Glis Glis Research Articles

Telomeres are elongated in older individuals in a hibernating rodent, the edible dormouse (Glis glis).

Telomere shortening is thought to be an important biomarker for life history traits such as lifespan and aging, and can be indicative of genome integrity, survival probability and the risk of cancer development. In humans and other animals, telomeres almost always shorten with age, with more rapid telomere attrition in short-lived species. Here, we show that in the edible dormouse (Glis glis) telomere length significantly increases from an age of 6 to an age of 9 years. While this finding could be due to higher survival of individuals with longer telomeres, we also found, using longitudinal measurements, a positive effect of age on the rate of telomere elongation within older individuals. To our knowledge, no previous study has reported such an effect of age on telomere lengthening. We attribute this exceptional pattern to the peculiar life-history of this species, which skips reproduction in years with low food availability. Further, we show that this “sit tight” strategy in the timing of reproduction is associated with an increasing likelihood for an individual to reproduce as it ages. As reproduction could facilitate telomere attrition, this life-history strategy may have led to the evolution of increased somatic maintenance and telomere elongation with increasing age.

Semaphorins Are Likely to Be Involved in the Control of Hibernation

Hibernation is unique mammals’ phenotype demonstrated surviving in seasonal adverse environment conditions. During hibernation, all of systems of organs undergo alterations in their metabolic activity and physiology similar to different physiological conditions associated with human diseases and injuries, which represent a proper model for studying new approaches in clinical treatment. In this study, we have analyzed expression of semaphorins in small hibernator edible dormouse (Glis glis). Semaphorins are factors which involved in a key process of axon guidance and cell–cell communication and can act as tumor suppressor. We found that gene coding Semaphorin-3D (SEMA3D), previously reported to be specific for brain and heart of mammals, represents one of the most upregulated transcripts in the muscles of the hibernating dormice. Furthermore, another member of the same family, Semaphorin-5B (SEMA5B), was strongly induced in the spinal cord of hibernating animals. These observations make semaphorin group, recently attracting more attention due to anti-tumor activity, one of the target for in-depth analysis in relation to the molecular mechanisms of hibernation.

Genetic differentiation of the edible dormouse Glis glis in the Stolowe Mountains (Poland)

This is a continuation of our study started in 2013, where we dealt with genetic diversity of the edible dormouse in the Stolowe Mountains National Park (south-western Poland). A total of 48 dormice from 5 localities were studied. Molecular study involved 12 microsatellite sequences. Low genetic variability of the studied population was found.

Sexual size monomorphism and body variation in the fat dormouse Glis glis in Slovakia

AbstractSexual size dimorphism (SSD) of the fat dormouse

Timing of breeding and second litters in edible dormouse (Glis glis)

In temperate zone the edible dormouse (Glis glis) is an obligate hibernator with a relatively short activity season during the summer. Young are born in seed-masting years, mostly in early August and there is a time constraint as they have to reach independence and sufficient body mass prior to hibernation into which they enter from late September to October. Given the seasonal time constraints, only one litter per year is known to occur in this rodent. Here we report on the timing of breeding in a Czech population of edible dormouse and on two proven cases when females produced two litters per season. Both cases concern very early breeding females which had lost their first litters prior to weaning. The second (replacement) litters were born late in the season and they were successfully weaned. We discuss that probably several factors like female condition, field research design or current phenological trends in extended growing seasons could lead to multiple breeding events in this species.

