Ecology Ecology: Interaction of living things with each other and their environment. The “non-living” environment is referred to as abiotic. The “living” component of the environment is referred to as biotic. Ecosystem: All the living and non-living components of an area that have the potential to interact with each other. Community: All the populations within an ecosystem that have the potential to interact with each other.

Ecology – population growth As populations interact with their biotic and abiotic environments, their numbers have the potential to change. Factors affecting population growth (note that this “growth can be positive or negative): 1. Births 2. Deaths 3. Migration (both immigration and emigration) (births – deaths) + (immigrants – emigrants) = change in population size This equation is a function of the biotic potential and the environmental resistance. Without environmental resistance (or until the point where environmental resistance Becomes an important factor), populations may exhibit exponential growth.

Ecology – population growth Biotic potential can be affected by many factors, including: The age of first reproduction The frequency of reproduction The average number of offspring per reproduction The duration of “reproductive life” The death-rate under ideal conditions

Ecology – population growth

Red line represents curve for reproductive maturity at age 4, whereas green line represents reproductive maturity at age 6.

Ecology – population growth

Ecology – regulation of population growth This is most common for short-lived, rapidly reproducing species. The “boom and bust” population cycle:

Ecology – regulation of population growth The S-curve population growth: May be the case for fast or slow growing organisms. Because of environmental resistance, the population may stabilize at or below their carrying capacity. Factors affecting environmental resistance may density-dependent or density-independent.

Ecology – regulation of population growth Density-dependant factors become more important as population size increases. note the effect of: Predators Parasites Diseases Competition, both interspecific and intraspecific

Ecology – ecosystem diversity

Ecology – ecosystem diversity near shore systems - estuary

Ecology – ecosystem diversity near shore systems – kelp forests

Ecology – ecosystem diversity near shore systems – Coral reefs

Ecology – ecosystem diversity near shore systems - Intertidal Area between the highest high tide and the lowest low tide. A highly productive area, the upper limit of organisms is determined by abiotic factors, whereas the lower limit is determined by biotic factors.

Ecology – ecosystem diversity near shore systems – open ocean

Ecology – ecosystem diversity near shore systems – deep ocean

Ecology There is a food-web associated with each of the ecosystems:

Ecology The food webs form an energy pyramid: