Publications

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adiaspiromycosis in the franklin's ground squirrel, spermophilus franklini, and pika, ochotona princeps, from alberta, canada.pulmonary adiaspiromycosis due to emmonsia crescens was diagnosed in three of six franklin's ground squirrels (spermophilus franklini) captured in rochester, central alberts, canada in the summer of 1971, and in one of 240 pikas (ochotona princeps) collected in southwestern alberta in 1969. granulomas measuring 0.5 to 1 mm in diameter were found in both lungs. these granulomas contained adiaspores measuring 60 to 400 mum in diameter. the disease was not found in six franklin's ground squirrels c ...1976943581
chromosome banding pattern relationships of hares, rabbits, and pikas (order lagomorpha). a phyletic interpretation.the chromosome banding patterns of the domestic rabbit, oryctolagus cuniculus, the brush rabbit, sylvilagus bachmani, and the snowshoe hare, lepus americanus, are nearly identical except for minor differences in the amount of constitutive heterochromatin present. the major mechanisms of chromosome evolution in leporid lagomorphs are centric fusion and addition of heterochromatin. the g- and c-banding patterns of the pika, ochotona princeps, revealed little easily recognized structural homology w ...1976975938
four new species of eimeria (protozoa: eimeriidae) from the pika ochotona princeps from alberta and o. pallasi from kazakhstan. 19724257769
structure of the oocysts and excystation processes of four eimeria spp. (protozoa: eimeriidae) from the colorado pika, ochotona princeps. 19734687509
physiology of thermoregulation in the pika, ochotona princeps. 19734696076
eimeria banffensis n. sp. (protozoa: eimeriidae) from the pika ochotona princeps from alberta. 19734699874
seasonal data on reproduction and body weights of pias (ochotona princeps). 19734706253
histology and morphology of the female reproductive tract of ochotona princeps. 19734761367
behavioral thermoregulation in the pika ochotona princeps: a field study using radiotelemetry. 19744819475
more information on the coccidian parasites (protozoa: eimeriidae) of the colorado pika, ochotona princeps, with a key to the species. 19744826122
success of reproduction in pikas, ochotona princeps (richardson). 19744854517
the structure of the oocyst and the excystation process of isospora marguardti sp. n. from the colorado pika, ochotona princeps. 19725032223
ochotona princeps (pika) myoglobin: an appraisal of lagomorph phylogeny.myoglobin was purified from skeletal muscle of the pika (ochotona princeps) and its primary structure was determined. this sequence was added to the set of 64 already known vertebrate myoglobin sequences and used to evaluate the phylogenetic position of the pika among other mammals, using a computerized search procedure based on maximum parsimony criteria. the pika is clearly related to the rabbit (oryctolagus cuniculus), with which it is traditionally associated as a member of the order lagomor ...19826952242
lung morphology of cursorial and non-cursorial mammals: lagomorphs as a case study for a pneumatic stabilization hypothesis.gross lung morphology is examined in representative species from four genera within the order lagomorpha (lepus californicus, sylvilagus nuttalli, oryctolagus cuniculus, ochotona princeps), and compared with a representative rodent out-group (spermophilus richardonsii). examination of pulmonary morphology reveals several correlations between the thoracic morphology and locomotor behavior. lepus, the most cursorial species, exhibits a distinct suite of characteristics: 1) tissue of the right cran ...19968916430
lagomorphs (rabbits, pikas and hares) do not use telomere-directed replicative aging in vitro.telomere shortening is used for replicative aging in primates and ungulates but not rodents. we examined telomere biology in rabbits to expand the comparative biology of telomere-directed replicative senescence within mammals. the order lagomorpha consists of two families; leporidae and ochotonidae. we examined telomere biology in species representing three leporid genera (european white rabbit, black-tailed jack rabbit, and swamp rabbit) and the monotypic ochotonid genus (north american pika). ...200515888323
mammal and flea relationships in the great basin desert: from h. j. egoscue's collections.host-parasite association among 58 flea species parasitizing 40 mammal species in the great basin desert of the western united states was investigated. increased flea species richness was correlated with larger geographic ranges and stable locomotion of hosts. hosts from habitats of moderately low productivity (sage and grass) and of peromyscus maniculatus size, 10-33 g, had the highest flea species richness. larger hosts had fewer flea species, but fleas were more prevalent. increased host spec ...200616729681
why museums matter: a tale of pinworms (oxyuroidea: heteroxynematidae) among pikas (ochotona princeps and o. collaris) in the american west.permanent and well-supported museum or natural history collections provide a solid foundation for the process of systematics research through creation of an empirical record which validates our understanding of the biosphere. we explore the role of museums in ongoing studies of the complex helminth fauna characteristic of pikas (ochotona spp.) in the american west. these studies address the taxonomy for pinworms of the labiostomatinae and the problems associated with the absence of adequate type ...200919593896
