
Julien G A MartinUniversity of Ottawa · Department of Biology
Julien G A Martin
PhD
About
79
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Introduction
Additional affiliations
June 2003 - May 2006
November 2010 - February 2013
January 2011 - present
Publications
Publications (79)
Responses of natural populations to climate change are driven by how multiple climatic and biotic factors affect survival and reproduction, and ultimately shape population dynamics. Yet, we lack a general understanding of the role of such mechanisms in moderating climate-change impacts across different species. Here, we synthesize how the joint eff...
Despite the advantages of lasting pair bonds and the prevalence of monogamy, at least in avian species, some individuals switch mates (divorce). Divorce is generally considered to be adaptive (i.e., conferring net fitness benefits), although its causes and consequences often remain unclear, most notably regarding the genetic basis of this behavior....
Climate change and its resulting effects on seasonality are known to alter a variety of animal behaviors including those related to foraging, phenology, and migration. While many studies focus on the impacts of phenological changes on physiology or fitness enhancing behaviors, fewer have investigated the relationship between variation in weather an...
Life history trade‐offs are one of the central tenets of evolutionary demography. Trade‐offs, depicting negative covariances between individuals' life history traits, can arise from genetic constraints, or from a finite amount of resources that each individual has to allocate in a zero‐sum game between somatic and reproductive functions. While theo...
The size and growth patterns of nestling birds are key determinants of their survival up to fledging and long‐term fitness. However, because traits such as feathers, skeleton and body mass can follow different developmental trajectories, our understanding of the impact of adverse weather on development requires insights into trait‐specific sensitiv...
The nonlinearity and fear hypothesis predicts that highly aroused vocal mammals and birds produce vocalizations (notably alarm calls and screams) which contain a variety of nonlinear phenomena (NLP). Such vocalizations often sound “noisy” because vocal production systems are over-blown when animals are highly aroused. While much is known about the...
In most animals, body mass varies with ecological conditions and is expected to reflect how much energy can be allocated to reproduction and survival. Because the sexes often differ in their resource acquisition and allocation strategies, variations in adult body mass and their consequences on fitness can differ between the sexes.
Assessing the rel...
Life history tradeoffs are one of the central tenets of evolutionary demography. Tradeoffs, depicting negative phenotypic or genetic covariances between individuals’ demographic rates, arise from a finite amount of resources that each individual has to allocate in a zero-sum game between somatic and reproductive functions. While theory predicts tha...
With global climates changing rapidly, animals must adapt to new environmental conditions with altered weather and phenology. The key to adapting to these new conditions is adjusting the timing of reproduction to maximize fitness. Using a long‐term dataset on a wild population of yellow‐bellied marmots ( Marmota flaviventer ) at the Rocky Mountain...
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 with...
With global climates changing rapidly, animals must adapt to new environmental conditions with altered weather and phenology. Key to adapting to these new conditions is adjusting the timing of reproduction to maximize fitness. Using a long-term dataset on a wild population of yellow-bellied marmots (Marmota flaviventer) at the Rocky Mountain Biolog...
All animals must face predation risks at some points in their lives and individuals may vary in how much risk they are willing to accept. While it is well recognized that sociality is a way to manage risks, and social group size effects are well studied, the specific ways in which different types of social relationships influence individual risk re...
The fate of natural populations is mediated by complex interactions among vital rates, which can vary within and among years. Although the effects of random, among‐year variation in vital rates have been studied extensively, relatively little is known about how periodic, nonrandom variation in vital rates affects populations. This knowledge gap is...
The timing of life events (phenology) can be influenced by climate. Studies from around the world tell us that climate cues and species' responses can vary greatly. If variation in climate effects on phenology is strong within a single ecosystem, climate change could lead to ecological disruption, but detailed data from diverse taxa within a single...
Repeated social interactions with conspecifics and/or heterospecifics during early development may drive the differentiation of behavior among individuals. Competition is a major form of social interaction and its impacts can depend on whether interactions occur between conspecifics or heterospecifics and the directionality of a response could be s...
Over the past three decades, root organ cultures (ROCs) have been the gold standard method for studying arbuscular mycorrhizal fungi (AMF) under in vitro conditions, and ROCs derived from various plant species have been used as hosts for AM monoxenic cultures. While there is compelling evidence that host identity can significantly modify AMF fitnes...
Repeated social interactions with conspecifics and/or heterospecifics during early development may drive the differentiation of behaviour among individuals. This behavioural differentiation may occur through individuals behaving more different from each other on average and/or individuals behaving more consistently. Competition is a major form of s...
