AP Environmental Science: Ecosystems and Species Interactions

Introduction

• Objective: Explain how resource availability influences species interactions.
• Key Topics:
  • Predator and prey relationships
  • Symbiosis
  • Competition and resource partitioning

Ecosystem Basics

• Individual: One single organism (a living thing).
• Population: Group of organisms of the same species.
• Community: All living organisms in a given area, including plants, animals, bacteria, and fungi.
• Ecosystem: Living organisms plus non-living components (rocks, soil, water).
• Biome: Large area with a similar climate, determining the types of plants and animals present (e.g., tropical rainforest).

Species Interactions

1. Competition

• Definition: Lose-lose situation where organisms compete over shared resources like food or shelter, limiting population size.

2. Predation

• Predation:
  • One organism uses another as its energy source.
  • Examples include herbivores (e.g., giraffes eating leaves) and true carnivores (e.g., leopards, lions).
• Parasites:
  • Smaller organism uses host for energy without necessarily killing it (e.g., sea lamprey on fish).
• Parasitoids:
  • Lay eggs inside a host; larvae eat the host (e.g., parasitic wasp with caterpillar).

3. Symbiosis

• Definition: Long-term interaction between two species living closely.
• Types:
  • Mutualism: Win-win; both species benefit (e.g., coral reef and algae).
  • Commensalism: One species benefits, the other is not significantly impacted (e.g., birds nesting in trees).
  • Parasitism: Parasites and hosts can be symbiotic due to long-term association.

4. Mutualism

• Example: Coral reef ecosystem with coral and algae.
  • Coral provides structure and CO2 for algae.
  • Algae provide sugars via photosynthesis for coral.
• Lichen: Example of organisms functioning as one (fungi and algae).

Competition and Resource Partitioning

• Definition: Both species lose from direct competition.
• Resource Partitioning: Allows species to share resources and reduce competition without direct confrontation.
  • Temporal Partitioning: Use resources at different times (e.g., wolves and coyotes hunting at different times).
  • Spatial Partitioning: Use different areas of a resource (e.g., grasses with different root depths).
  • Morphological Partitioning: Evolve different body features to utilize different parts of the resource (e.g., different jaw sizes in ferrets and ermines).

Practice FRQ

• Task: Identify two organisms that compete for a shared resource and describe how resource partitioning could reduce this competition.

Conclusion

• Reminder: Think like a mountain, write like a scholar.
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