Low genetic variability of the edible dormouse (Glis glis) in Stolowe Mountains National Park (Poland)—preliminary results

The edible dormouse (Glis glis) from Stolowe Mountains National Park (south-western Poland) was studied to reveal the genetic diversity of dormice living in the Polish Sudetes. Material (hair with roots) collected from 39 individuals (adults and juveniles) was used for genetic testing to perform population analyses. Molecular study involved two types of markers: nuclear DNA (11 microsatellite sequences) and mitochondrial DNA (fragment of cytochrome b of approximately 700 bp in length). Low genetic variability of the studied population was found. Two of the microsatellite loci proved to be completely monomorphic, whereas the degree of polymorphism of other microsatellites was also unexpectedly low. Only two haplotypes were found among all 39 individuals. Low genetic diversity of dormice from the Polish Sudetes, determined by genotyping of nuclear molecular markers, may be the consequence of fragmentation of this species’ population. Dormouse sites in Poland have been declining for decades due to deforestation and fragmentation of old forests. Therefore, dormice live in small populations in isolated habitats with increasing levels of homozygosity. Other possible causes of low genetic variability of G. glis are discussed as well.

Reproductive activity of male edible dormice (<i>Glis glis</i> L., 1766) in the peripheral population

The edible dormouse is a dendrobiont hibernating rodent breeding once a year. A peculiarity of the species biology is regular reproduction failure in non-mast years. In the center of the area it occurs due to the lack of male reproductive activity. In the studied population on the eastern periphery of the dormouse area previous studies proved the decisive role of mass resorption of embryos at females in the process. The dynamics of males reproductive activity and its impact on the reproduction were not considered previously in detail. In this work the periodicity and intensity of reproductive activity of males, depending on the age and phase of population cycle, was studied. Reproductive activity of the overwhelming majority of males was annually observed, the proportion of individuals not involved in reproduction did not exceed 6,7%. The age differences in the timing of beginning of the reproduction were revealed: yearlings came the first in the activity state and after them two-year and three-year and older individuals became active. The minimal duration of the mating period was observed in yearling males, the maximal in two-year, which were also characterized by the longest individual periods of reproductive activity. As a result of sharp fluctuations in the population age structure two-year males are the most important group in reproduction, but the three-year and older individuals in mast years are also able to ensure the reproduction of the population. The characteristic feature of reproduction was noted at yearling males: they began reproduction depending on body weight. Fluctuations in the male reproductive activity during the active period do not play a significant role in the regulation of reproduction. Shorter duration of reproductive activity of yearling animals in the years of reproduction failure is compensated by the later beginning of reproduction of three-year and older individuals. Nonsynchronous participation in breeding of males of different age groups provides the involvement in reproduction of maximal number of animals.

Fat Dormouse(Glis glisL.)Distribution Modeling in the Hyrcanian Relict Forests of Northern Iran

The fat dormouse (Glis glis L.) is a small arboreal and extreme habitat specialist mammal that is tightly linked to the deciduous mixed forests dominated by Beech (Fagus orientalis) and oaks (Quercus sp.). Despite its status in Iran as a least concern species, dormice face high risk of extinction in some parts of Europe. The unique life history and large scale distribution of the species in the Palearctic region made it as an ideal model species. This habitat specialist rodent is particularly sensitive to size and connectivity of the forest patches. The fat dormouse shows very deep molecular and morphological divergence in its eastern most parts of its global distribution, in the Hyrcanian refugium of the Northern Iran. Therefore modeling its distributional range can leads to identify biodiversity hotspots and planning conservation activities. The meteorological data, land cover types, topographical variables and geo-referenced points representing geographical locations of the fat dormouse populations (latitude/longitude) in the study area were used as the primary MaxEnt model input data. The predictive accuracy of the Fat Dormouse ecological niche model was significant (training accuracy of 93.3%). This approach successfully identified the areas of the fat dormouse presence across the study area. The result suggests that the maximum entropy modeling approach can be implemented in the next step towards the development of new tools for monitoring the habitat fragmentation and identifying biodiversity hotspots.

The large-scale removal of mammalian invasive alien species in Northern Europe.

