Evidence for Evolution

A slide extravaganza…

Types of evidence…

1. Evidence from the fossil record (dead things)

Fossil formation

Bones and shells undergo mineral replacement and are turned into rock

Soft material either disappears, or leaves an impression in the earth (that turns to rock)

A selection of fossils…

Fossils show transitions

The Archaeopterix -- between reptile and bird

Scallops

From early to modern horse

(Living things show transitions too)

Coelacanths - “the living fossil”

Types of evidence…

1. Evidence from the fossil record

Types of evidence…

1. Evidence from the fossil record2. Comparative Anatomy

A. Homologous Structures

Homo - logy

Homologous structures have the same underlying forms

Wing anatomy comparison

And compared to our arm…

Arm anatomy comparison

B. Analogous Structures

Ana - logy

Analogous structures have a similar outward appearance (but different underlying forms)

Types of evolution

Convergent evolution Distantly related organisms evolve similar external features

Divergent evolution A common ancestor gives

rise to organisms that evolve for different environments

Which goes with which? ….

Homologous structures

Analogous structures

Convergent evolutionDistantly related

organisms evolve similar external features

Divergent evolution A common ancestor

gives rise to organisms that become more different with time.

Which goes with which?

Homologous structures

Analogous structures

Convergent evolutionDistantly related

organisms evolve similar external features

Divergent evolution A common ancestor

gives rise to organisms that become more different with time.

C. Vestigial Structures

Vestige - a left-over/ remnant

Vestigial structures are evolutionary “leftovers” from an earlier ancestor

The “dew” claw of a wild cat

The human appendix

Rabbit Fetal Human Adult Human

Membranes in our eyes

Hip bones in whales

(Look at that “hand” too!)

Types of evidence…

1. Evidence from the fossil record2. Comparative Anatomy

Types of evidence…

1. Evidence from the fossil record2. Comparative Anatomy 3. Comparative Embryology

Human embryo at 5 weeks

Embryos…

…can you guess which one is human?

…how about now?

Embryos…

And now…

Were you right?

Types of evidence…

1. Evidence from the fossil record2. Comparative Anatomy 3. Comparative Embryology

Types of evidence…

1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence

Comparing DNA…

Determining relationships

DNA similarity between species is used to determine how closely related they are.

This is in turn used to construct possible evolutionary trees.

How closely related are these fellows?

Giant Panda

Brown Bear

Mystery critter! (I’m not telling)

…got your guess?

An Evolutionary Tree

…so why is he called a red panda?

This tree was constructed by looking at % similarity of DNA among “bears”

Types of evidence…

1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence

Types of evidence…

1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior

Behavioral similarities

Duck and other bird mating dancesHow primates carry their youngFish swimming motions and salamander

walksAnd on and on and on….

Types of evidence…

1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior

Types of evidence…

1. Evidence from the Fossil Record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence5. Behavior6. Direct observation

also known as microevolution

Artificial selection

Remember us?

And look at us!

And Natural Selection

Hawaiian Rock Wallabies!

The Beak of the Finch

Biologists Peter and Rosemary Grant documented natural selection occurring in populations of finches on the Galapagos islands over a period of only 20 years! This generation to generation changes in the frequency of certain traits is called microevolution.