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contrasting effects of climate change on seasonal survival of a hibernating mammal.seasonal environmental conditions shape the behavior and life history of virtually all organisms. climate change is modifying these seasonal environmental conditions, which threatens to disrupt population dynamics. it is conceivable that climatic changes may be beneficial in one season but result in detrimental conditions in another because life-history strategies vary between these time periods. we analyzed the temporal trends in seasonal survival of yellow-bellied marmots (marmota flaviventer) ...202032631981
gene expression shifts in yellow-bellied marmots prior to natal dispersal.the causes and consequences of vertebrate natal dispersal have been studied extensively, yet little is known about the molecular mechanisms involved. we used rna-seq to quantify transcriptomic gene expression in blood of wild yellow-bellied marmots (marmota flaviventer) prior to dispersing from or remaining philopatric to their natal colony. we tested 3 predictions. first, we hypothesized dispersers and residents will differentially express genes and gene networks since dispersal is physiologica ...202030971856
response of a remnant marmot population to habitat enhancement yields insights into marmot ecology.we evaluated the response of a remnant population of yellow-bellied marmots (marmota flaviventris) to targeted habitat enhancement in an ecological system that had been degraded during ~100 years of intensive livestock management, including marmot eradication. we used capture-recapture data and a novel use of a multistate framework to evaluate geographic expansion of the marmot population pre- and post-habitat enhancement. we also estimated age-structured survival, reproduction, and sex ratios. ...202032665739
older mothers produce more successful daughters.annual reproductive success and senescence patterns vary substantially among individuals in the wild. however, it is still seldom considered that senescence may not only affect an individual but also affect age-specific reproductive success in its offspring, generating transgenerational reproductive senescence. we used long-term data from wild yellow-bellied marmots (marmota flaviventer) living in two different elevational environments to quantify age-specific reproductive success of daughters b ...202032071200
assessing seasonal demographic covariation to understand environmental-change impacts on a hibernating mammal.natural populations are exposed to seasonal variation in environmental factors that simultaneously affect several demographic rates (survival, development and reproduction). the resulting covariation in these rates determines population dynamics, but accounting for its numerous biotic and abiotic drivers is a significant challenge. here, we use a factor-analytic approach to capture partially unobserved drivers of seasonal population dynamics. we use 40 years of individual-based demography from y ...202031970918
the effects of neurectomy and hibernation on bone properties and the endocannabinoid system in marmots (marmota flaviventris).hibernators have adapted a physiological mechanism allowing them to undergo long periods of inactivity without experiencing bone loss. however, the biological mechanisms that prevent bone loss are unknown. previous studies found meaningful changes, between active and hibernating marmots, in the endocannabinoid system of many tissues, including bone. cannabinoid receptors (cb1 and cb2) have divergent localization in bone. cb1 is predominately found on sympathetic nerve terminals, while cb2 is mor ...202031783174
correlates of maternal glucocorticoid levels in a socially flexible rodent.while it is generally accepted that social isolation has detrimental effects on social species, little is known about the importance of social interactions in less social species-particularly for wild reproductive females. we studied socially-flexible yellow-bellied marmots (marmota flaviventer) and asked whether features of the social environment are associated with maternal fecal glucocorticoid metabolite (fgm) concentrations. since changes in maternal baseline glucocorticoids may have positiv ...201931442430
cumulative reproductive costs on current reproduction in a wild polytocous mammal.the cumulative cost of reproduction hypothesis predicts that reproductive costs accumulate over an individual's reproductive life span. while short-term costs have been extensively explored, the prevalence of cumulative long-term costs and the circumstances under which such costs occur alongside or instead of short-term costs, are far from clear. indeed, few studies have simultaneously tested for both short-term and cumulative long-term reproductive costs in natural populations. even in mammals, ...201830598755
relaxing life of the city? allostatic load in yellow-bellied marmots along a rural-urban continuum.urban environments are expanding. as rural areas are urbanized, animals living in those environments must respond. examinations of ecological responses to urbanization are abundant, but much less work has focused on the physiological responses driving those ecological patterns, particularly in mammals. whether an animal interprets urbanized environments as stressful or not can help us understand, and even predict, the likelihood of individuals persisting in urbanized areas. unpredictable events ...201830591838
marmots do not consistently use their left eye to respond to an approaching threat but those that did fled sooner.in many vertebrates, the brain's right hemisphere which is connected to the left visual field specializes in the processing of information about threats while the left hemisphere which is connected to the right visual field specializes in the processing of information about conspecifics. this is referred to as hemispheric lateralization. but individuals that are too predictable in their response to predators could have reduced survival and we may expect selection for somewhat unpredictable respo ...201830538732
transient ltre analysis reveals the demographic and trait-mediated processes that buffer population growth.temporal variation in environmental conditions affects population growth directly via its impact on vital rates, and indirectly through induced variation in demographic structure and phenotypic trait distributions. we currently know very little about how these processes jointly mediate population responses to their environment. to address this gap, we develop a general transient life table response experiment (ltre) which partitions the contributions to population growth arising from variation i ...201830252195
seasonal changes in endocannabinoid concentrations between active and hibernating marmots (marmota flaviventris).hibernation is a naturally occurring model for studying diseases such as obesity and osteoporosis. hibernators, marmots (marmota flaviventris) among them, are able to nearly double their body mass by increasing fat stores prior to hibernation without the negative consequences of obesity. they are also physically inactive for extended periods of time without experiencing negative effects on the skeleton. the endocannabinoid system is involved in modulating neural signaling, circannual rhythms, be ...201829862861
