https://jvdwalle.github.io/indipop-lab/en/Recent content on IndiPop LabHugoen-CAThu, 01 Jan 2026 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/joanie/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/joanie/<p>Professor</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/JV_2.png"> </figure> <p>Research themes</p> <ul> <li>Population dynamics</li> <li>Vertebrates</li> <li>Marine mammals</li> <li>Population modeling</li> <li>Life history strategies</li> </ul> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/uqar_logo.png"> </figure> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/qcbs_logo_v2.png"> </figure>https://jvdwalle.github.io/indipop-lab/en/people/andreanne/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/andreanne/<p>Postdoctoral researcher</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/andreanne3.JPG"> </figure> <h3 id="project-description">Project description:</h3> <h4 id="harp-seal-demography-and-environmental-change">Harp Seal Demography and Environmental Change</h4> <p>I am interested in the mechanisms linking environmental variation, predator–prey interactions, and animal population dynamics in Arctic ecosystems. I am currently working to better understand how environmental change affects the dynamics of the Northwest Atlantic harp seal population. I use an integrated population model that combines demographic, climatic, and harvest data. First, I examine historical relationships between environmental variables and survival rates. I then incorporate these relationships into the model to project future population trajectories under different climate scenarios.</p>https://jvdwalle.github.io/indipop-lab/en/people/beatrice/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/beatrice/<p>Master&rsquo;s student</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/photo_BL.JPEG"> </figure> <h3 id="project-description">Project description:</h3> <h4 id="temporal-changes-in-spatial-distribution-of-eastern-hudson-bay-beluga-in-a-context-of-population-decline">Temporal changes in spatial distribution of Eastern Hudson Bay beluga in a context of population decline</h4> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/uqar_logo.png"> </figure> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/Logo-MPO-DFO.png"> </figure>https://jvdwalle.github.io/indipop-lab/en/people/maika/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/maika/<p>Undergraduate Student (Université de Sherbrooke)</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/Photo1_Maika.png"> </figure> <h3 id="project-description">Project description:</h3> <h4 id="flexibility-in-foetus-implantation-date-as-a-mechanism-for-birth-phenology-adjustment-in-grey-seals-halichoerus-grypus">Flexibility in foetus implantation date as a mechanism for birth phenology adjustment in grey seals (<em>Halichoerus grypus</em>)</h4> <p>Flexibility in the timing of implantation or variability in fetal growth appear to be mechanisms that may play a role in regulating the reproductive phenology of pinnipeds. Given the observed advance in the average birth date among Northwest Atlantic gray seals, the objective of my project is to examine the mechanisms and determinants of this species’ reproductive phenology. My project is based on fetal weight data from samples collected in the Gulf of St. Lawrence during the hunting season from 1994 to 2023.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2026-correcting-lipid-extraction-effects-on-nitrogen-isotopic-values-15n-in-cetacean-skin/Thu, 01 Jan 2026 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2026-correcting-lipid-extraction-effects-on-nitrogen-isotopic-values-15n-in-cetacean-skin/<p>Stable isotopes of carbon (δ13C) and nitrogen (δ15N) are widely used to study the feeding ecology of cetaceans, as they provide critical insights into diet and migratory behaviors. Lipids in tissues may bias the interpretation of δ13C. Because of this, lipids need to be extracted before measuring stable isotope ratios, but their removal may alter δ15N values. Using nearly 900 skin samples of five cetacean species, this study examined the impact of lipid extraction (Folch method) on skin δ15N values and developed mathematical corrections for these effects. The mathematical corrections were then validated with three species sampled in the same or other environments. Lipid extraction increased δ15N values in all species, albeit by a variable amount. This effect was accurately predicted by both species-specific and multi-species linear relationships. The proposed mathematical corrections across species and environments offer a cost-effective alternative to analysis of separate aliquots for δ13C and δ15N determination, and a valuable tool for retrospectively correcting existing lipid-extracted samples for which raw material may no longer exist.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2026-drivers-of-age-at-first-reproduction-in-the-wandering-albatross-i-diomedea-exulans-i-demographic-factors-environmental-conditions-and-sex-specific-responses/Thu, 01 Jan 2026 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2026-drivers-of-age-at-first-reproduction-in-the-wandering-albatross-i-diomedea-exulans-i-demographic-factors-environmental-conditions-and-sex-specific-responses/<p>Age at first reproduction is an important life-history trait that marks the beginning of reproductive allocation in long-lived organisms and drives patterns of life-history strategies. Demographic factors and environmental conditions likely affect age at first reproduction through multiple pathways: food resources availability and energy storage from birth to recruitment, competition for breeding sites and mate availability. Using a unique 35-year dataset of individual-based mark–recapture data from a wandering albatross (Diomedea exulans) population at Crozet (southern Indian Ocean), we investigated how demographic factors and environment influence age at first reproduction. The population experienced major fluctuations, declining by 50% in the 1970s before partially recovering in the 1980s. It was also exposed to important environmental changes, including variations in large-scale climate phenomena and changes in subtropical anticyclone systems like the Mascarene high pressure system. We used multi-event