an undetermined parasite in the lungs of a rock rabbit, ochotona princeps richardson (lagomorpha: ochotonidae). 194720262498
discovery of new ohbayashinema spp. (nematoda: heligmosomoidea) in ochotona princeps and ochotona cansus (lagomorpha: ochotonidae) from western north america and central asia, with considerations of historical biogeography.three new species of ohbayashinema (nematoda, heligmosomoidea) are described from localities in western north america and central asia. two of these species, ohbayashinema nearctica n. sp. and ohbayashinema aspeira n. sp., are parasitic in american pika, ochotona princeps. ohbayashinema nearctica is differentiated from the 5 known species of the genus parasitic in ochotonidae from the old world by very long spicules and an oblique axis of orientation for the ridges composing the synlophe. ohbaya ...201020557204
isolation and characterization of microsatellite loci for the collared pika (ochotona collaris) and their cross-amplification in five other ochotona species.we developed primers for eight polymorphic microsatellite loci isolated from the collared pika, ochotona collaris, and also tested nine loci previously developed for the american pika, o. princeps, for use in o. collaris. forty-six individuals from an o. collaris population in the southern yukon were genotyped using all 17 loci. the average number of alleles per locus was six and the average observed heterozygosity was 0.59. all loci were tested for use in four asian pika species and all but two ...200921564772
interannual variation in timing of parturition and growth of collared pikas (ochotona collaris) in the southwest yukon.the length of the snow-free season has a significant influence on reproduction and growth in northern alpine environments, and these life history traits may provide sensitive indicators of the responses of organisms to climate change. we examined growth rates and timing of parturition of collared pikas (ochotona collaris) from 1995-2002 in the ruby range, yukon territory, canada. growth rates were best described using a gompertz model, in which the asymptotic mass, determined from the average ma ...200421680498
return to beringia: parasites reveal cryptic biogeographic history of north american pikas.traditional concepts of the bering land bridge as a zone of predominantly eastward expansion from eurasia and a staging area for subsequent colonization of lower latitudes in north america led to early inferences regarding biogeographic histories of north american faunas, many of which remain untested. here we apply a host-parasite comparative phylogeographical (hpcp) approach to evaluate one such history, by testing competing biogeographic hypotheses for five lineages of host-specific parasites ...201121676975
evolutionary insights into il17a in lagomorphs.in leporids, il17a had been implicated in the host defense against extracellular pathogens, such as francisella tularensis that infects hares and rabbits and causes the zoonotic disease tularemia. here, we studied il17a from five lagomorphs, european rabbit, pygmy rabbit, brush rabbit, european brown hare, and american pika. we observed that this protein is highly conserved between these species, with a similarity of 97-99% in leporids and ~88% between leporids and american pika. the exon/intron ...201526788019
stress hormone concentration in rocky mountain populations of the american pika (ochotona princeps).the american pika (ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. pikas are declining within a large portion of their range, but previous studies have focused only on local pika extinction as a metric of change. we designed a procedure which can provide an earlier warning signal, based on non-invasive sampling and analysis of physiological stress in living pikas. pikas were sampled at several locations in the rocky mountains for the measur ...201327293611
endogenization of mouse mammary tumor virus (mmtv)-like elements in genomes of pikas (ochotona sp.).despite the finding in european rabbit and other leporid genomes of the first ever described endogenous lentivirus and of a european rabbit exclusive endogenous gammaretrovirus, until now no exogenous retroviruses have been isolated in lagomorpha species. nevertheless, looking for the presence of endogenous retroviruses (ervs) in the species genomes could lead to the discovery of retroviral lineages yet to be found in lagomorpha. different mammalian genomes harbor endogenous viral sequences phyl ...201526151606
genetic characterization of interleukins (il-1α, il-1β, il-2, il-4, il-8, il-10, il-12a, il-12b, il-15 and il-18) with relevant biological roles in lagomorphs.ils, as essential innate immune modulators, are involved in an array of biological processes. in the european rabbit (oryctolagus cuniculus) il-1α, il-1β, il-2, il-4, il-8, il-10, il-12a, il-12b, il-15 and il-18 have been implicated in inflammatory processes and in the immune response against rabbit hemorrhagic disease virus and myxoma virus infections. in this study we characterized these ils in six lagomorpha species (european rabbit, pygmy rabbit, two cottontail rabbit species, european brown ...201526395994
labiostomum coloradensis n. sp. (oxyuridae: nematoda) from the pika, ochotona princeps. 196114463826
