BIOL 3600 Chapter Notes - Chapter VIII: Inclusive Fitness, Vertically Transmitted Infection, Kin Selection
20 Nov 2018
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Document Summary
Virulence ~ parasite induced morbidity and mortality of host; more precise definitions, such as parasite induced host death rate or host fecundity reduction, are used for specific situations. The phase model of virulence: virulence is result of new interaction between hose and parasite, virulence changes as parasite adapts to new host. Phase 1: accidental infections: transmission chains are short and epidemics do not persist parasites have little opportunity to adapt to new hosts, avirulent accidental infections may outnumber virulent infections. Phase 2: evolution of virulence following successful invasion: transmission success determines whether it will persist and spread. Initial spread is typically epidemic and level of virulence of nonadapted parasite is unlikely to be close to optimum. Phase 3: evolution of optimal virulence: expected to evolve optimal level of virulence characterized by tradeoffs. The trade-off model: trade off model analyzes evolution of virulence; stresses importance of tradeoffs between parasite induced host death and other parasite fitness components.
