Fitness In Wild Populations Research Articles

Phenotypic homogenization and potential fitness constraints following non-native introgression in an endemic sportfish.

Introgressive hybridization may lead to contrasting evolutionary outcomes that are difficult to predict, since they depend on the fitness effects of endogenous genomic interactions and environmental factors. Conservation of endemic biodiversity may be more effective with require direct measurement of introgressed ancestry and fitness in wild populations, especially for keystone taxa at risk of hybridization following species introductions. We assessed the relationship of non-native ancestry with growth and body condition in the basin-restricted Neosho Bass (Micropterus velox; NB), focusing on two streams in the NB native range that are admixed extensively with non-native Smallmouth Bass (M. dolomieu; SMB). We quantified genetic composition of 116 fish from Big Sugar Creek (N=46) and Elk River (N=70) at 14 microsatellite loci. Using back-calculated total length-at-age estimated from sagittal otoliths, we assessed whether genetic ancestry explained variation in von Bertalanffy growth model parameters, accounting for sex and stream effects. We then assessed the relationship of ancestry and body condition. We found no differences in growth parameters by sex, stream, or ancestry, suggesting phenotypic homogenization which could be mediated by selection on body size. We found a negative correlation between SMB ancestry and condition, including lower condition in Big Sugar Creek, possibly reflecting a trade-off between maximum length and condition with respect to overall fitness. We show that ongoing non-native introgression, which may be augmented by anthropogenic SMB introductions, may attenuate evolutionary differentiation between species and directly influence fitness, possibly having critical implications for long-term persistence and management of adaptive potential in a popular and ecologically important endemic sportfish.

Adult telomere length is positively correlated with survival and lifetime reproductive success in a wild passerine.

Explaining variation in individual fitness is a key goal in evolutionary biology. Recently, telomeres, repeating DNA sequences capping chromosome ends, have gained attention as a biomarker for body state, physiological costs, and senescence. Existing research has provided mixed evidence for whether telomere length correlates with fitness, including survival and reproductive output. Moreover, few studies have examined how the rate of change in telomere length correlates with fitness in wild populations. Here, we intensively monitored an insular population of house sparrows, and collected longitudinal telomere and life history data (16 years, 1225 individuals). We tested whether telomere length and its rate of change predict fitness measures, namely survival, lifespan and annual and lifetime reproductive effort and success. Telomere length positively predicted short-term survival, independent of age, but did not predict lifespan, suggesting either a diminishing telomere length-survival correlation with age or other extrinsic factors of mortality. The positive association of telomere length with survival translated into reproductive benefits, as birds with longer telomeres produced more genetic recruits, hatchlings and reared more fledglings over their lifetime. In contrast, there was no association between telomere dynamics and annual reproductive output, suggesting telomere dynamics might not reflect the costs of reproduction in this population, potentially masked by variation in individual quality. The rate of change of telomere length did not correlate with neither lifespan nor lifetime reproductive success. Our results provide further evidence that telomere length correlates with fitness, and contribute to our understanding of the selection on, and evolution of, telomere dynamics.

Natural selection and genetic diversity maintenance in a parasitic wasp during continuous biological control application

Aphidius gifuensis is a parasitoid wasp and primary endoparasitoid enemy of the peach potato aphid, Myzus persicae. Artificially reared, captive wasps of this species have been extensively and effectively used to control populations of aphids and limit crop loss. However, the consequences of large-scale releasing of captive A. gifuensis, such as genetic erosion and reduced fitness in wild populations of this species, remains unclear. Here, we sequence the genomes of 542 A. gifuensis individuals collected across China, including 265 wild and 277 human-intervened samples. Population genetic analyses on wild individuals recovered Yunnan populations as the ancestral group with the most complex genetic structure. We also find genetic signature of environmental adaptation during the dispersal of wild populations from Yunnan to other regions. While comparative genomic analyses of captive wasps revealed a decrease in genetic diversity during long-term rearing, population genomic analyses revealed signatures of natural selection by several biotic (host plants) or abiotic (climate) factors, which support maintenance of the gene pool of wild populations in spite of the introduction of captive wasps. Therefore, the impact of large-scale release is reduced. Our study suggests that A. gifuensis is a good system for exploring the genetic and evolutionary effects of mass rearing and release on species commonly used as biocontrol agents.

