Divergent parasite faunas in adjacent populations of West Greenland caribou: suggested natural and anthropogenic influences

Authors: STEEL, JILLIAN - University Of Calgary; ORSEL, KARIN - University Of Calgary; CUYLER, CHRISTINE - Greenland Institute Of Natural Resources; Hoberg, Eric; KUTZ, SUSAN - University Of Calgary

Submitted to: International Journal for Parasitology: Parasites and Wildlife
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2013
Publication Date: 12/1/2013
Citation: Steel, J., Orsel, K., Cuyler, C., Hoberg, E.P., Kutz, S. 2013. Divergent parasite faunas in adjacent populations of West Greenland caribou: suggested natural and anthropogenic influences. International Journal for Parasitology: Parasites and Wildlife. 2:197-202.

Interpretive Summary: Knowledge of diversity for hosts and parasites is fundamental in understanding the historical and ongoing processes that have determined patterns of infection and disease in free-ranging and domesticated ungulates. Definitions of faunal diversity (species and their distribution) and the abiotic and biotic factors that have influenced spatial and temporal distributions are essential in predictions about how environmental and other factors will affect the occurrence and impact of parasites. Historical processes, ecological dynamics, geography, climate variation, and patterns of geographic colonization have all influenced extant distributions. Human activities have also played a key role in shaping the distribution of parasites in livestock and wildlife hosts. Here, we explored these associations in a relatively simple system involving parasitic nematodes distributed in Greenland caribou. Gastrointestinal parasite diversity was characterized in two adjacent populations of west Greenland caribou (Rangifer tarandus groenlandicus) through examinations of abomasa and small intestines of adult and subadult females collected during late winter. Differences in the parasites infecting these populations suggest certain parasites were lost when caribou colonized the region within the last several thousand years, and that other parasites were acquired from muskoxen and semi-domesticated Norwegian reindeer (Rangifer tarandus tarandus) much more recently (in the 20th century). Evidently, introductions of non-native ungulates played a major role in structuring parasite diversity in this region. This may, and perhaps should, raise concerns regarding current interest in supplementing declining caribou populations with introduced or translocated animals, even with those from nearby, or closely related, populations. These concerns do not apply solely to nematode parasites in this specific situation but emphasize the importance of understanding pathogen biodiversity in order to appropriately manage wildlife populations, particularly with respect to animal translocations, interfaces with domestic ungulates, and rapid environmental change in a regime of climate warming. Studies, such as this, by better describing regional biodiversity, provide fundamental information required by biologists, wildlife managers and disease specialists in international, federal and academic arenas to make informed decisions regarding the risks of parasite introductions with animal movements.

Technical Abstract: Gastrointestinal parasite diversity was characterized for two adjacent populations of west Greenland caribou (Rangifer tarandus groenlandicus) through examinations of abomasa and small intestines of adult and subadult females collected during late winter. Three trichostrongyline (Trichostrongylina: Nematoda) species were identified with faunal composition differing between the caribou populations. In caribou from Kangerlussuaq-Sisimiut, Marshallagia marshalli and Teladorsagia boreoarcticus were highly prevalent, with M. marshalli being the dominant species present in the abomasa. In contrast, Ostertagia gruehneri was found at 100% prevalence in Akia-Maniitsoq caribou, and was the only species present in that population. We hypothesis that faunal differences between the populations are a consequence of historical parasite loss during caribou colonization of the region approximately 4, 000 to 7, 000 years ago, followed by a more recent spill-over of parasites from muskoxen (Ovibos moschatus wardi) and semi-domesticated Norwegian reindeer (Rangifer tarandus tarandus) introduced to Kangerlussuaq-Sisimiut and Akia-Maniitsoq regions, respectively, in the 20th century. These differences between the populations suggest possible roles of historical biogeography and anthropogenic host movements in influencing the composition of west Greenland caribou parasite faunas.