2. Population Dynamics 2: Factors That Regulate Natural Populations

3. Factors: Density independent factors: an abiotic event that affects population growth in the same way, regardless of population density. EG: floods, weather, droughts, forest fires, hurricanes, tornadoes. Density dependent factors: are biotic interactions that vary in affect on population growth depending on the populations involved. If the population is well below the carrying capacity, density dependent factors won’t have a big affect.

4. Density-Dependent Factors: Competition: Intraspecific: members of own species compete for resources Interspecific: two or more populations compete for limited resources. Causes evolutionary change. Producer-Consumer and Predator-Prey Interactions: if there are limited predators, then the prey numbers go up, creating a sinusoidal growth pattern. Defence Mechanisms: Protective colouring: camouflage, mimicry, etc.

5. Symbiotic Relationships Symbiosis: an ecological relationship between two species living in direct contact. Parasitism: when a symbiont lives off and harms the host. EG viruses, some worms, insects, fungus. Ectoparasites live outside the host (mistletoe grows on other trees and feeds off their sap) Endoparasites live inside their host Mutualism: when both species benefit from the relationship EG lichens Commensalism: one partner benefits, the other does not, but is not harmed either.

6. Practice: Page 533 #1, 5, 7, 14, 16,