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Parasite/pathogen
Ecological immunity
| Question | Answer |
|---|---|
| Prevalance | Number of infected individuals in a population |
| Abundance | Total parasites of a species within the entire population, including zeros |
| Intensity | Average number of parasites per infected host |
| Richness | Number of parasite species in a population |
| Parasites across a population | - frequently over dispersed or clumped - meaning some individuals are heavily infected while others remain uninfected - the causes for this variation across a population is the principal interest of ecological immunology |
| Mackinnen et al. 2005 | - variation in the incidence of malaria among children in Kenya. - genetics and household explained much of the variation - children living in the 10% of infected houses had twice as many malaria infections as those in the 10% least infected houses |
| Variations due to external factors | Infection is affected by pre-infection defenses – like avoidance Includes: - Sex - Social status - Food availability - Nutritional status - Environmental conditions |
| Variations due to immunity response | Temperature Condition (e.g. stress) Social position Sex Age Geographic region |
| Cost of immunity | Evolution and maintenance: physiological/genetic factors Deployment: physiological/genetic/self-reactivity |
| Evolutionary trade offs and costs | -if traits were cost free in terms of Darwinian fitness then organisms that had a complete and faultless set of life histories would be able to evolve - But fitness comes with cost |
| Costs of maintaining an immune defence | - immune function always on stand by controlled by up/down regulation - comes with a cost - believed that immune function is somehow reduced due to less resources - seasonal variation in immune activity |
| Two main hypotheses | Increased corticosteroids due to low temps and reduced food can overtime decrease immune function (passive) |
| Hypothesis 1 | Hypothesis 1 suggests that winter immune enhancement is the result of active upregulation of immune activity to counteract winter suppression |
| Hypothesis 2 | Hypothesis 2 – immune activity is traded off during specific life phases – e.g. reproduction, both reproduction and immunity carry heavy costs so can only invest in one at a time |
| Tolerance | co-variance of infection intensity vs life fitness (linear or sigmoidal) |
Created by:
rose.coo
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