age, state, environment, and season dependence of senescence in body mass.senescence is a highly variable process that comprises both age-dependent and state-dependent components and can be greatly affected by environmental conditions. however, few studies have quantified the magnitude of age-dependent and state-dependent senescence in key life-history traits across individuals inhabiting different spatially structured and seasonal environments. we used longitudinal data from wild female yellow-bellied marmots (marmota flaviventer), living in two adjacent environments ...201829468024
strong social relationships are associated with decreased longevity in a facultatively social mammal.humans in strong social relationships are more likely to live longer because social relationships may buffer stressors and thus have protective effects. however, a shortcoming of human studies is that they often rely on self-reporting of these relationships. by contrast, observational studies of non-human animals permit detailed analyses of the specific nature of social relationships. thus, discoveries that some social animals live longer and healthier lives if they are involved in social groomi ...201829343594
oxytocin experiments shed light on mechanisms shaping prosocial and antisocial behaviors in non-human mammals.oxytocin has gained a reputation in popular culture as a simple "love drug" or "cuddle hormone", yet emerging biological evidence indicates that the effects of oxytocin are complex, mediating a suite of behavioral traits that range from ultrasocial to antisocial. here we provide a comprehensive review to assess the salience of oxytocin in the lives of free-living social mammals. we reviewed the literature to understand the potential effects of oxytocin in promoting prosocial and antisocial behav ...201728957521
exploring the bone proteome to help explain altered bone remodeling and preservation of bone architecture and strength in hibernating marmots.periods of physical inactivity increase bone resorption and cause bone loss and increased fracture risk. however, hibernating bears, marmots, and woodchucks maintain bone structure and strength, despite being physically inactive for prolonged periods annually. we tested the hypothesis that bone turnover rates would decrease and bone structural and mechanical properties would be preserved in hibernating marmots (marmota flaviventris). femurs and tibias were collected from marmots during hibernati ...201727617358
the effect of maternal glucocorticoid levels on juvenile docility in yellow-bellied marmots.maternal effects can have significant and long-term consequences on offspring behavior and survival, while consistent individual differences (i.e., personality) can have profound impacts on individual fitness. thus, both can influence population dynamics. however, the underlying mechanisms that determine variation in personality traits are poorly understood. maternal effects are one potential mechanism that may explain personality variation. we capitalized on a long-term study of yellow-bellied ...201728062231
genetic basis of between-individual and within-individual variance of docility.between-individual variation in phenotypes within a population is the basis of evolution. however, evolutionary and behavioural ecologists have mainly focused on estimating between-individual variance in mean trait and neglected variation in within-individual variance, or predictability of a trait. in fact, an important assumption of mixed-effects models used to estimate between-individual variance in mean traits is that within-individual residual variance (predictability) is identical across in ...201728182325
detection, prevalence and phylogenetic relationships of demodex spp and further skin prostigmata mites (acari, arachnida) in wild and domestic mammals.this study was conceived to detect skin mites in social mammals through real-time qpcr, and to estimate taxonomic demodex and further prostigmata mite relationships in different host species by comparing sequences from two genes: mitochondrial 16s rrna and nuclear 18s rrna. we determined the mite prevalence in the hair follicles of marmots (13%) and bats (17%). the high prevalence found in marmots and bats by sampling only one site on the body may indicate that mites are common inhabitants of th ...201627802314
elevation and vegetation determine cryptosporidium oocyst shedding by yellow-bellied marmots (marmota flaviventris) in the sierra nevada mountains.wildlife are increasingly recognized as important biological reservoirs of zoonotic species of cryptosporidium that might contaminate water and cause human exposure to this protozoal parasite. the habitat range of the yellow-bellied marmot (marmota flaviventris) overlaps extensively with the watershed boundaries of municipal water supplies for california communities along the foothills of the sierra nevada. we conducted a cross-sectional epidemiological study to estimate the fecal shedding of cr ...201525834788
heritability and genetic correlations of personality traits in a wild population of yellow-bellied marmots (marmota flaviventris).describing and quantifying animal personality is now an integral part of behavioural studies because individually distinctive behaviours have ecological and evolutionary consequences. yet, to fully understand how personality traits may respond to selection, one must understand the underlying heritability and genetic correlations between traits. previous studies have reported a moderate degree of heritability of personality traits, but few of these studies have either been conducted in the wild o ...201526214760
maternal effects on anogenital distance in a wild marmot population.in mammals, prenatal exposure to sex steroid hormones may have profound effects on later behavior and fitness and have been reported under both laboratory and field conditions. anogenital distance is a non-invasive measure of prenatal exposure to sex steroid hormones. while we know that intra-uterine position and litter sex ratio influence anogenital distance, there are other, heretofore unstudied, factors that could influence anogenital distance, including maternal effects. we capitalized on a ...201424651864
responses of high-elevation herbaceous plant assemblages to low glacial co₂ concentrations revealed by fossil marmot (marmota) teeth.atmospheric co2 cycles of the quaternary likely imposed major constraints on the physiology and growth of c3 plants worldwide. however, the measured record of this remains both geographically and taxonomically sparse. we present the first reconstruction of physiological responses in a late quaternary high-elevation herbaceous plant community from the southern rocky mountains, usa. we used a novel proxy-fossilized tooth enamel of yellow-bellied marmots (marmota flaviventris)-which we developed us ...201424916834
