1. Brainstorm You and the person next to you will list 3 examples of…..
Abiotic and biotic factors that affect population growth and decrease in size.

2. Chapter 9
Population Unit

3. Population Dynamics
Studying how populations change in size, density, age distribution, and population distribution.
Size: number of individuals
Density: how many are in a certain area
Age distribution: proportion of each age group
Population distribution: how the organisms arrange themselves in their habitat

4. Population Distribution
Clumping: Most common. Safety in numbers, social interaction, mating and caring for young, resources are clumped
Most
common.
Uniform: Not as common. Used because of scarcity of resources
Random: Quite rare. Can be hard to determine between truly random or largely “clumpy”

5. What goes up must come down
Increases in population: through birth or immigration
Decreases in population: through death or emigration.
Change in Population
Births + Immigration
Deaths + Emigration
Note: You should know difference between Immigration & Emigration!

6. Age Structure
What is expected to happen if a large % of the population is under the age of 10?
What is expected to happen if a large % of the population is over the age of 65?
What is expected to happen if there is an equal distribution in age?
Growth will remain stable, then increase in years
Growth will decrease
Growth remain stable

7. What stage are you?
Prereproductive stage: Those not through puberty; reproductively immature.
Reproductive stage: Those who are capable of reproduction
Postreproductive stage: Organisms that are too old to reproduce.
Note: while males are capable of reproduction longer, “survival of the fittest” can prevent them from breeding once they are too old.

8. Old Bio Stuff Abiotic vs. Biotic Factors That limit population growth
Living factors
Reproduction rates
Food supply
Habitat
Resistance to disease
Ability to adapt to change
Not living
Sunlight
Temperature
Climate
Chemical environment

9. (environmental resistance)
POPULATION SIZE
Growth factors
(biotic potential)
Favorable light
Favorable temperature
Favorable chemical environment
(optimal level of critical nutrients)
Abiotic
Biotic
High reproductive rate
Generalized niche
Adequate food supply
Suitable habitat
Ability to compete for resources
Ability to hide from or defend
against predators
Ability to resist diseases and parasites
Ability to migrate and live in other
habitats
Ability to adapt to environmental
change
Decrease factors
(environmental resistance)
Too much or too little light
Temperature too high or too low
Unfavorable chemical environment
(too much or too little of critical
nutrients)
Low reproductive rate
Specialized niche
Inadequate food supply
Unsuitable or destroyed habitat
Too many competitors
Insufficient ability to hide from or defend
Inability to resist diseases and parasites
Inability to migrate and live in other
Inability to adapt to environmental
Biotic potential = growth
Environmental resistance = decrease

10. A population will increase if….
A) Natality decreases
B) Mortality increases
C) Biotic potential increases
D) The environmental resistance increases

11. A population will increase if….
A) Natality decreases
B) Mortality increases
C) Biotic potential increases
D) The environmental resistance increases

12. Any of these would take place for answer C.
Favorable light
Favorable temperature
Favorable chemical environment
(optimal level of critical nutrients)
Abiotic
Biotic
High reproductive rate
Generalized niche
Adequate food supply
Suitable habitat
Ability to compete for resources
Ability to hide from or defend
against predators
Ability to resist diseases and parasites
Ability to migrate and live in other
habitats
Ability to adapt to environmental
change
Any of these would take place for answer C.
Biotic potential = growth

13. Exponential or Logistic Growth Curve?
“Boom and Bust”
“Boom then stable”

14. Environmental resistance
Logistic Growth
Will see exponential growth at first introduction to new environment. Video to follow this lecture.
Then, growth will be limited by environmental factors and will follow carrying capacity
S shaped
Population size (N)
Time (t)
Carrying capacity (K)
Environmental resistance
Biotic
potential
Exponential
growth

15. Clearer view of “J” and “S”

16. Going up…
Intrinsic rate of increase (r) is the rate the population would grow if it had unlimited resources.
Can be seen as the “boom” of the population.
r species: reproduce early in life, reproduce often, have many offspring each time.

17. Coming down…
Overshoot occurs when the population “booms” and is too great for the resources to support
Overshoot is followed by dieback, or the sudden decrease in population
Reproductive time lag: the amount of time it takes for the birth rate to fall and death rate to rise. If the time lag is too long, environmental damage can occur which further limits the carrying capacity.