Owing to sex-specific reproductive strategies, the mean and variance in annual offspring production may differ between the sexes. In addition, there may be sex-specific changes in reproductive performance with age (e.g. senescence). We used 20 and 50 years of longitudinal data on male and female yellow-bellied marmots, respectively, to investigate...
Species that hibernate generally live longer than would be expected based solely on their body size. Hibernation is characterized by long periods of metabolic suppression (torpor) interspersed by short periods of increased metabolism (arousal). The torpor–arousal cycles occur multiple times during hibernation, and it has been suggested that process...
Conservation strategies are rarely systematically evaluated, which reduces transparency, hinders the cost-effective deployment of resources, and hides what works best in different contexts. Using data on the iconic and critically endangered orangutan (Pongo spp.), we developed a novel spatiotemporal framework for evaluating conservation investments...
Any average pattern observed at the population level (cross‐sectional analysis) may confound two different types of processes: some processes that occur among individuals and others that occur within individuals. Separating within‐ from among‐individual processes is critical for our understanding of ecological and evolutionary dynamics.
The within‐...
Seasonal and ontogenetic variations in depth use by benthic species are often concomitant with changes in their spatial distribution. This has implications for the efficacy of spatial conservation measures such as marine protected areas (MPAs). The critically endangered flapper skate (Dipturus intermedius) is the designation feature of an MPA in Sc...
Seasonal and ontogenetic variations in depth use by benthic species are often concomitant with changes in their spatial distribution. This has implications for the efficacy of spatial conservation measures such as marine protected areas (MPAs). The critically endangered flapper skate (Dipturus intermedius) is the designation feature of an MPA in Sc...
The ability of individuals and populations to adapt to a changing climate is a key determinant of population dynamics. While changes in mean behaviour are well studied, changes in trait variance have been largely ignored, despite being assumed to be crucial for adapting to a changing environment. As the ability to acquire resources is essential to...
Species that hibernate live longer than would be expected based solely on their body size. Hibernation is characterized by long periods of metabolic suppression (torpor) interspersed by short periods of increased metabolism (arousal). The torpor-arousal cycles occur multiple times during hibernation, and it has been suggested that processes control...
Body mass is often viewed as a proxy of past access to resources and of future survival and reproductive success. Links between body mass and survival or reproduction are, however, likely to differ between age classes and sexes. Remarkably, this is rarely taken into account in selection analyses. Selection on body mass is likely to be the primary t...
Studies in natural populations are essential to understand the evolutionary ecology of senescence and terminal allocation. While there are an increasing number of studies investigating late-life variation in different life-history traits of wild populations, little is known about these patterns in social behaviour. We used long-term individual base...
Species that hibernate live longer than would be expected based solely on their body size. Hibernation is characterized by long periods of metabolic suppression (torpor) interspersed by short periods of increased metabolism (arousal). The torpor-arousal cycles occur multiple times during hibernation, and it has been suggested that processes control...
In social species, maternal social relationships, in addition to direct care, impact offspring survival but much of what we know about these effects comes from studies of obligately social and cooperatively breeding species. Yellow-bellied marmots ( Marmota flaviventer ) are a facultatively social species whose social groups vary in composition, si...
Logging and conversion of tropical forests in Southeast Asia have resulted in the expansion of landscapes containing a mosaic of habitats that may vary in their ability to sustain local biodiversity. However, the complexity of these landscapes makes it difficult to assess abundance and distribution of some species using ground-based surveys alone....
Using data on the iconic orangutan (Pongo spp.), we developed a novel spatiotemporal framework for evaluating conservation investments. We show that around USD 1 billion was invested between 1999 and 2019 into orangutan conservation by governments, non-governmental organizations, companies and communities. Broken down by allocation to different con...
Animal ecologists often collect hierarchically structured data and analyse these with linear mixed‐effects models. Specific complications arise when the effect sizes of covariates vary on multiple levels (e.g. within vs. among subjects). Mean centring of covariates within subjects offers a useful approach in such situations, but is not without prob...
Global climate change is shifting many species’ phenology and has created a number of key mismatches that threaten population persistence. Phenotypically plastic individuals have the ability to adjust their behaviour in response to environmental change. While phenotypic plasticity may serve as a buffer, it is generally not known whether in case thi...
Significance
Climate change is altering the seasonal environmental conditions to which animals have adapted, but the outcome may differ between seasons for a particular species. Demographic responses therefore need disentangling on a seasonal basis to make accurate forecasts. Our study shows that climate change is causing seasonally divergent demog...