hidden Markov models to estimate age-specific survival and breeding probabilities for each sex separately. From these models, we estimated the age at first reproduction through absorbing Markov chains while accounting for imperfect detection. We investigated how demographic factors (population density at birth and mate availability at recruitment) and environmental conditions (at birth and recruitment) influenced age at first reproduction through their effects on survival and breeding probabilities. Age at first reproduction declined across cohorts for both sexes from 1970 to the mid-1980s, then stabilized. Females recruited at 9.0 years in early cohorts versus 7.5 years in later ones; males declined from 10.2 to 9.2 years. Environmental conditions at birth, particularly the El Niño Southern Oscillation and the Mascarene high, influenced recruitment timing through delayed effects of natal condition on breeding probability rather than survival. Mate availability strongly facilitated earlier recruitment in both sexes, while natal population density delayed male recruitment specifically. Recruitment timing in wandering albatrosses is shaped primarily by developmental programming during the natal period rather than by immediate environmental triggers at sexual maturity, with mate availability and population density modulating these early-life effects in sex-specific ways. Given that recruitment is an important life-history event linked to population-level reproductive rates, accurate demographic projections require models accounting for cohort-specific effects under changing environments.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2026-drivers-of-population-dynamics-and-juvenile-mortality-in-northwest-atlantic-harp-seals/Thu, 01 Jan 2026 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2026-drivers-of-population-dynamics-and-juvenile-mortality-in-northwest-atlantic-harp-seals/<!-- raw HTML omitted -->https://jvdwalle.github.io/indipop-lab/en/publications/2026-linking-differences-in-personality-to-demography-in-the-wandering-albatross/Thu, 01 Jan 2026 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2026-linking-differences-in-personality-to-demography-in-the-wandering-albatross/<!-- raw HTML omitted -->https://jvdwalle.github.io/indipop-lab/en/publications/2025-abundance-estimate-and-harvest-impacts-on-belcher-islands-eastern-hudson-bay-and-james-bay-beluga-2024-update/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-abundance-estimate-and-harvest-impacts-on-belcher-islands-eastern-hudson-bay-and-james-bay-beluga-2024-update/<p>Distributed by the Government of Canada Publishing and Depository Services Program (Weekly acquisitions list 2025-43).</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-abundance-estimate-of-northwest-atlantic-harp-seals-i-pagophilus-groenlandicus-i-and-harvest-advice-for-2025-2029/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-abundance-estimate-of-northwest-atlantic-harp-seals-i-pagophilus-groenlandicus-i-and-harvest-advice-for-2025-2029/<p>Distributed by the Government of Canada Publishing and Depository Services Program (Weekly acquisitions list 2025-50).</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-accuracy-and-precision-of-an-umbilical-based-method-for-estimating-birthdates-of-pre-weaned-harbour-seal-pups/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-accuracy-and-precision-of-an-umbilical-based-method-for-estimating-birthdates-of-pre-weaned-harbour-seal-pups/<p>Fine-scale age estimation of animals can provide insight into important biological processes but can be logistically difficult to measure in wild populations. We evaluated the accuracy and precision of an umbilical-based method for fine-scale age and birthdate estimation in a wild population of harbour seal pups (Phoca vitulina) in the St. Lawrence Estuary, Quebec, Canada. Our method consists of attributing umbilicus degeneration scores to estimate pup age in days. To assess the methods validity, we first constructed a score attribution test with field pictures of pup umbilical cords at various stages of degeneration. The score attribution test was completed by 8 observers, and we measured the accuracy and precision of the umbilicus degeneration score attribution by calculating Cohen&rsquo;s kappa as well as intraclass correlation coefficient (ICC). We used data from 758 pups (captured between 1998 and 2023) for which an umbilical degeneration score was assigned in the field to evaluate the efficiency of the score test to estimate birthdate. Our findings showed that observers can accurately and precisely attribute umbilicus scores, with a Cohen&rsquo;s kappa mean value of 0.93 which represent almost perfect agreement and an ICC value of 0.92 which is considered excellent precision of the method. Our results indicated that the umbilical-based method can accurately estimate pup birthdates. We suggest the scoring method we developed provides a accurate approach to estimate age, when possible, to a previously used back-calculation method based on body mass. Incorporating the measurement of umbilical score more broadly in research protocol has the potential to open the door to a wide range of ecological studies, including birth phenology, which are important to better understand population and ecosystem dynamics.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-an-integrated-population-model-for-the-belcher-islands-eastern-hudson-bay-bel-ehb-beluga-whale-stock/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-an-integrated-population-model-for-the-belcher-islands-eastern-hudson-bay-bel-ehb-beluga-whale-stock/<p>Distributed by the Government of Canada Publishing and Depository Services Program (Weekly acquisitions list 2025-43).