19. Population Graphs
Number of individuals
Time
(b) Irregular

20. Population Graphs
Number of individuals
Time
(a) Stable

21. Population Graphs
Number of individuals
Time
(c) Cyclic

22. Population Graphs
Number of individuals
Time (
(d) Irruptive

23. Oscillations of the Two Populations Over Time

24. Population Density
Density-dependent controls: Limits populations that are too high.
Examples: competition for food, shelter, water; disease; parasites, predation
Density-independent controls: Decreases population regardless of size.
Examples: weather, temperature, natural disasters, habitat destruction, chemical changes in the environment

25. Who’s in control here? Top-down control: (Predator Controls Prey)
Structure of lower trophic levels depends on effect of consumers at high trophic levels.
Bottom-up control: (Prey Controls Predator)
Structure depends on prey availability and nutrient content from low trophic levels
Example: Hare population is controlled either by the lynx killing it (top-down) or by large numbers of hare using up their food source (bottom-up)

26. Let’s talk about sex…old bio stuff
Asexual reproduction: does not require sperm/egg. Mitosis – cell splitting. Bacteria reproduce this way. Only 3% of all species use this form
Sexual reproduction: requires sperm/egg, but not necessarily intercourse/copulation
Disadvantages:
Males don’t give birth
Increased chance of genetic defect/error
Courtship and mating rituals can be complex
Advantages: (get your mind out of the gutter!)
Genetic variety/diversity
Parents can divide responsibilities

27. What species are you? Carrying capacity K species; experience
Number of individuals
Time
Carrying capacity
K species;
experience
K selection
r species;
r selection

28. Remember – You are SPECIAL

29. Species r-selected Species K-selected Species
Found at bottom of population curve
Reproduce early in life
Reproduce frequently
Large numbers of offspring
Little to no parental care
Boom and bust populations
Examples:
Frogs
Cockroach
Dandelions
Mice
Most insects
Found at top of population curve
Reproduce later in life
Reproduce less frequently
Have less offspring at one time
Lower infant mortality
Logistic graph (stable at top)
Examples:
Humans
Elephants
Whales
Long-living plants (oaks, rain forest trees)

30. R-selected Species or K-selected species?
                                                                                                                                          

31. R-selected Species or K-selected species?
                                                                                                                                          

32. R-selected Species or K-selected species?

33. R-selected Species or K-selected species?
                                                                                                                                          

34. R-selected Species or K-selected species?
                                                                                                                                          

35. R-selected Species or K-selected species?
                                                                             

36. R-selected Species or K-selected species?
                                                                                                                                          
HINT: The Capybara is the largest rodent in the world

37. Percentage surviving (log scale)
Survivorship Curves
Early loss: high infant mortality (fish, frogs)
Constant loss: death rate even among all ages (song birds)
Late loss: low infant mortality (humans, elephants)
Percentage surviving (log scale)
100 10 1
Age
Early loss
Constant loss
Late loss

38. Isolation isn’t best… Problems when small, isolated populations exist.
Founder effect: small group is geographically isolated. May not have the genetic diversity to survive (coloring, fur cover, etc)
Demographic bottleneck: only a few surviving individuals may not have the genetic diversity to rebuild the population
Genetic drift: some individuals breed
more and dominate the gene pool
(wolves)
Inbreeding: related individuals in an
area mate. Can increase genetic
defects.

39. Tying in a few things from
Chapter 1

40. Oops! I did it again… Past mistakes that need to be stopped:
Reducing biodiversity by destroying, fragmenting and degrading habitats

41. Oops! I did it again… Past mistakes that need to be stopped:
Reducing biodiversity by simplifying natural ecosystems (monocultures – one type)

42. Oops! I did it again… Past mistakes that need to be stopped:
Unintentional strengthening of pest species and anti-biotic resistant bacteria

43. Oops! I did it again… Past mistakes that need to be stopped:
Elimination of natural predators (wolves, cougars, buffalo, eagles)

44. Oops! I did it again… Past mistakes that need to be stopped:
Over-harvesting renewable resources

45. Oops! I did it again… Past mistakes that need to be stopped:
Interfering with natural cycles in natural

46. Oops! I did it again… Past mistakes that need to be stopped:
Over dependence on fossil fuels

47. 4 Guidelines for a Sustainable Future
Our lives and economies are dependant on the earth and sun. They don’t depend on us.
Everything is interconnected.
You can’t change only one thing in nature
We cannot sustain our civilization if we deplete the natural capital. We must live off the biological interest of that capital.

48. Population Control Solar Energy Nutrient Recycling Biodiversity
PRINCIPLES OF
SUSTAINABILITY
Nutrient
Recycling
Biodiversity