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Behavioral variation in natural contests: integrating plasticity and personality
Couchoux, Charline; Garant, Dany; Aubert, Maxime; Clermont, Jeanne; Réale, Denis — 2020-11-04 <p>Animals often interact aggressively when competing over limited resources. Aggressive decisions can be complex, and may result from multiple sources of behavioral variation. The outcome of contests may be explained through contest theory and personality, by considering conjointly plasticity and individual consistency. This integrative approach also allows investigating individual differences in responsiveness to environmental changes. Here we observed multiple agonistic interactions occurring among eastern chipmunks (Tamias striatus) competing for food resources supplied at different distances from their burrows. Using an individual reaction norm approach, we found that the probability of winning a contest depended on an individual’s own intrinsic characteristics (mass, age, but not sex) but was also adjusted to characteristics of its opponents. Winning a contest also depended on extrinsic environmental characteristics such as distance to the contestants’ burrows, but not the order of arrival at the feeding patch. We found consistent individual differences in the probability of winning, potentially related to differences in aggressiveness and territoriality. We also found that individuals differed in their plasticity level in response to changes in different characteristics of their social and physical environments. Plasticity, personality and individual differences in responsiveness may thus all play a role in predicting contest outcome and in the evolution of animal contests.</p> https://creativecommons.org/publicdomain/zero/1.0/
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Data from: Exploration profiles drive activity patterns and temporal niche specialization in a wild rodent
Gharnit, Elouana; Bergeron, Patrick; Garant, Dany; Réale, Denis — 2020-03-02 <p>Individual niche specialization can have important consequences for competition, fitness, and ultimately population dynamics and ecological speciation. The temporal window and the level of daily activity are niche components that may vary with sex, breeding season, food supply, population density, and predator’s circadian rhythm. More recently, ecologists emphasized that traits such as dispersal and space use could depend on personality differences. Boldness and exploration have been shown to correlate with variation in foraging patterns, habitat use, and home range. Here we assessed the link between exploration, measured from repeated novel environment tests, activity patterns, and temporal niche specialization in wild eastern chipmunks (<i>Tamias striatus</i>). Intrinsic differences in exploration should drive daily activity patterns through differences in energy requirements, space use, or the speed to access resources. We used collar-mounted accelerometers to assess whether individual exploration profiles predicted: (1) daily overall dynamic body acceleration, reflecting overall activity levels; (2) mean activity duration and the rate of activity sequences, reflecting the structure of daily activity; and (3) patterns of dawn and dusk activity, reflecting temporal niche differentiation. Exploration and overall activity levels were weakly related. However, both dawn activity and rate of activity sequences increased with the speed of exploration. Overall, activity patterns varied according to temporal variability in food conditions. This study emphasizes the role of intrinsic behavioral differences in activity patterns in a wild animal population. Future studies will help us understand how yearly seasonality in reproduction, food abundance, and population density modulate personality-dependent foraging patterns and temporal niche specialization.</p>
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Data from: Environmental conditions affect spatial genetic structures and dispersal patterns in a solitary rodent
Dubuc Messier, Gabrielle; Garant, Dany; Bergeron, Patrick; Réale, Denis — 2012-08-17 The study of the spatial distribution of relatives in a population under contrasted environmental conditions provides critical insights into the flexibility of dispersal behaviour and the role of environmental conditions in shaping population relatedness and social structure. Yet few studies have evaluated the effects of fluctuating environmental conditions on relatedness structure of solitary species in the wild. The aim of this study was to determine the impact of interannual variations in environmental conditions on the spatial distribution of relatives [spatial genetic structure (SGS)] and dispersal patterns of a wild population of eastern chipmunks (Tamias striatus), a solitary rodent of North America. Eastern chipmunks depend on the seed of masting trees for reproduction and survival. Here, we combined the analysis of the SGS of adults with direct estimates of juvenile dispersal distance during six contrasted years with different dispersal seasons, population sizes and seed production. We found that environmental conditions influences the dispersal distances of juveniles and that male juveniles dispersed farther than females. The extent of the SGS of adult females varied between years and matched the variation in environmental conditions. In contrast, the SGS of males did not vary between years. We also found a difference in SGS between males and females that was consistent with male-biased dispersal. This study suggests that both the dispersal behaviour and the relatedness structure in a population of a solitary species can be relatively labile and change according to environmental conditions.
