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Personne :
Côté, Steeve D.

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Côté

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Steeve D.

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Université Laval. Département de biologie

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ncf10586946

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Voici les éléments 1 - 10 sur 109
  • PublicationAccès libre
    La flore des tourbières de l’île d’Anticosti lorsque soustraite au broutement par le cerf de Virginie
    (2017-06-21) Poulin, Monique; Bachand, Marianne; Pellerin, Stéphanie; Côté, Steeve D.; Courchesne, Milène
    Depuis son introduction, il y a plus d’une centaine d’années, le cerf de Virginie (Odocoileus virginianus Zimm.) a fortement perturbé la flore de l’île d’Anticosti. Les communautés forestières sont sans contredit celles qui ont été les plus affectées. Toutefois, le cerf exploite et perturbe aussi d’autres écosystèmes, comme les tourbières. Dans ce contexte, nous voulions savoir quelle serait la diversité végétale des tourbières à la suite du retrait du cerf. Pour ce faire, 53 exclos ont été mis en place en 2007 et suivis pendant 8 ans. Au total, 125 espèces végétales ont été identifiées dans l’ensemble des exclos en 2007 et 151 espèces après 8 ans d’exclusion du cerf, ce qui représente une hausse de 21 %. Le nombre d’espèces indicatrices, c’est-à-dire celles caractéristiques d’un habitat donné, a également augmenté, passant de 33 à 48, la hausse étant particulièrement importante dans les laggs (écotones entre la forêt et la tourbière). Le recouvrement des espèces préférées par le cerf a grandement augmenté, notamment celui du bouleau nain (Betula pumila L.) et de la sanguisorbe du Canada (Sanguisorba canadensis L.) (respectivement 2 et 8 fois). Au final, les tourbières de l’île d’Anticosti possèdent un potentiel de diversité végétale plus élevé qui peut s’exprimer avec l’arrêt du broutement par le cerf de Virginie.
  • PublicationRestreint
    Recognizing the importance of an all‐inclusive approach to brown bear conservation now and into the future
    (Springer, 2017-09-09) Pigeon, Karine; Cardinal, Étienne; Stenhouse, Gordon B. ; Côté, Steeve D.
    In their critique of our recent article in Oecologia (Pigeon et al. Oecologia 181:1101–1116, 2016a) investigating the influence of ambient temperature on brown bear habitat selection, Ordiz et al. (2017, current issue) argue that we downplay the role of human disturbance on bear behavior, and that we wrongly report on the findings of Ordiz et al. (Oecologia 166:59–67, 2011). We argue that our previous article in Oecologia (Pigeon et al. 2016a) by no means downplays the influence of human factors on bear behavior, and that we correctly stated that Ordiz et al. (2011) did not adequately consider the potential influence of temperature on their findings. Finally, we stress the relevance of considering all-inclusive approaches to the common goal of successful wildlife conservation.
  • PublicationRestreint
    Ecological impacts of deer overabundance
    (Annual Reviews Inc., 2004-06-10) Tremblay, Jean-Pierre; Rooney, Thomas P.; Dussault, Christian; Côté, Steeve D.; Waller, Donald M.
    Deer have expanded their range and increased dramatically in abundance worldwide in recent decades. They inflict major economic losses in forestry, agriculture, and transportation and contribute to the transmission of several animal and human diseases. Their impact on natural ecosystems is also dramatic but less quantified. By foraging selectively, deer affect the growth and survival of many herb, shrub, and tree species, modifying patterns of relative abundance and vegetation dynamics. Cascading effects on other species extend to insects, birds, and other mammals. In forests, sustained overbrowsing reduces plant cover and diversity, alters nutrient and carbon cycling, and redirects succession to shift future overstory composition. Many of these simplified alternative states appear to be stable and difficult to reverse. Given the influence of deer on other organisms and natural processes, ecologists should actively participate in efforts to understand, monitor, and reduce the impact of deer on ecosystems.
  • PublicationAccès libre
    An experimental study of how variation in deer density affects vegetation and songbird assemblages of recently harvested boreal forests
    (National Research Council, 2012-05-11) Tremblay, Jean-Pierre; Cardinal, Étienne; Côté, Steeve D.; Martin, Jean-Louis
