| variability in marine resources affects arctic fox population dynamics. | terrestrial predators in coastal areas are often subsidized by marine foods. in order to determine the potential impact on terrestrial prey, the numerical response of predators to each food source must be determined. in winter, arctic foxes (alopex lagopus) may forage on the frozen arctic ocean and scavenge carcasses of seals killed by polar bears (ursus maritimus), but the importance of this food source and its effect on the population cycles of arctic foxes and lemmings (their primary prey) ar ... | 2003 | 30893960 |
| pathogenesis of infection with sarcocystis rauschorum (apicomplexa) in experimentally infected varying lemmings (dicrostonyx richardsoni). | this study describes the sequential formation of lesions associated with the endogenous development of sarcocystis rauschorum (apicomplexa: sarcocystidae) in varying lemmings, dicrostonyx richardsoni. lethal doses of sporocysts (greater than 500) were orally administered to lemmings examined 1-6 days postinoculation (dpi) whereas sublethal doses were administered to lemmings examined subsequently. transient necrosis and purulent inflammation, in association with precystic merogony, occurred in t ... | 1987 | 3119871 |
| ultrastructural development of the sarcocyst of sarcocystis rauschorum (apicomplexa: sarcocystidae) in the varying lemming dicrostonyx richardsoni. | the development of the sarcocyst of sarcocystis rauschorum in its intermediate host was studied. lemmings were orally administered sporocysts of s. rauschorum obtained from snowy owls (nyctea scandiaca). beginning at 9 days postinoculation (dpi) and at various intervals to 84 dpi, skeletal muscle tissue taken from the infected lemmings was examined by electron microscopy. at 9 dpi the sarcocysts contained few metrocytes and the cyst wall was flat. the metrocytes underwent endodyogeny, and within ... | 1989 | 2498495 |
| ancient dna supports southern survival of richardson's collared lemming (dicrostonyx richardsoni) during the last glacial maximum. | collared lemmings (genus dicrostonyx) are circumpolar arctic arvicoline rodents associated with tundra. however, during the last glacial maximum (lgm), dicrostonyx lived along the southern ice margin of the laurentide ice sheet in communities comprising both temperate and boreal species. to better understand these communities and the fate of these southern individuals, we compare mitochondrial cytochrome b sequence data from three lgm-age dicrostonyx fossils from south of the laurentide ice shee ... | 2013 | 23495672 |
| effects of the protozoan parasite sarcocystis rauschorum on open-field behaviour of its intermediate vertebrate host, dicrostonyx richardsoni. | behaviour and activity levels were measured in varying lemmings experimentally infected with the heteroxenous parasite, sarcocystis rauschorum to test the hypothesis that the parasite alters behaviour of this intermediate host and thereby increases probability of transmission to the definitive host, the snowy owl (nyctea scandiaca). measures of short-term activity levels on a running wheel indicated no effect of the parasite, either directly, or indirectly as a result of illness. we observed beh ... | 1987 | 3108477 |