Unit 3 Ultimate Review Packet

Overview

• Focus on populations from both a natural ecosystem and human standpoint.
• First five topics: natural population dynamics.
• Last four topics: human population dynamics.

Natural Population Dynamics

3.1 Generalist vs. Specialist Species

• Specialist Species: Narrow niche, unique habitat/food needs (e.g., pandas).
• Generalist Species: Broad tolerance range, adaptable to changes (e.g., raccoons).
• Generalists thrive in changing ecosystems; specialists thrive in stable ecosystems.

Reproductive Strategies

• R-Strategists (Quantity over Quality)

  • Produce many offspring with little parental care.
  • High population growth rate, often smaller organisms.
  • Advantages in abundant resource environments.

• K-Strategists (Quality over Quantity)

  • Produce few offspring with high parental investment.
  • Larger organisms, longer lifespan, live near carrying capacity.
  • Advantages in competitive environments.

• Impact on Ecosystems

  • R-strategists can be invasive due to high reproduction.
  • K-strategists vulnerable to competition.

Survivorship Curves

• Type 1: High survival rate in early and middle life (K-selected species).
• Type 3: High mortality in early life (R-selected species).
• Type 2: Constant mortality rate throughout life (birds, small rodents).

Carrying Capacity

• Maximum number of individuals an ecosystem can support.
• Limiting Resources: food, water, shelter.
• Overshoot and Dieback: Population exceeds capacity, then a decline.
• Influenced by density-dependent factors (competition, disease) and density-independent factors (natural disasters).

Population Distribution

• Uniform: Evenly spaced (seabirds).
• Random: No predictable pattern (trees).
• Clumped: Group living species (herds).

Growth Models

• Exponential Growth: Ideal, unlimited resources (J-shaped curve).
• Logistic Growth: Realistic, limited by carrying capacity (S-shaped curve).

Human Population Dynamics

Age Structure Diagrams

• Visualize age cohorts (pre-reproductive, reproductive, post-reproductive).
• Population growth rate inferred from cohort sizes.
  • Larger pre-reproductive suggests high growth rate.
  • Equal cohorts suggest stable or slow growth.

Total Fertility Rate (TFR)

• Average number of children born per woman.
• Influenced by age of first child, economic, social, cultural factors.
• Education and economic opportunity lower TFR.

Birth and Death Rates

• Crude Birth Rate (CBR): Births per 1,000 people.
• Crude Death Rate (CDR): Deaths per 1,000 people.
• Growth Rate Calculation: (CBR - CDR) / 10.
• Doubling Time: Rule of 70, divide 70 by growth rate.

Malthusian Theory

• Population growth exceeds food supply, predicting famine.
• Technological advances (Green Revolution) increased food supply.

Demographic Characteristics

• Infant Mortality: High rates increase TFR.
• Replacement Level Fertility: Number of children needed to maintain population size.
• GDP: Economic indicator, correlates with educational and healthcare advancement.

Demographic Transition Model

• Phase 1 (Pre-Industrial): High birth/death rates, low growth.
• Phase 2 (Industrializing): Decreasing death rates, high growth.
• Phase 3 (Industrialized): Decreasing birth rates, growth slows.
• Phase 4 (Post-Industrial): Low birth rates, possible negative growth.

Conclusion

• Comprehensive review of population dynamics.
• Importance of understanding growth models and demographic transitions.
• Practice with population growth calculations and demographic analysis.