</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-neonatal-growth-patterns-sexual-dimorphism-and-compensatory-growth-in-harbour-seal-pups/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-neonatal-growth-patterns-sexual-dimorphism-and-compensatory-growth-in-harbour-seal-pups/<p>Juvenile survival, a fundamental parameter in the population dynamics of long-lived species, is often tightly linked to early-life body growth. Here, based on repeated mass measurements on 555 harbour seal Phoca vitulina pups marked between 1998 and 2023 in the St. Lawrence Estuary, we first characterized the shape of neonatal growth patterns of the pups using Bayesian hierarchical nonlinear models. Second, we evaluated the effect of sex on neonatal growth to better understand the development of sexual dimorphism in this species and tested for compensatory growth. Finally, we assessed the influence of local variables (wind speed, sea surface temperature, pup abundance and breeding site) during the neonatal stage on pup weaning mass. Our results showed that neonatal growth follows a Gompertz curve, characterized by minimal growth the first few days after birth, followed by a significant increase in mass until a stabilization near weaning (~30 d of age). We found no sex difference in the growth pattern, but males were slightly heavier at birth than females. Larger pups accumulated more mass than smaller pups, suggesting increasing returns for greater body mass at birth but no compensatory growth. Finally, wind speed, sea surface temperature, pup abundance and breeding site did not affect weaning mass. This study provides insight into the characterization of nonlinear growth in harbour seal pups. Monitoring neonatal growth provides a tool to assess potential patterns of juvenile survival, which are important in studies of population dynamics.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-review-of-the-atlantic-seal-management-strategy-precautionary-approach-framework/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-review-of-the-atlantic-seal-management-strategy-precautionary-approach-framework/<p>Distributed by the Government of Canada Publishing and Depository Services Program (Weekly acquisitions list 2026-05). &ldquo;The Atlantic Seal Management Strategy (ASMS) was the first Precautionary Approach (PA) framework developed for a fishery in Canada and was adopted in 2003, prior to the implementation of the Department of Fisheries and Oceans&rsquo; (DFO) PA Policy. Since then, it has been used to provide advice on sustainable harvest levels for Atlantic seals (harp, grey and hooded seals) and other marine mammal stocks in Canada. Components of the ASMS have been reviewed and refined since its implementation, however, in light of the time since the initial development of the ASMS, DFO Science was asked to review the current PA framework for Atlantic seals to ensure consistency with DFO&rsquo;s PA Policy. Here we review the ASMS PA framework and make recommendations for adjustments to the current strategy and suggestions for future work&rdquo;&ndash;Abstract, page iv.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2025-toward-a-unified-approach-to-modelling-adaptation-among-demographers-and-evolutionary-ecologists/Wed, 01 Jan 2025 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2025-toward-a-unified-approach-to-modelling-adaptation-among-demographers-and-evolutionary-ecologists/<p>Demographic and evolutionary modelling approaches are critical to understanding and projecting species responses to global environmental changes. Population matrix models have been a favoured tool in demography, but until recently, they failed to account for short-term evolutionary changes. Evolutionary-explicit demographic models remain computationally intensive, difficult to use and have yet to be widely adopted for empirical studies. Researchers focusing on short-term evolution often favour individual-based simulations, which are more flexible but less transferable and computationally efficient. Limited communication between fields has led to differing perspectives on key issues, such as how life-history traits affect adaptation to environmental change. We develop a new EvoDemo hyperstate matrix population model (EvoDemo-Hyper MPM) that incorporates the genetic inheritance of quantitative traits, enabling fast computation of evolutionary and demographic dynamics. We evaluate EvoDemo-Hyper MPM against individual-based simulations and provide analytical approximations for adaptation rates across six distinct scales in response to selection. We show that different methods yield equivalent results for the same biological scenario, although semantic differences between fields may obscure these similarities. Our results demonstrate that EvoDemo-Hyper MPM provides accurate, computationally efficient solutions, closely matching outcomes from individual-based simulations and analytical approximations under similar biological conditions. Adaptation rates per generation remain constant across species when selection acts on fertility but vary with other vital rates. Adaptation per time decreases with generation time unless selection targets adult survival, where intermediate life histories adapt fastest. Rates per generation, defined as the relative change in individual fitness, remain constant across species and vital rates. We discuss that no general prediction emerges about which species or life-history traits yield higher adaptation rates, as outcomes depend on life cycles, vital rates and the definition used. We provide Matlab and R code to support the application of our EvoDemo-Hyper MPM.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2024-cadre-l-gislatif-qu-b-cois-pour-la-protection-des-esp-ces-sauvages-en-situation-pr-caire-valuation-critique-et-recommandations-pour-une-r-vision-majeure/Mon, 01 Jan 2024 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2024-cadre-l-gislatif-qu-b-cois-pour-la-protection-des-esp-ces-sauvages-en-situation-pr-caire-valuation-critique-et-recommandations-pour-une-r-vision-majeure/<p>In Quebec, the Act Respecting Threatened or Vulnerable species (ARTV), adopted in 1989, aims to safeguard Quebec’s wild genetic diversity by protecting species at risk. However, since its implementation about 30 years ago, it has been repeatedly pointed out that the application of the Quebec legislative framework for the protection of wildlife species at risk was often slow and inadequate. The aim of this article is therefore to make a series of observations on the limits of current legislation and then propose nine urgent recommendations to improve the effectiveness of conservation efforts for species at risk in Quebec. Our recommendations aim to increase the efficiency and transparency of the designation process, reconsider com-pensation mechanisms for the loss of critical habitat, and harmonize species status between the federal and provincial levels. We hope that our article will pave the way for a constructive discussion leading to an improved protection of wildlife species in precarious situations and their persistence for future generations.