Firmicutes and Bacteroidetes contribute to mass gain variation in female obligate hibernators

Abstract Obtaining body condition is an important life history challenge that directly impacts individual fitness and is particularly important for hibernating animals, whose maintenance of adequate body fat and mass is essential for survival. It is well-documented that host-associated microorganisms play a vital role in animal physiology and behavior. Recent work demonstrates that gut microbes are associated with fat accumulation and obesity, particularly the phyla Firmicutes and Bacteroidetes. The focus of most microbiome studies has been on human health or involved lab-reared animals used as a model system. However, these microbes likely are important for individual fitness in wild populations and provide potential mechanistic insights into the adaptability and survival of wildlife. Here we tested whether symbiotic microorganisms within the phyla of Firmicutes and Bacteroidetes were associated with summer mass gain in an exceptionally well-studied wild population of yellow-bellied marmots (Marmota flaviventer) by analyzing 207 fecal samples collected over 5 summer active seasons. Results showed that marmots with higher mass gain rates had a greater relative abundance of Firmicutes. In contrast, a higher relative abundance of Bacteroidetes was associated with lower mass gain rates, but only for marmots living in harsher environments. Similar patterns were found at the family level where Ruminococcaceae, a member of Firmicutes, was associated with higher mass gain rates, and Muribaculaceae, a member of Bacteroidetes, was associated with lower mass gain rates in harsher environments. Although correlative, these results highlight the potential importance of symbiotic gut microbiota to mass gain in the wild—a trait associated with survival and fitness in many taxonomic groups.

Insights into the composition of gut microbiota in response to environmental temperature: The case of the Mongolia racerunner (Eremias argus)

Gut microbiota are essential to maintain host health and fitness largely through its influence with behavior, development and reproduction of host, particular among the amniotic ectothermic reptiles. Global warming effects on the composition of the host's gut microbiota in some taxa are generally known. Previous studies on reptiles in both natural habitats and lab-reared individuals have demonstrated that temperature changes can alter the composition and function of the host's gut microbiota. However, these effects on wild-caught reptiles are not well-understood. This study investigated changes in the composition of gut microbiota of wild-caught lizards (Eremias argus), which were experimentally exposed to two different temperatures. The results showed that the increase in temperature altered the gut microbiota; both the groups showed an altered and destabilized composition of gut microbiota in response to their adaptive states. The warming did not significantly alter the relative abundances of the main gut microbial communities in both the lizard genders, but increased those of predicted pathogenic bacterial genera, including Acinetobacter, Anaerotruncus, and Dehalobacterium. These results provided insights into the ecological adaptations of Eremias argus, but the body health and fitness of wild populations, concerning temperature changes, warrant further investigations.

Anthropogenic activities are associated with shorter telomeres in chicks of Ad\xe9lie penguin (Pygoscelis adeliae)

Defining the impact of anthropogenic stressors on Antarctic wildlife is an active aim for investigators. Telomeres represent a promising molecular tool to investigate the fitness of wild populations, as their length may predict longevity and survival. We examined the relationship between telomere length and human exposure in Adélie penguin chicks (Pygoscelis adeliae) from East Antarctica. Telomere length was compared between chicks from areas with sustained human activity and on neighboring protected islands with little or no human presence. Adélie penguin chicks from sites exposed to human activity had significantly shorter telomeres than chicks from unexposed sites in nearby protected areas, with exposed chicks having on average 3.5% shorter telomeres than unexposed chicks. While sampling limitations preclude our ability to draw more sweeping conclusions at this time, our analysis nonetheless provides important insights into measures of colony vulnerability. More data are needed both to understand the proximate causes (e.g., stress, feeding events) leading to shorter telomeres in chicks from human exposed areas, as well as the fitness consequences of reduced telomere length. We suggest to further test the use of telomere length analysis as an eco-indicator of stress in wildlife among anthropized sites throughout Antarctica.

