AP Biology Unit 8 Review: Ecology

Introduction

• Unit 8 covers complex concepts, mathematical models, extensive vocabulary.
• Topics include animal behavior, energy utilization and flow, population growth, community ecology, biodiversity, and ecosystem disruption.
• Review aims to prepare students for AP Bio exam and Unit 8 test.

Topic 8.1: Responses to the Environment

• Case Studies in Animal Behavior
  • Predator Warnings: Alarm signals in animals.
  • Example: Belding’s ground squirrel and African vervet monkeys.
  • Kin Selection and Inclusive Fitness
    • Kin selection: Gene value based on its promotion of survival in relatives.
    • Inclusive fitness: Altruism can increase allele frequency.
  • Study by Paul Sherman on Belding’s ground squirrels:
    • Females more likely to emit alarm calls due to kin selection.
• Eusociality
  • Social structure with reproductive division of labor (e.g., bees, ants, termites).
  • Explained by haplodiploidy in insects.

Topic 8.2: Energy Utilization and Flow

• Metabolism and Energy Use
  • Metabolism: Sum of all chemical processes in an organism.
  • Metabolic rate varies with temperature and size.
• Ectotherms vs. Endotherms
  • Ectotherms: Body temperature varies with environment.
  • Endotherms: Maintain constant temperature.
• Energy Flow in Ecosystems
  • Food chains and food webs illustrate energy transfer.
  • Trophic levels: Producers, consumers, decomposers.
  • 10% Rule: Only 10% of energy transfers between trophic levels.
• Biogeochemical Cycles
  • Carbon cycle: Involves photosynthesis, respiration, decomposition, and combustion.

Topics 8.3 to 8.4: Population Growth

• Population Dynamics
  • Four factors: Births, deaths, immigration, emigration.
• Growth Models
  • Exponential Growth: Rapid, unlimited growth.
  • Logistic Growth: Growth limited by carrying capacity (K).
• Factors Affecting Growth
  • Density-dependent: Competition, predation, disease.
  • Density-independent: Natural disasters.

Topic 8.5: Community Ecology

• Symbiotic Relationships
  • Types: Competition, mutualism, predation, herbivory, commensalism, parasitism.
• Niche Concepts
  • Fundamental vs. Realized Niche.
• Keystone Species and Trophic Cascades
  • Keystone species influence community structure (e.g., sea stars, wolves).
• Ecological Succession
  • Primary vs. secondary succession.
  • Climax community formation.

Topic 8.6: Biodiversity

• Components of Biodiversity
  • Ecosystem diversity, species diversity, genetic diversity.
• Benefits of Biodiversity
  • Increases resilience, provides ecosystem services.
• Simpson's Diversity Index
  • Measures species richness and evenness.

Topic 8.7: Ecosystem Disruption

• Human Impact on Ecosystems
  • Causes of biodiversity loss: Habitat destruction, overexploitation, fragmentation, invasive species, deforestation.
  • Sixth mass extinction driven by human activity.

Conclusion

• The review covers the breadth of Unit 8 and equips students with the knowledge needed for exams.
• Further study and practice recommended to fully master the material.