Ecology and Invasive Species

Definition: Invasive species are organisms introduced to a non-native environment where they outcompete native species due to aggressive behaviors.
Impact on Ecosystem:
- Invasive species tend to reduce biodiversity by dominating the resources in an ecology, leading to native species declines or extinctions.
- They disrupt local food webs and can alter the structure of the habitat.

Mechanism of Introduction:
- Commonly introduced through shipping processes, specifically through the ballast water of ships.
- Ships take in seawater (containing organisms) to maintain balance and release it upon reaching new environments, bringing potentially harmful species with them.
Example Context:
- Ships arriving from places like Japan may release ballast water in Savannah, Georgia, introducing non-native species that disrupt local ecosystems.

Concept of Niche:
- A niche is defined as the role or job an organism plays in its environment.
- Each niche can only be filled by one organism; competition arises when multiple organisms vie for the same niche, applying the principle of competitive exclusion.
Implications of Biodiversity:
- A greater variety of species (biodiversity) allows for more available niches, leading to a more stable ecosystem.

Six Main Relationships:
- Parasitism: One organism benefits while the other is harmed (e.g., ticks on dogs).
- Mutualism: Both organisms benefit from the relationship (e.g., pollinators and flowers).
- Commensalism: One organism benefits while the other is unaffected.
- Competition: Organisms compete for limited resources, impacting each other's survival.
- Predation: One organism hunts and eats another, contributing to dynamics of populations.
- Cooperation: Interaction between members of the same species that benefit group or population size.

Phases of Population Growth:
- Lag Phase (Phase 1): Slow growth as organisms acclimate to the environment.
- Exponential Growth Phase (Phase 2): Rapid increase in population when resources are abundant.
- Stationary Phase (Phase 3): Population levels off as resources become limited (approaching carrying capacity).
Carrying Capacity:
- The highest population size that an environment can sustainably support.
- Fluctuations can occur due to limiting factors that control population size.

Density Dependence:
- Predator populations increase as prey become more abundant.
- Example: Wolf and moose populations fluctuate based on their interaction; more moose leads to more wolves, which eventually leads to fewer moose as they're consumed.
Bioaccumulation:
- Accumulation of toxins in an organism as it consumes multiple contaminated food sources (e.g., barracuda and mercury poisoning).
- Higher trophic levels tend to have higher concentrations of toxins due to bioaccumulation.

Energy Transfer:
- Only about 10% of energy is passed from one trophic level to the next.
- For example, if a primary producer has 100 units of energy, a primary consumer receives 10 units, and a secondary consumer receives 1 unit.
Biomass Pyramid:
- The distribution of energy and matter within an ecosystem is demonstrated through the biomass pyramid, indicating that biomass decreases as you move up in trophic levels.

Case of Termite Mounds in Mozambique:
- Different species adapt to utilize various resources (plants) found on termite mounds, thus avoiding direct competition.
- Unique dietary preferences among species allow them to coexist.
Importance of Plant Diversity:
- Promotes coexistence by ensuring that species can access enough resources without outcompeting one another.

Niche Definition: The unique role of an organism in its habitat.
Competitive Exclusion Principle: No two species can occupy the same niche indefinitely.
Ecology Dynamics: Understanding these relationships is crucial for maintaining stable ecosystems.