Gene Flow in Phaseolus Beans and Its Role as a Plausible Driver of Ecological Fitness and Expansion of Cultigens

The genusPhaseolus, native to the Americas, is composed of more than eighty wild species, five of which were domesticated in pre-Columbian times. Since the beginning of domestication events in this genus, ample opportunities for gene flow with wild relatives have existed. The present work reviews the extent of gene flow in the genusPhaseolusin primary and secondary areas of domestication with the aim of illustrating how this evolutionary force may have conditioned ecological fitness and the widespread adoption of cultigens. We focus on the biological bases of gene flow in the genusPhaseolusfrom a spatial and time perspective, the dynamics of wild-weedy-crop complexes in the common bean and the Lima bean, the two most important domesticated species of the genus, and the usefulness of genomic tools to detect inter and intraspecific introgression events. In this review we discuss the reproductive strategies of severalPhaseolusspecies, the factors that may favor outcrossing rates and evidence suggesting that interspecific gene flow may increase ecological fitness of wild populations. We also show that wild-weedy-crop complexes generate genetic diversity over which farmers are able to select and expand their cultigens outside primary areas of domestication. Ultimately, we argue that more studies are needed on the reproductive biology of the genusPhaseolussince for most species breeding systems are largely unknown. We also argue that there is an urgent need to preserve wild-weedy-crop complexes and characterize the genetic diversity generated by them, in particular the genome-wide effects of introgressions and their value for breeding programs. Recent technological advances in genomics, coupled with agronomic characterizations, may make a large contribution.

Oxidative stress, metabolic activity and mercury concentrations in Antarctic krill Euphausia superba and myctophid fish of the Southern Ocean

Indicators of oxidative stress and metabolic capacity are key factors in understanding the fitness of wild populations. In the present study, these factors were evaluated in the pelagic Southern Ocean taxa Antarctic krill (Euphausia superba) and myctophid fish (Electrona antarctica, Gymnoscopelus braueri and G. nicholsi) to establish a baseline record for future studies. Mercury (Hg) concentrations were also analysed to evaluate its potential impacts on species biochemical performance. E. superba had higher metabolic activity than most of the myctophid species, which may explain the comparatively lower energy reserves found in the former. The activity of antioxidant enzymes showed, generally, a lower level in E. superba than in the myctophid species. The lack of any relationship between Hg concentrations and organisms' antioxidant and biotransformation defence mechanisms indicate that levels of Hg accumulated in the studied species were not high enough to affect their biochemical processes adversely.

Captive breeding and the conservation of the threatened houbara bustards

Translocation of captive-bred individuals to reinforce wild populations may be an important conservation approach for some species, but can be detrimental when employed to boost exploited wild populations, particularly where repeated long-term reinforcement aims to compensate for repeated unregulated offtake. We review evidence that captive breeding alters multiple physiological, life-history and temperamental traits through founder effects, genetic drift and unintended adaption to captivity; degrades learnt behaviours; and compromises biogeography, population structure and viability through introgression. We highlight these risks for the globally threatened African houbara Chlamydotis undulata and Asian houbara C. macqueenii, 2 bustard species hunted throughout much of their ranges and now subject to multiple large-scale captive-breeding programmes and translocations. In eastern Morocco, annual releases of captive-bred African houbara are 2‒3 times higher than original wild numbers, but no investigation of their potentially deleterious effects has, to our knowledge, been published, although most wild populations may now have been replaced by captive-bred domestic stock, which are reportedly not self-sustaining. Despite multiple decades of reinforcement, we are not aware of any analysis of the contribution of captive breeding to African houbara population dynamics, or of the genomic consequences. Asian houbara release programmes may also be promoting rather than preventing declines, and need to contextualise themselves through rigorous analyses of wild population numbers, demographic rates and threats, maintenance of phylogeographic concordance of released with supplemented populations, profiling of traits crucial to survival and the measurement and modelling of the impacts of reinforcement on physiological and behavioural fitness of wild populations.

