317 Works

Patient burden and clinical advances associated with post-approval monotherapy cancer drug trials: a systematic review

Benjamin Gregory Carlisle, Adélaïde Doussau & Jonathan Kimmelman
Objectives: After regulatory approval, drug companies, public funding agencies and academic researchers often pursue trials aimed at extending the uses of a new drug by testing it in new non-approved indications. Patient burden and clinical impact of such research is not well understood. Design/setting: We conducted a retrospective cohort study of post-approval clinical trials launched within five years after the drug's first approval, testing anticancer drugs in monotherapy in indications that were first pursued after...

Thermal stratification and fish thermal preference explain vertical eDNA distributions in lakes

Joanne Littlefair, Lee Hrenchuk, Paul Blanchfield, Michael Rennie & Melania Cristescu
Significant advances have been made towards surveying animal and plant communities using DNA isolated from environmental samples. Despite rapid progress, we lack a comprehensive understanding of the “ecology” of environmental DNA (eDNA), particularly its temporal and spatial distribution and how this is shaped by abiotic and biotic processes. Here, we tested how seasonal variation in thermal stratification and animal habitat preferences influence the distribution of eDNA in lakes. We sampled eDNA depth profiles of five...

Data from: Risk factors for possible REM sleep behavior disorder: a CLSA population-based cohort study

Chun Yao, Seyed-Mohammad Fereshtehnejad, Mark R. Keezer, Christina Wolfson, Amélie Pelletier & Ronald B. Postuma
Objective: Idiopathic REM sleep behavior disorder (RBD) is a powerful marker of prodromal neurodegenerative synucleinopathy, with 80% of patients ultimately phenoconverting to defined disease. Several environmental risk factors for RBD have been suggested, but associations vary between studies. We assessed sociodemographic, socioeconomic and clinical correlates of RBD in a 30,000-subject national cohort. Methods: Subjects aged 45-85 years in Canada were collected as part of the Canadian Longitudinal Study on Aging. Possible RBD (pRBD) was screened...

Data from: Do replicates of independent guppy lineages evolve similarly in a predator-free laboratory environment?

Kiyoko M. Gotanda, Amy Pack, Caroline Leblond & Andrew P. Hendry
The Trinidadian guppy is emblematic of parallel and convergent evolution, with repeated demonstrations that predation regime is a driver of adaptive trait evolution. A classic and foundational experiment in this system was conducted by John Endler 40 years ago, where male guppies placed into low-predation environments in the laboratory evolved increased color in a few generations. However, Endler’s experiment did not employ the now typical design for a parallel/convergent evolution study, which would employ replicates...

Data from: Individual variation in energy-saving heterothermy affects survival and reproductive success

Melanie Dammhahn, Manuelle Landry-Cuerrier, Denis Réale, Dany Garant & Murray M. Humphries
Given fundamental energetic trade-offs among growth, maintenance and reproduction, individual differences in energy saving should have consequences for survival and reproductive success. Many endotherms use periodic heterothermy to reduce energy and water requirements and individual variation in heterothermy should have fitness consequences. However, attempts to disentangle individual- and population-level variation in heterothermy are scarce. Here, we quantified patterns of heterothermy of 55 free-ranging eastern chipmunks (Tamias striatus), food-hoarding hibernators. Over five hibernation periods, we obtained...

Data from: The incidental response to uniform natural selection

Graham Bell
When populations are exposed to novel conditions of growth they often become adapted to a similar extent, and at the same time evolve some degree of impairment in their original environment. They may also come to vary widely with respect to characters which are uncorrelated with fitness, as the result of chance genetic associations among the founders, when these are a small sample from a large and variable ancestral population. I report an experiment in...

Data from: Community rescue in experimental metacommunities

Etienne Low-Décarie, Marcus Kolber, Paige Homme, Andrea Lofano, Alex J. Dumbrell, Andrew Gonzalez & Graham Bell
The conditions that allow biodiversity to recover following severe environmental degradation are poorly understood. We studied community rescue, the recovery of a viable community through the evolutionary rescue of many populations within an evolving community, in metacommunities of soil microbes adapting to a herbicide. The metacommunities occupied a landscape of crossed spatial gradients of the herbicide (Dalapon) and a resource (glucose), whereas their constituent communities were either isolated or connected by dispersal. The spread of...

Data from: Lichens: a limit to peat growth?

Lorna I. Harris, Tim R. Moore, Nigel T. Roulet & Andrew J. Pinsonneault
1. The fruticose lichens Cladina stellaris and Cladina rangiferina, form thick mats that can cover large areas of northern peatlands (above ~ 50° latitude), including the extensive peatlands of the Hudson Bay Lowland (HBL) in Canada, where lichens may cover up to 50 % of the landscape. Despite the abundance of lichens in northern peatlands, our understanding of their role within peatland ecosystems, and peat accumulation in particular, is limited. 2. We investigate the potential...