Numerous examples exist of successful mammalian invasive alien species (IAS) eradications from small islands (<10 km2), but few from more extensive areas. We review 15 large‐scale removals (mean area 2627 km2) from Northern Europe since 1900, including edible dormouse, muskrat, coypu, Himalayan porcupine, Pallas' and grey squirrels and American mink, each primarily based on daily checking of static traps. Objectives included true eradication or complete removal to a buffer zone, as distinct from other programmes that involved local control to limit damage or spread. Twelve eradication/removal programmes (80%) were successful. Cost increased with and was best predicted by area, while the cost per unit area decreased; the number of individual animals removed did not add significantly to the model. Doubling the area controlled reduced cost per unit area by 10%, but there was no evidence that cost effectiveness had increased through time. Compared with small islands, larger‐scale programmes followed similar patterns of effort in relation to area. However, they brought challenges when defining boundaries and consequent uncertainties around costs, the definition of their objectives, confirmation of success and different considerations for managing recolonisation. Novel technologies or increased use of volunteers may reduce costs. Rapid response to new incursions is recommended as best practice rather than large‐scale control to reduce the environmental, financial and welfare costs. © 2016 Crown copyright. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Экологии длиннохвостой неясыти на юго-западной границе своего распространения (Словения)

In Slovenia the Ural Owl ( Strix uralensis) is on its south-western limit of distribution and belongs to the southern subspecies Strix uralensis macroura . Dark coloured owls are characteristic for this subspecies and represent between 5 to 15% of the population. Slovenian breeding population size is estimated at 400 to 700 pairs. The densities of territories ranges between 0.9 to 13.4 territories per 10 km 2 , and the highest are reached in mountain forests of southern Dinaric region. In the forests with dominant deciduous trees, e.g. Beech ( Fagus sylvatica) and Pedinculate Oak ( Quercus robur) , the breeding densities are significantly higher than in the forests with higher proportion of coniferous trees, e.g. Norway Spruce ( Picea abies) . The species does not select specific altitude and throughout Slovenia it occurs between 150 and 1600 m a.s.l. The most of the nest found at natural nest-sites were in tree holes or semi-holes (56%) and at the tree stumps (20%). Nest boxes were occupied less frequently in Slovenia with occupancy rate of 29%. At least in mountain regions breeding begins quite late, between 15 March to 21 June. Average clutch size is 3.3 ± 1.0 eggs per nest. About 80% of all nests are successful raising at least one young. The diet shifts significantly between breeding and non-breeding period due to the seasonality in prey availability. According to the biomass the most important prey in breeding period are mice (Muridae), voles (Arvicollidae) and mole ( Talpa europaea ), but in the non-breeding period voles and dormice (Gliridae) predominate. Large Fat Dormouse ( Glis glis) seems to have very important role in the post-breeding period, but not in the breeding period due to its dormancy. As a large forest-dwelling predator the Ural Owl shapes the raptor community in the forest by excluding mezopredator species, as Tawny Owl ( Strix aluco) , what allows smaller raptors, e.g. Boreal Owl ( Aegolius funereus) to expend their ranges to lower elevations. However, this pattern is not general through the whole Ural Owl range since species ecology and morphology could be regionally quite different, therefore ecological studies from different parts of Ural Owl range are needed.

Male-biased litter sex ratio in the southernmost Iberian population of edible dormouse: a strategy against isolation?

Litter sex ratio is a key component of parental fitness due to its impact on lifetime reproductive success. Multiple causes may lay at the origin of sex ratio variation among species and populations, such as maternal condition, local resource competition, presence of helpers, habitat quality or inbreeding levels. Whereas variation in sex allocation between species is relatively well understood, it is still unclear how and why litter sex allocation differs within species. Here, we present an analysis of litter sex ratio variation in two populations of edible dormice (Glis glis) over nine years of study. Populations are situated in the Montnegre and Montseny massifs in Catalonia (NE Iberian Peninsula). The Montnegre population is nowadays an isolated population located at the southernmost range edge of the species in the Iberian Peninsula. Litter sex ratio was male-biased in Montnegre but balanced in Montseny, whereas both populations showed a balanced adult sex ratio. We suggest that this differential sex allocation investment in Montnegre, may be a strategy to overcome isolation effects in this massif, as males are the dispersing sex in this and other rodent species.

