Publications

experimental infection of richardson's ground squirrels (spermophilus richardsonii) with attenuated and virulent strains of brucella abortus.	a previous investigation of the safety of brucella abortus strain rb51 (srb51) in various nontarget species suggested that richardson's ground squirrels (spermophilus richardsonii) may develop persistent infections when orally inoculated with the vaccine. in the present study, srb51, b. abortus strain 19 (s19), and virulent b. abortus strain 9941 (s9941) were administered orally to richardson's ground squirrels to further characterize b. abortus infection in this species. six groups of nongravid ...	2009	19204348
regulation of liver glutamate dehydrogenase by reversible phosphorylation in a hibernating mammal.	glutamate dehydrogenase (gdh) is a key enzyme that links amino acid and carbohydrate metabolism in cells. regulation is likely most important when organisms are confronted with extreme stresses such as the low environmental temperatures and lack of food associated with winter. many small mammals, such as richardson's ground squirrels, spermophilus richardsonii, cope with these conditions by hibernating. animals enter long periods of profound torpor where metabolic rate is greatly suppressed, bod ...	2010	20674762
relative abundance of american badger (taxidea taxus) and red fox (vulpes vulpes) in landscapes with high and low rodenticide poisoning levels.	over the past decade, extensive poisoning campaigns have been conducted in southern saskatchewan to control richardson's ground squirrel spermophilus richardsonii (sabine, 1822) populations. such campaigns might impact on predator abundance by decreasing prey levels, and also through secondary poisoning. using spotlighting, we investigated the relative abundance of american badgers taxidea taxus (schreber, 1777) and red fox vulpes vulpes (linnaeus, 1758) in 2 study areas with road access and cro ...	2012	22405447
suppression of mapkapk2 during mammalian hibernation.	metabolic signaling coordinates the transition by hibernating mammals from euthermia into profound torpor. organ-specific responses by activated p38 mitogen activated protein kinase (mapk) are known to contribute to this transition. therefore, we hypothesized that the mapk-activated protein kinase-2 (mapkapk2), a downstream target of p38 mapk, would also be active in establishing the torpid state. kinetic parameters of mapkapk2 from skeletal muscle of richardson's ground squirrels, spermophilus ...	2012	22771537
the benefits of baseline glucocorticoid measurements: maximal cortisol production under baseline conditions revealed in male richardon's ground squirrels (urocitellus richardsonii).	wildlife capture methods can make it impractical or impossible to obtain baseline plasma glucocorticoid (gc) levels, and the time of capture of individual animals is often unknown so there may be little uniformity in the duration of capture-stress prior to blood collection. although baseline samples are preferred, if seasonal changes in capture-stress gc levels closely reflect seasonal baseline changes, then capture-stress gc levels can be used to infer at least the direction of change in baseli ...	2012	22814333
seasonal and sex differences in the hippocampus of a wild rodent.	studies across and within species suggest that hippocampus size is sexually dimorphic in polygamous species, but not in monogamous species. although hippocampal volume varies with sex, season and mating system, few studies have simultaneously tested for sex and seasonal differences. here, we test for sex and seasonal differences in the hippocampal volume of wild richardson's ground squirrels (urocitellus richardsonii), a polygamous species that lives in matrilineal, kin-based social groups and h ...	2013	22974551
effects of hibernation on regulation of mammalian protein phosphatase type-2-a.	hibernation is used by many small mammals for winter survival. animals undergo cycles of deep torpor characterized by strong reductions in metabolic rate, body temperature, and all physiological activities. one prominent biochemical mechanism involved in regulating coordinated transitions to and from the hypometabolic state is reversible protein phosphorylation, a dynamic covalent modification maintained by the actions of protein kinases and protein phosphatases. the present study characterizes ...	2013	23499617
mutation scanning-based identification of larval and nymphal ticks (acari: ixodidae) from richardson's ground squirrels (spermophilus richardsonii).	the objective of this study was to identify the tick species parasitizing richardson's ground squirrels (spermophilus richardsonii) in southern saskatchewan (canada). morphological examination of the adult ticks revealed the presence of three tick species, ixodes sculptus, ixodes kingi and dermacentor andersoni. however, given the difficulties in identifying some of the larval and nymphal (immature) ticks using this approach, pcr-based single-strand conformation polymorphism (sscp) and dna seque ...	2014	24075866
