Parasite-induced anorexia in a free-ranging mammalian herbivore: an experimental test using Soay sheep
Bibliographic record
Abstract
Theory suggests that gastrointestinal parasites can influence herbivore population dynamics by increasing host mortality rates. In addition, parasites may have a non-lethal range of both physiological and behavioural effects on their hosts. Two potential behavioural effects are parasite-induced anorexia and the alteration of diet selection patterns — both of which may influence plant communities without necessarily causing herbivore mortality. We report here the results of an experiment carried out in August–September 2001 to examine herbivore response to parasitism using feral Soay sheep ( Ovis aries L., 1758) living on Hirta, St. Kilda (Scotland, UK), as a model system. The aim of the experiment was to determine whether the sheep exhibit significant parasite-induced anorexia and whether diet selectivity was also altered in response to parasitism. The n-alkane technique was used to estimate forage intake rates and diet composition. Overall, intake rate increased with body mass and the mean (±SE) over both sexes was 737 ± 40 g DM / day (range 458–1241 g DM / day). However, we found no effect of parasite burden upon intake rate or selection patterns. The results of a power analysis imply that any reduction in intake rate was less than 30%, which is less than the 30%–60% reduction in intake rate recorded for domestic sheep under moderate parasite burdens. This suggests that Soay sheep are more resilient to parasitism than domestic breeds. Despite evidence to the contrary from simple farm-based studies, the lack of any effect on selection patterns in this case suggests that parasites do not cause significant alterations to the selection patterns of herbivores in complex non-agricultural environments.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".