Browsing by Author "Boutin, Stan"
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- ItemConservation triage at the trailing edge of climate envelopes(2020) Gilbert, Sophie L.; Broadley, Kate; Doran-Myers, Darcy; Droghini, Amanda; Haines, Jessica A.; Hämäläinen, Anni; Lamb, Clayton T.; Neilson, Eric W.; Boutin, StanSpecies protection via geographically fixed conservation actions is a primary tool for maintenance of biodiversity worldwide (Pimm et al. 2014). Yet, for many species, the assumption that currently suitable sites will remain so is undermined by climate change (Urban 2015; Wiens 2016). Climate-change-associated range shifts (Chen et al. 2011), a process driven by populations at the trailing edge of the climate envelope going extinct or moving and those at the leading edge becoming established, are becoming widespread around the world (Wiens 2016). We argue that conservation of populations of at-risk species should be prioritized across each species’ range based on future climatic suitability of an area with the goal of maintaining or increasing the number of viable populations range wide. Such range-wide prioritization could help conserve species in a changing climate when resources are limited; effort would be reallocated to viable populations (Oliver et al. 2012; Alagador & Cerdeira 2016). Promisingly, resistance to this approach (Oliver et al. 2016) may be waning. Many nongovernment organizations (e.g., International Panel on Climate Change, World Wildlife Fund) now use climate-informed range-wide approaches, as do some national and state agencies (e.g., Association of Fish & Wildlife Agencies 2018; Cornwall 2018). We aimed to advance discussion and implementation of climate-informed prioritization across species’ ranges and considered when populations behind the trailing edge of climate change should be deprioritized.
- ItemFitness consequences of peak reproductive effort in a resource pulse system(2017) Hämäläinen, Anni; McAdam, Andrew G.; Dantzer, Ben; Lane, Jeffrey E.; Haines, Jessica A.; Humphries, Murray M.; Boutin, StanThe age trajectory of reproductive performance of many iteroparous species features an early - life increase in performance followed by a late - life senescent decline. The largest contribution of lifetime reproductive success is therefore gained at the age at which reproductive performance peaks. Using long term data on North American red squirrels we show that the environmental conditions individuals encountered could cause variation among individuals in the “height” and timing of this peak, contributing to life history variation and fitness in this population that experiences irregular resource pulses. As expected, high peak effort was positively associated with lifetime reproductive output up to a high level of annual effort. Furthermore, individuals that matched their peak reproductive effort to an anticipated resource pulse gained substantial fitness benefits through recruiting more offspring over their lifetime. Individual variation in peak reproductive effort thus has strong potential to shape life history evolution by facilitating adaptation to fluctuating environments.
- ItemIndirect effects on fitness between individuals that have never met via an extended phenotype(2019) Fisher, David N.; Haines, Jessica A.; Boutin, Stan; Dantzer, Ben; Lane, Jeffrey E.; Coltman, David W.; McAdam, Andrew G.Interactions between organisms are ubiquitous and have important consequences for phenotypes and fitness. Individuals can even influence those they never meet, if they have extended phenotypes that alter the environments others experience. North American red squirrels (Tamiasciurus hudsonicus) guard food hoards, an extended phenotype that typically outlives the individual and is usually subsequently acquired by non-relatives. Hoarding by previous owners can, therefore, influence subsequent owners. We found that red squirrels breed earlier and had higher lifetime fitness if the previous hoard owner was a male. This was driven by hoarding behaviour, as males and mid-aged squirrels had the largest hoards, and these effects persisted across owners, such that if the previous owner was male or died in mid-age, subsequent occupants had larger hoards. Individuals can, therefore, influence each other's resource-dependent traits and fitness without ever meeting, such that the past can influence contemporary population dynamics through extended phenotypes.