1. Any average pattern observed at the population level may confound two different types of processes: some processes that occur among individuals and others that occur within individuals. Separating within- from among-individual processes is critical for our understanding of ecological and evolutionary dynamics.
2. The within-individual centerin...
The increase of structural growth rates to compensate for a poor initial body condition, defined as compensatory growth, may have physiological costs, but little is known about its effects on individual fitness in the wild. Yellow-bellied marmots (Marmota flaviventer) are obligate hibernators and depend on fat accumulation acquired during an approx...
Annual reproductive success and senescence patterns vary substantially among individuals in the wild. However, it is still seldom considered that senescence may not only affect an individual but also affect age-specific reproductive success in its offspring, generating transgenerational reproductive senescence. We used long-term data from wild yell...
Genetic factors underpinning phenotypic variation are required if natural selection is to result in adaptive evolution. However, evolutionary and behavioural ecologists typically focus on variation among individuals in their average trait values, and seek to characterise genetic contributions to this. As a result, less attention has been paid to if...
For many animals, group living mitigates predation risk and ensures survival. However, in yellow-bellied marmots, increased sociality is associated with lower female reproductive success, decreased female longevity and increased overwinter mortality for both males and females, which raises questions about the adaptive value of sociality in this fac...
Natural populations are exposed to seasonal variation in environmental factors that simultaneously affect several demographic rates (survival, development and reproduction). The resulting covariation in these rates determines population dynamics, but accounting for its numerous biotic and abiotic drivers is a significant challenge. Here, we use a f...
Behavior and metabolism are frontline reactions to environmental challenges that can covary in their response through at least two mechanisms. First, natural selection can generate correlation in phenotype among distinct populations if they are exposed to a common selective force. Thus, metabolism and behavior can exhibit phenotypic correlation amo...
Environmental factors drive the persistence of natural populations by causing complex, covarying responses in demographic processes (i.e., survival, growth, and reproduction). As most natural populations inhabit seasonal environments, overlooking seasonal differences in this covariation may obscure the mechanisms that buffer or amplify population r...
Warming global temperatures are affecting a range of aspects of wild populations, but the exact mechanisms driving associations between temperature and phenotypic traits may be difficult to identify. Here, we use a 36‐year data‐set on a wild population of red deer to investigate the causes of associations between temperature and two important compo...
In marine ecosystems, predator-prey interactions are known to structure critical processes (e.g., trophic transfer, nutrient regeneration) and have important implications for mediating community dynamics. However, the temporal and spatial scales over which these processes operate remain poorly understood mainly because the resolution provided by tr...
In a variety of taxa, individuals behave in consistently different ways. However, there are relatively few studies that empirically test the potential mechanisms underlying the causes and maintenance of these personality differences. Several hypotheses for the causes and maintenance of risky personality traits have been suggested but all have recei...
The cumulative cost of reproduction hypothesis predicts that reproductive costs accumulate over an individual's reproductive life span. While short‐term costs have been extensively explored, the prevalence of cumulative long‐term costs and the circumstances under which such costs occur alongside or instead of short‐term costs, are far from clear. I...
Senescence is a highly variable process that comprises both age-dependent and state-dependent components and can be greatly affected by environmental conditions. However, few studies have quantified the magnitude of age-dependent and state-dependent senescence in key life-history traits across individuals inhabiting different spatially structured a...
Humans in strong social relationships are more likely to live longer because social relationships may buffer stressors and thus have protective effects. However, a shortcoming of human studies is that they often rely on self-reporting of these relationships. By contrast, observational studies of non-human animals permit detailed analyses of the spe...
Natural selection is expected to favour the integration of dispersal and phenotypic traits allowing individuals to reduce dispersal costs. Accordingly, associations have been found between dispersal and personality traits such as aggressiveness and exploration, which may facilitate settlement in a novel environment. However, the determinism of thes...
Between-individual variation in phenotypes within a population is the basis of evolution. However, evolutionary and behavioural ecologists have mainly focused on estimating between-individual variance in mean trait and neglected variation in within-individual variance, or predictability of a trait. In fact, an important assumption of mixed-effects...
Describing and quantifying animal personality is now an integral part of behavioural studies because individually distinctive behaviours have ecological and evolutionary consequences. Yet, to fully understand how personality traits may respond to selection, one must understand the underlying heritability and genetic correlations between traits. Pre...
Phenotypic plasticity, the ability of an individual to modify its phenotype according to the conditions it experiences, is a source of between-individual variation and a mechanism by which individuals can cope with environmental change. Plasticity is expected to evolve in response to environmental heterogeneity, such as seasonality and year-to-year...