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Data from: Rapid evolutionary responses of life history traits to different experimentally-induced pollution in Caenorhabditis elegans
Dryad
Dutilleul, Morgan; Bonzom, Jean-Marc; Lecomte, Catherine; Goussen, Benoit; Daian, Fabrice; Galas, Simon; Réale, Denis — 2015-01-06 Background Anthropogenic disturbances can lead to intense selection pressures on traits and very rapid evolutionary changes. Evolutionary responses to environmental changes, in turn, reflect changes in the genetic structure of the traits, accompanied by a reduction of evolutionary potential of the populations under selection. Assessing the effects of pollutants on the evolutionary responses and on the genetic structure of populations is thus important to understanding the mechanisms that entail specialization to novel environmental conditions or resistance to novel stressors. Results Using an experimental evolution approach we exposed Caenorhabditis elegans populations to uranium, salt and alternating uranium-salt environments over 22 generations. We analyzed the changes in the average values of life history traits and the consequences at the demographic level in these populations. We also estimated the phenotypic and genetic (co)variance structure of these traits at different generations. Compared to populations in salt, populations in uranium showed a reduction of the stability of their traits structure and a higher capacity to respond by acclimation. However, the evolutionary responses of traits were generally lower for uranium than salt and the evolutionary responses in the alternating uranium-salt environment were between those of constant environments. Consequently, at the end of the experiment, the population rate of increase were higher in uranium than in salt and intermediate in the alternating environment. Conclusions Our multigenerational experiment confirmed that rapid adaptation to different polluted environments may involve different evolutionary responses resulting demographic consequences. These changes are partly explain by the effects of the pollutants on the genetic (co)variance structure of traits and the capacity of acclimation to novel conditions. Finally, our results in the alternating environment may confirm the selection of a generalist type in this environment.
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Data from: Social selection acts on behavior and body mass but does not contribute to the total selection differential in Eastern chipmunks
Dryad
Santostefano, Francesca; Garant, Dany; Bergeron, Patrick; Montiglio, Pierre-Olivier; Réale, Denis — 2019-11-04 <p>Through social interactions, phenotypes of conspecifics can affect an individual’s fitness, resulting in social selection. Social selection is assumed to represent a strong and dynamic evolutionary force that can act with or in opposition to natural selection. Few studies, however, have estimated social selection and its contribution to total selection in the wild. We estimated natural and social selection gradients on exploration, docility, and body mass, and their contribution to selection differentials, in a wild Eastern chipmunk population (<i>Tamias striatus</i>). We applied trait-based multiple regression models derived from classical phenotypic selection analyses, which allowed us to include several social partners (i.e., neighbors). We detected social selection gradients on female docility and male body mass, indicating that female with docile neighbors and males with large neighbors had lower fitness. In both sexes, social selection gradients varied with the season. However, we found no phenotypic assortment or disassortment for the studied traits. Social selection gradients, therefore, did not contribute to total selection differentials, and natural selection alone could drive phenotypic changes. Evaluating the factors that drive the evolution of the covariance between interacting phenotypes is necessary to understand the role of social selection as an evolutionary force. </p>
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Exploration and social environment affect inbreeding avoidance in a small mammal
Dryad
Vandal, Katherine; Garant, Dany; Bergeron, Patrick; Réale, Denis — 2023-11-27 <p><span lang="EN-CA">Individual exploration types are based on the cognitive speed-accuracy trade-off, which suggests that higher speed of information acquisition is done by sacrificing information quality</span><span lang="EN-CA">. In a mating context, fast exploration could thus increase the probability of finding mates at the cost of mating with kin or suboptimal partners. We tested this hypothesis by studying male mate choice patterns in a species with a scramble competition mating system. We used genotyping, localisation by radio-collar, trapping, and repeated exploration measures from a long-term study on wild Eastern chipmunks (<em>Tamias</em> <em>striatus</em>). We predicted that, according to the speed-accuracy trade-off hypothesis, slower-thorough explorers should be choosier than faster-superficial ones, and thus avoid inbreeding. We found that slower males reproduced more often with less related females, but only on one site where variance in relatedness and female density were high. Males showed no preference for their mates’ exploration type. Our results suggest that superficial exploration decreases male choosiness and increases the risk of inbreeding, but only under decreased mate search costs due to high variance in relatedness among mates (at high density). Our findings reveal exploration-related, among-individual variance in inbreeding, highlighting the complexity of mate choice, and showing that many aspects of an individual’s life contribute to animal decision-making.</span></p>
Dryad Translation missing: fr.blacklight.search.logo
Consumption of red maple in anticipation of beech mast-seeding drives reproduction in Eastern chipmunks