    Intense browsing by abundant large herbivores can threaten the ecological integrity of ecosystems by inducing modifications in the structure and composition of vegetation that trigger trophic cascades affecting plant and animal communities. We investigated the relationships between density of white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)), forest succession after clear-cut, and songbird communities on Anticosti Island, Quebec, Canada. We hypothesized that lower deer densities would alter the trajectory of forest succession after clear-cutting and lead to a rapid recovery of habitat attributes favorable to songbirds associated with a dense complex shrub layer. Six years after establishing a controlled browsing experiment (0, 7.5, 15, and >27 deer·km–2) in recent clearcuts, reducing deer densities ≤7.5 deer·km–2 initiated the restoration of balsam fir (Abies balsamea (L.) Mill.) forests and increased the regeneration of paper birch (Betula papyrifera Marshall). Increasing birch ground cover from 10% to 20% increased songbird total abundance, species richness, and diversity by 17%, 39%, and 31%, respectively. Alder Flycatcher (Empidonax alnorum Brewster, 1895) was only present at ≤7.5 deer·km–2 and strongly associated with birch regeneration. The regeneration of browse-resistant plants such as white spruce (Picea glauca (Moench) Voss) in some areas at high deer density favored the maintenance of many shrub-dependent songbirds but also species usually associated with forest canopy. Active management of deer populations in Canadian harvested boreal forests will mitigate losses in vegetation and songbirds caused by over-browsing.
  • PublicationAccès libre
    Maternal defensive behavior of mountain goats against predation by golden eagles
    (2009-04-01) Hamel, Sandra; Côté, Steeve D.
    Maternal defensive behavior against predators may appear risky but is common in many species. Herein we describe maternal defensive behavior of mountain goats (Oreamnos americanus) against Golden Eagle (Aquila chrysaetos) predatory attempts. We found that Golden Eagles attacked goats in 1.9% of sightings (n = 311 sightings of active Golden Eagles over 12 years) but were never successful. Mothers always defended their young against Golden Eagle attacks. Predation by Golden Eagles on young-of-the-year appears low for most ungulate species, including mountain goats. The benefits of defending offspring against eagles are likely high in ungulates, and we would therefore expect selection to favor maternal defensive behavior.
  • PublicationRestreint
    Massive breeding failures following a tsunami in a colonial seabird
    (SpringerLink, 2006-03-08) Viera, Vanessa; Le Bohec, Céline; Côté, Steeve D.; Groscolas, René
    Natural catastrophic events such as tsunamis may induce drastic decreases in breeding success of animal populations. We evaluate the impacts of flooding on the reproductive success of king penguins (Aptenodytes patagonicus) in the Crozet Archipelago. On 26 December 2004, a magnitude-9 earthquake created a large tsunami that flooded a colony at 6,500 km from the epicentre of the earthquake. On 30 January 2005, severe waves again flooded the colony. About 17–20% of the surface of the colony was impacted during each flood and 44% of the breeding birds abandoned their egg or chick following the two floodings. Although about 11% of birds laid another egg after the tsunami, none reproduced again after the second flood that happened later in the breeding season. Our results show that the tsunami directly affected the reproductive success of seabirds nesting near the coast.
  • PublicationRestreint
    Impacts of climate change on the seasonal distribution of migratory caribou
    (Blackwell-synergy, 2009-09-04) Sharma, Sapna; Couturier, Serge; Côté, Steeve D.
    Arctic ecosystems are especially vulnerable to global climate change as temperature and precipitation regimes are altered. An ecologically and socially highly important northern terrestrial species that may be impacted by climate change is the caribou, Rangifer tarandus. We predicted the current and potential future occurrence of two migratory herds of caribou [Rivière George herd (RG) and Rivière-aux-Feuilles (RAF) herd] under a Canadian General Circulation Model climate change scenario, across all seasons in the Québec–Labrador peninsula, using climatic and habitat predictor variables. Argos satellite-tracking collars have been deployed on 213 caribou between 1988 and 2003 with locations recorded every 4–5 days. In addition, we assembled a database of climate (temperature, precipitation, snowfall, timing and length of growing season) and habitat data obtained from the SPOT VEGETATION satellite sensor. Logistic regression models indicated that both climatic and physical habitat variables were significant predictors of current migratory caribou occurrence. Migratory caribou appeared to prefer regions with higher snowfall and lichen availability in the fall and winter. In the summer, caribou preferred cooler areas likely corresponding to a lower prevalence of insects, and they avoided disturbed and recently burnt areas. Climate change projections using climate data predicted an increased range for the RAF herd and decreased range for the RG herd during 2040–2069, limiting the herds to northeastern regions of the Québec–Labrador peninsula. Direct and indirect consequences of climate change on these migratory caribou herds possibly include alteration in habitat use, migration patterns, foraging behaviour, and demography, in addition to social and economic stress to arctic and subarctic native human populations.
  • PublicationRestreint