Data from: Linking macro-trends and micro-rates: re-evaluating micro-evolutionary support for Cope’s rule

Kiyoko M. Gotanda, Cristián Correa, Martin M. Turcotte, Gregor Rolshausen & Andrew P. Hendry
Cope's rule, wherein a lineage increases in body size through time, was originally motivated by macro-evolutionary patterns observed in the fossil record. More recently, some authors have argued that evidence exists for generally positive selection on individual body size in contemporary populations, providing a micro-evolutionary mechanism for Cope's rule. If larger body size confers individual fitness advantages as the selection estimates suggest, thereby explaining Cope's rule, then body size should increase over micro-evolutionary time scales....

Data from: Beyond shading: litter production by neighbours contributes to overyielding in tropical trees

Jurgis Sapijanskas, Catherine Potvin & Michel Loreau
The influence of biodiversity on ecosystem functioning is now well established. However, our ability to predict the ecological consequences of biodiversity changes remains limited by our poor understanding of the mechanisms underlying biodiversity effects. We disentangled the contributions of light competition and residual neighbourhood interactions in a ten-year-old biodiversity experiment with tropical trees that display overyielding, i.e., higher community-level yields in mixtures compared with monocultures. We developed models of individual tree growth that partition the...

Data from: The evolution of morphological diversity in continental assemblages of Passerine birds

Knud Andreas Jønsson, Jean Philippe Lessard, Robert E. Ricklefs & Jean-Philippe Lessard
Understanding geographic variation in the species richness and lineage composition of regional biotas is a long standing goal in ecology. Why do some evolutionary lineages proliferate while others do not, and how do new colonists fit into an established fauna? Here, we analyse the morphological structure of assemblages of passerine birds in four biogeographic regions to examine the relative influence of colonization history and niche-based processes on regional communities of passerine birds. Using morphological traits...

Data from: Phylogenetic diversity patterns in Himalayan forests reveal evidence for environmental filtering of distinct lineages

Stephanie Shooner, T. Jonathan Davies, Purabi Saikia, Jyotishman Deka, Sanjeeb Bharali, Om Prakash Tripathi, Lalbihari Singha, Mohammed Latif Khan & Selvadurai Dayanandan
Large‐scale environmental gradients have been invaluable for unraveling the processes shaping the evolution and maintenance of biodiversity. Environmental gradients provide a natural setting to test theories about species diversity and distributions within a landscape with changing biotic and abiotic interactions. Elevational gradients are particularly useful because they often encompass a large climatic range within a small geographical extent. Here, we analyzed tree communities in plots located throughout Arunachal Pradesh, a province in northeast India located...

Data from: Many-to-one form-to-function mapping weakens parallel morphological evolution

Cole J. Thompson, Newaz Ahmed, Thor Veen, Catherine Lynn Peichel, Andrew P. Hendry, Daniel I. Bolnick & Yoel E. Stuart
Evolutionary ecologists aim to explain and predict evolutionary change under different selective regimes. Theory suggests that such evolutionary prediction should be more difficult for biomechanical systems in which different trait combinations generate the same functional output: “many-to-one mapping”. Many-to-one mapping of phenotype to function enables multiple morphological solutions to meet the same adaptive challenges. Therefore, many-to-one mapping should undermine parallel morphological evolution, and hence evolutionary predictability, even when selection pressures are shared among populations. Studying...

Data from: Very low levels of direct additive genetic variance in fitness and fitness components in a red squirrel population

S. Eryn McFarlane, Stan Boutin, Murray M. Humphries, Andrew G. McAdam, Jamieson C. Gorrell & David W. Coltman
A trait must genetically correlate with fitness in order to evolve in response to natural selection, but theory suggests that strong directional selection should erode additive genetic variance in fitness and limit future evolutionary potential. Balancing selection has been proposed as a mechanism that could maintain genetic variance if fitness components trade off with one another and has been invoked to account for empirical observations of higher levels of additive genetic variance in fitness components...

Data from: Evolutionary inferences from the analysis of exchangeability

Andrew P. Hendry, Renaud Kaeuffer, Erika Crispo, Catherine Lynn Peichel & Daniel I. Bolnick
Evolutionary inferences are usually based on statistical models that compare mean genotypes and phenotypes (or their frequencies) among populations. An alternative is to use the actual distribution of genotypes and phenotypes to infer the “exchangeability” of individuals among populations. We illustrate this approach by using discriminant functions on principal components to classify individuals among paired lake and stream populations of threespine stickleback in each of six independent watersheds. Classification based on neutral and non-neutral microsatellite...

Data from: Unified pre- and postsynaptic long-term plasticity enables reliable and flexible learning

Rui Ponte Costa, Robert C. Froemke, Per Jesper Sjöström & Mark C. W. Van Rossum
Although it is well known that long-term synaptic plasticity can be expressed both pre- and postsynaptically, the functional consequences of this arrangement have remained elusive. We show that spike-timing-dependent plasticity with both pre- and postsynaptic expression develops receptive fields with reduced variability and improved discriminability compared to postsynaptic plasticity alone. These long-term modifications in receptive field statistics match recent sensory perception experiments. Moreover, learning with this form of plasticity leaves a hidden postsynaptic memory trace...