First Insights into the Population Genetic Structure and Heterozygosity-Fitness Relationship in Roe Deer Inhabiting the Area between the Alps and Dinaric Mountains.

Simple SummaryWe determined the genetic variability, population structure, and influence of genetic factors on two parameters of fitness (body mass and reproductive ability) in roe deer females in the contact zone between the Alps and the Dinaric Mountains by utilizing microsatellite variations in 214 individuals collected throughout Slovenia, Central Europe. Spatial differences in the genetic diversity of the species can be explained by population history, different approaches to population management and/or different connectivity among subpopulations. The population genetic structure confirms the high side fidelity of roe deer, but also shows the existence of admixtures of genes among different areas. We found evidence that genetic factors, including individual heterozygosity, influence body mass, confirming that heterozygosity positively affects fitness in wild populations. However, as the effect of genetic factors is usually masked or overruled by the influence of environmental factors, i.e., availability of resources, data on the joint influence of external and intrinsic factors on fitness and other life-history traits are needed to better predict the population dynamics of targeted species, which would enable sustainable, science-based population management.Across its pan-European distribution, the European roe deer (Capreolus capreolus) faces a wide diversity of environmental and climatic conditions; therefore, several factors, including intrinsic ones, shape life-history traits and cause significant variability in parameters of fitness. By utilizing microsatellite variations in 214 roe deer females collected throughout Slovenia, Central Europe, we determined the genetic variability and population structure of this species in the contact zone between the Alps and the Dinaric Mountains, i.e., over a wider area where data on the genetic outlook for this—the most common and widespread European wild ungulate—have been completely lacking so far. Throughout the country, we found moderate microsatellite diversity (Ho = 0.57–0.65) in relation to the observed heterozygosity reported for other roe deer populations in Europe. Spatial differences in genetic diversity of the species in Slovenia can be explained by population history linked to varying approaches to population management and/or different connectivity among subpopulations in topographically differentiated habitats. A country-wide pattern of genetic structure is clearly defined by separation of the populations into three groups present in the following regions: (i) Southern sub-Mediterranean and Karst regions, (ii) Central Slovenia, and (iii) the Sub-Pannonian Region in the north-east. This is also confirmed by evidencing a moderate isolation by distance, especially by separating southern samples (coastal Slovenia) from others. Levels of genetic differentiation vary among populations, which can be explained by the effect of natural geographical barriers or the presence of anthropogenic barriers such as urban areas and highways. In the subset of 172 yearling females, we analyzed the influence of genetic advantage (individual heterozygosity) and other genetic data (reflected in the structuring of the population) on body mass and reproductive ability. We found evidence that genetic factors influence the body mass of roe deer yearling females (explaining altogether 18.8% of body mass variance), and the level of individual heterozygosity alone also positively affected body mass, which is in accordance with the theory that heterozygosity is commonly positively correlated with fitness in wild populations. However, we did not uncover any effect of heterozygosity on two parameters of reproductive ability (fertility and potential reproductive outcome), indicating that several other factors, especially environmental ones, have a predominant effect on the parameters of fitness in roe deer.

Variation in individual reproductive performance amplified with population size in a long-lived carnivore.

