The phylogeographic predictions of the strict cospeciation and episodic host-switching models were tested using the North American pika/parasite assemblage, with a primary focus on the American pika, Ochotona
princeps (Richardson, 1828), and a suite of its endoparasitic cestodes and nematodes.
Skeletal and muscular differences in the hind limbs of Lepus, Sylvilagus and Ochotona
Royle's pika Ochotona
roylei and other small mammals (mainly voles) were frequently detected in the scats, as were bird feathers and occasionally also egg shells.
Sperm-specific lactate dehydrogenase, Anaerobic glycolysis, Skeletal muscle, Ochotona
curzoniae Plateau pika, Ldh-c, N-isopropyl oxamate, LDH activity.
The mammal fauna of the area includes the collared pika Ochotona
rufescens the migratory hamster Cricetulus migratorius
Also collared pikas Ochotona
collaris forage farther from the talus when pregnant (Holmes 1991), and bighorn sheep Ovis canadensis trade safety for access to more nutritious food during the last month of pregnancy (Berger 1991).
When yak, sheep, and horse grazing lowers the height of vegetation, Ochotona
curzoniae, a very susceptible host for E.
Forage selection by collared pikas, Ochotona
collaris, under varying degrees of predation risk.
As Mead and Mead (1989) pointed out, however, Pleistocene Dicrostonyx may only indicate boreal conditions and not necessarily tundra, just as Pleistocene Ochotona
may indicate boreal conditions and not necessarily talus slopes (Mead 1987; although see also Hafner 1993).