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Volume 14, Number 1—January 2008
THEME ISSUE
International Polar Year

Perspective

Integrated Approaches and Empirical Models for Investigation of Parasitic Diseases in Northern Wildlife

Eric P. Hoberg*Comments to Author , Lydden Polley†, Emily J. Jenkins†‡, Susan J. Kutz§, Alasdair M. Veitch¶, and Brett T. Elkin#
Author affiliations: *US Department of Agriculture Agricultural Research Service, Beltsville, Maryland, USA; †University of Saskatchewan Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada; ‡Environment Canada, Saskatoon, Saskatchewan, Canada; §University of Calgary Faculty of Veterinary Medicine, Calgary, Alberta, Canada; ¶Government of the Northwest Territories, Norman Wells, Northwest Territories, Canada; #Government of the Northwest Territories, Yellowknife, Northwest Territories, Canada

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Table 2

Responses to climate warming and drivers for emergence of parasites and parasitic diseases in Arctic systems

Numerical responses (changes in abundance of parasites)
1) Temperature-mediated increases in rates of development for free-living stages, or those in intermediate hosts
2) Reduced parasite generation time, e.g., shifts from multiyear to single-year cycles, or from single to multiple within year
3) Environment-mediated changes (increases or decreases) in survival rates for developmental stages
4) Extension of season for parasite growth and transmission resulting from earlier thaw in spring and/or later freeze during fall
5) Amplification of parasite populations over time through accelerated development, increased rates of transmission, survival, and availability
6) Increases in parasite prevalence and abundance
7) Changes in density-dependant linkages for hosts and parasites leading to altered patterns of abundance for host populations
Functional responses (changes in host and geographic ranges)
1) Shifting patterns of geographic range for hosts and parasites including latitudinal and/or altitudinal shifts
2) Alterations in host range for parasites through geographic and host colonization, successful establishment in naive host species or host populations
3) Changing phenology (timing) for habitat use through alteration of migration and migratory corridors, relative changes in spatial and temporal overlap
4) Modification of ecotones and contact zones including northward or southward expansion for hosts and/or parasites if environmental tolerances are not exceeded
5) Local extirpation because conditions exceed developmental tolerances
Microevolutionary responses
1) Local adaptation through selection for optimal patterns of development
2) Directional changes in gene frequencies for parasites
3) Geographic mosaics or ephemeral patterns of local adaptation and emergence
Cumulative/synergistic responses
1) Breakdown in mechanisms for ecologic isolation promoting faunal interchange for hosts and parasites and cascading changes in ecosystems
2) Variable and cumulative synergy affecting the structure of entire parasite–host communities during episodes of climate change

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