Chapter 8 Population Change Principles of Population Ecology

Chapter 8 Population Change

Principles of Population Ecology Population ecologists ask: 1) How many are in the population? 2) Are its numbers increasing / decreasing? 3) What is its pattern of reproduction? 4) What is its pattern of mortality?

Principles of Population Ecology Population Density: • Not enough to know just how many. • Need to know per unit area. 20 / 100 m 2 20 / 25 m 2

Principles of Population Ecology How Do Populations Change in Size? On a global scale (closed system):

Principles of Population Ecology How Do Populations Change in Size? On a local scale (open system):

Principles of Population Ecology How Do Populations Change in Size? Global scale: Growth rate Death rate r= b–d Birth rate

Principles of Population Ecology How Do Populations Change in Size? Local scale: Growth rate Death rate Emigration rate r = (b – d) + (i – e) Birth rate Immigration rate

Principles of Population Ecology Maximum Population Growthunder ideal conditions = intrinsic rate of increase J-shaped curve (exponential growth)

Principles of Population Ecology Environmental Resistance. Exponential growth cannot occur forever. What factors prevent it from doing so? S-shaped curve (logistic growth)

Principles of Population Ecology Overshooting the carrying capacity can lead to a population crash.

Reproductive Strategies Life History Strategies r-selected vs. high growth rate small body size early maturity short life span large broods little / no parental care K-selected slow growth rate large body size late maturity long life span small broods high parental care

Reproductive Strategies Survivorship

Factors that Affect Population Size Density-Dependent Factors • Factors that influence population growth when its density is high. • Predation, competition, disease.

Factors that Affect Population Size Density-Dependence and Boom-or-Bust Population Cycles

Factors that Affect Population Size Case-in-Point: Predatory Prey Dynamics on Isle Royale

Factors that Affect Population Size Density-Independent Factors • Regardless of population density, influences population growth. • Weather, fire.

The Human Population Human population size

The Human Population Current Population Numbers In 2004 = ~6. 4 billion Check out: http: //www. census. gov/main/www/popclock. html

The Human Population Current Population Numbers Rapid growth primarily due to drop in death rates

The Human Population Projecting Future Population Numbers When will zero population growth occur?

Demographics of Countries Most Populous Countries Insert Table 8. 1

Demographics of Countries Developed vs. Developing Countries Insert Table 8. 2 (note Demographics reconstruction)

Demographics of Countries Developed vs. Developing Countries Insert Table 8. 2 (note Demographics reconstruction)

Demographics of Countries Demographic Stages

Demographics of Countries Age Structure of Countries Generalized Age Structure

Demographics of Countries Examples:

Demographics of Countries Examples:

Demographics of Countries Examples:

Demographics of Countries Population Under Age 15:

Demographics of the US Case-in-Point: US Immigration