CHAPTER 15. Theory of Evolution. Charles Robert Darwin Born February 12 1809 – April 19 1882) He was an English Naturalist.
Theory of Evolution
on board as a
to learn as much
as possible about
the living things
he saw on the
Darwin was amazed by the tremendous diversity of living things. Scientists now have identified more than 1.7 million species of organisms.
When Darwin returned to England, he compared organisms to organisms that lived elsewhere. He also compared organisms on different islands in the Galapagos group.
He was surprised by some of the similarities and differences he saw.The Galapagos Islands
The Iguanas on the Islands had large claws that allowed them to grip slippery rocks while the iguanas on the mainland had smaller claws to climb trees.
Darwin was also fascinated in particular by the land tortoises in the Galápagos.
Giant tortoises varied in predictable ways from one island to another.
The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.
Layers show change
* Different organisms
lived at different times
* Species have differed
in a gradual sequence
of forms over time
similar types of organisms
* The model of Descent with
modification provides an
explanation for these
patterns of distribution.
have a different evolutionary origin)
Wxample: Convergent evol: WINGS of insects, birds and bats. (thes are also called analogous structures).
Divergent evol: Wings of a bat, the humam forearm and fingers,the flipper of a whale ,wing of a bird , foreleg of horse. These are also known as homologous structures.