BIL 330 Lecture Notes - Lecture 28: Parasitism, Vertically Transmitted Infection, Natural Selection
Document Summary
Essentially mutualistic in one environment and parasitism in the other. Factors reducing grading into parasitism: cheating occurs when one species receives a benefit but does not provide one in return, natural selection should favor cheating, but should also favor defense against cheating (e. g. , host sanctions) Less beneficial mycorrhizal fungi should receive less carbon if host can sanction. Researchers planted onions in pots that divided roots among soil with mutualistic fungi and soil with non-mutualistic fungi. Plants thwart cheating by sending more photosynthetic products to the beneficial fungi. Vertical transmission mutualist passed from parent to offspring: mutualism more likely because vertical transmission couples reproductive success of host and partner. Contrary to expectation, mutualism (m) was not significantly more context- dependent than competition (c) & predation (p) However, mutualisms more likely to shift effects from positive to negative or reverse. Community: assemblage of species in a given area and their interactions.
