Unit 3 Evidence of Evolution and Biodiversity Part 3 Evolution and Natural Selection

Who was Charles Darwin Studied medicine Hated the sight of blood Darwin was a Naturalist who studied plants and animals

Theory of Evolution Darwin set sail on the HMS beagle where he studied many different plants and animals Darwin learned that similar looking species lived close to each other and proposed that species do change over time The Theory of evolution is based on the idea that species are all related and change over time

“Natural Selection” Darwin’s Finches In The Galapagos Islands, Darwin collected species of finches (13) Each had a specialized diet and beak structure These finches all closely resembled a South American finch ancestral species On the trip Darwin saw things he could only attribute to a process called: “Natural Selection”

Darwin called this process by which populations change in response to their environment: Natural Selection

Darwin’s Finches

Natural Selection is based on these inferences: There is variation within populations Some variations are favorable Not all young produced in each generation can survive Individuals that survive and reproduce are those with favorable variations Favorable traits will increase in future generations. Survival of the Fittest

Types of Evolution Adaptive Radiation Divergent Evolution Co-Evolution Convergent Evolution

Adaptive Radiation Evolution of many diverse species from one common ancestor Ex: famous Galapagos finches discovered by Darwin

Divergent Evolution (spread apart) -Isolated populations evolve independently Ex: polar & grizzly bears changed independently due to different habitats

Coevolution (together) -Species that interact closely adapt to one another Ex: Flowers & Pollinators (Birds, Bees and Butterflies too)

Convergent Evolution (come together) -Unrelated species become more alike because they live in similar environments Ex: shark & dolphin

Speed of Evolution? 2 thoughts

Gradualism The idea that species evolve slowly and continuously over long periods of time, or “gradually”

Punctuated Equilibrium evolution occurs primarily through short bursts followed by lengthy periods of stasis. We see this in fossil data.