AP Biology Unit 8: Ecology

Introduction

• Presented by Mikey with AAL Prep Academy.
• Covers the last unit of AP Biology, focusing on various parts of ecology.
• Structured as a bottom-up approach.

Big Ideas in Ecology

Definition of Ecology

• Study of organisms and their environment.
• Hierarchy: Global, Landscape, Ecosystems, Community, Population Ecology.

Patterns of Environments

• Geographical distribution and types of biomes (rainforest, desert, tundra).
• Biomes influenced by types of plants (primary producers) and climate (precipitation, temperature).

Organismal Interactions with Environment

• Species develop features and behaviors in response to environmental factors.
• Example: Circadian rhythms aligned with Earth's 24-hour rotation cycle.

Population Ecology

Definition

• Population: Group of individuals of a single species in a general area.

Population Dynamics

• Focus on growth and shrinkage (birth, death, immigration, emigration).
• Growth models: Logistic growth model illustrates population size in finite environments.
• Carrying capacity (K): Maximum population size an environment can sustain.

Factors Affecting Population Growth

• Density-dependent factors: Resource limitation, toxin buildup, disease spread.
• Density-independent factors: Natural disasters.

Distribution Patterns

• Clumped, random, uniform distributions based on resources, behaviors.

Survivorship Curves

• Type 1: High infant survival, high old age mortality.
• Type 2: Consistent mortality rate.
• Type 3: High infant mortality, lower adult mortality.

Reproductive Strategies

• Semelparity: Single reproductive event (e.g., salmon).
• Iteroparity: Multiple reproductive events (e.g., humans, most mammals).

Community Ecology

Definition

• Community: Populations of different species interacting closely.

Interactions Among Species

• Competition: Minus-minus interaction, competitive exclusion, niche partitioning.
• Predation & Herbivory: Plus-minus interactions, adaptations like camouflage, warning coloration.
• Symbiosis: Mutualism (both benefit), commensalism (one benefits, other unaffected), parasitism (one benefits, one harmed).

Trophic Relationships

• Energy flow model: 10% of energy transferred between trophic levels.
• Food webs: Complex interactions, keystone species impact

Biodiversity

• High species richness and evenness increases resilience to pathogens, invasive species.
• Invasive species thrive due to high reproduction, rapid growth, and lack of natural predators.

Disturbances

• Disturbances (fire, floods) can recycle nutrients, create opportunities (intermediate disturbance hypothesis).
• Ecological succession: Primary (starts from bare rock) vs. secondary (post-disturbance but soil intact).

Ecosystems Ecology

Focus

• Flux of substances between biological and non-biological systems.
• Decomposers recycle nutrients, role of bacteria and fungi.
• Nutrient cycles: Water, carbon, phosphorus, nitrogen cycle.

Human Impact

• Anthropogenic carbon dioxide increases temperature, affects species distribution.
• Enzyme activity sensitive to temperature changes.

Conclusion

• Comprehensive overview of ecology for AP Biology exam preparation.
• Emphasizes understanding interactions and processes rather than memorizing equations.
• Encouragement to review previous content for exam preparedness.