Ecology and Symbiosis

Ecological Concepts

• Carrying capacity: the maximum number of individuals of a species that an environment can support indefinitely.

Symbiosis

• Three types of symbiosis:
  • Mutualism: both species benefit (e.g., clownfish and sea anemone)
  • Commensalism: one species benefits, the other is not affected (e.g., remora fish and shark)
  • Parasitism: one species benefits, the other is harmed (e.g., tapeworm and human)

Limiting Factors

• Abiotic limiting factor: a non-living factor that affects population growth (e.g., availability of water for a zebra population)
• Biotic limiting factor: a living factor that affects population growth (e.g., competition for food among zebras)

Predator-Prey Relationships

• Predation: killing and consuming another organism (e.g., lion and zebra)
• Competition: struggling for the same resources (e.g., zebras and antelopes competing for food)

Biodiversity

• Importance: maintains ecosystem stability, provides ecosystem services, and supports human well-being
• Decrease in biodiversity: can be caused by habitat destruction, pollution, climate change, and overexploitation
• Consequences: if one species' population decreases, other species in the food web may be affected

Ecological Roles

• Keystone species: has a disproportionate impact on its environment (e.g., sea otters and kelp forests)
• Dominant species: has a significant impact on its environment due to its abundance or size (e.g., elephants in savannas)
• Ecosystem engineer: modifies its environment in ways that benefit other species (e.g., beavers and their dams)

Biodiversity Hotspots

• Definition: areas with high levels of endemism and threatened species (e.g., Madagascar)

Human Impact on Ecosystems

• Human activities leading to extinction: habitat destruction, pollution, climate change, and overexploitation
• Invasive species: zebra mussels in the Great Lakes region
• Harm caused by invasive species: competition for resources, habitat destruction, and spread of disease

Forestry Practices

• Three types: clear-cutting, selective cutting, and reforestation
• Advantages and disadvantages: clear-cutting (efficient but destructive), selective cutting (minimizes damage but time-consuming), reforestation (restores ecosystem but slow process)

Acid Precipitation

• Effects: acidification of lakes, damage to forests and aquatic life, and negative impacts on human health

Pesticides

• Three types: insecticides, herbicides, and fungicides
• Intended targets: insects, weeds, and fungi
• Consequences: bioaccumulation, bioamplification, and harm to non-target species

Bioaccumulation and Bioamplification

• Bioaccumulation: the accumulation of pollutants in an organism's tissues
• Bioamplification: the increase in pollutant concentration as you move up the food chain
• Consequences: harm to humans and wildlife through the consumption of contaminated organisms

Pollution

• Increase in pollution over the past 50 years: population growth, industrialization, and increased resource consumption
• Types of pollution: land, water, and air pollution

Overexploitation

• Definition: the unsustainable use of resources
• Example: overfishing

Restoration Ecology

• Goal: to restore degraded ecosystems to their natural state
• Two practices: ecological restoration and ecosystem rehabilitation
• Intention: to restore ecosystem services and biodiversity