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2024-the-impact-of-boldness-on-demographic-rates-and-life-history-outcomes-in-the-wandering-albatross/Mon, 01 Jan 2024 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2024-the-impact-of-boldness-on-demographic-rates-and-life-history-outcomes-in-the-wandering-albatross/<p>Differences among individuals within a population are ubiquitous. Those differences are known to affect the entire life cycle with important consequences for all demographic rates and outcomes. One source of among-individual phenotypic variation that has received little attention from a demographic perspective is animal personality, which is defined as consistent and heritable behavioural differences between individuals. While many studies have shown that individual variation in individual personality can generate individual differences in survival and reproductive rates, the impact of personality on all demographic rates and outcomes remains to be assessed empirically. Here, we used a unique, long-term, dataset coupling demography and personality of wandering albatross (Diomedea exulans) in the Crozet Archipelago and a comprehensive analysis based on a suite of approaches (capture-mark-recapture statistical models, Markov chains models and structured matrix population models). We assessed the effect of boldness on annual demographic rates (survival, breeding probability, breeding success), life-history outcomes (life expectancy, lifetime reproductive outcome, occupancy times), and an integrative demographic outcome (population growth rate). We found that boldness had little impact on female demographic rates, but was very likely associated with lower breeding probabilities in males. By integrating the effects of boldness over the entire life cycle, we found that bolder males had slightly lower lifetime reproductive success compared to shyer males. Indeed, bolder males spent a greater proportion of their lifetime as non-breeders, which suggests longer inter-breeding intervals due to higher reproductive allocation. Our results reveal that the link between boldness and demography is more complex than anticipated by the pace-of-life literature and highlight the importance of considering the entire life cycle with a comprehensive approach when assessing the role of personality on individual performance and demography.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2023-genetic-rescue-from-protected-areas-is-modulated-by-migration-hunting-rate-and-timing-of-harvest/Sun, 01 Jan 2023 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2023-genetic-rescue-from-protected-areas-is-modulated-by-migration-hunting-rate-and-timing-of-harvest/<p>In terrestrial and marine ecosystems, migrants from protected areas may buffer the risk of harvest-induced evolutionary changes in exploited populations that face strong selective harvest pressures. Understanding the mechanisms favoring genetic rescue through migration could help ensure evolutionarily sustainable harvest outside protected areas and conserve genetic diversity inside those areas. We developed a stochastic individual-based metapopulation model to evaluate the potential for migration from protected areas to mitigate the evolutionary consequences of selective harvest. We parameterized the model with detailed data from individual monitoring of two populations of bighorn sheep subjected to trophy hunting. We tracked horn length through time in a large protected and a trophy-hunted populations connected through male breeding migrations. We quantified and compared declines in horn length and rescue potential under various combinations of migration rate, hunting rate in hunted areas and temporal overlap in timing of harvest and migrations, which affects the migrants&rsquo; survival and chances to breed within exploited areas. Our simulations suggest that the effects of size-selective harvest on male horn length in hunted populations can be dampened or avoided if harvest pressure is low, migration rate is substantial, and migrants leaving protected areas have a low risk of being shot. Intense size-selective harvest impacts the phenotypic and genetic diversity in horn length, and population structure through changes in proportions of large-horned males, sex ratio and age structure. When hunting pressure is high and overlaps with male migrations, effects of selective removal also emerge in the protected population, so that instead of a genetic rescue of hunted populations, our model predicts undesirable effects inside protected areas. Our results stress the importance of a landscape approach to management, to promote genetic rescue from protected areas and limit ecological and evolutionary impacts of harvest on both harvested and protected populations.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2023-individual-life-histories-neither-slow-nor-fast-just-diverse/Sun, 01 Jan 2023 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2023-individual-life-histories-neither-slow-nor-fast-just-diverse/<p>The slow-fast continuum is a commonly used framework to describe variation in life-history strategies across species. Individual life histories have also been assumed to follow a similar pattern, especially in the pace-of-life syndrome literature. However, whether a slow-fast continuum commonly explains life-history variation among individuals within a population remains unclear. Here, we formally tested for the presence of a slow-fast continuum of life histories both within populations and across species using detailed long-term individual-based demographic data for 17 bird and mammal species with markedly different life histories. We estimated adult lifespan, age at first reproduction, annual breeding frequency, and annual fecundity, and identified the main axes of life-history variation using principal component analyses. Across species, we retrieved the slow-fast continuum as the main axis of life-history variation. However, within populations, the patterns of individual life-history variation did not align with a slow-fast continuum in any species. Thus, a continuum ranking individuals from slow to fast living is unlikely to shape individual differences in life histories within populations. Rather, individual life-history variation is likely idiosyncratic across species, potentially because of processes such as stochasticity, density dependence, and individual differences in resource acquisition that affect species differently and generate non-generalizable patterns across species.