Individual variation in reproductive ability is a key component of natural selection within populations, driving the evolution of life histories and population responses to changing environmental conditions. Evidence that population density affects individual-level fitness in wild populations is limited, particularly for long-lived animals, which are difficult to observe on a biologically relevant scale. We tested for individual heterogeneity in reproductive performance in female grey seals (Halichoerus grypus) using 35yr of mark-resighting data at Sable Island, Canada (43.93°N 59.91°W). We used Bayesian generalized linear mixed-effect models and multistate open robust design mark-resight models to investigate whether population size negatively influences individual reproductive performance. We measured reproductive performance in two ways: reproductive frequency (the probability of returning to the island to breed) and annual provisioning performance (the probability of successfully weaning a pup given a female bred). Sighting histories of 1,655 known-aged females with a total of 22,961 pupping events were used for analysis. After accounting for effects of female age, parity, and random year effects, we found that both provisioning performance and reproductive frequency demonstrated a strong, positive correlation with population size. Among-individual variance in reproductive traits and responses to population size indicated considerable heterogeneity in overall reproductive performance. As population size grew, "robust" females increased their reproductive performance more than their more "frail" conspecifics in both reproductive traits, resulting in an amplification of differences among individuals. Consequently, simulations from posterior distributions revealed a large fitness consequence of heterogeneity in this population, with "frail" individuals having 47.1% fewer successful pups than more "robust" females (mean reproductive output±SD: 9.12±3.77 pups for frail individuals, 16.97±2.94 for robust individuals). Repeatability of overall reproductive performance across environments indicates individual quality may be more influential to lifetime reproductive success than costs associated with reproductive investment. This quantification of relative fitness and its dynamics is crucial to understanding broad evolutionary processes in natural populations.

Individual asymmetry as a predictor of fitness in the bat Carollia perspicillata.

The measurement of fitness in wild populations is a challenging task, and a number of proxies have been proposed with different degrees of success. Developmental instability/stability (DI) is an organismal property associated with variance in bilateral asymmetry (fluctuating asymmetry-FA) and a correlated effect on fitness. This study provides evidence to corroborate the hypothesis that asymmetry partly reflects DI and is correlated with a reduction in fitness measured by survival and reproduction in bats. We studied two colonies of the bat Carollia perspicillata in southeastern Brazil over 5years, marking and recapturing individuals. Gaussian mixture models for signed Forearm Asymmetry (ForA) distribution indicated that ~20% of asymmetry variation was due to DI heterogeneity among individuals. ForA, body condition (Scaled Mass Index-SMI) and Forearm Length (ForL) were used as predictors of survival probability in Cormack-Jolly-Seber models. Asymmetry was negatively associated with survival, whereas SMI and ForL were positively associated. The male C.perspicillata defend sites within the roost that are favoured by female harems, but there are mating opportunities for bachelor males, leading to both territorial disputes and sperm competition. As predicted by sexual selection, ForA was negatively associated with relative Testicle Length, a measure of reproductive potential. In females, ForA was negatively associated with the probability of two pregnancies (as opposed to one) in a given breeding season. The effect magnitudes and directions of associations suggest that asymmetry, even though not perfectly reflecting DI variation, is a useful predictor for fitness components in C.perspicillata.

Nest microclimate during incubation affects posthatching development and parental care in wild birds

It is widely accepted that recent increases in environmental temperature have had a causal effect on changing life histories; however, much of the evidence for this is derived from long-term observations, whereas inferences of causation require experimentation. Here, we assess effects of increased environmental temperature during incubation on posthatching development, nestling begging and parental care, and reproductive success in two wild, cavity-nesting songbirds, the Carolina wren and prothonotary warbler. We heated experimental nests only during incubation, which increased nest-cavity temperature by ca. 1 °C. This reduced the length of the incubation and nestling periods, and reduced fledging success in prothonotary warblers, while nestling Carolina wrens had similar fledging success but reduced body condition in response to increased temperature. Increased nest-cavity temperature during incubation also reduced posthatching begging by nestlings generally and parental care within Carolina wrens specifically, suggesting potential mechanisms generating these carry-over effects. Offspring body mass and fledging age are often predictive of post-fledging survival and recruitment. Thus, our results suggest that increasing temperatures may affect fitness in wild populations in species-specific ways, and induce life-history changes including the classic trade-off parents face between the size and number of offspring.

Limited hatchery introgression into wild brook trout (Salvelinus fontinalis) populations despite reoccurring stocking.

