1. Aim: How does geographic & reproductive isolation lead to speciation?

2. REVIEW:
Evolution has lead to the formation of new species(__________) from different ancient organisms.
Speciation
Species- a group of organisms that share certain characteristics & can mate with one another, producing fertile offspring.

3. I. Darwin’s explanation for evolution:
NATURAL SELECTION
HOW DOES EVOLUTION REALLY WORK?

4. Natural Selection According to Darwin nature controls evolution
The environment selects the characteristics best suited for survival in a particular area.

5. II. Geographic Isolation:
The idea that two populations of the same species of organism can evolve separately because of a geographic barrier.
III. Physical barriers:
*Mountains
*Bodies of water
*Lakes

6. IV. How does Geographic Isolation lead to Speciation?
*Those who have an adaptive variation will survive & reproduce in the different environments.
*This leads to different species with different variations.

7. V. Darwin’s Finches (Example of Geographic Isolation):
*All came from a common ancestor & due to different environments
on each island, new species evolved
that were adapted to their particular
environment.

8. VI. Adaptive Radiation: Evolution of many species from one common ancestor due to natural selection.

9. *Each group of finches adapted to its new environment, and through the process of natural selection, became different enough that interbreeding became impossible.

10. VII. Reproductive Isolation:
A reproductive barrier keeps similar species from interbreeding.
Ex…
*Timing- two similar species may have
different breeding seasons.
* Behavior- two similar species may have
different courtship or mating behaviors.

11. VII. How long does evolution take?
Evolution takes a
long time, but if
the environment
changes suddenly,
evolution will be
Faster.

12. *Summary Questions:
The diversity within the wild bird species in the diagram below can best be explained by which process?
(1) natural selection
(2) asexual reproduction
(3) ecological succession
(4) mitotic cell division

13. Choose one cartoon and write its number in the space below
Choose one cartoon and write its number in the space below. Identify one concept represented in that cartoon, and explain how this concept supports the theory of natural selection. Your answer must:
• identify one concept represented in the cartoon you choose [1]
• briefly explain the concept you identified [1]
• explain the relationship between this concept and the process of natural selection

14. *Overproduction
*More produced than
can survive.
*Best adapted will survive.

15. *Struggle for Survival
*Best adapted will survive.
*Those that survive will
pass these traits to
their offspring.

16. The diagram below illustrates a proposed evolutionary path of certain organisms, based on the theory of evolution.
Which statement could best be inferred from the information in this diagram?
(1) Evolution does not involve gradual change.
(2) Evolutionary changes can result in extinction.
(3) Evolution begins with plants.
(4) Evolution produces organisms that all fill the same niche.