congruent mammalian trees from mitochondrial and nuclear genes using bayesian methods.analyses of mitochondrial and nuclear gene sequences have often produced different mammalian tree topologies, undermining confidence in the merit of molecular approaches with respect to "traditional" morphological classification. the recent sequencing of the complete mitochondrial genomes of two additional rodents (spalax judaei and jaculus jaculus) and one lagomorph (ochotona princeps) has prompted us to reinvestigate the issue. using bayesian phylogenetics, we found phylogenetic relationships ...200414660685
rodent-pika parasite spillover in western north america.competition during the cenozoic expansion of the rodentia may have contributed to ecological niche reduction of pikas, which are now increasingly under threat as their habitat degrades under global climate change, while some rodents expand their ranges and overlap with pikas. range overlap carries the possibility of disease spillover. contemporary north american pikas are cold-adapted and relegated primarily to alpine environments where they subsist on relatively low-quality herbaceous diet. yet ...201728419257
sacral variability in tailless species: homo sapiens and ochotona princeps.homo sapiens is variable in number of sacral vertebrae, and this variability can lead to obstetrical complication. this study uses the comparative method to test the hypothesis that sacral variability in h. sapiens is associated with absence of a tail. three species of lagomorphs are studied: ochotona princeps (n = 271), which is tailless, and lepus californicus (n = 212) and sylvilagus audubonii (n = 206), which have tails. results show that o. princeps has (1) higher diversity index for number ...201728406565
limb bone morphology, bone strength, and cursoriality in lagomorphs.the primary aim of this study is to broadly evaluate the relationship between cursoriality (i.e. anatomical and physiological specialization for running) and limb bone morphology in lagomorphs. relative to most previous studies of cursoriality, our focus on a size-restricted, taxonomically narrow group of mammals permits us to evaluate the degree to which 'cursorial specialization' affects locomotor anatomy independently of broader allometric and phylogenetic trends that might obscure such a rel ...201425046350
lagomics-lagomorph genomics consortium: an international collaborative effort for sequencing the genomes of an entire mammalian order.the order lagomorpha comprises about 90 living species, divided in 2 families: the pikas (family ochotonidae), and the rabbits, hares, and jackrabbits (family leporidae). lagomorphs are important economically and scientifically as major human food resources, valued game species, pests of agricultural significance, model laboratory animals, and key elements in food webs. a quarter of the lagomorph species are listed as threatened. they are native to all continents except antarctica, and occur up ...201626921276
novel genomic resources for a climate change sensitive mammal: characterization of the american pika transcriptome.when faced with climate change, species must either shift their home range or adapt in situ in order to maintain optimal physiological balance with their environment. the american pika (ochotona princeps) is a small alpine mammal with limited dispersal capacity and low tolerance for thermal stress. as a result, pikas have become an important system for examining biotic responses to changing climatic conditions. previous research using amplified fragment length polymorphisms (aflps) has revealed ...201323663654
what to eat in a warming world: do increased temperatures necessitate hazardous duty pay?contemporary climate change affects nearly all biomes, causing shifts in animal distributions and resource availability. changes in resource selection may allow individuals to offset climatic stress, thereby providing a mechanism for persistence amidst warming conditions. whereas the role of predation risk in food choice has been studied broadly, the extent to which individuals respond to thermoregulatory risk by changing resource preferences is unclear. we addressed whether individuals compensa ...201829128981
apparent climate-mediated loss and fragmentation of core habitat of the american pika in the northern sierra nevada, california, usa.contemporary climate change has been widely documented as the apparent cause of range contraction at the edge of many species distributions but documentation of climate change as a cause of extirpation and fragmentation of the interior of a species' core habitat has been lacking. here, we report the extirpation of the american pika (ochotona princeps), a temperature-sensitive small mammal, from a 165-km2 area located within its core habitat in california's sierra nevada mountains. while sites su ...201728854268
individual-based analysis of hair corticosterone reveals factors influencing chronic stress in the american pika.glucocorticoids are often measured in wildlife to assess physiological responses to environmental or ecological stress. hair, blood, saliva, or fecal samples are generally used depending on the timescale of the stress response being investigated and species-specific considerations. here, we report the first use of hair samples to measure long-term corticosterone levels in the climate-sensitive american pika (ochotona princeps). we validated an immunoassay-based measurement of corticosterone extr ...201728649323