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2023-spatiotemporal-variation-in-pup-abundance-and-preweaning-survival-of-harbour-seals-i-phoca-vitulina-i-in-the-st-lawrence-estuary-canada/Sun, 01 Jan 2023 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2023-spatiotemporal-variation-in-pup-abundance-and-preweaning-survival-of-harbour-seals-i-phoca-vitulina-i-in-the-st-lawrence-estuary-canada/<p>Marine mammal populations worldwide greatly benefitted from conservation measures put in place since the 1970s following overexploitation, and many pinniped populations have recovered. However, threats due to bycatch, interspecific interactions or climate change remain, and detailed knowledge on vital rates, population dynamics, and their responses to environmental changes is essential for efficient management and conservation of wild populations. In this study, we quantified pup abundance and survival of individually marked harbour seal (Phoca vitulina Linnaeus, 1758) pups during the preweaning period at Bic Island and Métis sites in the St. Lawrence Estuary from 1998 to 2019. We used mark-recapture models to evaluate competing hypotheses regarding variation in daily preweaning survival rates and capture probability during the pups’ first 30 days of life. Pup abundance increased from 76 [95% CI: 59, 101] to 323 [95% CI: 233, 338] in the past two decades at Bic Island and from 66 [95% CI: 47, 91] to 285 [95% CI: 204, 318] at Métis. Preweaning survival was generally higher at Bic (0.73 [95% CI: 0.58, 0.82]) than at Métis (0.68 [95% CI: 0.52, 0.79]). We hypothesize that differences between habitats and human disturbance contribute to lower preweaning survival at Métis, but behavioural studies are needed to understand the impacts of disturbance on mother–pup interactions during the nursing period.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2022-boldness-predicts-divorce-rates-in-wandering-albatrosses-i-diomedea-exulans-i/Sat, 01 Jan 2022 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2022-boldness-predicts-divorce-rates-in-wandering-albatrosses-i-diomedea-exulans-i/<p>Personality predicts divorce rates in humans, yet how personality traits affect divorce in wild animals remains largely unknown. In a male-skewed population of wandering albatross (Diomedea exulans), we showed that personality predicts divorce; shyer males exhibited higher divorce rates than bolder males but no such relationship was found in females. We propose that divorce may be caused by the intrusion of male competitors and shyer males divorce more often because of their avoidance of territorial aggression, while females have easier access to mates regardless of their personality. Thus, personality may have important implications for the dynamics of social relationships.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2022-different-proxies-different-stories-imperfect-correlations-and-different-determinants-of-fitness-in-bighorn-sheep/Sat, 01 Jan 2022 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2022-different-proxies-different-stories-imperfect-correlations-and-different-determinants-of-fitness-in-bighorn-sheep/<p>Measuring individual fitness empirically is required to assess selective pressures and predicts evolutionary changes in nature. There is, however, little consensus on how fitness should be empirically estimated. As fitness proxies vary in their underlying assumptions, their relative sensitivity to individual, environmental, and demographic factors may also vary. Here, using a long-term study, we aimed at identifying the determinants of individual fitness in bighorn sheep (Ovis canadensis) using seven fitness proxies. Specifically, we compared four-lifetime fitness proxies: lifetime breeding success, lifetime reproductive success, individual growth rate, individual contribution to population growth, and three multi-generational proxies: number of granddaughters, individual descendance in the next generation, and relative genetic contribution to the next generation. We found that all proxies were positively correlated, but the magnitude of the correlations varied substantially. Longevity was the main determinant of most fitness proxies. Individual fitness calculated over more than one generation was also affected by population density and growth rate. Because they are affected by contrasting factors, our study suggests that different fitness proxies should not be used interchangeably as they may convey different information about selective pressures and lead to divergent evolutionary predictions. Uncovering the mechanisms underlying variation in individual fitness and improving our ability to predict evolutionary change might require the use of several, rather than one, the proxy of individual fitness.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2021-disentangling-direct-and-indirect-determinants-of-the-duration-of-maternal-care-in-brown-bears-environmental-context-matters/Fri, 01 Jan 2021 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2021-disentangling-direct-and-indirect-determinants-of-the-duration-of-maternal-care-in-brown-bears-environmental-context-matters/<p>The duration of maternal care, an important life-history trait affecting population dynamics, varies greatly within species. Yet, our understanding of its predictors is limited, mostly correlative and subject to misinterpretations, due to difficulties to disentangle the role of maternal- and offspring-related characteristics. We conducted path analysis on a dataset including 217 brown bear litters captured over a 29-year period in two populations in Sweden (‘North’ and ‘South’) facing contrasting environmental conditions to identify and quantify the causes of variation in the duration of maternal care (1.5 or 2.5 years). We