1. Ecology
Chapter 20

2. Ecology: the study of how living things interact with their environment

3. Section one: Living things & the environment
Habitat
Where an organism lives that provides the things it needs to survive
Different organisms need different habitats

4. Biotic Factors
All the living things in an environment

5. ABIOTIC FACTORS
All the nonliving things that affect organisms in their environment
Examples include water, soil, sunlight, temperature & oxygen

6. Levels of Organization
Start with an individual of one species
All the individuals of one species living in a certain area is called a population.

7. All the different populations of species in an area make up a community

8. Community of organisms, along with their nonliving surroundings make up an ecosystem

9. Population Size 4 ways to determine population size:
1. Direct Observation: count all the members of a population
2. Indirect Observation: looking at signs of organisms instead of actual numbers
Example: looking at swallow mud nests, count the number of entrance holes- on average each nest has 4 swallows- multiply

10. 3. Sampling: if population is large or spread over a large area you can’t count them all, you have to make an estimate based on reasonable assumptions.
4. Mark and Recapture Studies: Capture animals and mark them. Then come back two weeks later and capture again. Count how many marked and unmarked that you count. Use a mathematical formula to calculate the estimated total population.

11. Changes in Population Size
Birth & Death rate:
birth rate higher then death rate- population gets bigger
Death rate higher then birth rate= population gets smaller

12. Immigration & Emigration
Population size changes when animals move in and out of the population
Emigration is moving OUT of a population
Immigration is moving INTO a population

13. Population Density
How many organisms there are in a certain amount of area
Pop. Density= # of individuals/ Unit area
Example: 20 butterflies in 10 square meters of area, population density would be 2 butterflies per meter square

14. Limiting Factors Anything that stops a population from growing larger
Food & water
Space
Temperature
rainfall

15. Carrying Capacity
The number of individual an area can support

16. Exponential Growth
With unlimited resources, populations will grow unchecked: this is called exponential growth and is represented by a “J-Shaped” curve.

17. Logistic Growth
Occurs when there are limiting factors that keep population growth balanced- called an S-Curve

18. Interactions Among Organisms
Chapter 20

19. Predator/Prey
One thing (predator) eats something else (prey)

20. Adaptations for feeding
Ambush (camouflage)
Teeth
Night vision
echolocation

21. Defense Strategies Camouflage
False coloring- false eye- predators think organisms head is someplace else
Warning coloration: Bright colors to tell predators they are poisonous
Protective covering: porcupine

23. Camouflage

24. Mimicry

25. Warning Coloration

26. Symbiosis
Process by which two animals of different species live in close contact with one another
Three types of symbiotic relationships:
Mutualism
Commensalism
Parasitism

27. Mutualism Both species benefit from living together
Shark & teeth cleaning fish
Cleaning shrimp & fish
Crocodiles & cattle egrets
Humans & E.coli bacteria

28. Commensalism
One species benefits, other is neither harmed nor benefitted
Example: red tailed hawk and saguaro cactus

29. Parasitism One species benefits and the other is harmed Leeches Ticks
Hookworms
Tapeworms
botfly

30. Competition
Due to limiting factors- when a resource is limited organisms must compete for it
Usually the organism that competes the best reproduces more often & passes on those genes that allow it to be more successful- NATURAL SELECTION

31. Niche The role an organism plays in the environment- its lifestyle
Different from habitat (where it lives)

32. Primary Succession Occurs in an area where NO soil or organisms exist
The 1st species to populate that area is called a pioneer species
Moss or lichen
Break up the rocks and provide nutrients to the soil
Over time seeds land in the soil and grow
Grasses and shrubs often replace the pioneer plants

34. Secondary Succession
Series of changes that occur in an area where the ecosystem has been disturbed, BUT soil and organisms are still present
Natural disturbances: fire, flooding…
Human disturbances: logging, farming…

36. Succession
Series of predictable changes that occur in a community over time