared to those consuming fish. Advancements in dietary studies include the use of quantitative fatty acid signature analysis (QFASA) and differentiation of feeding habits within and between populations of North Atlantic (NA) killer whales. This comprehensive study assessed the concentrations of legacy and emerging POPs in 162 killer whales from across the NA. We report significantly higher mean levels of polychlorinated biphenyls (PCBs), organochlorine pesticides, and flame retardants in Western NA killer whales compared to those of Eastern NA conspecifics. Mean ∑PCBs ranged from ∼100 mg/kg lipid weight (lw) in the Western NA (Canadian Arctic, Eastern Canada) to ∼50 mg/kg lw in the mid-NA (Greenland, Iceland) to ∼10 mg/kg lw in the Eastern NA (Norway, Faroe Islands). The observed variations in contaminant levels were strongly correlated with diet composition across locations (inferred from QFASA), emphasizing that diet and not environmental variation in contaminant concentrations among locations is crucial in assessing contaminant-associated health risks in killer whales. These findings highlight the urgency for implementing enhanced measures to safely dispose of POP-contaminated waste, prevent further environmental contamination, and mitigate the release of newer and potentially harmful contaminants.

Killer whale innovation: teaching animals to use their creativity upon request.

Thinking flexibly is a skill that enables animals to adapt to changing environments, which enhances survival. Killer whales, Orcinus orca, as the ocean apex predator display a number of complex cognitive abilities, especially flexible thinking or creativity when it comes to foraging. In human care, smaller dolphins and other marine mammals have been trained to think creatively while under stimulus control. The results of these previous studies have demonstrated that bottlenose dolphins, Tursiops truncatus, can create original behaviors in response to an innovative cue. We trained and tested a total of nine killer whales from two different facilities on the innovate concept, using the same methodology. The killer whales ranged in age from 5 to 29 yrs with 4 females and 5 males. The results indicate that the killer whales demonstrated high fluency, originality, some elaboration, and flexibility in their behaviors. Individual variability was observed with younger animals demonstrating more variable behaviors as compared to the older animals. Males seemed to display less complex and lower energy behaviors as compared to females, but this impression may be driven by the age or size of the animal. These results support existing evidence that killer whales are dynamic in their thinking and behavior.

Assessing social structure: a data-driven approach to define associations between individuals.

Our interpretation of animal social structures is inherently dependent on our ability to define association criteria that are biologically meaningful. However, association thresholds are often based upon generalized preconceptions of a species' social behaviour, and the impact of using these arbitrary definitions has been largely overlooked. In this study we suggest a probability-based method for defining association thresholds using lagged identification rates on photographic records of identifiable individuals. This technique uses a simple model of emigration/immigration from photographable clusters to identify the time-dependent lag value between identifications of two individuals that corresponds to approximately 75% probability of being in close spatial proximity and likely associating. This lag value is then used as the threshold to define associations for social analyses. We applied the technique to a dataset of northern resident killer whales (Orcinus orca) in the Northeast Pacific and tested its performance against two arbitrary thresholds. The probabilistic association maximized the variation in association strengths at different levels of the social structure, in line with known social patterns in this population. Furthermore, variability in inferred social structure metrics generated by different association criteria highlighted the consequential effect of choosing arbitrary thresholds. Data-driven association thresholds are a promising approach to study populations without the need to subjectively define associations in the field, especially in societies with prominent fission-fusion dynamics. This method is applicable to any dataset of sequential identifications where it can be assumed that associated individuals will tend to be identified in close proximity. Supplementary Information: The online version contains supplementary material available at 10.1007/s42991-022-00231-9.

Age and sex influence social interactions, but not associations, within a killer whale pod.

Social structure is a fundamental aspect of animal populations. In order to understand the function and evolution of animal societies, it is important to quantify how individual attributes, such as age and sex, shape social relationships. Detecting these influences in wild populations under natural conditions can be challenging, especially when social interactions are difficult to observe and broad-scale measures of association are used as a proxy. In this study, we use unoccupied aerial systems to observe association, synchronous surfacing, and physical contact within a pod of southern resident killer whales (Orcinus orca). We show that interactions do not occur randomly between associated individuals, and that interaction types are not interchangeable. While age and sex did not detectably influence association network structure, both interaction networks showed significant social homophily by age and sex, and centrality within the contact network was higher among females and young individuals. These results suggest killer whales exhibit interesting parallels in social bond formation and social life histories with primates and other terrestrial social mammals, and demonstrate how important patterns can be missed when using associations as a proxy for interactions in animal social network studies.

Runs of homozygosity in killer whale genomes provide a global record of demographic histories.