showed that the causal determinants of the duration of maternal care were context-dependent. Contrary to their expected central role in the determination of the duration of maternal care, yearling mass and its direct determinants (i.e. litter size and maternal mass) were only important in the North population, where environmental conditions are harsher and the cost of extended maternal care presumably higher. In the South, the duration of maternal care was not caused by yearling mass nor any maternal or litter characteristics. Extension of maternal care may thus result from factors independent from maternal and offspring condition in the South, such as an artificial hunting-induced selection for longer maternal care through the legal protection of family groups. Our results provide an important contribution to our very limited knowledge of the direct and indirect determinants of the duration of maternal care and highlight the importance of accounting for the environmental context when assessing maternal reproductive tactics.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2021-the-interplay-between-hunting-rate-hunting-selectivity-and-reproductive-strategies-shapes-population-dynamics-of-a-large-carnivore/Fri, 01 Jan 2021 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2021-the-interplay-between-hunting-rate-hunting-selectivity-and-reproductive-strategies-shapes-population-dynamics-of-a-large-carnivore/<p>Harvest, through its intensity and regulation, often results in selection on female reproductive traits. Changes in female traits can have demographic consequences, as they are fundamental in shaping population dynamics. It is thus imperative to understand and quantify the demographic consequences of changes in female reproductive traits to better understand and anticipate population trajectories under different harvest intensities and regulations. Here, using a dynamic, frequency-dependent, population model of the intensively hunted brown bear (Ursus arctos) population in Sweden, we quantify and compare population responses to changes in four reproductive traits susceptible to harvest-induced selection: litter size, weaning age, age at first reproduction, and annual probability to reproduce. We did so for different hunting quotas and under four possible hunting regulations: (i) no individuals are protected, (ii) mothers but not dependent offspring are protected, (iii) mothers and dependent offspring of the year (cubs) are protected, and (iv) entire family groups are protected (i.e., mothers and dependent offspring of any age). We found that population growth rate declines sharply with increasing hunting quotas. Increases in litter size and the probability to reproduce have the greatest potential to affect population growth rate. Population growth rate increases the most when mothers are protected. Adding protection on offspring (of any age), however, reduces the availability of bears for hunting, which feeds back to increase hunting pressure on the nonprotected categories of individuals, leading to reduced population growth. Finally, we found that changes in reproductive traits can dampen population declines at very high hunting quotas, but only when protecting mothers. Our results illustrate that changes in female reproductive traits may have context-dependent consequences for demography. Thus, to predict population consequences of harvest-induced selection in wild populations, it is critical to integrate both hunting intensity and regulation, especially if hunting selectivity targets female reproductive strategies.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2020-trade-off-between-offspring-mass-and-number-the-lightest-offspring-bear-the-costs/Wed, 01 Jan 2020 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2020-trade-off-between-offspring-mass-and-number-the-lightest-offspring-bear-the-costs/<p>Life-history theory predicts a trade-off between offspring size and number. However, the role of intra-litter phenotypic variation in shaping this tradeoff is often disregarded. We compared the strength of the relationship between litter size and mass from the perspective of the lightest and the heaviest yearling offspring in 110 brown bear litters in Sweden. We showed that the mass of the lightest yearlings decreased with increasing litter size, but that the mass of the heaviest yearling remained stable, regardless of litter size. Consistent with a conservative reproductive strategy, our results suggest that mothers maintained a stable investment in a fraction of the litter, while transferring the costs of larger litter size to the remaining offspring. Ignoring intra-litter phenotypic variation may obscure our ability to detect a trade-off between offspring size and number.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2019-offspring-mass-variation-in-tree-swallows-a-case-of-bet-hedging/Tue, 01 Jan 2019 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2019-offspring-mass-variation-in-tree-swallows-a-case-of-bet-hedging/<p>The evolution of reproductive strategies is affected by the ability of organisms to deal with future environmental conditions. When environments are temporally unpredictable, however, it is difficult to anticipate optimal offspring phenotype. Diversification of offspring phenotypes, a strategy called diversified bet-hedging, may allow parents to maximize their fitness by reducing between-year variation in reproductive success. The link between diversification of offspring phenotypes and individual reproductive success, however, has rarely been documented empirically. We used an eight-year dataset (1215 broods, 870 females) on individually marked tree swallows (Tachycineta bicolor) to assess whether intra-brood mass variation was compatible with a diversified bet-hedging strategy. Intra-brood mass variation was weakly, but significantly repeatable within females, suggesting consistent individual differences. Greater intra-brood mass variation, however, was not associated with reduced between-year variation in reproductive success or increased female reproductive success. Moreover, contrary to diversified bet-hedging expectations, fledging success of large broods was greater when hatchlings had similar rather than variable masses. Our results suggest that intra-brood mass variation may not result from diversified bet-hedging, but rather from complex interactions between environmental, brood, and maternal characteristics.