deer mothers are sensitive to infant distress vocalizations of diverse mammalian species.acoustic structure, behavioral context, and caregiver responses to infant distress vocalizations (cries) are similar across mammals, including humans. are these similarities enough for animals to respond to distress vocalizations of taxonomically and ecologically distant species? we show that mule deer (odocoileus hemionus) and white-tailed deer (odocoileus virginianus) mothers approach a speaker playing distress vocalizations of infant marmots (marmota flaviventris), seals (neophoca cinerea and ...201425226186
yellow-bellied marmots: insights from an emergent view of sociality.ecological factors explain variation in sociality both within and between species of marmots-large alpine ground squirrels. fifty years of study, by me and my colleagues, of the yellow-bellied marmots (marmota flaviventris) at the rocky mountain biological laboratory, near crested butte, co, usa, has created opportunities to see how sociality changes with population and group size. over the past decades, we have witnessed a natural experiment whereby the population tripled in size. if we view so ...201323569297
early play may predict later dominance relationships in yellow-bellied marmots (marmota flaviventris).play has been defined as apparently functionless behaviour, yet since play is costly, models of adaptive evolution predict that it should have some beneficial function (or functions) that outweigh its costs. we provide strong evidence for a long-standing, but poorly supported hypothesis: that early social play is practice for later dominance relationships. we calculated the relative dominance rank by observing the directional outcome of playful interactions in juvenile and yearling yellow-bellie ...201323536602
ontogenetic variation of heritability and maternal effects in yellow-bellied marmot alarm calls.individuals of many species produce distinctive vocalizations that may relay potential information about the signaller. the alarm calls of some species have been reported to be individually specific, and this distinctiveness may allow individuals to access the reliability or kinship of callers. while not much is known generally about the heritability of mammalian vocalizations, if alarm calls were individually distinctive to permit kinship assessment, then call structure should be heritable. her ...201323466987
decreasing litter size of marmots over time: a life history response to climate change?the way that plants and animals respond to climate change varies widely among species, but the biological features underlying their actual response remains largely unknown. here, from a 20-year monitoring study, we document a continuous decrease in litter size of the alpine marmot (marmota marmota) since 1990. to cope with harsh winters, alpine marmots hibernate in burrows and their reproductive output should depend more on spring conditions compared to animals that are active year-round. howeve ...201323687884
fecal glucocorticoid metabolites in wild yellow-bellied marmots: experimental validation, individual differences and ecological correlates.natural selection is expected to shape phenotypic traits that permit organisms to respond appropriately to the environments in which they live. one important mechanism by which animals cope with changes in their environment is through physiological responses to stressors mediated by glucocorticoid hormones. here we perform biological and physiological validations of a minimally-invasive technique for assessing fecal corticosterone metabolites (fcms) in captive and wild groups of yellow-bellied m ...201222732084
yellow-bellied marmots (marmota flaviventris) preserve bone strength and microstructure during hibernation.reduced skeletal loading typically results in decreased bone strength and increased fracture risk for humans and many other animals. previous studies have shown bears are able to prevent bone loss during the disuse that occurs during hibernation. studies with smaller hibernators, which arouse intermittently during hibernation, show that they may lose bone at the microstructural level. these small hibernators, like bats and squirrels, do not utilize intracortical remodeling. however, slightly lar ...201222037004
litter sex composition affects life-history traits in yellow-bellied marmots.1. the presence of siblings might have long-lasting fitness consequences because they influence the early environment in which an animal develops. several studies under laboratory conditions have shown long-lasting consequences from the presence of male siblings in utero on morphology and life-history traits. however, in wild animals, such effects of litter sex composition are unexplored. 2. we capitalized on a long-term study of individually marked yellow-bellied marmots (marmota flaviventris) ...201221801175
sociality, individual fitness and population dynamics of yellow-bellied marmots.social behaviour was proposed as a density-dependent intrinsic mechanism that could regulate an animal population by affecting reproduction and dispersal. populations of the polygynous yellow-bellied marmot (marmota flaviventris) fluctuate widely from year to year primarily driven by the number of weaned young. the temporal variation in projected population growth rate was driven mainly by changes in the age of first reproduction and fertility, which are affected by reproductive suppression. dis ...201222017671
masculinized female yellow-bellied marmots initiate more social interactions.the presence of male siblings in utero influences female morphology and life-history traits because testosterone transferred among foetuses may masculinize females. similarly, litter sex composition might alter the display of sexually dimorphic behaviour, such as play and allogrooming, since they are modulated by androgens. we explored whether masculinization alters the frequency of play and sociopositive behaviour in female yellow-bellied marmots (marmota flaviventris). we found that masculiniz ...201221880621
no evidence of inbreeding avoidance despite demonstrated survival costs in a polygynous rodent.individuals are generally predicted to avoid inbreeding because of detrimental fitness effects. however, several recent studies have shown that limited inbreeding is tolerated by some vertebrate species. here, we examine the costs and benefits of inbreeding in a largely polygynous rodent, the yellow-bellied marmot (marmota flaviventris). we use a pedigree constructed from 8 years of genetic data to determine the relatedness of all marmots in our study population and examine offspring survival, a ...201222145620
older mothers follow conservative strategies under predator pressure: the adaptive role of maternal glucocorticoids in yellow-bellied marmots.when the maternal environment is a good predictor of the offspring environment, maternal glucocorticoid (gc) levels might serve to pre-program offspring to express certain phenotypes or life-history characteristics that will increase their fitness. we conducted a field study to assess the effects of naturally occurring maternal gc levels on their offspring in yellow-bellied marmots (marmota flaviventris) subjected to different predator pressures. maternal fecal corticosteroid metabolites (fcm) w ...201121930131
