1. Ecology
Chapter 20

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

3. Section 1: Living things & the environment
Habitat:
Where an organism lives that provides the things it needs to survive
Different organisms need different habitats
One area may contain many habitats
Food, water & shelter are provided in an organism's habitat.

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

7. Levels of Organization in an ecosystem:

8. The smallest level in an ecosystem is an organism
(1 individual).
All the individuals of one species living in a certain area is called a population.

9. All the different populations of species in an area make up a community.
To be considered a community, populations must live close enough together to interact.
Ex) Eat the same food, prey or be preyed on by other species, use the same resources (water, etc.) to live……

10. Ecosystem: the community of organisms that live in a particular area, along with their non-living surroundings.

12. What makes an ecosystem different from the other levels?
Organisms, populations & communities are all made up of biotic factors, or living things!
An ecosystem contains both biotic AND abiotic factors, or non-living things in a particular area.

13. Population Size There are 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

14. 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.

15. 4. Mark and Recapture Studies: Capture animals and mark them
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.

17. 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

18. Changes continued…
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

20. 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 squared.

21. Limiting Factors
An environmental factor that prevents a population from increasing.
These environmental factors include:
Food & water
Space
Temperature
Rainfall

23. The largest population that an area can support.
Carrying Capacity
The largest population that an area can support.

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

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

27. Interactions Among Organisms

28. Predator vs. Prey
Predator- An animal that hunts, kills, and eats another.
Prey- An animal that is killed and eaten by a predator.

29. Adaptations for feeding
Ambush (camouflage)
Teeth
Night vision
Echolocation

30. 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

31. Mimicry
The resemblance of one organism to another or to an object in its surroundings for protection from predators.

32. Symbiosis
A relationship between organisms of different species in which at least one organism benefits.
Three types of symbiotic relationships:
Mutualism
Commensalism
Parasitism

33. Mutualism BOTH species benefit from living together Examples:
Shark & teeth cleaning fish
Crocodiles & cattle egrets
Moray Eel & Cleaner Fish
*Moray Eel gets a clean mouth
*Cleaner Fish gets a meal

34. Commensalism Clown fish gets protection Anemone is unaffected
One species benefits, other is neither harmed nor benefitted
Example: Clown Fish
& Anemone
Clown fish gets protection
Anemone is unaffected

35. Parasitism Worm infects human blood stream Human may go blind
One species benefits and the other is harmed
Examples:
Leeches
Ticks
Hookworms
Tapeworms
botfly
Taenia worm in human eye
Worm infects human blood stream
Human may go blind

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

37. Niche
The role of an organism in its habitat, or how it makes its living.
Different from habitat (where it lives)

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

39. Primary Succession Occurs in an area where NO soil or organisms exist
Ex: Volcano erupting, resulting in an area of land

40. The 1st species to populate that area is called a pioneer species
Examples: 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

42. 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, tornado, etc.…
Human disturbances: logging, farming…