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2019-proximity-to-humans-is-associated-with-longer-maternal-care-in-brown-bears/Tue, 01 Jan 2019 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2019-proximity-to-humans-is-associated-with-longer-maternal-care-in-brown-bears/<p>Abstract: In the sexual conflict over the duration of maternal care, male mammals may improve their reproductive success by forcing early mother–offspring separation in species where lactation supresses estrus. However, when individual females benefit from continuing to care for their current offspring, they should adopt counter-strategies to avoid separation from offspring. Here, we tested whether spatial segregation from adult males and proximity to humans during the mating season could be associated with longer maternal care in the Scandinavian brown bear (Ursus arctos). Using resource selection functions (RSFs), we contrasted habitat selection patterns of adult males and those of adult females with yearlings that either provided 1.5 years of maternal care (“short-care females”) or continued care for an additional year (“long-care females”) during the mating season, the period when family break-ups typically occur. Males and short-care females had similar habitat selection patterns during the mating season. In contrast, habitat selection patterns differed between males and long-care females, suggesting spatial segregation between the two groups. In particular, long-care females used areas closer to human habitations compared with random locations (defined here as selection), whereas males used areas further to human habitations compared with random locations (defined here as avoidance). Our results show a correlation between habitat selection behavior and the duration of maternal care. We suggest that proximity to humans during the mating season may represent a female tactic to avoid adverse interactions with males that may lead to early weaning of offspring. Significance statement: In mammalian species where lactation supresses ovulation, males may gain a reproductive advantage by forcing early mother-offspring separation; however females can respond through behavioral tactics. We show that female brown bears with yearling cubs can spatially segregate from males during the mating season and that this behavior is associated with longer maternal care. Females selecting areas close to human habitations tend to keep their yearlings for an additional year, suggesting that human presence could have a shielding effect from males. Our study is among the few to explore sexual conflicts over the duration of maternal care close to weaning and shows that animals have the potential to adjust their behavioral tactics to make use of human-dominated landscapes.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2018-hunting-regulation-favors-slow-life-histories-in-a-large-carnivore/Mon, 01 Jan 2018 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2018-hunting-regulation-favors-slow-life-histories-in-a-large-carnivore/<p>As an important extrinsic source of mortality, harvest should select for fast reproduction and accelerated life histories. However, if vulnerability to harvest depends upon female reproductive status, patterns of selectivity could diverge and favor alternative reproductive behaviors. Here, using more than 20 years of detailed data on survival and reproduction in a hunted large carnivore population, we show that protecting females with dependent young, a widespread hunting regulation, provides a survival benefit to females providing longer maternal care. This survival gain compensates for the females&rsquo; reduced reproductive output, especially at high hunting pressure, where the fitness benefit of prolonged periods of maternal care outweighs that of shorter maternal care. Our study shows that hunting regulation can indirectly promote slower life histories by modulating the fitness benefit of maternal care tactics. We provide empirical evidence that harvest regulation can induce artificial selection on female life history traits and affect demographic processes.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2017-indirect-effects-of-bear-hunting-a-review-from-scandinavia/Sun, 01 Jan 2017 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2017-indirect-effects-of-bear-hunting-a-review-from-scandinavia/<p>Harvest by means of hunting is a commonly used tool in large carnivore management. To evaluate the effects of harvest on populations, managers usually focus on numerical or immediate direct demographic effects of harvest mortality on a population&rsquo;s size and growth. However, we suggest that managers should also give consideration to indirect and potential evolutionary effects of hunting (e.g., the consequences of a change in the age, sex, and social structure), and their effects on population growth rate. We define &ldquo;indirect effects&rdquo; as hunting-induced changes in a population, including human-induced selection, that result in an additive change to the population growth rate &ldquo;lambda&rdquo; beyond that due to the initial offtake from direct mortality. We considered 4 major sources of possible indirect effects from hunting of bears: (1) changes to a population&rsquo;s age and sex structure, (2) changes to a population&rsquo;s social structure, (3) changes in individual behavior, and (4) human-induced selection. We identified empirically supported, as well as expected, indirect effects of hunting based primarily on &gt;30 years of research on the Scandinavian brown bear (Ursus arctos) population. We stress that some indirect effects have been documented (e.g., habitat use and daily activity patterns of bears change when hunting seasons start, and changes in male social structure induce sexually selected infanticide and reduce population growth). Other effects may be more difficult to document and quantify in wild bear populations (e.g., how a younger age structure in males may lead to decreased offspring survival). We suggest that managers of bear and other large carnivore populations adopt a precautionary approach and assume that indirect effects do exist, have a potential impact on population structure, and, ultimately, may have an effect on population growth that differs from that predicted by harvest models based on direct effects alone.