litter sex ratios in richardson's ground squirrels: long-term data support random sex allocation and homeostasis.	when costs of producing male versus female offspring differ, parents may vary allocation of resources between sons and daughters. we tested leading sex-allocation theories using an information-theoretic approach and bayesian hierarchical models to analyse litter sex ratios (proportion males) at weaning for 1,049 litters over 24 years from a population of richardson's ground squirrels (urocitellus richardsonii), a polygynandrous, annually reproducing mammal in which litter size averages from six ...	2014	24385085
the effects of season and sex on dentate gyrus size and neurogenesis in a wild rodent, richardson's ground squirrel (urocitellus richardsonii).	sex and reproductive status affect hippocampal neurogenesis and dentate gyrus (dg) size in rodents. relatively few studies, however, address these two effects simultaneously and even fewer studies address this issue in wild populations. here, we examined seasonal and sex differences in neurogenesis and dg size in a wild, polygynous and social rodent, richardson's ground squirrel (uriocitellus richardsonii). based on the behavioral ecology of this species, we predicted that both neurogenesis and ...	2014	24813432
maternal gestational cortisol and testosterone are associated with trade-offs in offspring sex and number in a free-living rodent (urocitellus richardsonii).	the adaptive manipulation of offspring sex and number has been of considerable interest to ecologists and evolutionary biologists. the physiological mechanisms that translate maternal condition and environmental cues into adaptive responses in offspring sex and number, however, remain obscure. in mammals, research into the mechanisms responsible for adaptive sex allocation has focused on two major endocrine axes: the hypothalamic pituitary adrenal (hpa) axis and glucocorticoids, and the hypothal ...	2014	25353347
the size of non-hippocampal brain regions varies by season and sex in richardson's ground squirrel.	sex- and season-specific modulation of hippocampal size and function is observed across multiple species, including rodents. other non-hippocampal-dependent behaviors exhibit season and sex differences, and whether the associated brain regions exhibit similar variation with sex and season remains to be fully characterized. as such, we examined the brains of wild-caught richardson's ground squirrels (rgs; urocitellus richardsonii) for seasonal (breeding, non-breeding) and sex differences in the v ...	2015	25595988
measurement of free glucocorticoids: quantifying corticosteroid-binding globulin binding affinity and its variation within and among mammalian species.	plasma glucocorticoids (gcs) are commonly used as measures of stress in wildlife. a great deal of evidence indicates that only free gc (gc not bound by the specific binding protein, corticosteroid-binding globulin, cbg) leaves the circulation and exerts biological effects on gc-sensitive tissues. free hormone concentrations are difficult to measure directly, so researchers estimate free gc using two measures: the binding affinity and the binding capacity in plasma. we provide an inexpensive satu ...	2015	27293705
purification and properties of glycerol-3-phosphate dehydrogenase from the liver of the hibernating ground squirrel, urocitellus richardsonii.	cytosolic glycerol-3-phosphate dehydrogenase (g3pdh, ec 1.1.1.8) is an important branch point enzyme connecting lipid metabolism and carbohydrate metabolism. we investigated the dynamic nature of g3pdh by purifying the enzyme from the liver of richardson's ground squirrel (urocitellus richardsonii), a hibernating species, and analyzing its structural and functional changes during hibernation. kinetic parameters of purified g3pdh from ground squirrel liver were characterized at 37, 22 and 5°c and ...	2016	27521690
one plus one: binary alarm calls retain individual signature for longer periods than single-note alarms in the european ground squirrel (spermophilus citellus).	ground squirrels emit species-specific alarm calls that, among other characteristics, differ by the number of elements. unlike some species that produce single-element calls, e.g., the speckled ground squirrel (spermophilus suslicus), individual european ground squirrels (s. citellus) frequently emit binary-element calls in addition to single-element calls. we tested the hypothesis that the time stability of individuality encoded in alarm calls might be better retained by complicating their acou ...	2017	28219730
reproductive effort during gestation and lactation by richardson's ground squirrels.	reproductive effort by yearling and older female richardson's ground squirrels was studied over a 4-year period in southern alberta by obtaining serial weight records from marked individuals to compare the mother's mass at critical points in the annual cycle (emergence from hibernation, estrus, parturition, and litter emergence) with her litter's mass at birth and weaning. yearlings weighed only 80% of older adults at emergence from hibernation, but they mated at the same time as older females, ...	1989	28311904
