Evolution by Natural Selection

EVOLUTION BYNATURAL SELECTION

No Genetic Change Through Time (no evolution)

Scientists believed that all organisms were exactly how they have always been.

Then Lamarck came to town Jean Baptiste

Lamarck French biologist

Explained evolution! Wrong

Acquired Traits.

Artistic ability, Math ability, etc.

Darwin’s Life Charles Darwin Wanted to be a doctor

Couldn’t stand the sight of blood

Married his cousin

Sea voyages Voyage of Beagle Naturalist

On the HMS Beagle 5 year journey Observed

flora/fauna everywhere he went Catalogued Compared

Developed his theory based on observations and evidence.

Wrote several books Most famous was “On

the Origin of Species”

P.S. Mr. Chaney’s Favorite Book by Darwin is . . .

Drum roll please . . .

“The Formation of Vegetable Mould Through the Action of Worms.”

Darwin’s Theory “Descent with Modification.”

All species arise from pre-existing species

Generations pass, and species may change if the population has:

Genetic Variation An Overproduction of offspring A Struggle to Survive Differential Reproduction

*********Darwinian Fitness *********

So no one else figured this out until Darwin?!?!

Who has greater “Darwinian Fitness?”

Evidence for Evolution: Fossils Fossil Record

Rocks form in layers

Organisms in deeper, “older” rock, are older

Different organisms lived at different times

Today’s organisms are different from those of the past

Pennyslvania’s State Fossil! The Trilobite

Example of Fossil that supports evolution

Megatherium

Big Birds

TransitionFossils in adjacent layers are more alike than fossils from far apart layers

Evidence of Evolution: Transitional Species

Fossils of “in-between” organisms Used as a timeline!

Speaking of trilobites . . . . Here’s a Pakicetus! (not a good transition!)

Pakicetus

Vestigial TraitsVestige- a mark, trace, or sign

Archaeopteryx

Bird? Or Reptile?

Vestigial Traits

Diptera-Vestigial Wings

Snake “spurs”Vestigial Wings in Drosophila

Xanthopan morganii praedicta

“Predicted Moth”

Darwin predicted it’s existence before it had been observed.

Ridiculed by other scientists

Orchids have specific pollinators

Let’s Process! 1. How does the presence of vestigial traits

support the theory of evolution by natural selection?

2. Why is variation necessary for natural selection to occur

3. If a natural disaster wiped out all the small seeds in an area with a population of birds with varying beak size, how might the population be affected?

Darwinian Fitness

Who has GREATER fitness from the perspective of Darwin, and the theory of natural selection?