C4.1.13 Resource competition between endemic and invasive species Notes

Invasive Species Disrupt Ecosystems by Outcompeting Endemic Species

1. Invasive species often outcompete endemic species for limited resources, leading to significant ecological disruptions.
2. This competition can result in population declines, habitat displacement, and long-term ecosystem instability.

Example

1. Cane toads in Australia, which outcompete native species is an example of an invasive species.
2. More on this later...

Endemic vs. Invasive Species

Endemic Species

1. Naturally occurring in a specific region.
2. Highly adapted to local environmental conditions.
3. Often have specialized niches and rely on balanced ecosystem interactions.

Invasive Species

1. Non-native species are introduced, often by human activity.
2. Spread rapidly and can disrupt native ecosystems.
3. Often lack natural predators in their new environment.

The Competitive Exclusion Principle

1. If an invasive species has a competitive advantage, it can displace endemic species by:
   1. Outcompeting for Resources: Taking over food, water, or breeding sites.
   2. Occupying a Broader Niche: Exploiting more resources than native species.
   3. Reproducing More Rapidly: Growing in population faster than endemic competitors.

A Local Example: The Cane Toad in Australia

1. The Cane Toad (Rhinella marina) was introduced to Australia in 1935 to control agricultural pests.
2. Instead of helping, it became an invasive species, rapidly spreading across northern and eastern Australia.
3. Why Cane Toads Outcompete Native Species:
   1. Broad Diet: Generalist feeders, eating insects, small mammals, and even amphibians.
   2. Rapid Reproduction: A single female can lay up to 30,000 eggs at a time.
   3. Toxicity: Produces a potent toxin, killing most predators that try to eat them.
   4. High Adaptability: Thrives in diverse habitats, from wetlands to urban areas.

Impact on Endemic Species

The competitive advantages of cane toads have caused severe ecological damage, particularly for Australia’s native amphibians, reptiles, and predators.