| coccidia (protozoa, eimeriidae) of the pikas ochotona collaris, o. princeps, and o. hyperborea yesoensis. | | 1974 | 4421116 |
| pika and vole mitochondrial genomes increase support for both rodent monophyly and glires. | complete mitochondrial genomes are reported for a pika (ochotona collaris) and a vole (volemys kikuchii) then analysed together with 35 other mitochondrial genomes from mammals. with standard phylogenetic methods the pika joins with the other lagomorph (rabbit) and the vole with the other murid rodents (rat and mouse). in addition, with hedgehog excluded, the seven rodent genomes consistently form a homogeneous group in the unrooted placental tree. except for uncertainty of the position of tree ... | 2002 | 12234673 |
| demographic analysis of a declining pika ochotona collaris population: linking survival to broad-scale climate patterns via spring snowmelt patterns. | 1. demographic analysis is essential in order to determine which factors, such as survival, fertility and other life-history characteristics, have the greatest influence on a population's rate of growth (lambda). 2. we used life-table response experiments (ltres) to assess the relative importance of survival and fertility rates for an alpine lagomorph, the collared pika ochotona collaris, using 12 years (1995-2006) of census data. the ltre analysis was repeated for each of three subpopulations w ... | 2007 | 17714268 |
| species of coccidia (apicomplexa: eimeriidae) infecting pikas from alaska, u.s.a. and northeastern siberia, russia. | eighty-eight fecal samples from 2 species of pika, ochotona collaris and ochotona hyperborea, collected in alaska (n = 53) and russia (n = 35), respectively, were examined for the presence of coccidia (apicomplexa: eimeriidae). five oocyst morphotypes were observed. in o. collaris, we found eitmeria calentinei, eimeria cryptobarretti, and eimeria klondikensis, whereas in o. hyperborea, we found eimeria banffensis, e. calentinei, e. cryptobarretti, e. klondikensis, and isospora marquardti. this s ... | 2007 | 18163366 |
| influence of food hoarding behavior on the over-winter survival of pikas in strongly seasonal environments. | food hoarding is a behavioral adaptation of some herbivores to manage food availability through time and space. in strongly seasonal environments, where summer growing seasons are short relative to winter, an earlier start to hoarding should increase the amount of vegetation stored for winter and improve subsequent survival. we examined hoarding behavior ('haying') and its impact on survival for a small alpine lagomorph, the collared pika (ochotona collaris) in yukon, canada. we used a combinati ... | 2009 | 18987896 |
| 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 ... | 2009 | 19593896 |
| 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 ... | 2009 | 21564772 |
| 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 ... | 2004 | 21680498 |
| 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 ... | 2011 | 21676975 |
| colonization from divergent ancestors: glaciation signatures on contemporary patterns of genomic variation in collared pikas (ochotona collaris). | identifying the genetic structure of a species and the factors that drive it is an important first step in modern population management, in part because populations evolving from separate ancestral sources may possess potentially different characteristics. this is especially true for climate-sensitive species such as pikas, where the delimitation of distinct genetic units and the characterization of population responses to contemporary and historical environmental pressures are of particular int ... | 2015 | 26096099 |
| after the frass: foraging pikas select patches previously grazed by caterpillars. | interactions among herbivores can shape the structure of their communities and drive their dynamics. however, detecting herbivore interactions can be challenging when they are deferred in space or time. moreover, interactions among distantly related groups of herbivores, such as vertebrates and invertebrates, are poorly understood. we investigated the effect of invertebrate herbivory on the subsequent foraging choices of a small alpine-dwelling vertebrate, the collared pika (ochotona collaris). ... | 2013 | 23616644 |