Animal space use and spatial overlap can have important consequences for population‐level processes such as social interactions and pathogen transmission. Identifying how environmental variability ...and inter‐individual variation affect spatial patterns and in turn influence interactions in animal populations is a priority for the study of animal behaviour and disease ecology. Environmental food availability and macroparasite infection are common drivers of variation, but there are few experimental studies investigating how they affect spatial patterns of wildlife.
Bank voles (Clethrionomys glareolus) are a tractable study system to investigate spatial patterns of wildlife and are amenable to experimental manipulations. We conducted a replicated, factorial field experiment in which we provided supplementary food and removed helminths in vole populations in natural forest habitat and monitored vole space use and spatial overlap using capture–mark–recapture methods.
Using network analysis, we quantified vole space use and spatial overlap. We compared the effects of food supplementation and helminth removal and investigated the impacts of season, sex and reproductive status on space use and spatial overlap.
We found that food supplementation decreased vole space use while helminth removal increased space use. Space use also varied by sex, reproductive status and season. Spatial overlap was similar between treatments despite up to threefold differences in population size.
By quantifying the spatial effects of food availability and macroparasite infection on wildlife populations, we demonstrate the potential for space use and population density to trade‐off and maintain consistent spatial overlap in wildlife populations. This has important implications for spatial processes in wildlife including pathogen transmission.
Using a replicated, factorial field experiment in wildlife populations, the authors find that food supplementation and helminth removal impact space use but not spatial overlap of a wild rodent. These findings provide empirical evidence of how environmental and individual variation can influence contact‐ and proximity‐driven processes such as pathogen transmission.
As with many physiological performance traits, the capacity of endotherms to thermoregulate declines with age. Aging compromises both the capacity to conserve or dissipate heat and the thermogenesis, ...which is fueled by aerobic metabolism. The rate of metabolism, however, not only determines thermogenic capacity but can also affect the process of aging. Therefore, we hypothesized that selection for an increased aerobic exercise metabolism, which has presumably been a crucial factor in the evolution of endothermic physiology in the mammalian and avian lineages, affects not only the thermoregulatory traits but also the age-related changes of these traits. Here, we test this hypothesis on bank voles (
) from an experimental evolution model system: four lines selected for high swim-induced aerobic metabolism (A lines), which have also increased the basal, average daily, and maximum cold-induced metabolic rates, and four unselected control (C) lines. We measured the resting metabolic rate (RMR), evaporative water loss (EWL), and body temperature in 72 young adult (4 months) and 65 old (22 months) voles at seven ambient temperatures (13-32°C). The RMR was 6% higher in the A than in the C lines, but, regardless of the selection group or temperature, it did not change with age. However, EWL was 12% higher in the old voles. An increased EWL/RMR ratio implies either a compromised efficiency of oxygen extraction in the lungs or increased skin permeability. This effect was more profound in the A lines, which may indicate their increased vulnerability to aging. Body temperature did not differ between the selection and age groups below 32°C, but at 32°C it was markedly higher in the old A-line voles than in those from other groups. As expected, the thermogenic capacity, measured as the maximum cold-induced oxygen consumption, was decreased by about 13% in the old voles from both selection groups, but the performance of old A-line voles was the same as that of the young C-line ones. Thus, the selection for high aerobic exercise metabolism attenuated the adverse effects of aging on cold tolerance, but this advantage has been traded off by a compromised coping with hot conditions by aged voles.
Abstract
The results of a craniometric analysis of the bank vole (Myodes glareolus) were evaluated in this study. Twenty cranial variables were measured and evaluated on 149 skulls (78 males, 71 ...females) with respect to sex and age. The main aim of this study was to test the sexual dimorphism in skull size. Overall, our results showed that on average, the values for adult and subadult females of M. glareolus were higher than for males. Results presented here thus reveal sexual differences in the measured cranial traits, most expressed for the length of the mandible and the height of the mandible. The effect size was very large for the length of the first upper molar. Comparison of our results with those from other countries confirmed that there are regional differences. These findings highlight the need for craniometric analysis of species also at the regional level.
