Evolution part 2Chp15 Evidence and theory development

5 pieces of evidence1. Fossils2. Homologous and Analogous Structures3. Vestigial Structures4. Embryology5. Macromolecules

1. FossilsA TRACE of a long dead organism

Footprint, trash, poop, eggshell, nest, tools, amber

Usually found in sedimentary rockMold- an imprint in rock of the shape of an

organismCast- a filled mold; a model of the organismanimation

1. FossilsDistribution – Where located

1. FossilsLaw of superposition

What happened first?

Relative Age Versus

Absolute Age

Fossil Record:The theoretical ‘stack’ of all fossils, in order

Biogeography:Organisms that are relatively close (NJ and PA)

are more alike than organisms that are far apart. More pouched animals in Austrailia Galapagos Finches

2. Homologous/Analogous Structures

‘Homo’ means … so these are parts in different species of animals that are the same. Figs. 15-7 p289 15-8 p290

Analogous – same function but different structure

Homologous Structures

Analogous Structures

3. Vestigial StructuresAre features that seem to have no useful

functionWisdom Teeth, Appendix, tail bone – In

HumansPelvic Bone, Four chambered stomach like a

cow – In Whales

4. EmbryologyWhen they are

first growing MANY organisms start out looking the same, THEN start to develop differences

Tell us that they are somehow related

5. MacromoleculesMacro- “large” MoleculesProteins, Carbohydrates come from the DNAWhich means……………THE DNA IS SIMILARWhose DNA is yours MOST similar to?

Immediate Biological FamilyExamples- hemoglobin

Human to Gorilla ONE differenceHuman to Frog 67 differences

Common Ancestors

5. Macromolecules (Lab p334)

This tells us that frogs and humans had a common ancestor longer ago then humans and gorillas.

What could cause that one difference?Mutation!

How did we come up with this stuff?

History of Evolutionary TheoryCharles Darwin, DOB 1809, On the Origin of

Species by Means of Natural Selection, HMS Beagle – 1831-36

Greeks – life arose in water and more complex followed simpler ones

Later Aristotle said life was fixed (ps. he’s wrong)

Judeo-Christians agreedMid 1700s fossils of “strange animals” were

foundJean Baptiste de Lamark suggested

acquired traits were inherited. Used = got better, Unused = go away. (ps…he’s half wrong)

ACQUIRED TRAITS happen in a life time Your kids will have your tattoo

Dad wanted him to get into medicine, then he went to become a priest – Met John Henslow – took a cruise.

While on the boat he read Principles of Geology by Charles Lyell. “mountains rise cm by cm” The way the rain falls today is the same way it

fell 1billion years ago.UNIFORMITARIANISM

Learned about Thomas MalthusHuman population should be huge but - War,

Disease, Famine limits the population

So Darwin is on a cruise…Finds sea animal fossils thousands of feet above sea

levelFinds FINCHES similar to the mainland but

600miles out to sea GALAPAGOS ISLANDS Realizes that kids look like parents

After his trip, he thinks about this stuff for a little while…like 20years

Alfred Wallace sends him a paper that is the same idea that he has come to and Darwin quickly publishes. The conclusion…?

Descent with ModificationOrganisms that exist today are modified

versions of older organisms.The environment chooses the organisms that

are best fit to reproduce (natural selection).The better fit the organism the more babies it

will produce, the more of those genes are in the gene pool.

Traits that help an organism survive better and make more babies are ADAPTATIONS