comparison of the its1 and its2 rdna in eimeria callospermophili (apicomplexa:eimeriidae) from sciurid rodents.the taxonomy of the coccidia has historically been morphologically based. the purpose of this study was to establish if conspecificity of isolates of eimeria callospermophili from 4 ground-dwelling squirrel hosts (rodentia: sciuridae) is supported by comparison of rdna sequence data and to examine how this species relates to eimerian species from other sciurid hosts. eimeria callospermophili was isolated from 4 wild-caught hosts, i.e., urocitellus elegans, cynomys leucurus, marmota flaviventris ...201121506777
age and sex influence marmot antipredator behavior during periods of heightened risk.animals adjust their antipredator behavior according to environmental variation in risk, and to account for their ability to respond to threats. intrinsic factors that influence an animal's ability to respond to predators (e.g., age, body condition) should explain variation in antipredator behavior. for example, a juvenile might allocate more time to vigilance than an adult because mortality as a result of predation is often high for this age class; however, the relationship between age/vulnerab ...201121874082
scared and less noisy: glucocorticoids are associated with alarm call entropy.the nonlinearity and arousal hypothesis predicts that highly aroused mammals will produce nonlinear, noisy vocalizations. we tested this prediction by measuring faecal glucocorticoid metabolites (gcms) in adult yellow-bellied marmots (marmota flaviventris), and asking if variation in gcms was positively correlated with wiener entropy-a measure of noise. contrary to our prediction, we found a significant negative relationship: marmots with more faecal gcms produced calls with less noise than thos ...201121976625
proximate causes of natal dispersal in female yellow-bellied marmots, marmota flaviventris.we investigated factors influencing natal dispersal in 231 female yearling yellow-bellied marmots (marmota flaviventris) using comprehensive analysis of 10 years (1983-1993) of radiotelemetry and 37 years (1963-1999) of capture-mark-recapture data. only individuals whose dispersal status was verified, primarily by radiotelemetry, were considered. univariate analyses revealed that six of the 24 variables we studied significantly influenced dispersal: dispersal was less likely when the mother was ...201121560692
the potential to encode sex, age, and individual identity in the alarm calls of three species of marmotinae.in addition to encoding referential information and information about the sender's motivation, mammalian alarm calls may encode information about other attributes of the sender, providing the potential for recognition among kin, mates, and neighbors. here, we examined 96 speckled ground squirrels (spermophilus suslicus), 100 yellow ground squirrels (spermophilus fulvus) and 85 yellow-bellied marmots (marmota flaviventris) to determine whether their alarm calls differed between species in their a ...201121221515
is alarm calling risky? marmots avoid calling from risky places.alarm calling is common in many species. a prevalent assumption is that calling puts the vocalizing individual at increased risk of predation. if calling is indeed costly, we need special explanations for its evolution and maintenance. in some, but not all species, callers vocalize away from safety and thus may be exposed to an increased risk of predation. however, for species that emit bouts with one or a few calls, it is often difficult to identify the caller and find the precise location wher ...201021116460
heritability of anti-predatory traits: vigilance and locomotor performance in marmots.animals must allocate some proportion of their time to detecting predators. in birds and mammals, such anti-predator vigilance has been well studied, and we know that it may be influenced by a variety of intrinsic and extrinsic factors. despite hundreds of studies focusing on vigilance and suggestions that there are individual differences in vigilance, there have been no prior studies examining its heritability in the field. here, we present one of the first reports of (additive) genetic variati ...201020298440
to eat or not to eat: the effect of aicar on food intake regulation in yellow-bellied marmots (marmota flaviventris).mammals that hibernate (hibernators) exhibit a circannual rhythm of food intake and body mass. in the laboratory during the winter hibernation period, many hibernators enter a series of multi-day torpor bouts, dropping their body temperature to near ambient, and cease to feed even if food is present in their cage. the mechanism(s) that regulates food intake in hibernators is unclear. recently, amp-activated protein kinase (ampk) has been shown to play a key role in the central regulation of food ...201020511516
coupled dynamics of body mass and population growth in response to environmental change.environmental change has altered the phenology, morphological traits and population dynamics of many species. however, the links underlying these joint responses remain largely unknown owing to a paucity of long-term data and the lack of an appropriate analytical framework. here we investigate the link between phenotypic and demographic responses to environmental change using a new methodology and a long-term (1976-2008) data set from a hibernating mammal (the yellow-bellied marmot) inhabiting a ...201020651690
a test of the social cohesion hypothesis: interactive female marmots remain at home.individuals frequently leave home before reaching reproductive age, but the proximate causes of natal dispersal remain relatively unknown. the social cohesion hypothesis predicts that individuals who engage in more (affiliative) interactions are less likely to disperse. despite the intuitive nature of this hypothesis, support is both limited and equivocal. we used formal social network analyses to quantify precisely both direct and indirect measures of social cohesion in yellow-bellied marmots. ...200919493901
influence of local demography on asymptotic and transient dynamics of a yellow-bellied marmot metapopulation.despite recent advances in biodemography and metapopulation ecology, we still have limited understanding of how local demographic parameters influence short- and long-term metapopulation dynamics. we used long-term data from 17 local populations, along with the recently developed methods of matrix metapopulation modeling and transient sensitivity analysis, to investigate the influence of local demography on long-term (asymptotic) versus short-term (transient) dynamics of a yellow-bellied marmot ...200919249978
spatiotemporal variation in reproductive parameters of yellow-bellied marmots.spatiotemporal variation in reproductive rates is a common phenomenon in many wildlife populations, but the population dynamic consequences of spatial and temporal variability in different components of reproduction remain poorly understood. we used 43 years (1962-2004) of data from 17 locations and a capture-mark-recapture (cmr) modeling framework to investigate the spatiotemporal variation in reproductive parameters of yellow-bellied marmots (marmota flaviventris), and its influence on the rea ...200717687571