gut microbial communities of american pikas (ochotona princeps): evidence for phylosymbiosis and adaptations to novel diets.gut microbial communities provide many physiological functions to their hosts, especially in herbivorous animals. we still lack an understanding of how these microbial communities are structured across hosts in nature, especially within a given host species. studies on laboratory mice have demonstrated that host genetics can influence microbial community structure, but that diet can overwhelm these genetic effects. we aimed to test these ideas in a natural system, the american pika (ochotona pri ...201828502120
variation in subsurface thermal characteristics of microrefuges used by range core and peripheral populations of the american pika (ochotona princeps).microrefuges provide microclimates decoupled from inhospitable regional climate regimes that enable range-peripheral populations to persist and are important to cold-adapted species in an era of accelerated climate change. however, identifying and describing the thermal characteristics of microrefuge habitats is challenging, particularly for mobile organisms in cryptic, patchy habitats. we examined variation in subsurface thermal conditions of microrefuge habitats among different rock substrate ...201728261461
predictors of current and longer-term patterns of abundance of american pikas (ochotona princeps) across a leading-edge protected area.american pikas (ochotona princeps) have been heralded as indicators of montane-mammal response to contemporary climate change. pikas no longer occupy the driest and lowest-elevation sites in numerous parts of their geographic range. conversely, pikas have exhibited higher rates of occupancy and persistence in rocky mountain and sierra nevada montane 'mainlands'. research and monitoring efforts on pikas across the western usa have collectively shown the nuance and complexity with which climate wi ...201627902732
replicated landscape genetic and network analyses reveal wide variation in functional connectivity for american pikas.landscape connectivity is essential for maintaining viable populations, particularly for species restricted to fragmented habitats or naturally arrayed in metapopulations and facing rapid climate change. the importance of assessing both structural connectivity (physical distribution of favorable habitat patches) and functional connectivity (how species move among habitat patches) for managing such species is well understood. however, the degree to which functional connectivity for a species vari ...201627755691
mechanistic variables can enhance predictive models of endotherm distributions: the american pika under current, past, and future climates.how climate constrains species' distributions through time and space is an important question in the context of conservation planning for climate change. despite increasing awareness of the need to incorporate mechanism into species distribution models (sdms), mechanistic modeling of endotherm distributions remains limited in this literature. using the american pika (ochotona princeps) as an example, we present a framework whereby mechanism can be incorporated into endotherm sdms. pika distribut ...201727500587
plastic pikas: behavioural flexibility in low-elevation pikas (ochotona princeps).behaviour is an important mechanism for accommodating rapid environmental changes. understanding a species' capacity for behavioural plasticity is therefore a key, but understudied, aspect of developing tractable conservation and management plans under climate-change scenarios. here, we quantified behavioural differences between american pikas (ochotona princeps) living in an atypical, low-elevation habitat versus those living in a more-typical, alpine habitat. with respect to foraging strategy, ...201626851456
when can we measure stress noninvasively? postdeposition effects on a fecal stress metric confound a multiregional assessment.measurement of stress hormone metabolites in fecal samples has become a common method to assess physiological stress in wildlife populations. glucocorticoid metabolite (gcm) measurements can be collected noninvasively, and studies relating this stress metric to anthropogenic disturbance are increasing. however, environmental characteristics (e.g., temperature) can alter measured gcm concentration when fecal samples cannot be collected immediately after defecation. this effect can confound effort ...201626843934
modeling behavioral thermoregulation in a climate change sentinel.when possible, many species will shift in elevation or latitude in response to rising temperatures. however, before such shifts occur, individuals will first tolerate environmental change and then modify their behavior to maintain heat balance. behavioral thermoregulation allows animals a range of climatic tolerances and makes predicting geographic responses under future warming scenarios challenging. because behavioral modification may reduce an individual's fecundity by, for example, limiting ...201526811756
habitat availability and gene flow influence diverging local population trajectories under scenarios of climate change: a place-based approach.ecological niche theory holds that species distributions are shaped by a large and complex suite of interacting factors. species distribution models (sdms) are increasingly used to describe species' niches and predict the effects of future environmental change, including climate change. currently, sdms often fail to capture the complexity of species' niches, resulting in predictions that are generally limited to climate-occupancy interactions. here, we explore the potential impact of climate cha ...201626667878