sexual differences in over-winter torpor patterns of richardson's ground squirrels in natural hibernacula.	over-winter torpor patterns of richardson's ground squirrels hibernating in southern alberta were monitored with temperature-sensitive radiocollars to determine if these patterns differed between males and females in a manner related to the greater costs of mating effort by males than females. the hibernation season (from immergence to emergence) was composed of three periods: post-immergence euthermy, heterothermy, and pre-emergence euthermy. the hibernation season was shorter for juveniles tha ...	1992	28313089
evolutionary relationships among colonies of columbian ground squirrels as shown by mitochondrial dna.	mitochondrial dna (mtdna) from 71 columbian ground squirrels (spermophilus columbianus) collected in 12 locations in western canada were assayed for restriction-site variation with 10 endonucleases. five of these endonucleases revealed variant patterns, and the composite genotypes were used to develop a linear transformation series among the mtdna genotypes. two of the four clones had a wide distribution, while the remaining two clones were geographically restricted. the mtdna of columbian groun ...	1987	28564362
purification and characterization of skeletal muscle pyruvate kinase from the hibernating ground squirrel, urocitellus richardsonii: potential regulation by posttranslational modification during torpor.	ground squirrel torpor during winter hibernation is characterized by numerous physiological and biochemical changes, including alterations to fuel metabolism. during torpor, many tissues switch from carbohydrate to lipid catabolism, often by regulating key enzymes within glycolytic and lipolytic pathways. this study investigates the potential regulation of pyruvate kinase (pk), a key member of the glycolytic pathway, within the skeletal muscle of hibernating ground squirrels. pk was purified fro ...	2017	28918505
effects of arginine vasopressin on richardson's ground squirrel social and vocal behavior.	in nearly every vertebrate species examined thus far arginine vasopressin (avp) and its homologues modulate behavior; thus, providing rich systems for comparative research. in rodents, avp is best known for its modulation of social behavior; however, to date, research on avps effects on behavior have been limited to laboratory models and a few experiments using large outdoor enclosures. to extend our understanding of avps role in modulating social behavior and communication in an ecologically re ...	2018	29553774
a case of rapid recurrence of apocrine ductal carcinoma originating from the oral scent gland of a richardson's ground squirrel (urocitellus richardsonii).	a 3-year-old female richardson's ground squirrel developed a subcutaneous mass at the left oral angle. seven days after removal of the mass, the mass recurred and metastasized to the cervical lymph node. histologically, the primary mass was subdivided by fibrous trabeculae into various-sized neoplastic cell lobules showing a solid growth pattern with frequent mitoses and sometimes forming intracytoplasmic lumina. large to medium-sized lobules formed a central cyst plugged by comedo necrosis. neo ...	2018	30093788
temperature and serine phosphorylation regulate glycerol-3-phosphate dehydrogenase in skeletal muscle of hibernating richardson's ground squirrels.	glycerol-3-phosphate dehydrogenase (g3pdh) bridges carbohydrate and lipid metabolism by interconverting glycerol-3-phosphate (g3p) and dihydroxyacetone phosphate (dhap). this reversible reaction converts g3p derived from triglyceride hydrolysis to dhap that can then enter glycolysis or gluconeogenesis and, in the reverse reaction, makes g3p for use in triglyceride biosynthesis. small hibernating mammals rely almost exclusively on triglyceride reserves as their fuel for energy production during t ...	2019	30253108
like mother, like daughter: heritability of female richardson's ground squirrel urocitellus richardsonii cortisol stress responses.	activation of the hypothalamic-pituitary-adrenal (hpa) axis liberates glucocorticoids, which provides an acute indication of an individual's response to stressors. the heritability of the stress response in wild mammals, however, remains poorly documented. we quantified the cortisol stress response of female richardson's ground squirrels (rgss) to handling and physical restraint, testing for: (1) the effects of individual age, time of day, and sample latency; (2) repeatability within individuals ...	2018	30402055
central distribution of oxytocin and vasopressin 1a receptors in juvenile richardson's ground squirrels.	oxytocin and vasopressin are well-conserved peptides important to the regulation of numerous aspects of social behavior, including sociality. research exploring the distribution of the receptors for oxytocin (oxtr) and for vasopressin (avpr1a) in mammals has revealed associations between receptor distribution, sociality, and species' mating systems. given that sociality and gregariousness can be tightly linked to reproduction, these nonapeptides unsurprisingly support affiliative behaviors that ...	2019	30802986
gone girl: richardson's ground squirrel offspring and neighbours are resilient to female removal.	within matrilineal societies, the presence of mothers and female kin can greatly enhance survival and reproductive success owing to kin-biased alarm calling, cooperation in territory defence, protection from infanticidal conspecifics, joint care of young and enhanced access to resources. the removal of mothers by predators or disease is expected to increase the stress experienced by offspring via activation of their hypothalamic-pituitary-adrenal axis, increasing circulating glucocorticoids and ...	2019	31598313