The vector tick Ixodes ricinus feeding on an arboreal rodent-the edible dormouse Glis glis.

The reservoir competence and long life expectancy of edible dormice, Glis glis, suggest that they serve as efficient reservoir hosts for Lyme disease (LD) spirochetes. Their arboreality, however, may reduce the probability to encounter sufficient questing Ixodes ricinus ticks to acquire and perpetuate LD spirochetes. To define the potential role of this small arboreal hibernator in the transmission cycle of LD spirochetes, we examined their rate and density of infestation with subadult ticks throughout the season of activity. Of the 1081 edible dormice that we captured at five study sites in Southern Germany and inspected for ticks at 2946 capture occasions, 26 % were infested with at least one and as many as 26 subadult ticks on their ear pinnae. The distribution of ticks feeding on edible dormice was highly aggregated. Although only few individuals harbored nymphal ticks soon after their emergence from hibernation, the rate of nymphal infestation increased steadily throughout the season and reached about 35 % in September. Dormice inhabiting a site with few conspecifics seemed more likely to be infested by numerous ticks, particularly nymphs, than those individuals living in densely populated sites. Male dormice were more likely to be parasitized by numerous nymphs than were females, independent of their age and body mass. Our observation that season, population density, and sex affect the rates of ticks feeding on edible dormice suggests that the contribution of edible dormice to the transmission cycle of LD spirochetes depends mainly on their ranging behavior and level of activity.

The fat dormouse, Glis glis, in Lithuania: living outside the range of the European beech, Fagus sylvatica

Throughout most of the distributional range, the fat dormouse, Glis glis, relies heavily upon European beech as a key species in its habitat. In Lithuania however, situated beyond the continuous range of the beech, pedunculate oak becomes the essential tree in habitats of G. glis. In Lithuania, the dormouse activity season lasts from mid-May to mid-October, young are born during the short period from late July to mid-August, and the mean litter size is 5.9 young. Population density is low (0.8–2.0 ind./ha after hibernation and 1.2–4.8 ind./ha in autumn), but relatively stable. The mean body weights of adults (98 g after hibernation and 128 g before hibernation) are among the lowest across the range. Lithuanian dormice differ from those living in beech-dominated habitats by their lower population density and lower body weight. Such differences may be due to acorns being less suitable food for G. glis in comparison to beech nuts. In terms of inter-annual abundance dynamics, the G. glis population is comparatively stable as years in which dormice fail to reproduce are infrequent in Lithuania.

Influence of mortality and dispersal on sex ratio of the edible dormouse (Glis glis)

While most mammal populations show equalized sex ratios in their offspring, some species reveal deviations as a reaction to environmental circumstances. The recent study focuses on mortality, dispersal and biased sex ratio in the offspring of the edible dormouse (Glis glis) and their influence on next year's subadult population. Between 2002 and 2008 a male biased sex ratio in the offspring but an almost equal sex ratio of next year's subadult population has been found. Our results reveal that this deviation from the 1:1 sex ratio compensates a higher mortality rate of young males. The data used for this study were obtained from a mark and recapture project of monitoring the population biology of the edible dormouse performed north-east of Frankfurt/Main, Germany.

Nest box usage by old edible dormice (Glis glis) in breeding and non-breeding years

Evidence from the only woodland study in the U.K. of the non-native edible dormouse shows (using nest boxes inspected monthly), that whilst some or much breeding occurs in most years, non-breeding years also occur. This is understood to relate to the number of tree species flowering in spring and the amount of flower production. Morris & Morris (2010) used a small sample to show that some adult animals do not appear in the nest box inspection records during the non-breeding years, but are present during the next breeding year. We have subsequently refined and increased the database, collating information on a sample of 222 glis (136 female, 86 male) known to be alive for between 5 and 13 years during a continuous study period of 18 years. The number of old animals (living to at least five years) recorded in nest boxes is significantly different between years of breeding and non-breeding with up to 90 % absent. There is no evidence that they move elsewhere in the isolated wood. Both males and females displayed this trait. The paper discusses alternative explanatory options interpreted from this. The applied science impact is that if 18 month hibernation is proven the time and cost implications for population control planning are severe. Future research is aimed at demonstrating the reality.

