The Demographic Basis of Population Growth: A 32-Year Transient Life Table Response Experiment.

It has recently been recognised that populations are rarely in demographic equilibrium, but rather in a 'transient' state. To examine how transient dynamics influence our empirical understanding of the links between changes in demographic rates and population growth, we conducted a 32-year study of Columbian ground squirrels. The population increased rapidly for 10 years, followed by a 2-year crash, and a gradual 19-year recovery.

Population density and vegetation resources influence demography in a hibernating herbivorous mammal.

Demography of herbivorous mammal populations may be affected by changes in predation, population density, harvesting, and climate. Whereas numerous studies have focused on the effect of single environmental variables on individual demographic processes, attempts to integrate the consequences of several environmental variables on numerous functional traits and demographic rates are rare. Over a 32-year period, we examined how forage availability (vegetation assessed through NDVI) and population density affected the functional traits and demographic rates of a population of Columbian ground squirrels (Urocitellus columbianus), a herbivorous hibernating rodent.

Down-regulating the stress axis: Living in the present while preparing for the future.

The measurement of glucocorticoid (GC) hormones provides us with a window into the stress physiology of vertebrates and the adaptative responses they use to cope with predictable and unpredictable changes in the environment. Baseline GCs inform us about the metabolic demands they are subject to at that point in their yearly life-history stage, whereas GC changes (often increases) in response to acute challenges inform us on their capacity to cope with more immediate environmental challenges. However, baseline GC levels and the kinetics of GC responses to acute stressors can vary substantially among and within species, depending on individual characteristics (age, sex, condition, life-history stage).

Evolutionary trade-offs in dormancy phenology.

Seasonal animal dormancy is widely interpreted as a physiological response for surviving energetic challenges during the harshest times of the year (the physiological constraint hypothesis). However, there are other mutually non-exclusive hypotheses to explain the timing of animal dormancy, that is, entry into and emergence from hibernation (i.e.

How much multiple paternity should we expect? A study of birds and contrast with mammals.

Parentage analyses via molecular markers have revealed multiple paternity within the broods of polytocous species, reshaping our understanding of animal behavior, ecology, and evolution. In a meta-analysis of multiple paternity in bird and mammal species, we conducted a literature search and found 138 bird and 64 mammal populations with microsatellite DNA paternity results. Bird populations averaged 19.

On the Origin and Evolution of the Mosquito Male-determining Factor Nix.

The mosquito family Culicidae is divided into 2 subfamilies named the Culicinae and Anophelinae. Nix, the dominant male-determining factor, has only been found in the culicines Aedes aegypti and Aedes albopictus, 2 important arboviral vectors that belong to the subgenus Stegomyia. Here we performed sex-specific whole-genome sequencing and RNAseq of divergent mosquito species and explored additional male-inclusive datasets to investigate the distribution of Nix.

Sexes in sync: phenotypic plasticity, sexual selection and phenological synchrony between the sexes in a wild hibernator.

Desynchrony of phenological responses to climate change is a major concern for ecological communities. Potential uncoupling between one of the most fundamental divisions within populations, males and females, has not been well studied. To address this gap, we examined sex-specific plasticity in hibernation phenology in two populations of Columbian ground squirrels ().

Weathering the storm: Decreased activity and glucocorticoid levels in response to inclement weather in breeding Columbian ground squirrels.

Inclement weather can rapidly modify the thermal conditions experienced by animals, inducing changes in their behavior, body condition, and stress physiology, and affecting their survival and breeding success. For animals living in variable environments, the extent to which they have adapted to cope with inclement weather is not established, especially for hibernating species with a short active season that are constrained temporally to breed and store energy for subsequent hibernation. We examined behavioral (foraging activity) and physiological (body mass and fecal cortisol metabolites) responses of Columbian ground squirrels (Urocitellus columbianus), small hibernating rodents inhabiting open meadows in Rocky Mountains, to 3 events of inclement weather (two snow storms in May 2021 and May 2022, one heavy rainfall in June 2022).

Satellite Rearing of Aedes Mosquito Eggs: Synchronized Empirical Test of a Novel Mass Rearing Model.

Mosquito suppression strategies based on "rear and release" of male mosquitoes are attracting renewed interest from governments, municipalities, and private businesses. These include irradiation-based sterile insect technique, Wolbachia-based technologies, and genetic modification. Each of these approaches requires the mass rearing and release of adult male mosquitoes, which typically is accomplished via a rearing facility near the release site.

Effect of age on wingbeat frequency of Aedes aegypti and potential application for age estimation of mosquitoes.

To combat mosquito-borne diseases, a variety of vector control tools have been implemented. Estimating age structure in populations of vector species is important for understanding transmission potential. Age-grading techniques have been used as critical methods for evaluating the efficacy of vector control tools.

Two aspects of longevity are associated with rates of loss of telomeres in birds.

