1. Population Ecology

2. Ecology - Study of interactions among organisms and their environment
Conservation biology, environmentalism:
preservation of natural world

3. Biosphere Ecosystems Community Population Organism Figure 1.1
ECOSYSTEM LEVEL Eucalyptus forest
COMMUNITY LEVEL All organisms in eucalyptus forest
POPULATION LEVEL Group of flying foxes
ORGANISM LEVEL Flying fox
Brain
Spinal cord
ORGAN SYSTEM LEVEL Nervous system
ORGAN LEVEL Brain
Nerve
TISSUE LEVEL Nervous tissue
CELLULAR LEVEL Nerve cell
MOLECULAR LEVEL Molecule of DNA
Figure 1.1

4. Population Ecology Population- how to measure?
Growth rates: J shaped, S shaped
K, r, and reproductive strategies
Human population

5. How are populations measured?
Population density = number of individuals in a given area or volume
count all the individuals in a population
estimate by sampling

6. mark-recapture method depends on likelihood of recapturing the same individual

7. The dispersion pattern of a population refers to the way individuals are spaced within their area
Clumped -
Uniform:
Random: no pattern

8. Figure 35.2C

9. How do populations grow?
Idealized models describe two kinds of population growth
1. exponential growth
2. logistic growth

10. A J-shaped growth curve, described by the equation G = rN, is typical of exponential growth
G = the population growth rate
r = the intrinsic rate of increase, or an organism's maximum capacity to reproduce
N = the population size

11. Figure 35.3A

12. 1500 high intrinsic rate of increase r = 0.06 1000 low intrinsic
Population size
zero population
growth
500
r = 0
Figure: 29-06
Title:
The intrinsic rate of increase (r).
Caption:
If the birth rate exceeds the death rate, then the population size will increase over time (r = 0.02), r = 0.06 in the example). If the birth rate equals the death rate, then the population size will stay constant (r = 0). Finally, if the birth rate is lower than the death rate, the population size will decrease over time (r = 0.05). Note what dramatic effects a small change in r can have over time, in this case on a population whose starting size is 500 individuals.
negative intrinsic
rate of increase
r = -0.05 5 10 15 20
Time (years)

13. 2. Logistic growth is slowed by population-limiting factors
K = Carrying capacity is the maximum population size that an environment can support
Figure 35.3B

14. logistic growth curve K = carrying capacity
The term (K - N)/K accounts for the leveling off of the curve
Figure 35.3C

16. Multiple factors may limit population growth
declining birth rate or increasing death rate
The regulation of growth in a natural population is determined by several factors
limited food supply
the buildup of toxic wastes
increased disease
predation

17. Density Dependent Factors
Competition
Predation
Parasitism
disease

18. Density Independent Factors
Natural disasters
Weather
Seasonal cycles
Human activities

19. About every 10 years, both hare and lynx populations have a rapid increase (a "boom") followed by a sharp decline (a "bust")
Figure 35.5

20. Survivorship curves plot the proportion of individuals alive at each age
Three types of survivorship curves reflect important species differences in life history
Figure 35.6

21. Evolution shapes life histories
An organism's life history is the series of events from birth through reproduction to death
Life history traits include
the age at which reproduction first occurs
the frequency of reproduction
the number of offspring
the amount of parental care given
the energy cost of reproduction

22. Principles of population ecology may be used to
manage wildlife, fisheries, and forests for sustainable yield
reverse the decline of threatened or endangered species
reduce pest populations

23. The Spread of Shakespeare's Starlings
In 1890, a group of Shakespeare enthusiasts released about 120 starlings in New York's Central Park

24. Today: over 100 million starlings, spread over N. Amer.
Current
1955
Current
1955
1945
1935
1925
1945
1905
1915
1925
1935
1925
1935

26. The starling population in North America has some features in common with the global human population
Both are expanding and are virtually uncontrolled
Both are harming other species

27. Why We Live in Interesting Times…
Pre 2000 A.D.
More youth than elderly
More rural than urban
Post 2010 A.D.
More elderly than youth
More urban than rural
People alive A.D. have seen:
Highest growth rate (2.1%/year)
Population double during their lifetime
More people have lived in the last 100 years, than in all of human history before 1900!

28. “An Essay on the Principle of Population”
Thomas Malthus (1798)
“An Essay on the Principle of Population”
Populations grow geometrically while supporting resources grow arithmetically
Population, if not purposefully checked (“preventative checks”), would outpace resources and lead to unplanned “positive checks” that would return population to sustainable levels

29. HUMAN POPULATION GROWTH
Earth's population: 6 billion (Oct 12, 1999)
Every second, five people are born and two people die, a net gain of three people.
Every day, ,000 = 2 x Champaign-Urbana
This year, ,000,000 = Mexico
This decade +1,000,000,000 = China

30. THE HUMAN POPULATION doubled three times in the last three centuries
about 6.1 billion and may reach 9.3 billion by the year 2050
improved health and technology have lowered death rates

31. The history of human population growth
Figure 35.8A

32. Also reveals social conditions, status of women
The age structure of a population is the proportion of individuals in different age-groups
RAPID GROWTH
SLOW GROWTH
ZERO GROWTH/DECREASE
Kenya
United States
Italy
Male
Female
Male
Female
Male
Female
Ages 45+
Ages 45+
Ages 15–44
Ages 15–44
Under 15
Under 15
Percent of population
Percent of population
Percent of population
Also reveals social conditions, status of women
Figure 35.9B

33. The ecological footprint represents the amount of productive land needed to support a nation’s resource needs
The ecological capacity of the world may already be smaller than its ecological footprint

34. Ecological footprint in relation to ecological capacity
Figure 35.8B

35. Per capita CO2 emissions (metric tons of carbon) Total CO2 emissions
(billion metric tons of carbon) 1 2 3 4 5 6
0.5 1
1.5
U.S.
5.48
U.S.
1.49
China
0.75
China
0.91
Russia
2.65
Russia
0.39
Japan
2.51
Japan
0.32
India
Figure: 29-14ab
Title:
Use of resources per person.
Caption:
The use of natural resources per person (or “per capita”) varies greatly from one country to the next. The average resident of a developed country, such as the United States, uses far more resources than the average resident of a less-developed country, such as India, and this has environmental consequences. (a) One measure of resource use is per-capita carbon dioxide (CO2) emissions: the amount of CO2 a country releases into the atmosphere through human-caused activities, divided by the number of people that country has. The graph displays per-capita CO2 emissions for five countries in 1997, as measured in metric tons of carbon. (b) The differences in per-capita emissions have significant consequences for total emissions within a country. In 1997 the United States released twice as much CO2 into the atmosphere as China, even though it had only one-fifth as many people as China.
0.29
India
0.28

36. What next?

37. Figure 2.10x