Inferring the rules of social interaction in migrating caribou

Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa. This article is part of the theme issue ‘Collective movement ecology’

Range expansion of muskox lungworms track rapid arctic warming: implications for geographic colonization under climate forcing

Rapid climate warming in the Arctic results in multifaceted disruption of biodiversity, faunal structure, and ecosystem health. Hypotheses have linked range expansion and emergence of parasites and diseases to accelerating warming globally but empirical studies demonstrating causality are rare. Using historical data and recent surveys as baselines, we explored climatological drivers for Arctic warming as determinants of range expansion for two temperature-dependent lungworms, Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis, of muskoxen (Ovibos moschatus) and caribou (Rangifer tarandus), in the Canadian Arctic Archipelago from 1980 through 2017. Our field data shows a substantial northward shift of the northern edge of the range for both parasites and increased abundance across the expanded ranges during the last decade. Mechanistic models parameterized with parasites’ thermal requirements demonstrated that geographical colonization tracked spatial expansion of permissive environments, with a temporal lag. Subtle differences in life histories, thermal requirements of closely related parasites, climate oscillations and shifting thermal balances across environments influence faunal assembly and biodiversity. Our findings support that persistence of host-parasite assemblages reflects capacities of parasites to utilize host and environmental resources in an ecological arena of fluctuating opportunity (alternating trends in exploration and exploitation) driving shifting boundaries for distribution across spatial and temporal scales

Draft Genome Assembly of an Iconic Arctic Species: Muskox (Ovibos moschatus)

Muskoxen (Ovibos moschatus) are Arctic species within the Caprinae subfamily that are economically and culturally significant to northern Indigenous communities. Low genetic diversity from repeated genetic bottlenecks, coupled with the effects of Arctic warming (e.g., heat stress, changing forage, pathogen range expansions), present conservation concerns for this species. Reference genome assemblies enhance our ecological and evolutionary understanding of species (which in turn aid conservation efforts). Herein, we provide a full draft reference genome of muskox using Illumina Hiseq data and cross-species scaffolding. The final reference assembly yielded a genome of 2,621,890,883 bp in length, a scaffold N50 of ~13.2 million, and an annotation identifying ~19.3 k genes. The muskox genome assembly and annotation were then used to reconstruct a phylogenetic tree which estimated muskoxen diverged from other ungulate species~12 Mya. To gain insight into the demographic history of muskoxen we also performed pairwise sequentially Markovian coalescent (PSMC) that identified two population bottlenecks coinciding with major glaciation events contributing to the notoriously low genetic variation observed in muskoxen. Overall, this genome assembly provides a foundation for future population genomic studies, such as latitudinal analyses, to explore the capacity of muskoxen to adapt to rapidly changing environments

How to be sure to measure all the ammonia in the original samples by infrared spectroscopy / Comment s'assurer de mesurer toute l'ammoniac présente dans un échantillon par spectroscopie infrarouge

Infrared (IR) spectroscopy is used more and more to quantify different substances. Quantitative analysis puts some particular challenges when working with gas samples such as being sure of a calibration, the value of pressure and temperature, the amount of analyte with good precision. While working with different gases, we have observed that ammonia, NH3(g), showed a variable signal with time. Some others observed the same phenomenon. Ammonia presents a particular challenge for quantification with a decreasing signal. We consider this phenomenon as adsorption on the inside walls of the cell; this is not surprising when one considers the polarity of the molecule and the literature based on this behaviour for this gas. A series of experiments were made and quantitative results compared very well with calculations from validated data from the public database HITRAN

A Caribou Decline Foreshadowed by Inuit in the Central Canadian Arctic: A Retrospective Analysis