Data from: Using playback of territorial calls to investigate mechanisms of kin discrimination in red squirrels

Julia Shonfield, Jamieson C. Gorrell, David W. Coltman, Stan Boutin, Murray M. Humphries, David Wilson & Andrew G. McAdam
Kin recognition can facilitate kin selection and may have played a role in the evolution of sociality. Red squirrels (Tamiasciurus hudsonicus) defend territories using vocalizations known as rattles. They use rattles to discriminate kin, though the mechanism underlying this ability is unknown. Our objective was to distinguish between the mechanisms of prior association, where animals learn the phenotypes of kin they associate with early in life, and phenotype matching/recognition alleles, where animals use a template...

Data from: Divergence maintained by climatic selection despite recurrent gene flow: a case study of Castanopsis carlesii (Fagaceae)

Ye Sun, Yann Surget-Groba & Shaoxiong Gao
Local adaptation to different environments has the potential to maintain divergence between populations despite recurrent gene flow and is an important driver for generating biological diversity. In this study, we investigate the role of adaptation in the maintenance of two parapatric varieties of a forest tree. We used sequence variation of chloroplastic DNA and restriction site-associated DNA to investigate the genetic structure of two varieties of Castanopsis carlesii in subtropical China and relate it to...

Data from: Cardiac plasticity influences aerobic performance and thermal tolerance in a tropical, freshwater fish at elevated temperatures

Elizabeth A. Nyboer & Lauren J. Chapman
Fishes faced with novel thermal conditions often modify physiological functioning to compensate for elevated temperatures. This physiological plasticity (thermal acclimation) has been shown to improve metabolic performance and extend thermal limits in many species. Adjustments in cardiorespiratory function are often invoked as mechanisms underlying thermal plasticity because limitations in oxygen supply have been predicted to define thermal optima in fishes, however few studies have explicitly linked cardiorespiratory plasticity to metabolic compensation. Here we quantify thermal...

Data from: Coevolution of cultural intelligence, extended life history, sociality, and brain size in primates

Sally E. Street, Ana F. Navarrete, Simon M. Reader & Kevin N. Laland
Explanations for primate brain expansion and the evolution of human cognition and culture remain contentious despite extensive research. While multiple comparative analyses have investigated variation in brain size across primate species, very few have addressed why primates vary in how much they use social learning. Here, we evaluate the hypothesis that the enhanced reliance on socially transmitted behavior observed in some primates has coevolved with enlarged brains, complex sociality, and extended lifespans. Using recently developed...

Data from: Global macroevolution and macroecology of passerine song

William David Pearse, Ignacio Morales-Castilla, Logan S. James, Maxwell Farrell, Frédéric Boivin & T. Jonathan Davies
Studying the macroevolution of the songs of Passeriformes (perching birds) has proved challenging. The complexity of the task stems not just from the macroevolutionary and macroecological challenge of modelling so many species, but also from the difficulty in collecting and quantifying birdsong itself. Using machine learning techniques, we extracted songs from a large citizen science dataset, and then analysed the evolution, and biotic and abiotic predictors of variation in birdsong across 578 passerine species. Contrary...

Data from: Quantifying climate sensitivity and climate-driven change in North American amphibian communities

David A. W. Miller, Evan H. Campbell Grant, Erin Muths, Staci M. Amburgey, Michael J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T. J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A. G. Rittenhouse, Susan C. Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price … & Brent H. Sigafus
Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 86 North American study areas. The effect of climate on local colonization and persistence probabilities varies among eco-regions and depends on local...

Data from: Evolutionary rescue of sexual and asexual populations in a deteriorating environment

Josianne Lachapelle & Graham Bell
The environmental change experienced by many contemporary populations of organisms poses a serious risk to their survival. From the theory of evolutionary rescue we predict that the combination of sex and genetic diversity should increase the probability of survival by increasing variation and thereby the probability of generating a type that can tolerate the stressful environment. We tested this prediction by comparing experimental populations of Chlamydomonas reinhardtii that differ in sexuality and in the initial...

Data from: Projected polar bear sea ice habitat in the Canadian Arctic Archipelago

Stephen G. Hamilton, Laura Castro De La Guardia, Andrew E. Derocher, Vicki Sahanatien, Bruno Tremblay & David Huard
Background: Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 – 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. Principal Findings: Shifts away from multiyear ice to...

Data from: INTREPAD: a randomized trial of naproxen to slow progress of presymptomatic Alzheimer disease

Pierre-Francois Meyer, Jennifer Tremblay-Mercier, Jeannie Leoutsakos, Cecile Madjar, Marie-Elyse Lafaille-Magnan, Melissa Savard, Pedro Rosa-Neto, Judes Poirier, Pierre Etienne & John Breitner
Objective: Evaluate the safety and efficacy of low-dose naproxen for prevention of progression in pre-symptomatic AD among cognitively intact persons at-risk. Methods: INTREPAD, a two-year double-masked pharmaco-prevention trial, enrolled 195 AD family history-positive elderly (mean age 63 years) screened carefully to exclude cognitive disorder. These were randomized 1:1 to naproxen sodium 220mg twice-daily or placebo. Multimodal imaging, neurosensory, cognitive and (in ~50%) CSF biomarker evaluations were performed at Baseline, 3, 12, and 24 months. A...

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