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 length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage. We first reconstructed demographic history for each population as changes in effective population size through time using the pairwise sequential Markovian coalescent (PSMC) method. We found a subset of populations declined in effective population size during the Late Pleistocene, while others had more stable demography. Genomes inferred to have undergone ancestral declines in effective population size, were autozygous at hundreds of short ROH (<1 Mb), reflecting high background relatedness due to coalescence of haplotypes deep within the pedigree. In contrast, longer and therefore younger ROH (>1.5 Mb) were found in low latitude populations, and populations of known conservation concern. These include a Scottish killer whale, for which 37.8% of the autosomes were comprised of ROH >1.5 Mb in length. The fate of this population, in which only two adult males have been sighted in the past five years, and zero fecundity over the last two decades, may be inextricably linked to its demographic history and consequential inbreeding depression.

First confirmed reports of the isolation of Brucella ceti from a Risso's dolphin Grampus griseus and a killer whale Orcinus orca.

Brucella ceti has been recovered from a number species of cetaceans worldwide over the last 25 yr. Here we report, for the first time, the recovery of B. ceti from a Risso's dolphin Grampus griseus and a killer whale Orcinus orca. Recovery from an abdominal mass in the dolphin provides further evidence of the systemic pathogenic potential for B. ceti infection in cetaceans. The isolation of B. ceti ST23 (porpoise cluster) from a killer whale from a group known to eat other marine mammals raises the possibility of infection via ingestion. This report takes the number of cetacean species in UK coastal waters from which B. ceti has been isolated to 11 and highlights the value of routine, comprehensive and specific screening for significant pathogens such as Brucella sp. by strandings networks.

Genetic identification of Anisakis spp. (Nematoda: Anisakidae) from cetaceans of the Southwestern Atlantic Ocean: ecological and zoogeographical implications.

Adult Anisakis Dujardin, 1845 were found in two specimens of killer whale Orcinus orca and one specimen of franciscana Pontoporia blainvillei stranded from off the coast of Buenos Aires Province, Argentina. Genetic identification of the nematodes (N = 144) was performed by sequence analysis of the mitochondrial (mtDNA cox2) and the nuclear (nas 10 nDNA) gene loci. Anisakis pegreffii and Anisakis berlandi were detected in the two individuals of O. orca, while Anisakis typica and A. pegreffii were identified in P. blainvillei. Morphological and morphometric analysis also carried out on adult specimens of A. pegreffii and A. berlandi has allowed to underlining the usefulness of genetic/molecular markers in their recognition. This represents the first record of A. pegreffii in O. orca and P. blainvillei and of A. berlandi in O. orca. This is also the first sympatric and syntopic occurrence, as adults, of A. pegreffii and A. berlandi from the Austral Region of the Atlantic Ocean waters. These results provide insights into the knowledge of the host ranges and geographical distribution of these parasites in the basin waters of the region. Pontoporia blainvillei showed low abundance values of infection with Anisakis spp., which is the general pattern for coastal dolphins in the area, whereas O. orca harboured higher abundance of Anisakis spp. than those previously recorded among cetacean species in the Argentine Sea. Differences in the Anisakis spp. distribution and their parasitic loads, observed among the three host specimens, are discussed in relation to the oceanographic parameters, as well as to the host ecology. The usefulness of genetic/molecular markers in the recognition of adults of the sibling species A. pegreffii and A. berlandi with considerable overlapping in morphometric and morphological characters was underlined. The distribution of Anisakis species from Southwestern Atlantic waters is discussed in relation to their value as indicators for studies on the zoogeography of their hosts at a regional-scale level.

Behavioral context of echolocation and prey-handling sounds produced by killer whales (Orcinus orca) during pursuit and capture of Pacific salmon (Oncorhynchus spp.).

Availability of preferred salmonid prey and a sufficiently quiet acoustic environment in which to forage are critical to the survival of resident killer whales (Orcinus orca) in the northeastern Pacific. Although piscivorous killer whales rely on echolocation to locate and track prey, the relationship between echolocation, movement, and prey capture during foraging by wild individuals is poorly understood. We used acoustic biologging tags to relate echolocation behavior to prey pursuit and capture during successful feeding dives by fish-eating killer whales in coastal British Columbia, Canada. The significantly higher incidence and rate of echolocation prior to fish captures compared to afterward confirms its importance in prey detection and tracking. Extremely rapid click sequences (buzzes) were produced before or concurrent with captures of salmon at depths typically exceeding 50 m, and were likely used by killer whales for close-range prey targeting, as in other odontocetes. Distinctive crunching and tearing sounds indicative of prey-handling behavior occurred at relatively shallow depths following fish captures, matching concurrent observations that whales surfaced with fish prior to consumption and often shared prey. Buzzes and prey-handling sounds are potentially useful acoustic signals for estimating foraging efficiency and determining if resident killer whales are meeting their energetic requirements.