faecal glucocorticoid metabolites and alarm calling in free-living yellow-bellied marmots.when individuals of a variety of species encounter a potential predator, some, but not all, emit alarm calls. to explain the proximate basis of this variation, we compared faecal glucocorticoid metabolite concentrations in live-trapped yellow-bellied marmots (marmota flaviventris) between occasions when they did and did not emit alarm calls. we found that marmots had significantly higher glucocorticoid levels when they called than when they did not call, suggesting that stress or arousal may pla ...200617148318
effects of patch quality and network structure on patch occupancy dynamics of a yellow-bellied marmot metapopulation.1. the presence/absence of a species at a particular site is the simplest form of data that can be collected during ecological field studies. we used 13 years (1990-2002) of survey data to parameterize a stochastic patch occupancy model for a metapopulation of the yellow-bellied marmot in colorado, and investigated the significance of particular patches and the influence of site quality, network characteristics and regional stochasticity on the metapopulation persistence. 2. persistence of the y ...200616903056
spatiotemporal variation in survival rates: implications for population dynamics of yellow-bellied marmots.spatiotemporal variation in age-specific survival rates can profoundly influence population dynamics, but few studies of vertebrates have thoroughly investigated both spatial and temporal variability in age-specific survival rates. we used 28 years (1976-2003) of capture-mark-recapture (cmr) data from 17 locations to parameterize an age-structured cormack-jolly-seber model, and investigated spatial and temporal variation in age-specific annual survival rates of yellow-bellied marmots (marmota fl ...200616676546
noninvasive estimation of body composition in small mammals: a comparison of conductive and morphometric techniques.body fat stores may serve as an index of condition in mammals. thus, techniques that measure fat content accurately are important for assessing the ecological correlates of condition in mammal populations. we compared the ability of two conductive techniques, bioelectrical impedance analysis (bia) and total body electrical conductivity (tobec), to predict body composition with that of morphometric methods in three small mammal species: red squirrels (n=13), snowshoe hares (n=30), and yellow-bell ...200612529850
group hibernation does not reduce energetic costs of young yellow-bellied marmots.we investigated mechanisms of energy conservation during hibernation. the amount of time torpid was significantly less for groups of three young marmots than for marmots hibernating singly. mean daily mass loss (dml; as mg d(-1) g(-1) immergence mass) averaged 1.33 for single marmots and 1.46 for grouped young. animals were active 17.3% of the time, which used 82.4% of the energy, and were torpid 82.7% of the time, which used 17.6% of the energy expenditure. during longer torpor bouts, more time ...200614988804
fat-cell mass, serum leptin and adiponectin changes during weight gain and loss in yellow-bellied marmots (marmota flaviventris).leptin and adiponectin are proteins produced and secreted from white adipose tissue and are important regulators of energy balance and insulin sensitivity. seasonal changes in leptin and adiponectin have not been investigated in mammalian hibernators in relationship to changes in fat cell and fat mass. we sought to determine the relationship between serum leptin and adiponectin levels with seasonal changes in lipid mass. we collected serum and tissue samples from marmots (marmota flaviventris) i ...200415517283
comparison of surface temperature in 13-lined ground squirrel (spermophilus tridecimlineatus) and yellow-bellied marmot (marmota flaviventris) during arousal from hibernation.surface temperatures (ts) of eight 13-lined ground squirrels and seven yellow-bellied marmots were measured during arousal from hibernation using infrared thermography (irt) and recorded on videotape. animals aroused normally in 5 degrees c cold rooms. body temperatures were recorded during arousal using both cheek pouch and interscapular temperature probes. warming rate in arousal was exponential. mean mass specific warming rates show the squirrels warm faster (69.76 degrees c/h/kg) than the ma ...200415369834
seasonal, tissue-specific regulation of akt/protein kinase b and glycogen synthase in hibernators.yellow-bellied marmots (marmota flaviventris) exhibit a circannual cycle of hyperphagia and nutrient storage in the summer followed by hibernation in the winter. this annual cycle of body mass gain and loss is primarily due to large-scale accumulation of lipid in the summer, which is then mobilized and oxidized for energy during winter. the rapid and predictable change in body mass makes these animals ideal for studies investigating the molecular basis for body weight regulation. in the study de ...200414656767
reliability and the adaptive utility of discrimination among alarm callers.unlike individually distinctive contact calls, or calls that aid in the recognition of young by their parents, the function or functions of individually distinctive alarm calls is less obvious. we conducted three experiments to study the importance of caller reliability in explaining individual-discriminative abilities in the alarm calls of yellow-bellied marmots (marmota flaviventris). in our first two experiments, we found that calls from less reliable individuals and calls from individuals ca ...200415315902
sociality and individual fitness in yellow-bellied marmots: insights from a long-term study (1962-2001).theoretical and empirical studies suggest that the age of first reproduction (the age at which reproduction begins) can have a substantial influence on population dynamics and individual fitness. using complete survival and reproductive histories of 428 female yellow-bellied marmots (marmota flaviventris) from a 40-year study (1962-2001), we investigated causes and fitness consequences of delayed maturity. most females (86%) died without reproducing. the age of first reproduction of females that ...200312768406
energetics of hibernating yellow-bellied marmots (marmota flaviventris).yellow-bellied marmots (rodentia: sciuridae) typically hibernate for eight months. this study explored energetic costs of hibernation in young and adults at 10 and 6 degrees c. age significantly affected the percent time torpid, total and mass-specific vo(2), use of energy during torpor, and daily mass loss at 6 degrees c. thus young had a higher mass-specific vo(2) during a torpor bout, which was attributed to higher metabolism during deep torpor. total vo(2) during a bout was higher in young a ...200312507613
climate change is affecting altitudinal migrants and hibernating species.calendar date of the beginning of the growing season at high altitude in the colorado rocky mountains is variable but has not changed significantly over the past 25 years. this result differs from growing evidence from low altitudes that climate change is resulting in a longer growing season, earlier migrations, and earlier reproduction in a variety of taxa. at our study site, the beginning of the growing season is controlled by melting of the previous winter's snowpack. despite a trend for warm ...200010677510