Multiple mating and multiple paternity in polytocous species have been mostly studied from an adaptive (i.e., cost-benefit) perspective. Disease, time, energy, and the risk of injuries are well-known costs of multiple mating, yet from both male and female perspectives, a number of genetic and non-genetic benefits have also been identified. The effe...
In mammals, prenatal exposure to sex steroid hormones may have profound effects on later behavior and fitness and have been reported under both laboratory and field conditions. Anogenital distance is a non-invasive measure of prenatal exposure to sex steroid hormones. While we know that intra-uterine position and litter sex ratio influence anogenit...
Personality traits are important because they can affect individual survival as well as how a population may respond to environmental change. How these traits arise, whether they are maintained throughout ontogeny, and how environmental factors differentially affect them throughout life is poorly understood. Understanding these pathways is importan...
Background/Question/Methods
Individuals in a population may adjust their phenotypic response to varying environmental conditions. Such plastic responses often entail changes in an individual’s behavioral, morphological or physiological traits and may affect population dynamics. Here we investigate the extent to which individuals in a population e...
Individuals of many species produce distinctive vocalizations that may relay potential information about the signaller. The alarm calls of some species have been reported to be individually specific, and this distinctiveness may allow individuals to access the reliability or kinship of callers. While not much is known generally about the heritabili...
Personality, the presence of persistent behav105ioral differences among individuals over time or contexts, potentially has important ecological and evolutionary consequences. However, a lack of knowledge about its genetic architecture limits our ability to understand its origin, evolution, and maintenance. Here, we report on a genome-wide quantitat...
Hind-foot length is a widely used index of skeletal size in population ecology. The accuracy of hind-foot measurements, however, has not been estimated. We quantified measurement error in adult hind-foot length in yellow-bellied marmots (Marmota flaviventris (Audubon and Bachman, 1841)), mountain goats (Oreamnos americanus (de Blainville, 1816)), a...
Aggregation is thought to enhance an animal’s security through effective predator detection and the dilution of risk. A decline in individual vigilance as group size increases is commonly reported in the literature and called the group size effect. However, to date, most of the research has only been directed toward examining whether this effect oc...
Because variation in age of first reproduction can have major effects on individual fitness and population dynamics, it is important to understand what maintains that variability. Although early primiparity is assumed to be costly, it is sometimes associated with high lifetime reproductive success. We used a long-term study on bighorn sheep Ovis ca...
1. Interest in measuring individual variation in reaction norms using mixed-effects and, more specifically, random regression models have grown apace in the last few years within evolution and ecology. However, these are data hungry methods, and little effort to date has been put into understanding how much and what kind of data we need to collect...
The terminal allocation and senescence hypotheses make opposite predictions about how age-specific reproductive effort should vary during old age. There is empirical support for both hypotheses, although reports on senescence are more numerous. Individual heterogeneity and selective mortality, however, decrease our ability to measure how reproducti...
Although mixed effects models are widely used in ecology and evolution, their application to standardized traits that change within season or across ontogeny remains limited. Mixed models offer a robust way to standardize individual quantitative traits to a common condition such as body mass at a certain point in time (within a year or across ontog...
Several theories predict the evolution of bias in progeny sex ratio based on variations in maternal or offspring reproductive value. For mammals, however, tests of sex-bias theories have produced inconsistent results, and no clear patterns have emerged. Each theory is based on assumptions that are difficult to satisfy, and empirical tests require l...
Here, we present estimates of heritability and selection on network traits in a single population, allowing us to address the evolutionary potential of social behavior and the poorly understood link between sociality and fitness. To evolve, sociality must have some heritable basis, yet the heritability of social relationships is largely unknown. Re...
Several studies of large mammals report no direct reproductive costs for females. Individual heterogeneity may hide fitness costs of reproduction, but mothers could also transfer some costs to their offspring. Using data on 442 lambs weaned by 146 bighorn sheep (Ovis canadensis) ewes at Ram Mountain, Alberta, we studied how reproductive effort vari...
Animals must allocate some proportion of their time to detecting predators. In birds and mammals, such anti-predator vigilance has been well studied, and we know that it may be influenced by a variety of intrinsic and extrinsic factors. Despite hundreds of studies focusing on vigilance and suggestions that there are individual differences in vigila...
Recent theoretical work suggests that personality is a component of life history, but links between personality and either age-dependent reproductive success or life-history strategy are yet to be established. Using quantitative genetic analyses on a long-term pedigree we estimated indices of boldness and docility for 105 bighorn sheep rams (Ovis c...