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

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

6. 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

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

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

9. 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)

10. 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.

11. Energy flow through an ecosystem
Energy transfer: all energy comes from the sun and is transferred from one organism to another.
Most of the interactions among members of different species occur when one organism feeds on another

12. 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).

13. Producers
Organisms that take in & use energy from the sun or some other source to produce food.
Examples: algae & plants

14. Consumers Ex.: frog, lion
Organisms that take in energy when they feed on producers or other consumers.
1st level consumer: eats the producers
2nd level consumer: eats the 1st level consumer
Ex.: frog, lion

15. Decomposers Ex.: bacteria, mushrooms (fungi)
Organisms that take in energy (food) from dead organisms breaking down the remains of organisms & returning it to the soil so other plants can grow.
Ex.: bacteria, mushrooms (fungi)

16. Niche: a species’ specific role in its community (habitat)
Ex. A red fox is a predator that feeds on small mammals, amphibians & insects in its habitat

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

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

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

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

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

22. Energy enters most ecosystems in the form of heat from the sun.
Then it’s transferred into chemical energy by producers then passed to consumers as food.
Then given back off as heat.

23. Cycles of matter
Many important materials (water, carbon, & nitrogen) make up your body & cycle through the environment.

24. 1. Water cycle
Process of evaporation, condensation, & precipitation

25. 2. Carbon cycle
Plants absorb CO2 & combines it with water for their needs
In photosynthesis, the plants use the carbon atoms from the CO2 to make sugars.

26. Carbon cycle continued…
Animals eat the producers & other consumers and return the CO2 back into the air through respiration.
Animals & plants die then carbon is returned back to soil during decomposition.

27. Nitrogen Cycle….
Nitrogen is “fixed” by bacteria in the soil then absorbed by plants & animals for their use.

28. Major Biomes of the world:
1. Aquatic: includes freshwater and saltwater (oceans)
2. Desert:
2 Kinds: hot/dry(little rain) and cold (snow), few plants grow in either and few animals live in them Ex. Great Basin in Utah, Sahara Desert in Northern Africa

29. 3. Forest (rainforest, deciduous): lots of different vegetation & animals that live there, climate can be moderate temperatures or really cold
rainforest
Deciduous forest

30. 4. Grasslands: mainly grasses, flowers and herbs grow here (not a lot of trees), animals, climate varies (can be humid/wet and hot summer/cold winter) Ex. Plains of Africa
5. Tundra- coldest biome, few plants and few animals, located in the Northern Hemisphere

31. Interactions among living organisms

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

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

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

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

36. 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

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

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