Endangered wood bison (Bison bison athabascae) is the largest terrestrial mammal in the American ... more Endangered wood bison (Bison bison athabascae) is the largest terrestrial mammal in the American continent. Animal health is an important issue in their conservation, and Sarcocystis cruzi may be a cause of clinical disease in Bovidae. Hearts of eight wood bison from Alaska, USA were examined for sarcocysts by histology, transmission electron microscopy, pepsin digestion, and molecularly. Sarcocystis bradyzoites were found in pepsin digests of all eight and sarcocysts were found in histologic sections of myocardium of four bison. Sarcocysts were thin-walled and ultrastructurally consistent with S. cruzi. Characterization of DNA obtained from lysis of pepsin liberated bradyzoites by PCR-RFLP and subsequent phylogenetic analyses matched with that previously reported for S. cruzi infecting cattle in the USA. Collectively, data indicate that wood bison is a natural intermediate host for S. cruzi.
Background/Question/Methods Prey populations may be regulated by predation at low densities. In t... more Background/Question/Methods Prey populations may be regulated by predation at low densities. In theory, if a prey population is released from predation, a shift to a high density equilibrium determined by food supply is possible. However, empirical evidence of state changes in ungulate populations from low to high density are scarce despite numerous predator control experiments. We present a case study from interior Alaska as a unique example of a multi-ungulate, multi-predator system that shifted to an alternate “stable” state partly due to a wolf control program and harvest management. Moose and caribou numbers sharply declined during the 1960’s and early 1970’s in game management unit 20A due to a combination of severe weather, overharvest, and predation. Wolf populations and ungulate harvest rates were reduced for a 7-year period (1976-1982), and the response of wolves and ungulates were monitored using repeated aerial surveys and radio-telemetry. We synthesized data on wolf, mo...
Endangered wood bison (Bison bison athabascae) is the largest terrestrial mammal in the American ... more Endangered wood bison (Bison bison athabascae) is the largest terrestrial mammal in the American continent. Animal health is an important issue in their conservation, and Sarcocystis cruzi may be a cause of clinical disease in Bovidae. Hearts of eight wood bison from Alaska, USA were examined for sarcocysts by histology, transmission electron microscopy, pepsin digestion, and molecularly. Sarcocystis bradyzoites were found in pepsin digests of all eight and sarcocysts were found in histologic sections of myocardium of four bison. Sarcocysts were thin-walled and ultrastructurally consistent with S. cruzi. Characterization of DNA obtained from lysis of pepsin liberated bradyzoites by PCR-RFLP and subsequent phylogenetic analyses matched with that previously reported for S. cruzi infecting cattle in the USA. Collectively, data indicate that wood bison is a natural intermediate host for S. cruzi.
Background/Question/Methods Prey populations may be regulated by predation at low densities. In t... more Background/Question/Methods Prey populations may be regulated by predation at low densities. In theory, if a prey population is released from predation, a shift to a high density equilibrium determined by food supply is possible. However, empirical evidence of state changes in ungulate populations from low to high density are scarce despite numerous predator control experiments. We present a case study from interior Alaska as a unique example of a multi-ungulate, multi-predator system that shifted to an alternate “stable” state partly due to a wolf control program and harvest management. Moose and caribou numbers sharply declined during the 1960’s and early 1970’s in game management unit 20A due to a combination of severe weather, overharvest, and predation. Wolf populations and ungulate harvest rates were reduced for a 7-year period (1976-1982), and the response of wolves and ungulates were monitored using repeated aerial surveys and radio-telemetry. We synthesized data on wolf, mo...
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Papers by Tom Seaton