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?