Population structure of edible dormouse in Poland: the role of habitat fragmentation and implications for conservation

AbstractThe effects of habitat fragmentation and the resulting decreases in effective population sizes are not easy to document because they take place over many generations and may be affected by factors other than demographic ones. Here, we used 22 microsatellite loci to investigate genetic structure and diversity in populations of edible dormice Glis glis from habitats that varied widely in area and in the degree of connectivity to other populations. We found that populations from the most fragmented north‐western region of Poland were characterized by extremely limited gene flow and low genetic diversity compared to less fragmented populations from southern Poland. STRUCTURE analysis revealed three genetic groups in Poland, which might reflect adaptation to environmental conditions across south‐north and east‐west gradients, but could also be due to historical patterns of post‐glacial colonization. The latter hypothesis is suggested by the observation that southern populations from Poland grouped with those from the Balkans based on microsatellite data; however, the fact that all Polish populations shared western mtDNA cytochrome b haplotypes is inconsistent with this scenario. We discuss the consequences of our findings for the conservation of the edible dormouse in Poland.

It takes two to tango: Phagocyte and lymphocyte numbers in a small mammalian hibernator

Immunity is energetically costly and competes for resources with other physiological body functions, which may result in trade-offs that impair fitness during demanding situations. Endocrine mediators, particularly stress hormones, play a central role in these relationships and directly impact leukocyte differentials. To determine the effects of external stressors, energetic restraints and competing physiological functions on immune parameters and their relevance for fitness, we investigated leukocyte profiles during the active season of a small obligate hibernator, the edible dormouse (Glis glis), in five different study sites in south-western Germany. The highly synchronized yearly cycle of this species and the close adaptation of its life history to the irregular abundance of food resources provide a natural experiment to elucidate mechanisms underlying variations in fitness parameters. In contrast to previous studies on hibernators, that showed an immediate recovery of all leukocyte subtypes upon emergence, our study revealed that hibernation results in depleted phagocyte (neutrophils and monocytes) stores that recovered only slowly. As the phenomenon of low phagocyte counts was even more pronounced at the beginning of a low food year and primarily immature neutrophils were present in the blood upon emergence, preparatory mechanisms seem to determine the regeneration of phagocytes before hibernation is terminated. Surprisingly, the recovery of phagocytes thereafter took several weeks, presumably due to energetic restrictions. This impaired first line of defense coincides with lowest survival probabilities during the annual cycle of our study species. Reduced survival could furthermore be linked to drastic increases in the P/L ratio (phagocytes/lymphocytes), an indicator of physiological stress, during reproduction. On the other hand, moderate augmentations in the P/L ratio occurred during periods of low food availability and were associated with increased survival, but reproductive failure. In this case, the stress response probably represents an adaptive reaction that contributes to survival by activating energy resources. In contrast to our expectation, we could not detect an amplification of stress through high population densities. Summarized, results of our study clearly reveal that the leukocyte picture of active edible dormice responds sensitively to physiological conditions associated with hibernation, reproductive activity and food availability and can be linked to fitness parameters such as survival. Thus edible dormice represent an excellent model organism to investigate regulatory mechanisms of the immune system under natural conditions.

How to spend the summer? Free-living dormice (Glis glis) can hibernate for 11 months in non-reproductive years.

