Lecture Notes: AP Bio Unit 8 - Ecology
Lecture Summary
This lecture covers AP Biology Unit 8 on Ecology, focusing on how organisms respond to their environments and exchange information, and the energy strategies of organisms. Key topics include responses of organisms to environmental changes, exchange of information through various communication methods, reproductive strategies of organisms, energy conservation and expenditure in organisms, and population dynamics with regard to resource availability.
Organism Responses to the Environment
- Phototropism (plants growing towards light) and photoperiodism (plants blooming based on day length).
- Hibernation/Brumation (animals entering a dormant state).
- Circadian rhythms (aligning gene expression and hormone levels with the sun cycle).
- Changes in gene expression (e.g., arctic animals changing fur color).
Organism Communication
- Chemical communication via pheromones affecting behavior and physiology. Pheromones can signal mating readiness or danger.
- Visual signals: examples include fireflies lighting up, dogs raising fur, and human blushing.
- Auditory communication: whale songs or howling.
- Tactile communication: animals showing affection through touch, like baboons grooming.
- Communication can indicate dominance, find food, establish territory, and ensure reproductive success.
Reproductive Strategies and Natural Selection
- R vs. K selection theory: R-selected species produce many offspring with high mortality rates, while K-selected species invest heavily in fewer offspring with higher survival chances.
- Examples of innate behaviors: Ducklings imprinting on their mother, sea turtles moving towards the ocean light.
- Cooperative behaviors increase individual fitness and the survival of the species.
Energy Strategies and Thermoregulation
- Endotherms and Ectotherms: Endotherms use metabolic heat to maintain temperature; ectotherms depend on environmental heat.
- Metabolic rates vary with animal size and environmental conditions.
- Thermoregulation in animals: involves using body features like fat, feathers, or large ears for heat regulation.
Population Dynamics and Ecosystems
- Population growth models: Exponential growth (unlimited resources) and logistic growth (limited by carrying capacity).
- Survivorship curves: illustrate different survival rates across species' lifespans.
- Predator-prey dynamics impact population sizes and can cause oscillations in ecosystem populations based on available resources.
- Density-dependent vs. Density-independent factors: affect population growth through phenomena like competition, predation, and environmental conditions.
Community Ecology
- Role of energy and matter: Transfers through food webs define ecosystem structures.
- Species diversity and resilience: Communities with more species diversity tend to be more resilient to disturbances like invasive species.
- Community interactions: influence population dynamics and ecosystem health, demonstrating the importance of keystone species and trophic levels.
This lecture provides foundational knowledge on how ecological principles influence the behavior, survival, and interaction of organisms within ecosystems, emphasizing the importance of understanding these dynamics for managing and conserving biodiversity.