- ItemQuantifying fear effects on prey demography in nature(2018) Peers, Michael J. L.; Majchrzak, Yasmine N.; Neilson, Eric W.; Lamb, Clayton T.; Hämäläinen, Anni; Haines, Jessica A.; Garland, Laura; Doran-Myers, Darcy; Broadley, Kate; Boonstra, Rudy; Boutin, StanIn recent years, it has been argued that the effect of predator fear exacts a greater demographic toll on prey populations than the direct killing of prey. However, efforts to quantify the effects of fear have primarily relied on experiments that replace predators with predator cues. Interpretation of these experiments must consider two important caveats: (1) the magnitude of experimenter-induced predator cues may not be realistically comparable to those of the prey’s natural sensory environment, and (2) given functional predators are removed from the treatments, the fear effect is measured in the absence of any consumptive effects, a situation which never occurs in nature. We contend that demographic consequences of fear in natural populations may have been overestimated because the intensity of predator cues applied by experimenters in the majority of studies has been unnaturally high, in some instances rarely occurring in nature without consumption. Furthermore, the removal of consumption from the treatments creates the potential situation that individual prey in poor condition (those most likely to contribute strongly to the observed fear effects via starvation or reduced reproductive output) may have been consumed by predators in nature prior to the expression of fear effects, thus confounding consumptive and fear effects. Here, we describe an alternative treatment design that does not utilize predator cues, and in so doing, better quantifies the demographic effect of fear on wild populations. This treatment substitutes the traditional cue experiment where consumptive effects are eliminated and fear is simulated with a design where fear is removed and consumptive effects are simulated through the experimental removal of prey. Comparison to a natural population would give a more robust estimate of the effect of fear in the presence of consumption on the demographic variable of interest. This approach represents a critical advance in quantifying the mechanistic pathways through which predation structures ecological communities. Discussing the merits of both treatments will motivate researchers to go beyond simply describing the existence of fear effects and focus on testing their true magnitude in wild populations and natural communities.
- ItemSex- and context-specific associations between personality and a measure of fitness but no link with life history traits(2020) Haines, Jessica A.; Nason, Sarah E.; Skurdal, Alyshia M. M.; Bourchier, Tenal; Boutin, Stan; Taylor, Ryan W.; McAdam, Andrew G.; Lane, Jeffrey E.; Kelley, Amanda D.; Humphries, Murray M.The pace-of-life syndrome hypothesis posits that personality traits (i.e. consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e. active and aggressive) with an earlier age at first reproduction, a shorter life span and higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels, Tamiasciurus hudsonicus. Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females, regardless of mast experience, there was no association between activity and lifetime pup production, but there was a positive association between aggression and lifetime pup production. In males that experienced a mast, there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production, but there was a negative association between aggression and lifetime pup production. Lifetime recruit production (number of adult offspring recruited into the breeding population) in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels.
- ItemSexually selected infanticide by male red squirrels in advance of a mast year(2018) Haines, Jessica A.; Coltman, David W.; Dantzer, Ben; Gorrell, Jamieson C.; Humphries, Murray M.; Lane, Jeffrey E.; McAdam, Andrew G.; Boutin, StanNorth American red squirrels (Tamiasciurus hudsonicus) anticipate when white spruce (Picea glauca), their primary food source, will produce large amounts of cones in infrequent and irregular mast years (Boutin et al. 2006). Cones mature in autumn and are then available as food for red squirrels, but females produce larger, and often multiple, litters the preceding spring and summer in anticipation of the upcoming mast. Because this pulse of the cone food resource follows the birth of the litter, it cannot be a source of energy for the female to produce young; instead, there must be cues for increased reproductive investment by the females prior to mast cone production, perhaps through consumption of buds on the masting trees (Boutin et al. 2006, 2013). Boutin et al. (2006) only studied females; whether male behavior anticipates mast years is still unstudied. At our study area in the Yukon, 2014 was a mast year for spruce cone production in late summer (Lamontagne et al. 2005). J. A. Haines was observing male red squirrel mating behavior during spring 2014, giving her an unanticipated opportunity to document the previously unstudied effects of a mast year on male red squirrels.
- ItemThe ecological significance of secondary seed dispersal by carnivores(2017) Hämäläinen, Anni; Broadley, Kate; Droghini, Amanda; Haines, Jessica A.; Lamb, Clayton T.; Boutin, Stan; Gilbert, Sophie L.Animals play an important role in the seed dispersal of many plants. It is increasingly recognized, however, that the actions of a single disperser rarely determine a seed's fate and final location; rather, multiple abiotic or animal dispersal vectors are involved. Some carnivores act as secondary dispersers by preying on primary seed dispersers or seed predators, inadvertently consuming seeds contained in their prey's digestive tracts and later depositing viable seeds, a process known as diploendozoochory. Carnivores occupy an array of ecological niches and thus range broadly on the landscape. Consequently, secondary seed dispersal by carnivores could have important consequences for plant dispersal outcomes, with implications for ecosystem functioning under a changing climate and across disturbed landscapes where dispersal may be otherwise limited. For example, trophic downgrading through the loss of carnivores may reduce or eliminate diploendozoochory and thus compromise population connectivity for lower trophic levels. We review the literature on diploendozoochory and conclude that the ecological impact of a secondary vs. primary seed disperser depends on the relative dispersal distances, germination success, and the proportion of seeds exposed to secondary dispersal by carnivores. None of the studies up to present day have been able to rigorously assess the ecological significance of this process. We provide a framework of the components that determine the significance of diploendozoochory across systems and identify the components that must be addressed in future studies attempting to assess the ecological importance of diploendozoochory.