Suitability Analysis of Acoustic Refugia for Endangered Killer Whales (Orcinus orca) Using the GIS-based Logic Scoring of Preference Method.

An emerging priority in marine noise pollution research is identifying marine "acoustic refugia" where noise levels are relatively low and good-quality habitat is available to acoustically sensitive species. The endangered Southern Resident population of killer whales (Orcinus orca) that inhabits the transboundary Salish Sea in Canada and the USA are affected by noise pollution. Geographic Information Systems (GIS) and spatial multicriteria evaluation (MCE) methods have been used to operationalize suitability analysis in ecology and conservation for site selection problems. However, commonly used methods lack the ability to represent complex logical relationships between input criteria. Therefore, the objective of this study is to apply a more advanced MCE method, known as Logic Scoring of Preference (LSP), to identify acoustic refugia for killer whales in the Salish Sea. This GIS-based LSP-MCE approach considers multiple input criteria by combining input data representing killer whale habitat requirements with noise pollution and other factors to identify suitable acoustic refugia. The results indicate the locations of suitable acoustic refugia and how they are affected by noise pollution from marine vessels in three scenarios developed to represent different levels of vessel traffic. Identifying acoustic refugia can contribute to efforts to reduce the effect of marine noise pollution on killer whale populations by highlighting high-priority areas in which to implement policies such as traffic-limiting measures or marine protected areas. Moreover, the proposed LSP-MCE procedure combines criteria in a stepwise manner that can support environmental management decision-making processes and can be applied to other marine suitability analysis contexts.

The Oscillatory ReConstruction Algorithm adaptively identifies frequency bands to improve spectral decomposition in human and rodent neural recordings.

Neural oscillations are routinely analyzed using methods that measure activity in fixed frequency bands (e.g., alpha, 8-12 Hz), although the frequency of neural signals varies within and across individuals based on numerous factors including neuroanatomy, behavioral demands, and species. Furthermore, band-limited activity is an often assumed, typically unmeasured model of neural activity, and band definitions vary considerably across studies. Together, these factors mask individual differences and can lead to noisy spectral estimates and interpretational problems when linking electrophysiology to behavior. We developed the Oscillatory ReConstruction Algorithm ("ORCA"), an unsupervised method to measure the spectral characteristics of neural signals in adaptively identified bands, which incorporates two new methods for frequency band identification. ORCA uses the instantaneous amplitude, phase, and frequency of activity in each band to reconstruct the signal and directly quantify spectral decomposition performance using each of four different models. To reduce researcher bias, ORCA provides spectral estimates derived from the best model and requires minimal hyperparameterization. Analyzing human scalp EEG data during eyes-open and eyes-closed "resting" conditions, we first identify variability in the frequency content of neural signals across subjects and electrodes. We demonstrate that ORCA significantly improves spectral decomposition compared with conventional methods and captures the well-known increase in low-frequency activity during eye closure in electrode- and subject-specific frequency bands. We further illustrate the utility of our method in rodent CA1 recordings. ORCA is a novel analytic tool that allows researchers to investigate how nonstationary neural oscillations vary across behaviors, brain regions, individuals, and species.NEW & NOTEWORTHY Neural oscillations show substantial variability within and across individuals and brain regions, yet most existing studies analyze oscillations using canonical, fixed-frequency bands. Thus, there is an ongoing need for tools that capture oscillatory variability in neural signals. Toward this end, Oscillatory ReConstruction Algorithm is a novel and adaptive analytic tool that allows researchers to measure neural oscillations with more precision and less researcher bias.

Cultural specialization and genetic diversity: Killer whales and beyond.

Culturally-transmitted ecological specialization can reduce niche breadths with demographic and ecological consequences. I use agent-based models, grounded in killer whale biology, to investigate the potential consequences of cultural specialization for genetic diversity. In these models, cultural specialization typically reduces the number of mitochondrial haplotypes, mitochondrial haplotype diversity, mitochondrial nucleotide diversity, and heterozygosity at nuclear loci. The causal route of this decline is mostly indirect, being ascribed to a reduction in absolute population size resulting from cultural specialization. However, small group size exacerbates the decline in genetic diversity, presumably because of increased founder effects at the initiation of each cultural ecotype. These results are concordant with measures of low genetic diversity in the killer whale, although culturally-transmitted ecological specialization alone might not be sufficient to fully account for the species' very low mitochondrial diversity. The process may also operate in other species.