1. HOW POPULATIONS GROW
Chapter
5-1

2. I. Characteristics of Populations
=Area inhabited by a population
=The # of individuals per unit area
=Rate at which a population changes size
=Different ages of the organisms in a population
A. Geographic Distribution
B. Density
C. Growth rate
D. Age structure

3. II. Population Density
The number of individuals per unit area

4. A. Cactus: small #’s Low density B. Shrubs: higher #’s High density
II. Population Density
A. Cactus: small #’s
Low density
B. Shrubs: higher #’s
High density

5. III. Population Growth Factors that affect population size:
=the amount of births
=the amount of deaths
=moving into an area
=moving out of an area
A. Birth Rate
B. Death Rate
C. Immigration
D. Emigration

6. IV. How is the Population Affected? Increase or Decrease
A.  birth rate &  death rate
B.  birth rate &  death rate
C.  immigrants &  emigrants
D.  immigrants &  emigrants
Decrease
Increase

7. V. Exponential Growth B. Produces a J – shaped Curve when graphed
A. Will occur under IDEAL conditions
1. unlimited resources
2. no predators
3. no disease
4. plenty of space
B. Produces a J – shaped Curve when graphed

9. VI. Logistic Curve S- Curve
A. In ecosystems:
1. Resources are limited
2. Predators
3. Disease
B. The growth of populations slows or stops (actually averages out to a steady size) When:
1. Birth rate = death rate
2. Immigration = emigration
C. Leveled-off population reached its carrying capacity

10. Logistic Curve S-Curve

12. 1. Carrying Capacity (K)
The largest number of organisms that a given ecosystem can support

13. K selected species
The letter K represents the carrying capacity of a habitat for members of a given sort of organism.

14. K selected species Organisms that are K-strategists
occupy more stable environments.
Are larger in size and have longer life expectancies.
stronger or are better protected
generally are more energy efficient.
They produce, during their life spans, fewer progeny, but place a greater investment in each
Examples:
elephants, and humans

15. K selected species
Their reproductive strategy is to grow slowly, live close to the carrying capacity of their habitat and produce a few progeny each with a high probability of survival.

16. R- selected species
r represents the slope of the line representing exponential growth.

17. R selected species Organisms that are r-strategists
typically live in unstable, unpredictable environments.
reproduce rapidly (exponentially). They
have little investment in any one progeny individual
they are typically weak and subject to predation
They have short life spans, are generally small, quick to mature and waste a lot of energy.
Typical examples of r-strategists are
salmon
corals
insects
bacteria

18. R-selected species
The “strategic intent” is to flood the habitat with progeny so that, regardless of predation or mortality, at least some of the progeny will survive to reproduce.

20. R and K selected organisms
Characteristics of r- and K-selected organisms
r-organisms
K-organisms
short-lived
long-lived
small
large
weak
strong or well-protected
waste a lot of enrgey
energy efficient
less intelligent
more intelligent
have large litters
have small litters
reproduce at an early age
reproduce at a late age
little care for offspring
much care for offspring