AP Biology Unit 8: Ecology

Introduction

• The last unit of AP Biology focuses on Ecology.
• Understanding the organization of the world from a biological perspective.

Levels of Organization

1. Organism
   • Individual living entity.
2. Population
   • Group of the same species living in a specific area.
3. Community
   • Multiple populations interacting in an area.
4. Ecosystem
   • Includes all living (biotic) and non-living (abiotic) components.
5. Biosphere
   • Sum of all ecosystems on Earth.

Animal Behavior

• Focuses on what organisms do in response to environmental stimuli.
• Innate Behaviors: Reflexes and fixed action patterns.
• Learned Behaviors: Habituation, imprinting, and conditioning.

Tinbergen's Four Questions

1. What causes the behavior? (Stimulus)
2. How does it develop? (Innate vs. learned)
3. How does it affect fitness?
4. How did it evolve?

Environmental Cues

• Migration: Moving from one place to another.
• Hibernation: Sleeping through winter.
• Estivation: Sleeping through summer.
• Circadian Rhythms: 24-hour body cycles.

Endotherms vs. Ectotherms

• Endotherms: Generate own heat (warm-blooded).
• Ectotherms: Rely on environmental heat (cold-blooded).
• Energy requirements differ significantly.

Metabolic Rates

• BMR (Basal Metabolic Rate): Endotherms.
• SMR (Standard Metabolic Rate): Ectotherms.

Temperature Regulation

• Endotherms: Shivering, brown fat, vasoconstriction/dilation.
• Ectotherms: Behavioral thermoregulation (basking).

Life History

• Strategies for reproduction and survival.
• Semelparity: Single reproductive event.
• Iteroparity: Multiple reproductive cycles.

Population Growth

• Exponential Growth: Unlimited resources.
• Logistic Growth: Limited by carrying capacity.

Factors Affecting Growth

• Density-Dependent: Competition, disease.
• Density-Independent: Natural disasters.

Food Webs

• Producers (Autotrophs): Create own food.
• Consumers (Heterotrophs): Consume others for energy.
• Decomposers: Break down dead material.

Energy Transfer

• Only 10% of energy is transferred to the next trophic level.

Community Interactions

• Interspecific interactions: Between different species.
• Competition: -/-
• Predation: +/-
• Symbiosis: Mutualism (+/+), Commensalism (+/0), Parasitism (+/-)

Biodiversity

• Species Richness: Number of different species.
• Relative Abundance: Proportion of each species.

Human Impact on Ecology

• Invasive Species: Disrupt local ecosystems.
• Climate Change: Alters habitats, impacts species.
• Extinctions: Loss of biodiversity impacts ecosystems.

Conclusion

• Ecology covers complex interactions in the natural world.
• Understanding these concepts is crucial for conservation and managing ecosystems.