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2016-can-hunting-data-be-used-to-estimate-unbiased-population-parameters-a-case-study-on-brown-bears/Fri, 01 Jan 2016 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2016-can-hunting-data-be-used-to-estimate-unbiased-population-parameters-a-case-study-on-brown-bears/<p>Quantifying temporal changes in harvested populations is critical for applied and fundamental research. Unbiased data are required to detect true changes in phenotypic distribution or population size. Because of the difficulty of collecting detailed individual data from wild populations, data from hunting records are often used. Hunting records, however, may not represent a random sample of a population. We aimed to detect and quantify potential bias in hunting records. We compared data from a long-term monitoring project with hunting records of brown bears (Ursus arctos) in Sweden and investigated temporal trends (1996-2013) in the ratio of yearlings to adult females, yearling mass and adult female mass. Data from hunting records underestimated the decline in yearling and adult female mass over time, most likely owing to the legal protection of family groups from hunting, but reflected changes in the ratio of yearlings to adult females more reliably. Although hunting data can be reliable to approximate population abundance in some circumstances, hunting data can represent a biased sample of a population and should be used with caution in management and conservation decisions.</p>https://jvdwalle.github.io/indipop-lab/en/publications/2014-stomach-temperature-records-reveal-nursing-behaviour-and-transition-to-solid-food-consumption-in-an-unweaned-mammal-the-harbour-seal-pup-i-phoca-vitulina-i/Wed, 01 Jan 2014 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/publications/2014-stomach-temperature-records-reveal-nursing-behaviour-and-transition-to-solid-food-consumption-in-an-unweaned-mammal-the-harbour-seal-pup-i-phoca-vitulina-i/<p>Knowledge of milk transfer from mother to offspring and early solid food ingestions in mammals allows for a greater understanding of the factors affecting transition to nutritional independence and pre-weaning growth and survival. Yet studies monitoring suckling behaviour have often relied on visual observations, which might not accurately represent milk intake. We assessed the use of stomach temperature telemetry to monitor suckling and foraging behaviour in free-ranging harbour seal (Phoca vitulina) pups during lactation. Stomach temperature declines were analysed using principal component and cluster analyses, as well as trials using simulated stomachs resulting in a precise classification of stomach temperature drops into milk, seawater and solid food ingestions. Seawater and solid food ingestions represented on average 15.3±1.6% [0-40.0%] and 0.7±0.2% [0-13.0%], respectively, of individual ingestions. Overall, 63.7% of milk ingestions occurred while the pups were in the water, of which 13.9% were preceded by seawater ingestion. The average time between subsequent ingestions was significantly less for seawater than for milk ingestions. These results suggest that seawater ingestion might represent collateral ingestion during aquatic suckling attempts. Alternatively, as solid food ingestions (n = 19) were observed among 7 pups, seawater ingestion could result from missed prey capture attempts. This study shows that some harbour seals start ingesting prey while still being nursed, indicating that weaning occurs more gradually than previously thought in this species. Stomach temperature telemetry represents a promising method to study suckling behaviour in wild mammals and transition to nutritional independence in various endotherm species. © 2014 Sauvé et al.</p>https://jvdwalle.github.io/indipop-lab/en/people/kayla/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/kayla/<p>Master&rsquo;s Student (Université de Sherbrooke)</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/kayla2.jpeg"> </figure> <h3 id="project-description">Project description:</h3> <h4 id="comparison-of-the-birth-phenology-of-harbour-seals-phoca-vitulina-and-grey-seals-halichoerus-grypus-in-response-to-climate-change-in-the-estuary-and-gulf-of-st-lawrence">Comparison of the birth phenology of harbour seals (<em>Phoca vitulina</em>) and grey seals (<em>Halichoerus grypus</em>) in response to climate change in the Estuary and Gulf of St. Lawrence.</h4> <p>Phenological responses to climate change vary enormously between species. It is imperative to understand these responses, as they can have major consequences for the survival of youngs. This can result in a time lag between births and the abundance of resources, leading to a lack of resources at the time when they are needed by the young.</p>https://jvdwalle.github.io/indipop-lab/en/people/sophie/Mon, 01 Jan 0001 00:00:00 +0000https://jvdwalle.github.io/indipop-lab/en/people/sophie/<p>PhD Student</p> <figure class="ma0 w-75"><img src="https://jvdwalle.github.io/indipop-lab/images/Sophie.jpg"> </figure> <h3 id="project-description">Project description:</h3> <h4 id="determinants-of-predictability-of-vertebrate-population-time-series">Determinants of predictability of vertebrate population time series</h4> <p>One of the main challenges in wildlife management and conservation is predicting the potential for animal populations and species to persist. The knowledge gained from monitoring population abundance makes possible, in some cases, to anticipate their expected trajectories during the coming century. However, the complexity of ecological systems, species’ intrinsic characteristics, unpredictable events and changing environmental conditions limit the predictive power of models. To date, the factors and disturbances influencing this predictability remain poorly understood. Consequently, the objective of my research project is to improve our understanding of the determinants of predictability and its sensitivity to environmental disturbances, which is essential to ensure the long-term persistence of animal populations under global change.</p>