1. ECOLOGY &
the ENVIRONMENT

2. ECOLOGY The study of interactions among organisms & their environment
Ecologists divide environmental factors that influence organisms into 2 groups: ABIOTIC and BIOTIC.

3. ABIOTIC NONLIVING PARTS OF THE ENVIRONMENT
Ex: Water, light, temperature, air, soil
Air is a mixture of 3 main gases: oxygen, carbon dioxide, & nitrogen (used by plants & animals

4. Soil type is determined by the amounts of sand, humus, & clay that it contains
Humus: decaying matter found in soil

5. BIOTIC Living or once-living organisms in the environment
Can be arranged into levels of organization:

6. 1. organism
1 individual from a population
Example: catfish

7. 2. Population
All the individuals of one species that live in the same area at the same time.
Example: All the catfish living in a lake at the same time

8. 3. community
Populations of different species that interact in some way
Example: Population of bass and all the species they interact with it

9. 4. ecosystem
All the communities in an area & the abiotic factors that affect them
Example: lake, pond, coral reef, forest, etc.

10. 5. Biome
Large region with plants & animals well adapted to soil & climate of the region
Example: Mountain, rainforests, tundra, desert, grasslands, temperate forests (where we live)

11. 6. biosphere
All the ecosystems on earth; the part of the earth that supports life
Example: Top part of the earth’s crust, all the waters that cover the Earth’s surface, the surrounding atmosphere, & all the biomes.

12. Interactions among living organisms

13. 1. Population size
The number of individuals in a population

14. 2. Population Density
The number of individuals in a population that occupy a definite area

15. Classroom population density
Length of room (m) X width (m)
# of students
=A (in m2)
= how much space each person has

16. 3. Population spacing How organisms are arranged in a given area
Can be evenly, random, or clumped
clumped
EVEN
random

17. 4. Limiting factors
Any biotic or abiotic factor that limits the number of individuals in a population
Ex: drought, fewer plants, fewer nesting sites, predators

18. Food, water, & space are all factors in the growth populations in an ecosystem
If an environment had no limiting factors, the population would INCREASE.

19. 5. Carrying capacity
Largest number of individuals of a species that an environment can support & maintain for a long period of time.

20. Energy flow through ecosystems
Most of the interactions among members of different species occur when one organism feeds on another

21. When one organism is food for another organism, some of the energy in the first organism (the food) is transferred to the second organism (the eater).

22. producers
Organisms that take in & use energy from the sun or some other source to produce food.
Another name for producer is autotroph.
Examples: algae & plants

23. Consumers
Organisms that take in energy when they feed on producers or other consumers.
Another name for consumer is heterotroph.

24. decomposers
Organisms that take in energy from organisms that have died by breaking down the remains of organisms.

25. Scavenger
Organisms that feed on dead animals or plant material present in its habitat.

26. Characteristics of Autotrophs vs. Heterotrophs
Are producers
Are consumers and decomposers
Plants, bacteria, and algae
Need food
Animals, humans, monkeys
Both are living things
Get food from autotrophs
Make food from water, sunlight, and CO²
Autotrophs
Heterotrophs
Need water, sunlight, and air
Means “self nutrition”
Means “other nutrition”
Characteristics of Autotrophs vs. Heterotrophs

27. Movement of energy through a community can be diagrammed as a food chain or food web.

28. Food chain
Simple way of showing how energy passes from one organism to another.
Usually 3 or 4 links

29. Example of food chain:
Water plant insects
bluegill bass
Grass grasshopper frog snake owl

30. Energy pyramid
Compares energy available at each level of the food chain in an ecosystem
As you move from level to level, energy decreases.

31. 2. Food web
Series of overlapping food chains that exist in an ecosystem
More complete model of feeding relationships.

32. Primary Consumer-an animal that feeds on plants; a herbivores
Secondary Consumer-an animal that eats primary consumers and plants. They are omnivores.
Tertiary Consumer-an animal that eats secondary consumers. They are carnivores.

33. Other Ecological Terms to Know:
Symbiosis is a close relationship that may occur when two organisms of different species live together.
There are several different kinds of symbiotic relationships:
1) Mutualism: Both species benefit. The two organisms help each other. An example would be a honey bee and a dandelion. The honey bee gets to eat the pollen from the flower. The dandelion uses the bee to spread its pollen to another flower.

34. More Ecological Terms cont.
2) Commensalism: One species benefits. The other species is unaffected. A common example is an animal using a plant for shelter. An American Robin benefits by building its nest in a Red Maple tree. The tree is unaffected.
3) Parasitism: Ones species benefits. The other species is harmed. An example would be a deer tick and a White-tailed Deer. The tick gets food from the deer without killing it. The deer is harmed by losing blood to the tick, and possibly by getting an infected wound or disease.
4) Predation: A predator/ prey relationship. An example is an owl hunting a mouse.
5) Cooperation: Organisms work together for a common or mutual benefit. An example would be a group of lionesses hunting prey.