Download Patterns in Evolution

Patterns in Evolution
Divergent Evolution
• Defined: closely related species become
increasingly different
• Cause: Different environments
• Ex: Red fox (forest) vs. Kit fox (desert)
Convergent Evolution
• Defined: different species evolve similar traits due to a
similar environment
• Ex: Tuna (fish) and dolphins (mammals)
– Advantage: Smooth, streamlined, flippers
– Distantly related species with a similar environment
(ocean)
Coevolution
• Defined: 2 or more species evolve in response to
changes in each other
• Ex: Plants and Insects
– Plants: provide insects with nectar
– Insect: transfers pollen from one plant to another
Hummingbirds: Beak shape
depends on flower shape
Which hummingbird had adapted to feeding on the
nectar of curved flowers?
Extinction
• Background Extinctions:
– Less severe; local level
– Forest fires, habitat destruction
• Mass Extinctions:
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learn more
– Very severe; global level
– 5 identified in earth’s history (volcanic activity,
meteor strikes)
How Fast Does Evolution Occur?
• No exact time frame
• Gradualism: slow & steady change of 1 species into another
– Small changes continually build
• Punctuated Equilibrium: Rapid periods of evolution
– Due to sudden environment change
– Ex: Mammal diversity exploded after dinosaur extinction
• Examples of both models exist
Gradualism
of the Horse
Kobe Kuiz
• How is convergent and divergent evolution different?
• What is thought to bring different organisms such as fish and dolphins to
have evolved a similar body plan?
• What is coevolution?
• What does a flower gain from a close relationship with a hummingbird?
• What does the hummingbird gain?
• How is gradualism and punctuated equilibrium different?