Edible dormice are arboreal rodents adapted to yearly fluctuations in seed production of European beech, a major food source for this species. In years of low beech seed abundance, dormice skip reproduction and non-reproductive dormice fed ad libitum in captivity can display summer dormancy in addition to winter hibernation. To test whether summer dormancy, that is, a very early onset of hibernation, actually occurs in free-living dormice, we monitored core body temperature (Tb) over ~12 months in 17 animals during a year of beech seeding failure in the Vienna Woods. We found that 8 out of 17 dormice indeed re-entered hibernation as early as in June/July, with five of them having extreme hibernation durations of 11 months or more (total range: 7.8–11.4 months). Thus, we show for the first time that a free-living mammal relying on natural food resources can continuously hibernate for >11 months. Early onset of hibernation was associated with high body mass in the spring, but the distribution of hibernation onset was bimodal with prolonged hibernation starting either early (prior to July 28) or late (after August 30). This could not be explained by differences in body mass alone. Animals with a late hibernation onset continued to maintain high nocturnal Tb’s throughout summer but used short, shallow torpor bouts (mean duration 7.44 ± 0.9 h), as well as occasional multiday torpor for up to 161 h.Electronic supplementary materialThe online version of this article (doi:10.1007/s00360-015-0929-1) contains supplementary material, which is available to authorized users.

Habitat preferences of edible dormouse,Glis glis italicus: implications for the management of arboreal mammals in Mediterranean forests

Research on arboreal mammals living in Mediterranean forests is poor. Molecular research assessed the existence of an evolutionary significant unit in the edible dormouse populations living in south Italy, Sicily and Sardinia, and we decided to investigate the environmental factors capable of explaining its occurrence and abundance in Sicily, for a better management of these populations. We assessed the species habitat preferences by setting 25 large and 25 small nestboxes in five sample areas along an altitudinal gradient of the Madonie Range, and recorded habitat variables, food availability, and demographic data for two years. To obtain synthetic descriptors of the dormice habitat requirements, we extracted uncorrelated linear combinations of original variables by Principal Component Analysis; then we modelled habitat preferences of dormice by Generalized Linear Models, and selected the best models by Akaike's information criterion and model averaging. Dormice abundances varied markedly between the two years of study. Population peaked and reproduced in 2010, a masting year of oaks and beeches. In the following non-masting year, a much lower number of adults and yearlings used nestboxes, without any sign of reproduction. In both years we found a significant effect of altitudinal vegetation belt. Dormice seem to prefer mixed broad-leaved and evergreen (cork, holm) oak forests below 800-1300 m a.s.l, to beech forests at higher altitude, and avoid coniferous plantations. Inside these woodlands they seem to prefer monotypic and mature oak-stands with dense canopies. Large nestboxes are more preferred than small ones only during reproductive years. Protection of large and mature woodland from wildfires and forestry management caring the retention of significant elements like old trees, logs and litter mounds are necessary to maintain the habitat of edible dormouse in Southern Mediterranean forests. Artificial nestboxes are a viable device to help population restocking in degraded forests.

Diet of the fat dormouse (Glis glis) on the northern periphery of its distributional range

We studied the seasonal and annual variation in diet composition of the fat dormouse (Glis glis) in Lithuania, a locality situated on the northern periphery of the dormouse range and outside of the range of the European beech (Fagus sylvatica). After emergence from hibernation, dormice fed on oak acorns (from the previous year), inflorescences of various trees, vegetative parts of plants and food of animal origin (birds, their eggs and insects). In June, soft mast and seeds of birches supplemented the dormouse diet, and diet composition was the most diverse during this period. In July, raspberries and fruits of glossy buckthorn constituted the bulk of dormouse diet, but seeds of birches dominated in a specific year. Hard mast (mainly acorns) dominated the diet of G. glis from August until the beginning of hibernation in October. A high prevalence of acorns, comparatively high proportion of birch seeds and low proportion of food of animal origin in the diet, as well as feeding on fruits of glossy buckthorn, are specific features of feeding by G. glis in Lithuania. The diet of G. glis on the northern periphery of its range resembles its diet on the eastern periphery of the range where beech trees are also absent. According to the composition of G. glis diet, feeding conditions in both of these peripheral regions are poorer in comparison to central or southern regions.