american pika in a low-elevation lava landscape: expanding the known distribution of a temperature-sensitive species.in 2010, the american pika (ochotona princeps fenisex) was denied federal protection based on limited evidence of persistence in low-elevation environments. studies in nonalpine areas have been limited to relatively few environments, and it is unclear whether patterns observed elsewhere (e.g., bodie, ca) represent other nonalpine habitats. this study was designed to establish pika presence in a new location, determine distribution within the surveyed area, and evaluate influences of elevation, v ...201526380695
climate tolerances and habitat requirements jointly shape the elevational distribution of the american pika (ochotona princeps), with implications for climate change effects.some of the most compelling examples of ecological responses to climate change are elevational range shifts of individual species, which have been observed throughout the world. a growing body of evidence, however, suggests substantial mediation of simple range shifts due to climate change by other limiting factors. understanding limiting factors for a species within different contexts, therefore, is critical for predicting responses to climate change. the american pika (ochotona princeps) is an ...201526244851
from promise to practice: pairing non-invasive sampling with genomics in conservation.conservation genomics has become an increasingly popular term, yet it remains unclear whether the non-invasive sampling that is essential for many conservation-related studies is compatible with the minimum requirements for harnessing next-generation sequencing technologies. here, we evaluated the feasibility of using genotyping-by-sequencing of non-invasively collected hair samples to simultaneously identify and genotype single nucleotide polymorphisms (snps) in a climate-sensitive mammal, the ...201526244114
relating sub-surface ice features to physiological stress in a climate sensitive mammal, the american pika (ochotona princeps).the american pika (ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. pikas are declining within a large portion of their range, and ongoing research suggests loss of sub-surface ice as a mechanism. however, no studies have demonstrated physiological responses of pikas to sub-surface ice features. here we present the first analysis of physiological stress in pikas living in and adjacent to habitats underlain by ice. fresh fecal samples were co ...201525803587
the importance of biologically relevant microclimates in habitat suitability assessments.predicting habitat suitability under climate change is vital to conserving biodiversity. however, current species distribution models rely on coarse scale climate data, whereas fine scale microclimate data may be necessary to assess habitat suitability and generate predictive models. here, we evaluate disparities between temperature data at the coarse scale from weather stations versus fine-scale data measured in microhabitats required for a climate-sensitive mammal, the american pika (ochotona ...201425115894
determinants of pika population density vs. occupancy in the southern rocky mountains.species distributions are responding rapidly to global change. while correlative studies of local extinction have been vital to understanding the ecological impacts of global change, more mechanistic lines of inquiry are needed for enhanced forecasting. the current study assesses whether the predictors of local extinction also explain population density for a species apparently impacted by climate change. we tested a suite of climatic and habitat metrics as predictors of american pika (ochotona ...201424834730
landscape effects on gene flow for a climate-sensitive montane species, the american pika.climate change is arguably the greatest challenge to conservation of our time. most vulnerability assessments rely on past and current species distributions to predict future persistence but ignore species' abilities to disperse through landscapes, which may be particularly important in fragmented habitats and crucial for long-term persistence in changing environments. landscape genetic approaches explore the interactions between landscape features and gene flow and can clarify how organisms mov ...201424383818
radiocarbon dating of american pika fecal pellets provides insights into population extirpations and climate refugia.the american pika (ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. we explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. carbon was extracted from pellets collected at 43 locations in the western great basin, usa, including three known occupied sites and 40 sites of uncertain status at range margins or where previous stud ...201829210235
adaptive divergence along environmental gradients in a climate-change-sensitive mammal.in the face of predicted climate change, a broader understanding of biotic responses to varying environments has become increasingly important within the context of biodiversity conservation. local adaptation is one potential option, yet remarkably few studies have harnessed genomic tools to evaluate the efficacy of this response within natural populations. here, we show evidence of selection driving divergence of a climate-change-sensitive mammal, the american pika (ochotona princeps), distribu ...201324198948