identification of bacteria in the rocky mountain wood tick, dermacentor andersoni, using single-strand conformation polymorphism (sscp) and dna sequencing.	pcr-based single-strand conformation polymorphism (sscp) analyses combined with dna sequencing of the prokaryotic 16s ribosomal (r) rna gene encompassing the hypervariable v4 region was used to determine the bacterial composition of rocky mountain wood ticks (dermacentor andersoni) attached to richardson's ground squirrels (urocitellus richardsonii) and questing on vegetation in southern saskatchewan, canada. the bacteria present in questing adult ticks from saskatchewan landing provincial park ...	2020	31953633
call-specific patterns of neural activation in auditory processing of richardson's ground squirrel alarm calls.	richardson's ground squirrels use alarm calls to warn conspecifics about potential predatory threats. chirp calls typically indicate high levels of threat from airborne predators, while whistle calls are associated with lower levels of threat from terrestrial predators. these types of calls primarily elicit escape behaviors and increased vigilance in receivers, respectively. while much is known about the neural mechanisms involved in the production of vocalizations, less is known about the mecha ...	2020	32307882
effects of scent lure on camera trap detections vary across mammalian predator and prey species.	camera traps are a unique survey tool used to monitor a wide variety of mammal species. camera trap (ct) data can be used to estimate animal distribution, density, and behaviour. attractants, such as scent lures, are often used in an effort to increase ct detections; however, the degree which the effects of attractants vary across species is not well understood. we investigated the effects of scent lure on mammal detections by comparing detection rates between 404 lured and 440 unlured ct statio ...	2020	32396558
burrowing richardson's ground squirrels affect plant seedling assemblages via environmental but not seed bank changes.	in grassland ecosystems, burrowing mammals create disturbances, providing habitat for animal species and increasing plant community diversity. we investigated whether seedling assemblages on richardson's ground squirrel urocitellus richardsonii mounds result from seed rearrangement or environmental changes that favor germination of certain species over others. to test whether ground squirrels rearrange the seed bank by burrowing, we compared seed compositions among mounds, burrows, and undisturb ...	2020	32440282
regulation of the α-ketoglutarate dehydrogenasecomplex during hibernation in a small mammal, the richardson's ground squirrel (urocitellus richardsonii).	the citric acid cycle (cac) is a central metabolic pathway that links carbohydrate, lipid, and amino acid metabolism in the mitochondria and, hence, is a crucial target for metabolic regulation. the α-ketoglutarate dehydrogenase complex (kgdc) is the rate-limiting step of the cac, the three enzymes of the complex catalyzing the transformation of α-ketoglutarate to succinyl-coa with the release of co2 and reduction of nad to nadh. during hibernation, the metabolic rate of small mammals is suppres ...	2020	32445798
characterizing the regulation of pyruvate kinase in response to hibernation in ground squirrel liver (urocitellus richardsonii).	the richardson's ground squirrel (urocitellus richardsonii) undergoes numerous changes to its core physiological and metabolic processes over the months it spends hibernating during the winter. winter torpor is characterized by an overall reduction in metabolic rate, a lowering of core body temperature, and a switch to preferential consumption of lipids instead of carbohydrates. the alterations in central metabolic pathways are often accomplished by the regulation of key enzymes within the glyco ...	2020	32592750
pathology of ground squirrels in a research colony.	this paper presents a retrospective review of the postmortem findings in a colony of wild-caught ground squirrels used inmedical research. the species included in this study were richardson's ground squirrel urocitellus richardsonii, columbianground squirrel urocitellus columbianus and golden-mantled ground squirrel callospermophilus lateralis. the pathologicfindings in 160 ground squirrels from this colony demonstrated a wide variety of conditions, with chronic nephritis andhepatic adenomas bei ...	2020	33036668
richardson's ground squirrel (urocitellus richardsonii) alarm call receivers experience an auditory continuity illusion.	auditory continuity illusions are perceptual illusions in which receivers perceive an auditory signal as continuous when part of the signal has been removed or obfuscated by a louder noise. richardson's ground squirrels (urocitellus richardsonii) communicate alarm acoustically in noisy natural settings. thus, we tested whether they experience an auditory continuity illusion by presenting free-living squirrels with repeated whistle alarm calls within which every second syllable remained unmanipul ...	2020	33090849