Dryad
Tissier, Mathilde; Réale, Denis; Garant, Dany; Bergeron, Patrick — 2020-01-10 1. Understanding the determinants of reproduction is a central question in evolutionary ecology. In pulsed resources environments, the reproduction and population dynamics of seed consumers is driven by pulsed production of seeds by trees, or mast-seeding. In Southern Québec, eastern chipmunks (Tamias striatus) exclusively reproduce during the summer before and the spring after a mast-seeding event of American beech. They thus seem to anticipate beech mast by reproducing during early summer, so that juveniles can emerge at the time of maximum beechnut abundance during late summer. 2. However, the cues allowing chipmunks to anticipate beech mast remain unknown, and the existence of the anticipation process itself has been questioned. To tackle those issues, we investigated the links between the nutritional ecology and reproduction of adult chipmunks and compared their spring diet in mast- vs post-mast years. 3. We monitored female’s reproductive status (N=446), analyzed cheek pouch contents at capture (n=3761 captures), and recorded seed production by deciduous trees on three different sites in Mont-Sutton from 2006 to 2018. 4. Results revealed a systematic shift in chipmunk diet towards red maple seeds in springs preceding a beech mast, with red maple seeds composing more than 77% of chipmunk diet. However, red maple consumption was unrelated to red maple production, but was related to beech seed production in the upcoming fall. We also found that red maple consumption best predicted the proportion of females in summer estrus. 5. Our results confirm that chipmunks anticipate beech mast-seeding and suggest a key role of red maple consumption in that anticipation. Results also suggest that red maple seeds may contain nutrients or secondary-plant components essential to sustain or trigger the summer reproduction in chipmunks, which allow them to remain synchronized with pulsed productions of both red maple and beech and improve their fitness. 08-Jan-2020
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Linking genetic, morphological, and behavioural divergence between inland island and mainland deer mice
Dryad
Miller, Joshua; Garant, Dany; Perrier, Charles; Juette, Tristan; Jameson, Joël; Réale, Denis; Normandeau, Eric; Bernatchez, Louis — 2021-12-21 <p>The island syndrome hypothesis (ISH) stipulates that, as a result of local selection pressures and restricted gene flow, individuals from island populations should differ from individuals within mainland populations. Specifically, island populations are predicted to contain individuals that are larger, less aggressive, more sociable, and that invest more in their offspring. To date, tests of the ISH have mainly compared oceanic islands to continental sites, and rarely smaller spatial scales such as inland watersheds. Here, using a novel set of genome-wide SNP markers in wild deer mice (Peromyscus maniculatus) we conducted a genomic assessment of predictions underlying the ISH in an inland riverine island system: analysing island-mainland population structure, and quantifying heritability of phenotypes thought to underlie the ISH. We found clear genomic differentiation between island and mainland populations and moderate to high marker-based heritability estimates fo r overall variation in traits previously found to differ in line with the ISH between mainland and island locations. FST outlier analyses highlighted 12 loci associated with differentiation between mainland and island populations. Together these results suggest that the island populations examined are on independent evolutionary trajectories, the traits considered have a genetic basis (rather than phenotypic variation being solely due to phenotypic plasticity). Coupled with the previous results showing significant phenotypic differentiation between island and mainland groups in this system, this study suggests that the ISH can hold even on a small spatial scale.</p>
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Exploration and diet specialization in eastern chipmunks - Québec - Canada
Gharnit, Elouana; Dammhahn, Melanie; Garant, Dany; Réale, Denis — 2022-03-08 <p style="text-align:justify;">Individual diet specialization (IDS) is widespread and can affect the ecological and evolutionary dynamics of populations in significant ways. Extrinsic factors (e.g., food abundance) and individual variation in energetic needs, morphology, or physiology, have been suggested as drivers of IDS. Behavioral traits like exploration and boldness can also impact foraging decisions, although their effects on IDS have not yet been investigated. Specifically, variation among individuals in exploratory behavior and their position along <span lang="EN-US" style="background:white;">the exploration/exploitation trade-off </span>may <span lang="EN-US" style="background:white;">affect their foraging behavior, acquisition of food items and home-range size, which may in turn influence</span> the diversity of their diet. Here we analyzed stable carbon and nitrogen isotopes in hair of wild eastern chipmunks, <em>Tamias striatus,</em> to investigate the influence of individual differences in exploration on IDS. We found that exploration profile, sex, and yearly fluctuations in food availability explained differences in the degree of dietary specialization and in plasticity in stable carbon and stable nitrogen over time. Thus, consistent individual differences in exploration can be an important driver of within-population niche specialization and could therefore affect within-species competition. Our results highlight the need for a more thorough investigation of the mechanisms underlying the link between individual behavioral differences and diet specialization in wild animal populations.</p>

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