Chapters 19 & 20 Ecologies

The study of the interactions between organisms & their environments is . . . ecology!

Remember! Hierarchy of biological organization

A population is . . .what?

Variables to population structure Population density Dispersion patterns

What can happen to a population size? Dynamics due to

Populations can grow quickly Exponential growth Exponential growth of rabbits

Limitations to population growth Density dependent factors carrying capacity

Logistic growth

Limitations to population growth Density independent factors

Levels of ecological study Organismal Population Community Ecosystem

Community ecology Interspecific interactions

Each organism has a niche Ecological niche: The more similar 2 niches are,

Keystone species impact diversity A keystone species

Trophic structures show interactions The pattern of feeding relationships consisting of several levels food chain: food web:

Food webs

Missing from most food chain & food web diagrams. . . ! Detritivores: Decomposers:

Community response to disturbance A disturbance can result from

Response to disturbance ecological succession Two kinds of succession

Primary succession Starts in lifeless area without even soil

Primary succession

Secondary succession Occurs when disturbance destroyed existing community but left soil intact

Secondary succession

Levels of ecological study Organismal Population Community Ecosystem

An ecosystem has two parts Ecosystem biologists study biotic abiotic

Biomes Terrestrial biomes’ Aquatic biomes’

In an ecosystem, Energy flows

In an ecosystem, Chemicals cycle

Cycling chemicals Carbon: Nitrogen: Phosphorus: