2. Population Ecology

3. Population Dynamics Population:
All the individuals of a species that live together in an area
Demography:
The statistical study of populations, allows predictions to be made about how a population will change
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

4. Population Dynamics Three Key Features of Populations Size Density
Dispersion
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

5. Three Key Features of Populations
Size: number of individuals in an area
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

6. Three Key Features of Populations
Growth Rate:
Birth Rate (natality) - Death Rate (mortality)
How many individuals are born vs. how many die
Birth rate (b) − death rate (d) = rate of natural increase (r)
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

8. Three Key Features of Populations
Density: measurement of population per unit area or unit volume
Pop. Density = # of individuals ÷ unit of space
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

9. How Do You Affect Density?
Immigration: movement of individuals into a population
Emigration: movement of individuals out of a population

10. 3. Density-dependent factors: Biotic factors in the environment that have an increasing effect as population size increases (disease, competition, parasites)
4. Density-independent factors: Abiotic factors in the environment that affect populations regardless of their density (temperature, weather)

11. Population Dispersion

12. Three Key Features of Populations
Dispersion: describes the spacing of organisms relative to each other
Clumped
Uniform
Random
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

13. 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
Mark-Recapture Method

14. How Do Populations Grow?
Idealized models describe two kinds of population growth:
Exponential Growth
2. Logistic Growth

15. Carrying Capacity Carrying Capacity (k):
The maximum population size that can be supported by the available resources
There can only be as many organisms as the environmental resources can support
Although several species may share a habitat they each have their own niche. A niche is a very narrow range where a species fits within a habitat.

16. Exponential Growth Curve
Figure 35.3A

17. Logistic Growth Curve

18. Factors Limiting Growth Rate
Declining birth rate or increasing death rate are caused by several factors including:
Limited food supply
The buildup of toxic wastes
Increased disease
Predation

19. Reproductive Strategies
R Strategists
Short life span
Small body size
Reproduce quickly
Have many young
Little parental care
Ex: cockroaches, weeds, bacteria

20. Reproductive Strategies
K Strategists
Long life span
Large body size
Reproduce slowly
Have few young
Provides parental care
Ex: humans, elephants

21. 1. What type of growth model does this graph show?

22. 2. If angelfish produce hundreds of young several times a year, which statement below is true?
Angelfish have a k-strategy reproductive pattern.
Angelfish have a r-strategy reproductive pattern

23. 3. If an aquarium holds 80 L of water and contains 170 guppies, what is the approximate density of the guppy population?

24. 4. Which is a density-independent factor?
A severe drought
An intestinal parasite
A fatal virus
Severe overcrowding

26. Why is the lifespan of this finch with an eye disease most likely reduced?
The bird cannot mate.
The bird cannot find food or water.
The bird spreads the disease to others.
The bird cannot survive a temperature change.

27. Increase in population density Increased immunity
Which is a possible reason for the relative quick spread of the shown disease?
An abiotic factor
A decrease food supply
Increase in population density
Increased immunity

28. What is the reproductive strategy of the animal in the photo
What is the reproductive strategy of the animal in the photo. Explain your answer.

29. The Human Population Doubled three times in the last three centuries
About 7.3 billion and may reach 9.3 billion by the year 2050
Improved health and technology have lowered death rates

30. History of the Human Population

31. Human Population Growth
J curve growth
Grows at a rate of about 80 million yearly
r =1.3%
Why doesn’t environmental resistance take effect?
Altering their environment
Technological advances
The cultural revolution
The agricultural revolution
The industrial-medical revolution

32. Trends in Human Population Growth
The change in population from high birth rate and death rates to low birth rates and death rates is called demographic transition.
Zero population growth occurs when births plus immigration equals deaths plus emigration.

33. Age Distribution
Distribution of males and females in each age group of a population
Pre-reproduction (before 20 yrs old)
Reproduction( yrs old)
Post-reproduction ( 45 and up)
Used to predict future population growth

35. What is the dispersion pattern of herding animals, birds that flock together, and fish that form schools?
Clumped
Random
Uniform
Unpredictable