1. What is ecology?

2. Ecology
Ecology = scientific study of the interactions among organisms and between organisms and their environment (surroundings)
Each organism plays a role in their “household” (the environment) = ‘niche’
Interactions produce a web of interdependence between organisms and the environment
The environment and interactions are constantly changing (dynamic)

3. Levels of Organization-big->small
Biosphere = portions of the planet where all life exists (land, water, air, etc)
Biome = group of ecosystems that have the same climate and similar dominant communities
Ecosystem = collection of all the organisms that live in a particular place together with their nonliving (physical) environment
Communities = different populations that live together in a defined area
Populations = groups of individuals that belong to the same species and live in the same area
Species = group of organisms so similar that they can breed and produce fertile offspring
Individual = one member of a specific species

4. Figure 3-2 Ecological Levels of Organization
Section 3-1
Go to Section:

5. Energy flow Every organism needs energy to power life’s processes
Energy is obtained through interactions with the environment
The flow of energy through an ecosystem is one of the most important factors that determines the system’s capacity to sustain life

6. Populations INCREASES– immigration; higher birth rate than death rate
DECREASES– emmigration; higher death rate than birth rate

7. Producers Sunlight is the main energy source of life on Earth
Only plants & certain bacteria can capture energy from sunlight or inorganic chemicals and use that energy to produce food = autotrophs
Autotrophs are also called producers,
Some autotrophs use light energy to convert carbon dioxide & water into oxygen & sugars through the chemical reaction photosynthesis (plants/algae)
Some use chemical energy to produce carbohydrates in absence of light through chemosynthesis (bacteria)

8. Consumers Must acquire energy from other organisms = heterotrophs
Heterotrophs are also called consumers
Herbivores = eat only plants
Carnivores = eat only animals
Omnivores = eat both plants and animals
Detritivores = eat plant/animal remains and other dead matter called detritus
Decomposers = break down organic matter

9. Feeding Relationships
Energy flows through an ecosystem in one direction
Energy flows from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)– FOOD CHAIN
Feeding relationships among organisms in an ecosystem usually form a network of complex interactions shown as a food web
Each step in a food chain/web = trophic level

10. Food Chain

11. Food Web
Section 3-2
Go to Section:

12. Trophic Levels Each step in a food chain or web is a trophic level.
The first trophic level is the producers.
The second trophic level is the consumers (herbivores).
The third and fourth levels are more consumers (omnivores and the carnivores).

13. Ecological Pyramids
The amount of energy or matter in each trophic level of a food chain/web of an ecosystem can be represented by an ecological pyramid
Energy pyramid = only about 10% of the energy stored in one trophic level is passed on to the next higher level, because most of the energy is used for life processes and some is released into the environment as heat
Biomass pyramid = potential total amount of living tissue within a given trophic level (grams per unit area) for each trophic level in an ecosystem
Pyramid of numbers = relative number of individual organisms at each trophic level

14. Ecological Pyramids Section 3-2 Energy Pyramid
Shows the relative amount of
energy available at each trophic
level. Organisms use about 10
percent of this
energy for
life processes.
The rest is lost
as heat.
Pyramid of Numbers
Shows the relative
number of individual
organisms at each
trophic level.
Biomass Pyramid
Represents the amount of
living organic matter at each
trophic level. Typically, the
greatest biomass is at the
base of the pyramid.
Go to Section: