Modelling Impacts of Climate Change on Host-Parasite Dynamics, with Applications to Muskoxen in the Canadian Arctic
Bibliographic record
Abstract
Human, wildlife, and livestock populations are frequently burdened by macroparasite infections, whose sub-lethal effects have negative implications for health, quality-of-life, and economic potential. Many macroparasites have complex lifecycles with multiple stages that are exposed to ambient environmental temperatures. Given the well-documented thermal sensitivity of macroparasite vital rates, the potential impact of ongoing climate change on host-parasite dynamics has gained much attention. The goal of this thesis is to advance our understanding of the effects of temperature on parasite dynamics and how temperature change in the future might alter host population stability, the severity of infection among hosts, and the geographical distribution of parasites. In Chapter 1, I explore the stability and regulation of a basic host-macroparasite model in which the development and mortality of free-living transmission stages are temperature dependent. I find that warmer temperatures generally lead to larger host populations, greater system resilience to perturbations, and a lower probability of oscillatory dynamics. Beyond certain upper and lower temperature thresholds, however, system stability rapidly deteriorates. In Chapter 2, I use a lifecycle-based model to examine the effects of temperature on parasite infection in the face of changing host population densities. I find that changes in density of the muskox host significantly influences intensity and prevalence of its lungworm under future warming, but that the qualitative nature of this influence is reversed when temperature sensitive stages of the parasite lifecycle are subject to density-dependent regulation. Under these circumstances, predictions of infection severity diverge from those of the well-known parasite fitness metric, R0. In Chapter 3, I use a seasonally forced lifecycle-based model to estimate the fundamental thermal niche of the muskox lungworm from Chapter 2 to understand the role of temperature in the ongoing range expansion of this parasite. Model predictions are consistent with the parasite’s observed distribution in the Canadian Arctic, providing proof-of-concept that temperature-sensitive lifecycle-based models can predict parasite range expansions under a warming climate. This thesis highlights the role temperature plays in the spread of macroparasites and the dynamics and health of infected host populations, while emphasizing how temperature affects predictions of host-parasite dynamics in a warming environment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".