Cross-continental comparison of parasite communities in a wide-ranging carnivore suggests associations with prey diversity and host density.

Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host-parasite associations is important, particularly for wide-ranging species for which host range shifts and climate change could alter host-parasite interactions and their effects on ecosystem function.Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf-parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large-scale processes that shape host-parasite interactions across populations, with the wolf as a model organism.By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density-prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator-prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.

Canid hybridization: contemporary evolution in human-modified landscapes.

Contemporary evolution through human-induced hybridization occurs throughout the taxonomic range. Formerly allopatric species appear especially susceptible to hybridization. Consequently, hybridization is expected to be more common in regions with recent sympatry owing to human activity than in areas of historical range overlap. Coyotes (Canis latrans) and gray wolves (C. lupus) are historically sympatric in western North America. Following European settlement gray wolf range contracted, whereas coyote range expanded to include eastern North America. Furthermore, wolves with New World (NW) mitochondrial DNA (mtDNA) haplotypes now extend from Manitoba to Québec in Canada and hybridize with gray wolves and coyotes. Using mtDNA and 12 microsatellite markers, we evaluated levels of wolf-coyote hybridization in regions where coyotes were present (the Canadian Prairies, n = 109 samples) and absent historically (Québec, n = 154). Wolves with NW mtDNA extended from central Saskatchewan (51°N, 69°W) to northeastern Québec (54°N, 108°W). On the Prairies, 6.3% of coyotes and 9.2% of wolves had genetic profiles suggesting wolf-coyote hybridization. In contrast, 12.6% of coyotes and 37.4% of wolves in Québec had profiles indicating hybrid origin. Wolves with NW and Old World (C. lupus) mtDNA appear to form integrated populations in both regions. Our results suggest that hybridization is more frequent in historically allopatric populations. Range shifts, now expected across taxa following climate change and other human influence on the environment, might therefore promote contemporary evolution by hybridization.

Diseases and parasites in wolves of the Riding Mountain National Park region, Manitoba, Canada.

We examined wolf (Canis lupus) blood and fecal samples from the Riding Mountain National Park (RMNP) region of Manitoba, Canada. In 601 fecal samples collected during two study periods in RMNP and the Duck Mountain Provincial Park and Forest (DMPPF) we found gastrointestinal helminth eggs from Alaria sp. (15.5%), Capillaria sp. (1.0%), taeniid tapeworms (30.8%), Toxascaris sp. (1.7%), Toxocara sp. (0.2%), Trichuris sp. (2.2%), and Moniezia sp. (0.5%). In addition, we found Demodex sp. (0.2%) and the protozoal cysts/oocysts of Sarcocystis sp. (37.3%), Cryptosporidium sp. (1.2%), coccidia (Isospora sp. or Eimeria sp.) (1.7%), and Giardia sp. (29.5%). No fecal shedding of canine parvovirus (CPV, n=387) was detected. All 18 blood samples collected in RMNP showed CPV exposure and eight of 18 blood samples indicated canine distemper virus (CDV) exposure. One wolf died from CDV. Our results are consistent with previous findings on pathogens affecting wolves and with high Giardia sp. prevalence in wolves inhabiting agricultural regions.