BIO-8 Lecture Notes - Lecture 18: Rhizobium, Biotic Component, Mechanical Equilibrium
Document Summary
Ecological interaction in which interactors benefit (+/+) Don"t confuse with symbiosis, the living together of 2 or more organisms of different species. Symbiosis any situation where 2 organisms live together, predators and preys could be symbiotic. Commensalism: one interactor benefits, the other neither benefits nor is harmed. Cattle egret: +; wildebeest gets no positive or negative effect (+/0) Bad model because both populations will grow to infinity. Insert pictures: for graphs, draw vertical line determine if birth or death rate higher (if birth higher r positive and exponential increase but don"t see that in nature, if death higher r negative, density-dependent rates, e. g. death rates. Insert pictures: where 2 curves cross, birth and death rate equal; system is in equilibrium. When move density below equilibrium in 1st picture, population would go extinct. If density, below equilibrium and population goes extinct. In second picture, birth rate has positive density dependence. In first picture, r has positive density dependence.