    Adult survival in migratory caribou is negatively associated with MHC functional diversity
    (Nature, 2020-07-29) Gagnon, Marianne; Yannic, Glenn; Boyer, Frédéric; Côté, Steeve D.
    Genes of the major histocompatibility complex (MHC) are involved in acquired immunity in vertebrates. Only a few studies have investigated the fitness consequences of MHC gene diversity in wild populations. Here, we looked at the association between annual survival and body mass and MHC–DRB exon 2 (MHC–DRB) genetic diversity, obtained from high-throughput sequencing, in two declining migratory caribou (Rangifer tarandus) herds. To disentangle the potential direct and general effects of MHC–DRB genetic diversity, we compared different indices of diversity that were either based on DNA-sequence variation or on physicochemical divergence of the translated peptides, thereby covering a gradient of allelic-to-functional diversity. We found that (1) body mass was not related to MHC–DRB diversity or genotype, and (2) adult survival probability was negatively associated with point accepted mutation distance, a corrected distance that considers the likelihood of each amino acid substitution to be accepted by natural selection. In addition, we found no evidence of fluctuating selection over time on MHC–DRB diversity. We concluded that direct effects were involved in the negative relationship between MHC functional diversity and survival, although the mechanism underlying this result remains unclear. A possible explanation could be that individuals with higher MHC diversity suffer higher costs of immunity (immunopathology). Our results suggest that genetic diversity is not always beneficial even in genes that are likely to be strongly shaped by balancing selection.
  • PublicationAccès libre
    Spring-loaded reproduction : effects of body condition and population size on fertility in migratory caribou (Rangifer tarandus)
    (Canadian Science Publishing, 2013-06-21) Pachkowski, Mélanie Dawn; Côté, Steeve D.; Festa-Bianchet, Marco
    In many ungulates, female fecundity is affected by body condition and has important effects on population dynamics.In some species, females adopt a conservative strategy, reducing reproductive effort when population density is high. Weinvestigated what factors affect the probability of gestation in adult female caribou (Rangifer tarandus(L., 1758)) from theRivière-George herd in northern Quebec and Labrador over 5 years that spanned various population sizes and trends. Similar toother populations of migratory caribou, the probability that a female was pregnant in spring increased with body mass andpercent body fat. The probability of gestation appeared to be reduced by high infestation of warbles (Hypoderma tarandi(L., 1758)).The proportion of females pregnant varied between years and was lower at high population size. Females of similar mass,however, were pregnant regardless of whether the population was increasing at low density, had reached a peak, or wasdeclining. Compared with other ungulates that reduce maternal expenditure at high density, female caribou of the Rivière-George herd may have a risk-prone reproductive strategy
  • PublicationAccès libre
    Caribou herd dynamics : impacts of climate change on traditional and sport harvesting
    (Université Laval, ArcticNet Inc., 2012-01-01) Tremblay, Jean-Pierre; Festa-Bianchet, Marco; Dussault, Christian; Hins, Caroline; Brodeur, Vincent; Côté, Steeve D.; Simard, M.; Le Corre, Mael René Vincent; Taillon, Joëlle; Sharma, Sapna
    Caribou (Rangifer tarandus) are a key species in Arctic ecosystems including northern Québec and Labrador. They play a central role in the ecology of predators and the structure of Arctic plant communities. In addition, caribou provide socioeconomic and cultural benefits from subsistence and sport hunting activities. Changes in the distribution and abundance of caribou due to global climate change would have serious biological, societal, and economic implications. Direct and indirect consequences of climate change on migratory caribou herds may include alteration in habitat use, migration patterns, foraging behaviour and demography. For example, caribou may experience a further northerly shift in distribution due to several factors including longer ice-free periods, increases in snowfall and extreme weather events, alterations in the fire regime, and changes in the distribution of insects and predators. Future research by Caribou Ungava, a research group interested in the ecology of migratory caribou in the context of climate change, will address the factors outlining variations in the population dynamics of caribou, implications for survival and reproduction, as well as the response of caribou habitat to different climate change scenarios. Management efforts focusing on mitigating greenhouse gases to reduce the potential effects of climate change, preserving high quality habitat, limiting anthropogenic landscape disturbances, and managing hunting in a sustainable manner, could alleviate stressors on migratory caribou of the QuébecLabrador peninsula.