1. Biology, 9th ed, Sylvia Mader
Chapter 46
Chapter 46
Ecology of Populations
Ecology of Populations

2. Demographics of Populations Population Growth Models
Outline
Scope of Ecology
Demographics of Populations
Population Density and Distribution
Population Growth Models
Survivorship Curves
Age Distributions
Regulation of Population Size
Life History Patterns
Human Population Growth
Environmental Impact

3. Scope of Ecology Ecology
The study of the interactions of organisms with
other organisms, and
The physical environment
Habitat - Place where an organism lives
Population - All the individuals of a species within a particular space
Community – Specified populations interacting with each other
Ecosystem - Community interacting with environment

4. Ecological Levels

5. Density and Distribution of Populations
Biology, 9th ed, Sylvia Mader
Density and Distribution of Populations
Chapter 46
Ecology of Populations
Population Density - Number of individuals per unit area or volume
Population Distribution - Pattern of dispersal of individuals within a space of interest
Ecologists analyze what causes the spatial and temporal “patchiness” of organisms
Limiting factors are factors that predominantly determine whether a species lives in a habitat
2.D.1: Temperature
2.D.1: Sunlight
2.D.1: Population density
Resources are living and nonliving components of an environment that support living organisms (light, water, space, mates and food). Limiting factors are environmental aspects that determine where an organism lives.

6. Distribution Patterns of the Creosote Bush

7. Environmental Resistance
Population Growth
Exponential Growth
Rate of increase increases as the total number of females increases
Biotic Potential
Maximum population growth that can possibly occur under ideal circumstances
Environmental Resistance
All environmental conditions that prevent populations from achieving biotic potential
Biotic potential is having full effect and birthrate is a maximum during exponential growth

8. Mortality Patterns A cohort Survivorship
Composed of all the members of a population born at the same time
Survivorship
The probability that newborn individuals of a cohort will survive to a particular age
Survivorship Curves

9. Survivorship Curves

10. What proportion of the population falls into various age categories
Age Distributions
What proportion of the population falls into various age categories
At least three structures possible
Increasing
Stable
Decreasing

11. Age Structure Diagrams

12. Patterns of Reproduction

13. Model for Exponential Growth

14. Logistic Growth Logistic growth
Occurs when environmental resistance retards exponential growth
Growing populations must eventually come under the control of environmental resistance

15. Model for Logistic Growth

16. Regulation of Population Size
Biology, 9th ed, Sylvia Mader
Regulation of Population Size
Chapter 46
Ecology of Populations
Density-dependent Factors
Number of organisms present influences the effect of the factor
Competition
Predation
Density-independent Factors
Number of organisms present does not influence the effect of the factor
Natural disasters
2.D.1: Population density
2.D.3: Hurricanes, floods, earthquakes, volcanoes, fires

17. Density-dependent Effect

18. Density-independent Effect

19. Carrying Capacity Carrying Capacity
The maximum number of individuals of a species the environment can continuously support
The closer the population to the carrying capacity, the greater the environmental resistance

20. Density-dependent Effects - Competition

21. Density-dependent Effects - Predation

22. r - Strategists (Opportunistic)
Life History Patterns
r - Strategists (Opportunistic)
Produce large numbers of offspring
Small body size
Early maturity
No parental care
Controlled by density-independent factors
Good dispersers and colonizers

23. k - Strategists (Equilibrium)
Life History Patterns
k - Strategists (Equilibrium)
Produce small numbers of offspring
Large body size
Late maturity
Significant parental care
Controlled by density-dependent factors
Specialists

24. Parental Care Among Frogs and Toads

25. Life History Strategies

26. Human Population Growth
Human population has an exponential growth pattern
Doubling time currently estimated at 53 years
Population Size
Billion
Billion
Billion
Billion

27. More-Developed Countries (MDCs)
Country Development
More-Developed Countries (MDCs)
Slow population growth
High standard of living
Completed Demographic Transition
North America and Europe
Less-Developed Countries (LDCs)
Rapid population growth
Low standard of living
Latin America
Africa and Asia

28. World Population Growth

29. Age Structure Diagrams
Age Distributions
Age Structure Diagrams
Show proportions of population at various age groups
Divide populations into three age groups
Pre-Reproductive
Reproductive
Post-Reproductive

30. Age Structure Diagrams (2002

31. Environmental impact of a population is measured in terms of:
Population size
Resource consumption per capita
Resultant pollution

32. Environmental Impact Caused by MDCs & LDCs

33. Biology, 9th ed, Sylvia Mader
Chapter 46
Ending Slide Chapter 46
Ecology of Populations
Ecology of Populations