5.5 Speciation; Patterns in Evolution

Patterns in Evolution

4 patterns can lead to formation of new species:

1. Divergent Evolution

2. Adaptive Radiation

3. Convergent Evolution

4. Coevolution

Divergent Evolution

• two or more species evolve from a common ancestral species due to disruptive selection or genetic drift

Adaptive Evolution

• divergent evolution occurs rapidly because many new habitats open up to a colonizing species

Convergent Evolution

• two species that do not share a recent common ancestor develop very similar structural or behavioural features because they experience similar selective forces

• Sharks and dolphins are very similar in morphology, not because they have a recent common ancestor, but because they share a common environmental niche

Coevolution

• one species evolves in response to evolution of another species

• Some flowering plants have coevolved with their pollinators, so that only one species of insect is able to pollinate a given plant species

Leaf cutter ants have coevolved with a specific species of fungus

1. Ants don’t eat leaves they cut

2. Ants use leaves to grow fungus that they eat