an intriguing shift occurs in the novel protein phosphatase 1 binding partner, tctex1d4: evidence of positive selection in a pika model.t-complex testis expressed protein 1 domain containing 4 (tctex1d4) contains the canonical phosphoprotein phosphatase 1 (ppp1) binding motif, composed by the amino acid sequence rvsf. we identified and validated the binding of tctex1d4 to ppp1 and demonstrated that indeed this protein is a novel ppp1 interacting protein. analyses of twenty-one mammalian species available in public databases and seven lagomorpha sequences obtained in this work showed that the ppp1 binding motif 90rvsf93 is presen ...201324130861
understanding relationships among abundance, extirpation, and climate at ecoregional scales.recent research on mountain-dwelling species has illustrated changes in species distributional patterns in response to climate change. abundance of a species will likely provide an earlier warning indicator of change than will occupancy, yet relationships between abundance and climatic factors have received less attention. we tested whether predictors of counts of american pikas (ochotona princeps) during surveys from the great basin region in 1994-1999 and 2003-2008 differed between the two per ...201323951716
the idiosyncrasies of place: geographic variation in the climate-distribution relationships of the american pika.although climate acts as a fundamental constraint on the distribution of organisms, understanding how this relationship between climate and distribution varies over a species' range is critical for addressing the potential impacts of accelerated climate change on biodiversity. bioclimatic niche models provide compelling evidence that many species will experience range shifts under scenarios of global change, yet these broad, macroecological perspectives lack specificity at local scales, where un ...201323865236
draft genome sequence of the tibetan antelope.the tibetan antelope (pantholops hodgsonii) is endemic to the extremely inhospitable high-altitude environment of the qinghai-tibetan plateau, a region that has a low partial pressure of oxygen and high ultraviolet radiation. here we generate a draft genome of this artiodactyl and use it to detect the potential genetic bases of highland adaptation. compared with other plain-dwelling mammals, the genome of the tibetan antelope shows signals of adaptive evolution and gene-family expansion in genes ...201323673643
genetic evidence for restricted dispersal along continuous altitudinal gradients in a climate change-sensitive mammal: the american pika.when faced with rapidly changing environments, wildlife species are left to adapt, disperse or disappear. consequently, there is value in investigating the connectivity of populations of species inhabiting different environments in order to evaluate dispersal as a potential strategy for persistence in the face of climate change. here, we begin to investigate the processes that shape genetic variation within american pika populations from the northern periphery of their range, the central coast m ...201222720034
spatially explicit models of dynamic histories: examination of the genetic consequences of pleistocene glaciation and recent climate change on the american pika.a central goal of phylogeography is to identify and characterize the processes underlying divergence. one of the biggest impediments currently faced is how to capture the spatiotemporal dynamic under which a species evolved. here, we described an approach that couples species distribution models (sdms), demographic and genetic models in a spatiotemporally explicit manner. analyses of american pika (ochotona princeps) from the sky islands of the central rocky mountains of north america are used t ...201222702844
on the generality of a climate-mediated shift in the distribution of the american pika (ochotona princeps).alpine species are among those most threatened by climatic shifts due to their physiological and geographic constraints. the american pika (ochotona princeps), a small mammal found in mountainous, rocky habitats throughout much of western north america, has experienced recent population extirpations in the great basin linked to climatic drivers. it remains unclear whether these patterns of climate-related loss extend to other portions of the species' range. we investigated the distribution of th ...201121939069
a noninvasive hair sampling technique to obtain high quality dna from elusive small mammals.noninvasive genetic sampling approaches are becoming increasingly important to study wildlife populations. a number of studies have reported using noninvasive sampling techniques to investigate population genetics and demography of wild populations. this approach has proven to be especially useful when dealing with rare or elusive species. while a number of these methods have been developed to sample hair, feces and other biological material from carnivores and medium-sized mammals, they have la ...201121445038
testing alternative models of climate-mediated extirpations.biotic responses to climate change will vary among taxa and across latitudes, elevational gradients, and degrees of insularity. however, due to factors such as phenotypic plasticity, ecotypic variation, and evolved tolerance to thermal stress, it remains poorly understood whether losses should be greatest in populations experiencing the greatest climatic change or living in places where the prevailing climate is closest to the edge of the species' bioclimatic envelope (e.g., at the hottest, drie ...201020349838
