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The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world.

Disability measures in multiple sclerosis (MS) rely heavily on ambulatory function, and current metrics fail to capture potentially important variability in walking behavior. We sought to determine whether remote step count monitoring using a consumer-friendly accelerometer (Fitbit Flex) can enhance MS disability assessment. 99 adults with relapsing or progressive MS able to walk ≥2-min were prospectively recruited. At 4 weeks, study retention was 97% and median Fitbit use was 97% of days. Substudy validation resulted in high interclass correlations between Fitbit, ActiGraph and manual step count tally during a 2-minute walk test, and between Fitbit and ActiGraph (ICC = 0.76) during 7-day home monitoring. Over 4 weeks of continuous monitoring, daily steps were lower in progressive versus relapsing MS (mean difference 2546 steps, p

The Neoproterozoic Era was an interval characterized by profound environmental and biological transitions. Existing age models for Neoproterozoic nonglacial intervals largely have been based on correlation of carbonate carbon isotope values, but there are few tests of the assumed synchroneity of these records between basins. In contrast to the ash-poor successions typically targeted for Neoproterozoic chemostratigraphy, the Tonian to Cryogenian Tambien Group (Tigray region, Ethiopia) was deposited in an arc-proximal basin where volcanic tuffs suitable for U-Pb geochronology are preserved within the mixed carbonate-siliciclastic sedimentary succession. The Tambien Group culminates in a diamictite interpreted to correlate to the ca. 717–662 Ma Sturtian snowball Earth glaciation. New physical stratigraphic data and high-precision U-Pb dates from intercalated tuffs lead to a new stratigraphic framework for the Tambien Group that confirms identification of negative δ13C values from Assem Formation limestones with the ca. 800 Ma Bitter Springs carbon isotope stage. Integration with data from the Fifteenmile Group of northwestern Canada constitutes a positive test for the global synchroneity of the Bitter Spring Stage and constrains the stage to have started after 811.51 ± 0.25 Ma and to have ended before 788.72 ± 0.24 Ma. These new temporal constraints strengthen the case for interpreting Neoproterozoic carbon isotope variation as a record of large-scale changes to the carbon cycle and provide a framework for age models of paleogeographic change, geochemical cycling, and environmental evolution during the radiation of early eukaryotes.

Synthesizing uniform and high concentrations of 3He within minerals via high‐energy proton irradiation is paramount for 4He/3He thermochronology and helium diffusion kinetic studies. Proton irradiations of geological material have hitherto exclusively been routinely conducted at the Francis H. Burr Proton Therapy Center (FHB); we thus explored alternative irradiation protocols at two European‐based facilities with the intention to improve the accessibility and efficiency in obtaining 4He/3He data. We conducted a single irradiation at the Paul Scherrer Institute (PSI) using an approach most similar to that used at FHB (wide, high‐energy beam), and four irradiations at the Helmholtz Zentrum Berlin (HZB) using a newly developed in‐vacuum irradiation protocol in a narrow, lower‐energy but high‐intensity beam. Internal shards of Durango apatite were irradiated in all experiments; 4He/3He release spectra and bulk 3He concentrations of PSI and HZB‐irradiated Durango shards were compared to those from FHB to assess the quality of each experiment in terms of the quantity and uniformity of synthesized 3He. While 3He was uniformly synthesized in PSI‐irradiated Durango shards, the bulk 3He concentration was below the required threshold due to limitations on the maximum allotted proton flux. Over the course of four irradiation experiments at HZB, the protocol evolved to ensure that uniform and high concentrations of 3He can be consistently induced. Furthermore, we demonstrate how HZB irradiations can be replicated using computer simulations, permitting the use of simulations to inform future modifications of the irradiation protocol in order to optimize the uniformity of the 3He distribution across all irradiated samples. Key Points: 4He/3He Thermochronology requires the synthesis of uniform and high concentrations of 3He within minerals via proton irradiationDurango apatite was irradiated at three proton irradiation facilities for quality assessment and comparisonA new in‐vacuum and high‐intensity irradiation protocol was established that has potential to improve the throughput of 4He/3He analyses [ABSTRACT FROM AUTHOR]