sociality, mating system and reproductive skew in marmots: evidence and hypotheses.marmot species exhibit a great diversity of social structure, mating systems and reproductive skew. in particular, among the social species (i.e. all except marmota monax), the yellow-bellied marmot appears quite different from the others. the yellow-bellied marmot is primarily polygynous with an intermediate level of sociality and low reproductive skew among females. in contrast, all other social marmot species are mainly monogamous, highly social and with marked reproductive skew among females ...200011074309
social enhancement of fitness in yellow-bellied marmots.the yellow-bellied marmot (marmota flaviventris) is a social, ground-dwelling squirrel that lives either individually or in kin groups of from two to five adult females. philopatry and daughter recruitment lead to the formation and persistence of matrilines at habitat sites. by using 37 years of demographic data for 12 habitat sites, we could determine long-term trends in the effects of group size on two measures of fitness, survivorship and net reproductive rate, which otherwise are obscured by ...200011035771
the effect of a linseed oil diet on hibernation in yellow-bellied marmots (marmota flaviventris).the essential fatty acids (efas), alpha-linolenic acid (18:3,n-3) and linoleic acid (18:2,n-6) are known to be important for mammalian hibernation. in marmots (marmota flaviventris), reducing both dietary efas alters hibernation patterns by causing an increase in energy expenditure, but hibernation still occurs. in this study, marmots fed a diet high in alpha-linolenic acid, with normal linoleic acid levels, had significantly (p < 0.05) more alpha-18:3 in their wat and plasma unesterified fatty ...200010713281
why do yellow-bellied marmots call? 19989790720
a test of the acoustic adaptation hypothesis in four species of marmots.acoustic signals must be transmitted from a signaller to a receiver during which time they become modified. the acoustic adaptation hypothesis suggests that selection should shape the structure of long-distance signals to maximize transmission through different habitats. a specific prediction of the acoustic adaptation hypothesis is that long-distance signals of animals in their native habitat are expected to change less during transmission than non-native signals within that habitat. this predi ...19989933550
yellow-bellied marmot and golden-mantled ground squirrel responses to heterospecific alarm callswhen two species have predators in common, animals might be able to obtain important information about predation risk from the alarm calls produced by the other species. the behavioural responses of adult yellow-bellied marmots, marmota flaviventris, and golden-mantled ground squirrels, spermophilus lateralis, to conspecific and heterospecific alarm calls were studied to determine whether interspecific call recognition occurs in sympatric species that rarely interact. in a crossed design, marmot ...19989514669
seasonal changes in enzymes of lipogenesis and triacylglycerol synthesis in the golden-mantled ground squirrel (spermophilus lateralis).in order to determine whether critical enzyme activities of glycerolipid synthesis change seasonally in the golden-mantled ground squirrel (spermophilus lateralis), we collected summer and winter samples of liver, brown adipose tissue (bat), and white adipose tissue (wat). compared with fatty acid synthase activity during hibernation, summer activities were 2.5- to 8-fold higher in adipose tissue and liver. diacylglycerol acyltransferase (dgat) activity was 2.6-fold higher in wat during the summ ...19979440219
predicting seasonal diet in the yellow-bellied marmot: success and failure for the linear programming model.seasonal diet selection in the yellow-bellied marmot (marmota flaviventris) was studied at two sites in montana during 1991 and 1992. a linear programming model of optimal diet selection successfully predicted the composition of observed diets (monocot versus dicot) in eight out of ten cases early in the active season (april-june). during this period, adult, yearling and juvenile marmots selected diets consistent with the predicted goal of energy maximisation. however, late in the active season ...199728307479
comparison of the responses to hypoxia, ischaemia and ischaemic preconditioning in wild marmot and laboratory rabbit hearts.marmots (marmota flaviventris) are burrowing mammals that may be subjected to low levels of oxygen and high levels of carbon dioxide in their underground environment. since marmots successfully deal with this physiological challenge, we hypothesized that the isolated perfused marmot heart would be damaged less and recover better from a bout of induced hypoxia or ischaemia than would the heart of a comparison animal, the new zealand laboratory rabbit (oryctolagus cuniculus). isolated marmot and r ...19968867278
natal dispersal and genetic structure in a population of the european wild rabbit (oryctolagus cuniculus).a combination of behavioural observation, dna fingerprinting, and allozyme analysis were used to examine natal dispersal in a wild rabbit population. rabbits lived in territorial, warren based social groups. over a 6-year period, significantly more male than female rabbits moved to a new social group before the start of their first breeding season. this pattern of female philopatry and male dispersal was reflected in the genetic structure of the population. dna fingerprint band-sharing coefficie ...19957735526
resting and field metabolic rates of adult male yellow-bellied marmots, marmota flaviventris.resting metabolic rate (rmr) and field metabolic rate (fmr) of wild-caught males were estimated from oxygen consumption and the doubly-labeled water method, respectively. the average fmr:rmr ratio of 6.9 was much greater than ratios reported for other mammals. total fmr (kj/day) increased and specific rmr (kj/kg/day) decreased with time. neither total rmr nor specific fmr were significantly related to time. the decrease in specific rmr may result from a circannual decrease in maintenance expendi ...19947915660
the effect of a low essential fatty acid diet on hibernation in marmots.we investigated the effect of an essential fatty acid (efa)-deficient diet on hibernation patterns in yellow-bellied marmots (marmota flaviventris). fatty acid (fa) analysis of white adipose tissue (wat) from animals maintained for 2 mo on the efa-deficient diet suggested that little or no efas were present in the gonadal or omental fat depots. hibernation about lengths of the efa-deficient animals were significantly shorter (p < 0.01) than control animals. stated another way, these animals arou ...19938476117
