1. What kind of plants do we see in a climax community?
Agenda for Thursday May 26th
Communities and populations notes
Random sampling lab

2. Community
Def. – a group of interacting populations that occupy the same area at the same time
Different organisms occupy different biomes
Different adaptations

3. Communities
Limiting factors – any biotic or abiotic factor that limits the number, reproduction, or distribution of an organism
Sunlight, food, temperature
Tolerance – ability of an organism to survive when subjected to abiotic or biotic factors
Upper and lower limit = range

5. Recall…
Populations – members of a single species that live in once place at a single time

6. Population Characteristics
Population Density – # of organisms per area
Dispersion – pattern of spacing of a population within an area
Based on available resources (food)
3 types
Uniform
Clumped
Random

7. Dispersion Pattern: Uniform

8. Dispersion Pattern: Clumped

9. Dispersion Pattern: Random

11. Dispersion Smaller animals usually clump
Larger animals usually independent
Fish
Q: What advantage do smaller fish (animals) gain by forming schools (clumped groups)?
Safety, confuses predators

12. Q: Which type of population distribution allows you to predict more accurately how many individuals reside in a given area?

13. Determine how many oak trees are in the forest using the random sampling technique. Use the grid.7 3 5 8
Agenda for Friday May 27th
Quiz
Population sampling techniques
Mark and recapture

14. Question
If you were in charge of a team given the responsibility to determine the number of sunfish in Horseshoe Lake, discuss with a partner how would you accomplish this task.

15. Sampling
 A technique called sampling is sometimes used to estimate population size.
Organisms in a few small areas are counted and projected to the entire area. 
Example: A biologist counts 10 squirrels living in a 200 square foot area, she could predict that there are 100 squirrels living in a 2000 square foot area. 

16. Questions
A biologist collected 1 gallon of pond water and counted 50 paramecium.  Based on the sampling technique, how many paramecium could be found in the pond if the pond were 1,000 gallons?
What are some problems with this technique?  What could affect its accuracy?

17. Mark and Recapture
Biologists use traps to capture the animals alive and mark them in some way 
Animals are returned unharmed to environment 
Animals trapped and data is taken on how many are captured with tags
A mathematical formula is then used to estimate population size

19. Formula for Mark and Recapture
Ecologists marked 20 bears in an area. Over 5 years they captured 100 bears. Of those 100 captured 50 had a tag. What is the population of the bears?
Population estimate = (total number captured) x (original # with mark)
(Total number captured with mark)

20. What is mark and recapture?
Agenda for Tuesday May 31st
Mark and recapture notes and lab
Finish population notes

21. Mark and Recapture Concerns
Capturing the animal could injure the animal or scientist
Disturb animal's normal behavior pattern
The marks used to track the animals, such as ear punches, may cause injury to the animals or get lost between captures
Marked animals may be more or less attractive to predators because of markings
Assumes all animals require the same effort to get caught,
might catch the weaker or younger animals more
Some animals learn to fear the traps and avoid recapture
or become trap-happy and attempt to get caught when they learn there is food involved and that they will be re-released

22. Population Ranges Limiting Factors
Abiotic conditions
Temperature
Humidity
Rainfall
Sunlight
Biotic conditions
Predators
Competitors
parasites

23. Density independent factors
Def. – any factor that does not depend on the number of organisms in a population in a given area
Abiotic
Weather – drought, flooding, extreme heat/cold, tornados, hurricanes
Water
Fire
Sunlight

25. Density Dependent Factors
Def. – any factor that depends on the number of organisms in a population in a given area
Biotic factors
Predation, disease, parasites, competition

26. Predation
More members of a population = more predators

27. Disease/Parasites
Outbreaks of disease tend to occur when population size has increased
Disease is transmitted faster
True for humans as well as animals
Parasites increase at higher densities

28. Competition When resources become limited animals compete
Within a population or between 2 different species
Lead to starvation – population can decrease

29. Population Growth Rate
How do we figure out population growth rate?
Must know birthrate and mortality
Emigration – moving out of a pop.
Immigration – moving into a pop.
Immigration rate = emigration rate
Calculating growth rate
=(population at end – population at beginning)
Population at beginning

30. Different Growth Rates

31. What is a density dependent factor
What is a density dependent factor? What is a density independent factor?
Agenda for Wednesday June 1st
Finish notes
Human pop. Graphing
Biodiversity

32. Exponential Growth Rate
Starts slow – few organisms
Faster because all organisms are reproducing
Rarely happens
WHY?
Limiting factors – food, space

33. Logistical Growth Rate
Logistic growth occurs when a population’s growth slows or stops following exponential growth
Carrying capacity

34. Carrying Capacity
Maximum number of individuals that an environment can support for the long term
Limited by energy, water, oxygen, nutrients available
Population grows until carrying capacity
Births outnumber deaths
Exceed carrying capacity then deaths outnumber births

35. Reproductive strategies
R-strategy (rate strategists)
Produce as many offspring as possible in a short time
Little energy in raising young
K-strategists (carrying capacity strategy)
Few offspring that have a better chance of living
Expend a lot of energy raising young

36. Human Population Growth

37. Trends in Human Population Growth
Was slow and stable
Recent increase in growth
Technology – agriculture, medicine, shelters
Developing countries add more than developed countries

38. More trends Zero population growth Age structure
birth rate + immigration rate = death rate + emigration rate
Age structure
# of males and females in three age groups
Pre-reproductive (0-19), reproductive (20-44), and
post –reproductive (45-80+)

40. Human Carrying Capacity
Humans have a carrying capacity
Technology allows an increase in carrying capacity
Concerns about reaching/exceeding carrying capacity
resources being used

41. Describe what is happening to the population in the graph below.
Agenda for Wednesday Jan 26th
Finish Notes
Human pop. graph