AP Environmental Science: Ecosystems

Lecture Overview

• Objective: Explain how resource availability influences species interactions.
• Topics Covered:
  • Predator-prey relationships
  • Symbiosis
  • Competition and resource partitioning
• Skill to Practice: Describing an environmental concept.

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 animals, plants, bacteria, and fungi.
• Ecosystem: Includes both living (biotic) and nonliving (abiotic) components like rocks, soil, and water interacting together.
• Biome: A large area with a similar climate that determines the types of plants and animals living there.
  • Example: Tropical rainforest is warm with high rainfall, supporting diverse species.

Species Interactions

• Competition:

  • Lose-lose situation where organisms fight over shared resources like food or shelter.
  • Limits population size due to scarce resources.

• Predation:

  • One organism uses another as a food source; positive for predator, negative for prey.
  • Types of Predation:
    • Herbivores: Considered predators because they consume plants.
    • True Predators: Carnivores like lions that consume other animals.
    • Parasites: Smaller organisms exploit host for energy without necessarily killing it (e.g., sea lamprey, mosquitoes).
    • Parasitoids: Lay eggs inside host, leading to the host's death (e.g., parasitic wasps).

• Symbiosis: Long-term interaction between different species living closely.

  • Mutualism: Both species benefit (e.g., coral reefs with algae).
  • Commensalism: One species benefits, the other is unaffected (e.g., birds nesting in trees).
  • Parasitism: Parasites live in close association with their hosts.

Detailed Look at Mutualism

• Coral Reefs:

  • Coral species provide structure and CO2 for algae.
  • Algae provide sugars for coral via photosynthesis.
  • Both species are interdependent.

• Lichen:

  • Symbiotic relationship between fungi and algae.
  • They function as a single organism, with fungi providing nutrients and algae providing energy.

Competition and Resource Partitioning

• Resource Partitioning: Reduces competition by allowing species to share resources differently.
  • Temporal Partitioning: Different times for resource usage (e.g., wolves and coyotes).
  • Spatial Partitioning: Different areas of a shared resource (e.g., grass roots at different soil depths).
  • Morphological Partitioning: Evolution of different body features to utilize resources differently (e.g., different jaw sizes in predators).

Practice FRQ

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