Due to increased anthropogenic pressures on many fish populations, supplementing wild populations with captive‐raised individuals has become an increasingly common management practice. Stocking programs can be controversial due to uncertainty about the long‐term fitness effects of genetic introgression on wild populations. In particular, introgression between hatchery and wild individuals can cause declines in wild population fitness, resiliency, and adaptive potential and contribute to local population extirpation. However, low survival and fitness of captive‐raised individuals can minimize the long‐term genetic consequences of stocking in wild populations, and to date the prevalence of introgression in actively stocked ecosystems has not been rigorously evaluated. We quantified the extent of introgression in 30 populations of wild brook trout (Salvelinus fontinalis) in a Pennsylvania watershed and examined the correlation between introgression and 11 environmental covariates. Genetic assignment tests were used to determine the origin (wild vs. captive‐raised) for 1,742 wild‐caught and 300 hatchery brook trout. To avoid assignment biases, individuals were assigned to two simulated populations that represented the average allele frequencies in wild and hatchery groups. Fish with intermediate probabilities of wild ancestry were classified as introgressed, with threshold values determined through simulation. Even with reoccurring stocking at most sites, over 93% of wild‐caught individuals probabilistically assigned to wild origin, and only 5.6% of wild‐caught fish assigned to introgressed. Models examining environmental drivers of introgression explained <3% of the among‐population variability, and all estimated effects were highly uncertain. This was not surprising given overall low introgression observed in this study. Our results suggest that introgression of hatchery‐derived genotypes can occur at low rates, even in actively stocked ecosystems and across a range of habitats. However, a cautious approach to stocking may still be warranted, as the potential effects of stocking on wild population fitness and the mechanisms limiting introgression are not known.

Batrachochytrium dendrobatidis is present in Poland and associated with reduced fitness in wild populations of Pelophylax lessonae.

The fungus Batrachochytrium dendrobatidis (Bd) is a pathogen associated with global declines of amphibians. We used qPCR to detect Bd in 255 samples from 10 Polish populations of 8 species. We found Bd infection in 3 species (Bombina variegata, Pelophylax lessonae, P. esculentus). The infection intensity in P. lessonae reached a maximum of 58400 genomic equivalents of zoospores (GE), and the 2 most heavily infected individuals died. Previous observations of the populations that included infected individuals showed reduced body size, failure to reproduce, and mortalities of adults. These data highlight the importance of emerging diseases, and the need to recognize them as an important factor in conservation of the genus Pelophylax in Poland and Central and Eastern Europe.

Environmental, not individual, factors drive markers of biological aging in black bears

Aging negatively affects individual survival and reproduction; consequently, characterizing the factors behind aging can enhance our understanding of fitness in wild populations. The drivers of biological age are diverse, but often related to factors like chronological age or sex of the individual. Recently, however, environmental factors have been shown to strongly influence biological age. To explore the relative importance of these influences on biological aging in a free-ranging and long-lived vertebrate, we quantified the length of telomeres—highly conserved DNA sequences that cap the ends of eukaryotic chromosomes and a useful molecular marker of biological age—for black bears sampled throughout Colorado, and measured a variety of environmental variables (habitat productivity, human development, latitude, elevation) and individual characteristics (age, sex, body size, genetic relatedness). Our extensive sampling of bears (n = 245) revealed no relationships between telomere length and any individual characteristics. Instead, we found a broad-scale latitudinal pattern in telomere length, with bears in northern Colorado possessing shorter telomeres. Our results suggest that environmental characteristics overwhelm individual ones in determining biological aging for this large carnivore.

Human Disturbance during Early Life Impairs Nestling Growth in Birds Inhabiting a Nature Recreation Area

Nature recreation conflicts with conservation, but its impacts on wildlife are not fully understood. Where recreation is not regulated, visitors to natural areas may gather in large numbers on weekends and holidays. This may increase variance in fitness in wild populations, if individuals whose critical life cycle stages coincide with periods of high human disturbance are at a disadvantage. We studied nestling development of blue tits (Cyanistes caeruleus) in a natural area where recreation activities intensify during weekends and other public holidays at picnic and leisure facilities, but not in the surrounding woods. In nests located near recreation facilities, blue tit nestlings that hatched during holidays developed slowly, and fledged with low body mass and poor body condition. However, nestlings that hatched outside of holidays and weekends in these nest boxes developed normally, eventually attaining similar phenotypes as those hatching in the surrounding woods. Within-brood variance in body mass was also higher in broods that began growing during holidays in disturbed areas. Our results show that early disturbance events may have negative consequences for wild birds if they overlap with critical stages of development, unveiling otherwise cryptic impacts of human activities. These new findings may help managers better regulate nature recreation.