To investigate the effects of chronic exposure to low-dose radiation on bone marrow (BM) hematopoiesis of bank voles inhabiting the radioactively contaminated territory of the Chornobyl exclusion ...zone.
Animals were collected within the highly radioactive area of the so-called Red Forest located close to the destroyed 4th reactor of the Chornobyl Nuclear Power Plant. Radioecological investigations included evaluation of radiocontamination of soil samples by
90
Sr and
137
Cs, levels of incorporated radionuclides in animals' bodies and organs, as well as the absorbed dose rates. The study of peripheral blood and BM parameters combined with cytogenetic analysis of BM micronucleated polychromatic erythrocytes (MNPCEs) and standard metaphase test was carried out.
The blood system of the exposed animals manifested significant changes in peripheral blood parameters (anemia and leucocyte formula left shift), ineffective differentiation, and maturation of BM cells, particularly relevant to the erythroid and granulocyte pools. Increased yields of BM MNPCEs and chromosomal aberrations, including dicentrics (dics) and Robertsonian fusion-like configurations (Rbts), were revealed.
Observed disturbances in the BM and peripheral blood suggest functional instability and inefficient compensatory and recovery reactions of the blood system of the bank voles from the contaminated areas of the Chornobyl exclusion zone. We assume that they are the consequences both of direct radiation exposure and hereditary pathological changes that have formed in a number of generations inhabiting radioactively contaminated areas.
Consistent interindividual differences in behaviour, or animal personality, are emerging as an important determinant of a wide range of life history traits and fitness. Individual behaviour, however, ...may be constrained by between-individual variability in energy metabolism and may become unstable owing to intrinsic and extrinsic stressors. Here we tested the relationship between personality and physiology using wild-caught bank voles, Myodes glareolus, that varied according to mtDNA type (original or introgressed from Myodes rutilus). Personality traits and their within-individual consistency were assessed using an open field test and basal metabolic rate (BMR) was measured in an open-flow respirometer. A significant relationship was found between individuals' consistent (repeatable) personality trait (principal component analysis score reflecting individual differences in proactivity) and their consistent (repeatable) residual BMR (body mass corrected); however, this association depended on mtDNA type and sex. Particularly, the males with original mtDNA showed a positive relationship between proactive behaviour and BMR, which supports the increased-intake model, stating that BMR is positively related to the capacity to engage in costly behaviours. However, this relationship was disrupted in introgressed males, and showed a negative trend in females, suggesting the alternative compensation model. According to our findings, it is likely that consistent differences in behavioural patterns and mtDNA types promote variation between individuals in energy metabolism.
•We tested the association between animal personality and basal metabolic rate.•Personality and metabolism were consistent over a substantial part of voles' lives.•Increased-intake model, positive association, was supported in males.•Compensation model, negative trend, was suggested in females.•The associations were disrupted in animals with introgressed mtDNA.
Currently, the effects of chronic, continuous low dose environmental irradiation on the mitochondrial genome of resident small mammals are unknown. Using the bank vole (Myodes glareolus) as a model ...system, we tested the hypothesis that approximately 50 generations of exposure to the Chernobyl environment has significantly altered genetic diversity of the mitochondrial genome. Using deep sequencing, we compared mitochondrial genomes from 131 individuals from reference sites with radioactive contamination comparable to that present in northern Ukraine before the 26 April 1986 meltdown, to populations where substantial fallout was deposited following the nuclear accident. Population genetic variables revealed significant differences among populations from contaminated and uncontaminated localities. Therefore, we rejected the null hypothesis of no significant genetic effect from 50 generations of exposure to the environment created by the Chernobyl meltdown. Samples from contaminated localities exhibited significantly higher numbers of haplotypes and polymorphic loci, elevated genetic diversity, and a significantly higher average number of substitutions per site across mitochondrial gene regions. Observed genetic variation was dominated by synonymous mutations, which may indicate a history of purify selection against nonsynonymous or insertion/deletion mutations. These significant differences were not attributable to sample size artifacts. The observed increase in mitochondrial genomic diversity in voles from radioactive sites is consistent with the possibility that chronic, continuous irradiation resulting from the Chernobyl disaster has produced an accelerated mutation rate in this species over the last 25 years. Our results, being the first to demonstrate this phenomenon in a wild mammalian species, are important for understanding genetic consequences of exposure to low‐dose radiation sources.