when cold is better: climate-driven elevation shifts yield complex patterns of diversification and demography in an alpine specialist (american pika, ochotona princeps).the genetic consequences of climate-driven range fluctuation during the pleistocene have been well studied for temperate species, but cold-adapted (e.g., alpine, arctic) species that may have responded uniquely to past climatic events have received less attention. in particular, we have no a priori expectation for long-term evolutionary consequences of elevation shifts into and out of sky islands by species adapted to alpine habitats. here, we examined the influence of elevation shifts on geneti ...200919663994
inferring divergence times within pikas (ochotona spp.) using mtdna and relaxed molecular dating techniques.although several studies have recently addressed phylogenetic relationships among asian pikas (ochotona spp.), the north american species have been relatively neglected and their monophyly generally unquestioned or assumed. given the high degree of intraspecific diversity in pelage and call structure, the recent identification of previously unrecognized species of pika in asia, and the increasing evidence for multiple trans-beringian dispersals in several small mammal lineages, the monophyly of ...200919501176
long-term dynamics in a metapopulation of the american pika.a 20-yr study of a metapopulation of the american pika revealed a regional decline in occupancy in one part of a large network of habitat patches. we analyze the possible causes of this decline using a spatially realistic metapopulation model, the incidence function model. the pika metapopulation is the best-known mammalian example of a classical metapopulation with significant population turnover, and it satisfies closely the assumptions of the incidence function model, which was parameterized ...199818811362
pattern does not equal process: what does patch occupancy really tell us about metapopulation dynamics?patch occupancy surveys are commonly used to parameterize metapopulation models. if isolation predicts patch occupancy, this is generally attributed to a balance between distance-dependent recolonization and spatially independent extinctions. we investigated whether similar patterns could also be generated by a process of spatially correlated extinctions following a unique colonization event (analogous to nonequilibrium processes in island biogeography). we simulated effects of spatially correla ...200218707420
habitat-specific demography: evidence for source-sink population structure in a mammal, the pika.theory suggests that populations may persist in sink habitats that cannot support replacement-level birth rates. although it is commonly believed that organisms that can actively select habitat should rarely occur in sinks, the frequency of use of sinks in free-ranging species is not well-documented. we found that a population of american pikas ( ochotona princeps, lagomorpha) inhabiting distinct alpine habitats (meadow and snowbed) in wyoming, usa, had habitat-specific demographic rates that pr ...200312647141
pikas (ochotona princeps : lagomorpha) as allogenic engineers in an alpine ecosystem.pikas (ochotona princeps: lagomorpha) build caches of vegetation ("haypiles"), which serve as a food source during winter in alpine and subalpine habitats. haypiles appear to degrade over time and form patches of nutrient-rich soils in barren talus and scree areas. we sampled soils underneath and next to haypiles, and plants growing on and near haypiles in an alpine cirque in northwestern wyoming, usa, to determine the effects of pika food caches on n, c, and c/n ratios in soils and plants. we f ...199828307784
the effect of habitat fragmentation on dispersal patterns, mating behavior, and genetic variation in a pika (ochotona princeps) metapopulation.habitat fragmentation is becoming increasingly common, yet, the effect of habitat spatial structure on population dynamics remains undetermined for most species. populations of a single species found in fragmented and nonfragmented habitat present a rare opportunity to examine the effect of habitat spatial structure on population dynamics. this study investigates the impact of highly fragmented habitat on dispersal patterns, mating behavior, and genetic variation in a pika (ochotona princeps) po ...199728307630
nonrandom mating in pikas ochotona princeps: evidence for inbreeding between individuals of intermediate relatedness.the extent and effect of inbreeding in natural populations remain largely undetermined. pikas ochotona princeps have been considered a likely candidate for close inbreeding in natural populations due to observations of frequent juvenile philopatry (colonization of natal home range or neighbouring home range) and high levels of spatial overlap and social tolerance between neighbouring individuals of the opposite sex. a 4-year investigation of inbreeding in pikas, however, has revealed that disper ...19979301072
