1. Ch 50

2. Ecology of Populations
Ecology: the study of interactions of organisms with other organisms and with the physical environment

3. Population: members of the same species living in the same area

4. Community: all the different populations in an area

5. Population or Community?

6. Ecosystem: the community plus the nonliving factors

8. Biosphere: all the areas of the earth that supports life

9. Watch the Battle at Kruger. How many populations can you count?

10. Day Two: Population Characteristics

11. Ecologists ask questions about where species occur and why species occur where they do
Figure
Chemical
factors
Why is species
X absent from
an area?
Does dispersal
limit its
distribution?
Area inaccessible
or insufficient time
Predation, parasitism,
competition, disease
Water, oxygen, salinity,
pH, soil nutrients, etc.
Do biotic factors
(other species)
Temperature, light,
soil structure, fire,
moisture, etc.
Do abiotic factors
Physical
Yes No

12. Ch 52

13. Demography - the statistical study of a population; how they change over time (density, distribution, rate of growth) Population density: number of individuals per unit area

14. Factors that affect Density
Figure 40.14
Births and
immigration
add individuals to
a population.
Deaths and
emigration
remove individuals
from a population.
Births
Immigration
Deaths
Emigration

15. Why? Population distribution:
pattern of dispersal of individuals: random, clumped, uniform
Figure 40.15
(a) Clumped
(c) Random
(b) Uniform
Why?

16. Life Table/Age Structure Diagrams
age-specific summary of the survival pattern of a population
It follows he fate of a cohort, a group of individuals of the same age, from birth to death

17. AGE STRUCTURE DIAGRAMS

18. Figure 46.16

20. Survivorship curve - probability of newborn individuals surviving to a particular age
Late Loss (Type I) Constant loss (Type II) - death is often unrelated to age Early loss (Type III)

21. Figure 46.4c

22. Figure 46.4d

23. You can create a survivorship curve of a human population by studying cemetery data
(Demography Lab)

24. Compare the two curves below: Which country is probably the better place to live? Defend your answer.

25. Per Capita Rate of Increase
Change in population size can be defined by the equation −
Change in
population
size
Births
Immigrants
entering
Deaths
Emigrants
leaving
Population  
Population growth = rN (r = growth rate, N = original population size)

26. The population growth rate can be expressed mathematically as
 bN −mN
where N is the change in population size, t is the time interval, B is the number of births, and D is the number of deaths
Zero Population Growth
- same number enters as leaves the population

27. Population Growth Models
J-shaped curve showing exponential growth of a population
Requires unlimited resources
S-shaped curve shows how a population becomes limited by environmental factors
Logistic Growth Carrying Capacity: the maximum size of a population that an area can support
dN = rN dt
dN = rN(K-N)
dt K

29. the elephant population in Kruger National Park, South Africa, grew exponentially after hunting was banned
Figure 40.18
6,000
Year
Elephant population
2,000
8,000
4,000
1900
1930
1940
1950
1960
1970
1910
1920

30. Carrying capacity (K) is the maximum population size the environment can support

32. The Logistic Growth Model
per capita rate of increase declines as carrying capacity is reached dN dt
 rmaxN
(K −N) K

33. 1,000 Number of generations Population size (N)  1.0N 10 15 5 2,000
Figure 40.19
1,000
Number of generations
Population size (N)
 1.0N 10 15 5
2,000
1,500
500 dt dN
Exponential
growth
Population growth
begins slowing here.
K  1,500
(1,500  N)
Logistic growth

34. Number of Paramecium/mL
Figure 40.20
1,000
Time (days)
Number of Paramecium/mL 10 15 5
(a) A Paramecium population
in the lab
800
200
400
600
140
160 30
(b) A Daphnia (water flea) population in the lab 40 60 20
100
120 80
Number of Daphnia/50 mL
180
150 90

35. Regulation of Population Size
Density Independent Factors: weather and other natural disasters Density Dependent Factors: food, space, water, parasitism, competition

36. Figure 46.10
Density Independent Factor (Flash Flood) – it will have the same impact on a small pop as it does on a large pop.
60% loss for both
- growth limited by the environment

37. Figure 46.11
Density Dependent Factor – as number increases, not all of them will have access to resources
-the denser the population,
the faster the resources get used up

38. Figure 46.12

39. Life History Patterns
K-strategists - small numbers of offspring, usually parental care (Kangaroo)
R-strategists - large numbers of offspring, no care, low survivability (Roaches)

41. Figure 46.14a

42. Figure 46.14b

43. Figure 46.13

45. HUMAN POPULATION GROWTH
Current World Population: 7 billion (and growing)
The human population is now in an exponential part of a J-shaped growth curve.
World population increases the equivalent of one medium-sized city (216,000) per day and 79 million per year.
The doubling time is the length of time for a population size to double, now 53 years.
Zero population growth is when the birthrate equals the death rate and the population size remains steady.
The world population may level off at 8, 10.5 or 14.2 billion, depending on the decline in net reproductive rate.

46. Biotic Potential: maximum rate at which a population could grow given optimal conditions (food, water, space)
Factors that influence biotic potential:
1. age of reproduction
2. frequency of reproduction
3. number of offspring produced
4. reproductive life span
5. average death rate under ideal conditions

47. Penguins only hatch ONE offspring during a season, never twins
Penguins only hatch ONE offspring during a season, never twins.  That offspring may not survive its first year.  Parents cannot start over if offspring dies. 

48. Don’t forget, a population can refer to plants, fungi and bacteria…..
Algae bloom

49. How to calculate Population Size
Mark and recapture
Random Sample