Here's a breakdown of what happens:
1. Competition:
- Both species require the same limited resources (food, space, mates, etc.).
- They will compete for these resources, leading to a struggle for survival.
2. Competitive Advantage:
- One species will likely have a slight competitive advantage due to factors like:
- Better adaptation: They may be better at acquiring resources, avoiding predators, or tolerating environmental conditions.
- Greater reproductive rate: They may reproduce faster, producing more offspring.
- Disease resistance: They may be more resistant to diseases that affect the other species.
3. Outcomes:
- Competitive Exclusion: The species with the competitive advantage will gradually outcompete the other, eventually leading to its extinction or forced migration to a different area.
- Resource Partitioning: Sometimes, species can adapt to avoid direct competition. They may specialize in slightly different aspects of the shared niche, leading to resource partitioning. This allows both species to coexist, albeit with a reduced niche compared to if they were alone.
- Character Displacement: One or both species may evolve to have different traits, reducing competition. For example, they may develop different beak sizes to exploit different food sources.
Examples:
* Darwin's Finches: On the Galapagos Islands, different finch species evolved different beak shapes and sizes to exploit different food sources, reducing competition for the limited resources.
* Red Squirrel vs. Grey Squirrel: The introduction of the grey squirrel to the UK has led to the decline of the native red squirrel, due to competition for food and habitat.
Key takeaways:
- Competitive exclusion is a powerful force in shaping ecosystems.
- Species that attempt to occupy the same niche will face intense competition, leading to a winner and a loser.
- Resource partitioning and character displacement can sometimes allow species to coexist, but competition often leads to a winner-takes-all scenario.