seasonal changes in critical enzymes of lipogenesis and triacylglycerol synthesis in the marmot (marmota flaviventris).fatty acid metabolism and triacylglycerol synthesis are critical processes for the survival of hibernating mammals that undergo a prolonged fasting period. fatty acid synthase, fatty-acid-coa ligase, diacylglycerol acyltransferase, and monoacylglycerol acyltransferase activities were measured in liver and in white and brown adipose tissue, in order to determine whether enzymes of lipogenesis and triacylglycerol synthesis vary seasonally during hibernation in the yellow-bellied marmot (marmota fl ...19938300920
adaptations of myocardial beta-adrenergic receptor complex in hibernating marmots.properties of marmot (marmota flaviventris) myocardial beta-adrenergic receptor complex (beta-ar) were evaluated during hibernation (h), in summer (s) animals, and in animals aroused from hibernation (c). the results obtained for s and c animals were identical, and only the results for c animals are shown. in h-animal myocardial membrane preparations assayed at 37 degrees c, isoproterenol-dependent adenylate cyclase activity (aca) was consistently higher, whereas the synergistic contribution of ...19938285287
ventilatory accommodation of changing oxygen demand in sciurid rodents.ventilation was measured across a range of o2 consumption rates in four sciurid rodents: tamias minimus (47 g), spermophilus lateralis (189 g), s. beecheyi (531 g), and marmota flaviventris juveniles (1054 g) and adults (2989 g). maximum thermogenic oxygen consumption was measured for all but adult m. flaviventris. aerobic scopes (maximum/minimum o2 consumption rates) were 4.6, 3.8, 5.4, and 4.8 in t. minimus, s. lateralis, s. beecheyi, and juvenile m. flaviventris, respectively. aerobic scope w ...19921494030
factors affecting oxygen consumption in wild-caught yellow-bellied marmots (marmota flaviventris).1. all age groups gained mass during the active season, but mass-gain of adult females was delayed during lactation. 2. the relationship of body mass to metabolic rate varied widely; when the relationship was significant, r2 varied from 10.3 to 72.6%. body mass affects vo2 more during lactation than at any other period. 3. mean vo2 of adult males was higher in june than that of adult, non-lactating females. 4. vo2 of reproductive females was significantly higher during lactation than during gest ...19921361896
seasonal changes in hormone-sensitive and lipoprotein lipase mrna concentrations in marmot white adipose tissue.white adipose tissue (wat) and plasma samples were obtained from yellow-bellied marmots (marmota flaviventris) throughout the year. mean plasma triacylglycerol (tg), free fatty acids (ffas), and glycerol were determined. there was a clear increase in ffas and decrease in mean tg and glycerol during the hibernation period when animals were fasting, suggesting increased lipolysis. rna was isolated from wat biopsies at four times in the year: spring, summer, fall, and winter. there were significant ...19921539724
monoaminc and metabolite levels in the cerebrospinal fluid of hibernating and euthermic marmots.cerebrospinal fluid from yellow-bellied marmots, marmota flaviventris, was analysed for monoamine and monoamine metabolite content during euthermia and deep hibernation. dopamine (da) levels were decreased, while da metabolite levels, dihydroxyphenylacetic acid (dopac) and homovanillic acid (hva), were dramatically increased in hibernating marmots. serotonin (5-ht) and 5-hydroxyindoleacetic acid (5hiaa) levels were also greatly enhanced during hibernation while norepinephrine (ne) levels were on ...199210607025
seasonal changes in csf insulin levels in marmots: insulin may not be a satiety signal for fasting in winter.plasma insulin (pi) reportedly crosses the blood-brain barrier in mammals and acts with the central nervous system (cns) to reduce food intake. animals that hibernate (hibernators) eat little or no food from early winter (november) to spring (april). this lack of food intake may be due to elevated pi concentrations acting within the cns. in this study, we determined whether hibernators have altered insulin levels within the cns at different times during the circannual cycle of metabolism and fee ...19912012243
seasonal glucose uptake in marmots (marmota flaviventris): the role of pancreatic hormones.1. glucose uptake was measured throughout the year in marmots (marmota flaviventris) by the hyperglycemic clamp technique. during each 2 hr experiment, the plasma glucose level was maintained at 215 mg/dl while blood samples were collected and analysed for glucose, insulin, glucagon, cortisol and catecholamines. 2. glucose uptake was calculated from the glucose infusion rate, changes in the glucose pool (using a correction factor), and urinary glucose excretion. 3. in autumn, animals peaked in b ...19911685387
factors affecting corticosteroid concentrations in yellow-bellied marmots.1. bound and total corticosteroid concentrations of yellow-bellied marmots (marmota flaviventris) were lowest in may after emergence from hibernation and peaked in august prior to immergence. 2. total corticosteroids were affected by age but not by sex or reproductive status. 3. there was no consistent relationship between measures of population density and concentrations of corticosteroids; when a significant relationship occurred, only 22-34% of the variation was explained. 4. social status an ...19911673377
plasma and white adipose tissue lipid composition in marmots.white adipose tissue biopsies and plasma samples were obtained from hibernating yellow-bellied marmots (marmota flaviventris) maintained in the laboratory. in addition, biopsies and plasma samples were obtained from normothermic animals in the field and laboratory. measurement of plasma free fatty acid (fa) levels indicated that winter laboratory animals exhibited increased lipolysis. additionally, analysis of white adipose tissue triacylglycerol revealed that the fa composition of the storage f ...19902337195
age-class differences in the pattern of hibernation in yellow-bellied marmots, marmota flaviventris.age-related differences in the patterns of body temperature regulation during hibernation were found in yellow-bellied marmots. the timing of all entrances into and arousals from torpor was determined from continuous records of thermocouples mounted in each animal's nest box. older marmots spent more time at high body temperatures following periodic arousals from torpor than did juveniles undergoing their first season of hibernation. in addition, older marmots spontaneously terminated their hibe ...199028313142
techniques for immobilizing and bleeding marmots and woodrats.blood samples were obtained in the field by femoral vein puncture in bushy-tailed woodrats (neotoma cinerea) and yellow-bellied marmots (marmota flaviventris) that had been injected intramuscularly with ketamine hydrochloride. dosages ranged from 50 mg/kg for marmots to 30 to 110 mg/kg for woodrats. sedated animals were handled easily, and a volume of blood sufficient for hematological assays or electrophoresis could be collected.19892668571