Changes in the environment and fishing have been shown to affect life-history characteristics, such as size or age of maturation, in a number of finfish and invertebrates. The American lobster (Homarus americanus) supports Canada's most valuable fishery and exploitation rates are high. Female size-at-maturity (SM) is an important parameter in management of this species, as it is used in establishing minimum legal size regulations. In this study, we show with historical and recent data that SM of female American lobsters has declined across most of Canada, in some areas by as much as 30%, over the past 10-80 years. The spatial patterns of these declines are inconsistent with patterns of rising ocean temperature and lobster abundance (density). They are, however, strongly correlated to the strength of size-based fishery selection, and egg-per-recruit modeling indicates a gain in lifetime egg production associated with observed SM declines under a range of realistic harvesting scenarios. These findings suggest that the marked decrease we document in SM of female American lobsters in Canada over the past century represents an evolutionary response to intense exploitation. Il a ete demontre que des changements dans le milieu et dans la peche ont une incidence sur les caracteristiques du cycle biologique, comme la taille ou l'age a la maturation, chez differents poissons a nageoires et invertebres. Le homard (Homarus americanus) supporte la plus importante peche au Canada du point de vue economique, et les taux d'exploitation sont eleves. La taille a la maturite (TM) des femelles constitue un parametre important dans la gestion de cette espece, puisqu'elle est utilisee dans l'etablissement des reglements visant la taille minimum legale. Nous demontrons, a la lumiere de donnees historiques et recentes, que la TM des homards femelles a diminue presque partout au Canada au cours des 10 a 80 dernieres annees, cette diminution atteignant 30 % dans certaines regions. La distribution spatiale de ces diminutions ne coincide pas avec les motifs de rechauffement des oceans ou d'abondance des homards (densite). Elle est toutefois fortement correlee a la force de la selection basee sur la taille dans la peche, et la modelisation du nombre d'reufs par recrue indique une augmentation de la production d'reufs pendant la duree de vie associee aux baisses de TM observees pour un eventail de scenarios de recolte realistes. Ces constatations donnent a penser que la baisse marquee que nous documentons de la TM des homards femelles au Canada au cours du dernier siecle represente une reaction evolutive a l'exploitation intense. [Traduit par la Redaction], Introduction The American lobster (Homarus americanus) currently supports Canada's most valuable fishery (Fisheries and Oceans Canada 2016a; Rochette et al. 2018). The commercial lobster fishery began in Canada in the [...]

In 2010, more than 20 associations representing harvesters from five provinces bordering the range of American lobster (Homarus americanus) in Canada, from the Gulf of Maine to southern Labrador, joined government research scientists at Fisheries and Oceans Canada (and one provincial department) and researchers from Canadian universities (two English- and four French-speaking) to establish the Lobster Node. This partnership was formed to address knowledge gaps on lobster productivity, stock structure, and connectivity through collaborative research under the auspices of the Canadian Fisheries Research Network (CFRN), which was funded by the Natural Sciences and Engineering Research Council of Canada. In so doing, the research partners overcame barriers of geography, language, culture, education, and, in some cases, longstanding disputes around management and conservation measures. This paper reviews why and how the Lobster Node was formed, what it achieved scientifically, what benefits (and challenges) it provided to the partners, and why it succeeded. It concludes by advocating for the creation of a permanent collaborative platform to conduct research in support of lobster fisheries in Canada. En 2010, plus de 20 associations representant des pecheurs de cinq provinces bordant l'aire de distribution du homard Americain (Homarus americanus) au Canada, du Golfe du Maine au sud du Labrador, se sont joints a des chercheurs gouvernementaux au Ministere des Peches et Oceans Canada (et un ministere provincial) et des chercheurs d'universites canadiennes (deux anglophones et quatre francophones) pour etablir le Groupe Homard. Ce partenariat fut forme afin de combler des lacunes de connaissances au niveau de la productivite, de la structure et de la connectivite des stocks de homard par l'entremise de recherche collaborative sous les auspices du Reseau canadien de recherche sur la peche (RCRP), finance par le Conseil de recherches en sciences naturelles et en genie du Canada. Ce faisant, les partenaires ont du surmonter des obstacles lies a la geographie, la langue, la culture, l'education et, dans certains cas, des differends historiques autour des mesures de gestion et de conservation. Cet article explique pourquoi et comment le Groupe Homard a ete forme, ce qu'il a accompli scientifiquement, quels avantages (et defis) il a donnes aux partenaires, et pourquoi cette initiative fut couronnee de succes. Nous concluons en plaidant pour la creation d'une plate-forme collaborative permanente pour mener des recherches en appui a la peche au homard au Canada., Introduction It has been argued that Canada does not invest sufficient resources in research on the American lobster (Homarus americanus; hereinafter lobster), considering the species' socioeconomic importance to the country [...]

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