The diet of an individual is a result of the availability of dietary items and the individual's foraging skills and preferences. Behavioural differences may thus influence diet variation, but the ...evolvability of diet choice through behavioural evolution has not been studied. We used experimental evolution combined with a field enclosure experiment to test whether behavioural selection leads to dietary divergence. We analysed the individual dietary niche via stable isotope ratios of nitrogen (
N) and carbon (
C) in the hair of an omnivorous mammal, the bank vole, from four lines selected for predatory behaviour and four unselected control lines. Predatory voles had higher hair
N values than control voles, supporting our hypothesis that predatory voles would consume a higher trophic level diet (more animal versus plant foods). This difference was significant in the early but not the late summer season. The
C values also indicated a seasonal change in the consumed plant matter and a difference in food sources among selection lines in the early summer. These results imply that environmental factors interact with evolved behavioural tendencies to determine dietary niche heterogeneity. Behavioural selection thus has potential to contribute to the evolution of diet choice and ultimately the species' ecological niche breadth.
The problem of identifying the sensitivity of living organisms to ionizing irradiation remains relevant, considering the spread of anthropogenic environmental pollution. The study on the effect of ...single X-ray irradiation (1,5 Gy) on peripheral blood of bank voles (Myodes glareolus (Schreber, 1780)) captured within territories with background radiation level was conducted. Hematological indicators, characterizing the overall condition of performance of the body, were determined dynamically on the first and seventh days after exposure to detect both early changes and the rate of recovery processes. The patterns and features of the main components of leukocyte formula found in peripheral blood of irradiated animals are being discussed. Differences between irradiated and control mouse-like rodents are shown, using parameters of erythrocytes and leukocytes. The analysis of changes in the peripheral blood of irradiated bank voles indicates the high reserve capacity of the body, according to its ability to restore homeostasis.
The concept of historic radiation doses associated with accidental radioactive releases and their role in leading to radiation-induced non-targeted effects on affected wild animals are currently ...being evaluated. Previous research studying Fukushima butterfly, Chernobyl bird and fruit fly populations shows that the effects are transgenerational, underlined by the principles of genomic instability, and varied from one species to another. To further expand on the responses of and their sensitivity in different taxonomically distinct groups, the present study sought to reconstruct historic radiation doses and delineate their effects on bank voles (Clethrionomys glareolus) found within a 400-km radius of the Chernobyl Nuclear Power Plant meltdown site. Historic dose reconstruction from the whole-body dose rates for the bank vole samples for their parental generation at the time of radioactive release was performed. Relationships between the historic doses and cytogenetic aberrations and embryonic lethality were examined via graphical presentations. Results suggest that genomic instability develops at the historic dose range of 20–51 mGy while a radioadaptive response develops at the historic dose range of 51–356 mGy. The Linear No-Threshold (LNT) relationship was absent at historic doses of lower than 356 mGy at all generations. However, LNT was apparent when the very high historic dose of 10.28 Gy in one sampling year was factored into the dose response curve for the bank vole generation 21–22. It is worth being reminded that natural mutation accumulation and other environmental stressors outside the realm of dose effects could contribute to the observed effects in a multiple-stressor environment. Nevertheless, the consistent development of genomic instability and radio-adaptive response across generations and sampling sites unearths the utmost fundamental radiobiological principle of transgenerational non-targeted effects. As a result, it calls for better attention and regulation from global governing bodies of environmental health protection.
•Low historic radiation doses cause non-targeted effects in rodents near Chernobyl.•Genomic instability found 21–22 generations after initial radiation exposure.•Frequency of aberrations and embryonic loss are dependent on historic dose.•Variation from LNT model seen for doses below 1Gy.
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