effects of acomastylis rossii tannins on a mammalian herbivore, the north american pika, ochotona princeps.i investigated the effects of tannin consumption, using plant tannins naturally occurring in the diet, on a herbivorous mammal, the north american pika, ochotona princeps. the objectives were to determine if a high-tannin diet influenced protein and dry matter apparent digestibility, fiber digestibility and production of detoxification by-products. additionally, i examined the possibility that pikas produce salivary tannin-binding proteins, a potential mechanism for avoiding detrimental effects ...199628307602
disparate determinants of summer and winter diet selection of a generalist herbivore, ochotona princeps.the north american pika, ochotona princeps, is a generalist herbivore that simultaneously selects two distinct diets: one consumed immediately (summer diet), the other harvested, transported, and stored for later consumption (winter diet). i investigated factors influencing diet selection at two sites on the west knoll of niwot ridge, boulder county, colorado during 1991 and 1992. the composition of summer and winter diets differed significantly from each other as well as from the relative abund ...199628307863
case reports of bot fly myiasis in pikas (ochotona princeps).six cases of bot fly (cuterebra spp.) myiasis in pikas (ochotona princeps) are reported from oregon and montana. these are the first known cases of cuterebra parasitism of pikas.1979522225
evolution of litter-size in the pika, ochotona princeps (richardson). 197328563674
adrenal weights in relation to reproductive status in the pika, ochotona princeps (richardson). 19705528608
ovarian histology of ochotona princeps, the rocky mountain pika. 195214924254
a new species of oxyurid nematode from a pika, ochotona princeps figginsi. 194924536546
severe acute respiratory syndrome coronavirus 2 (sars-cov-2) exhibits high predicted binding affinity to ace2 from lagomorphs (rabbits and pikas).severe acute respiratory syndrome coronavirus 2 (sars-cov-2) is responsible for the pandemic covid-19. the virus infects human cells by binding of the virus spike to the cell receptor ace2. the crystal structure of sars-cov-2 spikes in complex with human ace2 has recently been solved, and the main amino acid residues involved in the virus-receptor complex have been detected. to investigate the affinity of ace2 of lagomorphs to the sars-cov-2 spike, ace2 sequences from rabbits and american pikas ...202032825305
ecological consequences of anomalies in atmospheric moisture and snowpack.although increased frequency of extreme-weather events is one of the most secure predictions associated with contemporary climate change, effects of such events on distribution and abundance of climate-sensitive species remain poorly understood. montane ecosystems may be especially sensitive to extreme weather because of complex abiotic and biotic interactions that propagate from climate-driven reductions in snowpack. snowpack not only protects subnivean biotas from extreme cold, but also influe ...201930710338
behavioural plasticity modulates temperature-related constraints on foraging time for a montane mammal.contemporary climate change is altering temperature profiles across the globe. increasing temperatures can reduce the amount of time during which conditions are suitable for animals to engage in essential activities, such as securing food. behavioural plasticity, the ability to alter behaviour in response to the environment, may provide animals with a tool to adjust to changes in the availability of suitable thermal conditions. the extent to which individuals can alter fitness-enhancing behaviou ...201930449046
the role of spatial structure in the collapse of regional metapopulations.many wildlife populations are either naturally, or as a result of human land use, patchily distributed in space. the degree of fragmentation-specifically the remaining patch sizes and habitat configuration-is an important part of population dynamics. demographic stochasticity is also likely to play an important role in patchy habitats that host small local populations. we develop a simulation model to evaluate the significance of demographic stochasticity and the role fragmentation plays in the ...201830347111
identification of a contact zone and hybridization for two subspecies of the american pika (ochotona princeps) within a single protected area.genetic variation is the basis upon which natural selection acts to yield evolutionary change. in a rapidly changing environment, increasing genetic variation should increase evolutionary potential, particularly for small, isolated populations. however, the introduction of new alleles, either through natural or human-mediated processes, may have unpredictable consequences such as outbreeding depression. in this study, we identified a contact zone and limited gene flow between historically separa ...201829995897
adaptive population divergence and directional gene flow across steep elevational gradients in a climate-sensitive mammal.the ecological effects of climate change have been shown in most major taxonomic groups; however, the evolutionary consequences are less well-documented. adaptation to new climatic conditions offers a potential long-term mechanism for species to maintain viability in rapidly changing environments, but mammalian examples remain scarce. the american pika (ochotona princeps) has been impacted by recent climate-associated extirpations and range-wide reductions in population sizes, establishing it as ...201829693300
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