Telomeres, the terminal repetitive DNA sequences at the ends of linear chromosomes, have strong associations with longevity in some major taxa. Longevity has been linked to rate of decline in telomere length in birds and mammals, and absolute telomere length seems to be associated with body mass in mammals. Using a phylogenetic comparative method and 30 species of birds, we examined longevity (reflected by maximum lifespan), absolute telomere length, the rate of change in telomere length (TROC), and body mass (often strongly associated with longevity) to ascertain their degree of association.

Effects of the social environment on vertebrate fitness and health in nature: Moving beyond the stress axis.

Social interactions are a ubiquitous feature of the lives of vertebrate species. These may be cooperative or competitive, and shape the dynamics of social systems, with profound effects on individual behavior, physiology, fitness, and health. On one hand, a wealth of studies on humans, laboratory animal models, and captive species have focused on understanding the relationships between social interactions and individual health within the context of disease and pathology.

Telomere dynamics in female Columbian ground squirrels: recovery after emergence and loss after reproduction.

Telomeres are specialized non-coding DNA sequences located at the end of chromosomes and that protect genetic information. Telomere loss over lifespan is generally viewed as a phenomenon associated with aging in animals. Recently, telomere elongation after hibernation has been described in several mammals.

Territorial scent-marking effects on vigilance behavior, space use, and stress in female Columbian ground squirrels.

Social environments can profoundly affect the behavior and stress physiology of group-living animals. In many territorial species, territory owners advertise territorial boundaries to conspecifics by scent marking. Several studies have investigated the information that scent marks convey about donors' characteristics (e.

The Effects of Boric Acid Sugar Bait on Trans-Infected Male (ZAP Males) in Laboratory Conditions.

The field release of trans-infected male mosquitoes, as well as the use of toxic sugar baits, is a novel and promising candidate technique for integrated mosquito management programs. However, the methods of action of the two techniques may not be complementary, because the method releases mosquitoes into the environment expecting a wild population reduction in subsequent generations while the toxic baits are intended to reduce the wild population by killing mosquitoes. This laboratory study was conducted to evaluate the effectiveness of boric acid toxic sugar baits on trans-infected male , relative to wild-type males.

The influence of phylogeny and life history on telomere lengths and telomere rate of change among bird species: A meta-analysis.

Longevity is highly variable among animal species and has coevolved with other life-history traits, such as body size and rates of reproduction. Telomeres, through their erosion over time, are one of the cell mechanisms that produce senescence at the cell level and might even have an influence on the rate of aging in whole organisms. However, uneroded telomeres are also risk factors of cell immortalization.

Demographic responses to climate change in a threatened Arctic species.

The Arctic is undergoing rapid and accelerating change in response to global warming, altering biodiversity patterns, and ecosystem function across the region. For Arctic endemic species, our understanding of the consequences of such change remains limited. Spectacled eiders (), a large Arctic sea duck, use remote regions in the Bering Sea, Arctic Russia, and Alaska throughout the annual cycle making it difficult to conduct comprehensive surveys or demographic studies.

Parental investment in the Columbian ground squirrel: empirical tests of sex allocation models.

Parental allocation of resources into male or female offspring and differences in the balance of offspring sexes in natural populations are central research topics in evolutionary ecology. Fisher (Fisher, R. A.

When More is Less: Mosquito Population Suppression Using Sterile, Incompatible and Genetically Modified Male Mosquitoes.

The current review of the Sterile Insect Technique (SIT) is motivated by new technologies and the recent renaissance of male release field trials, which is driving an evolution in mosquito control and regulation. Practitioners that are releasing male mosquitoes would do well to learn from past successes and failures, including political and public engagement complications. With examples that include nuanced integrations of the different technologies, e.

Multiple paternity and the number of offspring: A model reveals two major groups of species.

Parentage analyses via microsatellite markers have revealed multiple paternity within the broods of polytocous species of mammals, reptiles, amphibians, fishes and invertebrates. The widespread phenomenon of multiple paternity may have attending relationships with such evolutionary processes as sexual selection and kin selection. However, just how much multiple paternity should a species exhibit? We developed Bayesian null models of how multiple paternity relates to brood sizes.

Fluctuating optimum and temporally variable selection on breeding date in birds and mammals.

Temporal variation in natural selection is predicted to strongly impact the evolution and demography of natural populations, with consequences for the rate of adaptation, evolution of plasticity, and extinction risk. Most of the theory underlying these predictions assumes a moving optimum phenotype, with predictions expressed in terms of the temporal variance and autocorrelation of this optimum. However, empirical studies seldom estimate patterns of fluctuations of an optimum phenotype, precluding further progress in connecting theory with observations.

Integrating Mortality Risk and the Adaptiveness of Hibernation.

Low mortality rate is often associated with slow life history, and so far, has mainly been assessed through examinations of specific adaptations and lifestyles that limit mortality risk. However, the organization of activity time budgets also needs to be considered, since some activities and the time afforded for performing them may expose animals to higher mortality risks such as increased predation and/or increased metabolic stress. We examined the extent of activity time budgets contribution to explaining variation in life history traits in mammals.