The Dolphin and Union (DU) caribou herd (Rangifer tarandus groenlandicus x pearyi), locally referred to as Island caribou, is a unique and at-risk ecotype of caribou that ranges on Victoria Island and the adjacent mainland in the central Canadian Arctic. To facilitate the incorporation of traditional knowledge (TK) and better inform the required species recovery plan, we analyzed an archived set of TK interviews done in Ekaluktutiak and Kugluktuk, Nunavut, in 2003. The overarching theme throughout the interviews was that the DU caribou were dynamic, constantly adapting to the changing environment around them. Accounts provided previously unexplored connections between temporal and spatial trends in DU caribou distribution, population, ecology, and disease syndromes. Findings of fewer animals, range shift, and increased observations of disease in the late 1990s and early 2000s suggest that early signs of the declines that have resulted in the herd being reassessed as endangered today were already apparent to Kugluktukmiut in 2003. In contrast, Ekaluktutiakmiut were seeing a stable population. Shifts in caribou range and consequently harvesting ranges were described by both communities, but more evident in Kugluktuk. When combined, the differing accounts of the two communities provided a deeper understanding of caribou ecology and trends across seasons, years, and a broad spatial range. Community differences demonstrate the cruciality of considering unique place-based perspectives and the importance of mobilizing TK from communities and knowledge keepers throughout the caribou range for a herd-level understanding. This study highlights the importance of timely analyses and reporting on TK studies to ensure a nimble conservation response in a rapidly changing environment.  Le troupeau de caribou (Rangifer tarandus groenlandicus x pearyi) de Dolphin-et-Union (DU), couramment appelé, dans cette région, le caribou de l’île, est un écotype de caribou unique et à risque dont l’aire de répartition s’étend sur l’île Victoria et sur la terre ferme adjacente dans le centre de l’Arctique canadien. Afin de faciliter l’intégration des connaissances traditionnelles (CT) et de mieux éclairer le plan nécessaire de rétablissement de l’espèce, nous avons analysé et archivé une série d’entrevues sur les CT réalisées en 2003 à Ekaluktutiak et à Kugluktuk, au Nunavut. Le thème principal qui est ressorti de ces entrevues était que les caribous de DU sont dynamiques et qu’ils s’adaptent continuellement à leur environnement en pleine évolution. Les descriptions obtenues par le passé n’exploraient pas les liens entre les tendances temporelles et spatiales en matière de distribution, de population, d’écologie et de syndromes de maladies caractérisant le caribou de DU. Les constatations indiquant la présence d’un moins grand nombre de bêtes, le décalage de l’aire de répartition et l’observation accrue de maladies vers la fin des années 1990 et le début des années 2000 suggèrent que les signes avant-coureurs de déclin qui ont mené à la réévaluation du troupeau, maintenant considéré comme en voie de disparition, étaient déjà visibles pour les gens de Kugluktuk en 2003. De leur côté, les gens d’Ekaluktutiak étaient témoins d’une population stable. Le décalage de l’aire de répartition du caribou et, par conséquent, des aires de récolte, a été décrit par ces deux collectivités, mais il était plus évident à Kugluktuk. Ensemble, les descriptions divergentes des deux collectivités ont permis de mieux comprendre l’écologie du caribou et les tendances le caractérisant au fil des saisons et des années, sur une vaste répartition spatiale. Les différences enregistrées dans ces collectivités attestent de la grande importance de considérer les perspectives uniques à divers lieux et l’importance de mobiliser les CT des collectivités et des gardiens du savoir à l’échelle de l’aire de répartition du caribou afin de comprendre le troupeau. Cette étude fait ressortir l’importance de produire des analyses ponctuelles et de communiquer les résultats des études des CT afin de donner lieu à une intervention de conservation adroite dans un environnement en évolution rapide.

Morphological keys to advance the understanding of protostrongylid biodiversity in caribou (Rangifer spp.) at high latitudes

The Protostrongylidae is a diverse family of nematodes capable of causing significant respiratory and neuromuscular disease in their ungulate and lagomorph hosts. Establishing the species diversity and abundance of the protostrongylid fauna has been hindered because the first stage larvae, commonly referred as dorsal spined larvae (DSL), that are shed in the feces are morphologically very similar among several genera. We aimed to determine the protostrongylid diversity and distribution in caribou (Rangifer tarandus groenlandicus and R. t. pearyi) in the central and high Canadian Arctic. We first developed, tested and validated a morphological diagnostic guide for the DSL of two important protostrongylids, Parelaphostrongylus andersoni and Varestrongylus eleguneniensis, and then applied this guide to determine the prevalence and intensity of infection of these parasites in fecal samples from 242 caribou. We found that DSL of V. eleguneniensis and P. andersoni can be differentiated morphologically based on the structural differences at the caudal extremity. The presentation and morphology of the dorsal spine, and caudoventral bulging at the start of the tail extension were identified as the key identifying features. The two species were found in caribou on the arctic mainland and southern Victoria Island in single and co-infections, but the prevalence and intensity of infection was low. No protostrongylids were detected in caribou from the high arctic islands. Through this study, we provide a simple, efficient, and robust method to distinguish the DSL of the two protostrongylids, and present the current status of infection in different herds of caribou of the central Canadian Arctic. We report new geographic and host records for P. andersoni infection in Dolphin and Union caribou herd. Keywords: Parelaphostrongylus andersoni, Varestrongylus eleguneniensis, Diagnostic parasitology, Morphological diagnosis, Dorsal spined larvae, Canadian Arctic, Dolphin and Union caribo

A missing piece in the Arctic food web puzzle? Stomach contents of Greenland sharks sampled in Svalbard, Norway

Harbour seals in Svalbard have short longevity, despite being protected from human hunting and having limited terrestrial predation at their haulout sites, low contaminant burdens and no fishery by-catch issues. This led us to explore the diet of Greenland sharks (Somniosus microcephalus) in this region as a potential seal predator. We examined gastrointestinal tracts (GITs) from 45 Greenland sharks in this study. These sharks ranged from 229 to 381 cm in fork length and 136-700 kg in body mass; all were sexually immature. Seal and whale tissues were found in 36. 4 and 18. 2%, respectively, of the GITs that had contents (n = 33). Based on genetic analyses, the dominant seal prey species was the ringed seal (Pusa hispida); bearded seal (Erignathus barbatus) and hooded seal (Cystophora cristata) tissues were each found in a single shark. The sharks had eaten ringed seal pups and adults based on the presence of lanugo-covered prey (pups) and age determinations based on growth rings on claws (≤1 year and adults). All of the whale tissue was from minke whale (Balenoptera acutorostrata) offal, from animals that had been harvested in the whale fishery near Svalbard. Fish dominated the sharks\u27 diet, with Atlantic cod (Gadus morhua), Atlantic wolffish (Anarhichas lupus) and haddock (Melanogrammus aeglefinus) being the most important fish species. Circumstantial evidence suggests that these sharks actively prey on seals and fishes, in addition to eating carrion such as the whale tissue. Our study suggests that Greenland sharks may play a significant predatory role in Arctic food webs. © 2012 Springer-Verlag