Strong nonlinear selection against fluctuating asymmetry in wild populations of a marine fish.

Theoretical links between fluctuating asymmetry (FA) and fitness have led many to use FA as a proxy for average fitness. However, studies examining whether asymmetry actually correlates with individual fitness in wild populations are relatively rare and often use simple measures of association (e.g., correlation coefficients). Consequently, the pattern of selection on asymmetry in the wild is seldom clear. We examined selection on FA of pectoral fin morphology in two wild populations of a marine fish (the kelp perch; Brachyistius frenatus). As expected, variance in signed FA in each initial sample was significantly greater than that found in the surviving population, indicating selection against FA. Our estimate of the fitness surface confirmed perfect symmetry as the phenotypic optimum and indicated strong, nonlinear selection against asymmetry. No difference in the form of selection was detected between populations. However, the level of FA in the initial samples varied among populations, leading to an overall difference in the level of selective mortality. Our results suggest that selection on asymmetry in wild populations may be strongly nonlinear, and indicate that the demographic costs of asymmetry may play a substantial role in the dynamics of populations.

Fitness implications of seasonal climate variation in Columbian ground squirrels.

The influence of climate change on the fitness of wild populations is often studied in the context of the spring onset of the reproductive season. This focus is relevant for climate influences on reproductive success, but neglects other fitness‐relevant periods (e.g., autumn preparation for overwintering). We examined variation in climate variables (temperature, rainfall, snowfall, and snowpack) across the full annual cycle of Columbian ground squirrels (Urocitellus columbianus) for 21 years. We investigated seasonal climate variables that were associated with fitness variables, climate variables that exhibited directional changes across the study period, and finally observed declines in fitness (−0.03 units/year; total decline = 37%) that were associated with directional changes in climate variables. Annual fitness of adult female ground squirrels was positively associated with spring temperature (r = 0.69) and early summer rainfall (r = 0.56) and negatively associated with spring snow conditions (r = −0.44 to −0.66). Across the 21 years, spring snowmelt has become significantly delayed (r = 0.48) and summer rainfall became significantly reduced (r = −0.53). Using a standardized partial regression model, we found that directional changes in the timing of spring snowmelt and early summer rainfall (i.e., progressively drier summers) had moderate influences on annual fitness, with the latter statistically significant (ρ = −0.314 and 0.437, respectively). The summer period corresponds to prehibernation fattening of young and adult ground squirrels. Had we focused on a single point in time (viz. the onset of the breeding season), we would have underestimated the influences of climate change on our population. Rather, we obtained a comprehensive understanding of the influences of climate change on individual fitness by investigating the full lifecycle.

Selection of optimal spawning pairs to maintain genetic variation among captive populations of Acipenseridae based on the polymorphism of microsatellite loci

Abstract The American paddlefish, Polyodon spathula (Walbaum), is an endangered acipenserid fish. Its wild populations are supplemented with stocking material that is obtained by conducting artificial spawning in aquaculture conditions. When fish are bred in captivity, it is important to select breeding pairs that will produce the most genetically diverse progeny, since this permits maintaining the fitness of wild populations. Breeding pairs of land animals are selected successfully based on the polymorphism of their microsatellite loci. This theoretical paper asks how to adapt this technique to fish so that American paddlefish spawners can be paired with the aim of producing restocking material in aquaculture that maintains genetic variation. To test our calculating techniques, we used actual data on the polymorphism of the microsatellites from paddlefish broodstock at the Pogorze fish farm (Poland). The data enabled us to do calculations that showed which spawner pairs would create the most genetically diverse offspring and how to assemble sets of spawning pairs that would be best for maintaining genetic variation. The method presented in this paper can be used for breeding fish in aquaculture to help conserve species. It could also be used in a computer program which would automate calculations and present them in easy-to-read tables and graphs.