effects of anesthetics on cardiovascular responses of the marmot marmota flaviventris.the effects of pentobarbital (30 mg/kg), urethan (2 g/kg), chloralose/urethan (50 mg/kg, 500 mg/kg), and thiobutabarbital (inactin, 100 mg/kg) on the mean arterial pressure (bp) and heart period (hp) of marmota flaviventris were examined. anesthesia significantly decreased bp by 22-27 mm hg and hp by 123-151 msec. in a series of paired studies with eight marmots it was found that pentobarbital increased the bp response to phenylephrine and almost abolished the baroreflex hp responses to phenylep ...19883135153
seasonal variation of cardiovascular function in the marmot, marmota flaviventris.monthly measurements of heart rate, mean arterial pressure, and cardiac output were made on active and hibernating marmots from the time of emergence from hibernation through the next hibernation period. from these measurements cardiac index, stroke index, and total peripheral resistance were calculated on the basis of estimated lean body mass. heart rate was low after emergence (132 +/- 9.5 beats (b)/min), peaked in august (160 +/- 9.3 b/min), and then fell slightly in september and october. du ...19873621978
pancreatic a and b cell stimulation in euthermic and hibernating marmots (marmota flaviventris): effects of glucose and arginine administration.in euthermic and hibernating marmots (marmota flaviventris), the pancreatic a and b cells respond in the appropriate secretory manner to glucose or arginine injection. although reduced, this response, is clearly present in hibernating marmots. when glucose is administered to euthermic or hibernating marmots, plasma insulin concentrations rise and glucagon levels fall. while similar results are obtained in hibernation, the time period of the response is much longer due to the slowing of temperatu ...19863522674
seasonal changes in pancreatic b-cell function in euthermic yellow-bellied marmots.fasting plasma insulin (pi) and glucose (pg) concentrations were measured throughout the body weight cycle of marmots. animals gained weight during summer, and in late fall body weight peaked, after which they ceased feeding. each month euthermic animals were injected intra-arterially with either dextrose (500 mg/kg) or porcine insulin (0.1 u/kg), and blood samples were collected over the subsequent 2 h. during weight gain fasting pi concentration and pancreatic b-cell response to injected dextr ...19853895984
plasma melatonin rhythms in euthermic marmots (marmota flaviventris).plasma melatonin concentrations were measured in marmots (marmota flaviventris) maintained under three short-day (4l:20d; 8l:10d; 10l:14d) and one long-day (14l:10d) photoperiod(s). each animal had a daily rhythm of plasma melatonin with elevated plasma melatonin levels occurring during the dark period of the lighting cycle. there were no significant differences between any peak values during the night. the mean duration of elevated night melatonin concentrations was significantly different betw ...19846704469
seasonal changes of food and water consumption and urine production of the marmot, marmota flaviventris.in early spring, food and water consumption and the excretion and clearances of urine and solutes reached maximal rates. water consumption exceeded food intake and urine production and plasma osmolality was lowest. toward early and late summer, water intake decreased faster than food consumption and urine production. urea excretion and clearances diminished with food consumption, while creatinine clearance decreased only slightly. plasma osmolality increased. the data are consistent with rehydra ...19846143645
hematological values for free-ranging yellow-bellied marmots.1. hemoglobin, packed cell volume, erythrocytes, leucocytes, mcv, mch and mchc were determined for a population of marmota flaviventris over a period of seven years. 2. there was no significant difference in hematology among years, between sexes, or between seasons for adults and yearlings. 3. early season juveniles had significantly lower pcv, hb and erythrocyte counts than did late season juveniles. there were no significant differences in hematological values among adults, yearlings and late ...19836130889
genetic variation in social mammals: the marmot model.the social substructure and the distribution of genetic variation among colonies of yellow-bellied marmots, when analyzed as an evolutionary system, suggests that this substructure enhances the intercolony variance and retards the fixation of genetic variation. this result supports a traditional theory of gradual evolution rather than recent theories suggesting accelerated evolution in social mammals.198017749329
environmental harshness, heat stress, and marmota flaviventris.yellow-bellied marmots (marmota flaviventris) were studied at three sites in central oregon. juveniles substantially reduced their foraging activity when equivalent black-body temperatures exceeded their upper critical temperature. inclusion of heat stress into estimates of environmental harshness drastically reduced the differences in available foraging time between high elevation and low elevation sites.197928310295
spinal cord, hypothalamic, and air temperature: interaction with arousal states in the marmot.yellow-bellied marmots, marmota flaviventris, prepared with u-shaped thermodes in the epidural space of the thoracic vertebral canal, a thermode in the preoptic hypothalamus, and cortical surface and hippocampal electrodes, were used to investigate the interaction of arousal states with temperature regulation. it was found that arousal state of the animal influences the thermoregulatory responses initiated in either the spinal cord or hypothalamus. further, changes in ambient temperature affecte ...1979434182
cns regulation of body temperature in euthermic and hibernating marmots (marmota flaviventris).hypothalamic thermosensitivity of marmots was characterized during euthermia and hibernation. hypothalamic temperature (thy) was manipulated with chronically implanted, water-perfused thermodes while the animal's rate of oxygen consumption was continuously measured. the threshold thy for eliciting an increase in metabolic heat production (mhp) and the proportionality constant (alphamhp) relating rate of mhp to thy were determined. in four euthermic marmots alphamhp averaged -1.1 w-kg-1-degrees c ...1977871176
concentration of urine by the hibernating marmot.studies wer performed with marmots (marmota flaviventris) of both sexes that had chronic arterial, venous, and bladder catheters. urine collection was performed during hibernation and urine osmolalities (611.6 not equal to 166.1 sd) were found to be lower than those of aroused animals (1264 not equal to 472.9 sd), but hypertonic to plasma. peak osmolality of meduallary slices was found to be in the range of osmotic pressures of urine obtained from hibernating or aroused animals. after single inj ...19751130537
parameters of oxygen delivery in the species marmota flaviventris: at sea level and 12,000 feet. 19744153877
renal function of the awake and hibernating marmot marmota flaviventris. 19725027082
influence of hypothermia on renal function of the marmot, marmota flaviventris. 19715137284
radio tracking of dispersing yellow bellied marmots. 19685753220
sounds and communications of the yellow-bellied marmot (marmota flaviventris). 19665918244
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