1. How does a species evolve from preexisting species?
Speciation
How does a species evolve from preexisting species?

2. What is a Species?
Group of organisms that look alike, can interbreed, & mate to produce fertile offspring in nature

3. What do you get when you breed a donkey and a horse?
A MULE!!!
Does the mule fit the definition of a species?

4. Why does a MULE NOT fit the definition of a species??
Can interbreed
X Produce fertile offspring
Do so in nature

5. What do get when you breed a tiger and a lion?
A LIGER!!!
Does the liger fit the definition of a species?

6. Why does a LIGER NOT fit the definition of a species??
Can interbreed
X Produce fertile offspring
X Do so in nature

7. Speciation = evolution of a new species
Happens b/c reproductive isolation
3 ways

8. 1. Behavioral Isolation
B/C different courtship rituals or other reproductive behaviors, like bird calls/songs
Ex. Eastern
& Western
Meadowlark

9. 2. Geographical Isolation
When physical barriers (mountains, rivers, highways) separate populations
Ex: Grand Canyon squirrels, Darwin’s finches

10. 3. Temporal Isolation B/C pops reproduce @ different times
Ex. species of orchids & frogs

11. Speciation can occur slowly or quickly
2 theories

12. Gradualism
Species originate through a slow, steady change in adaptations
Proposed by
Darwin
Supported by
the fossil
record

13. Punctuated Equilibrium
Speciation occurs quickly in rapid bursts, with long periods of stability
Caused by environmental changes (ex. 3 isolations)
Supported by fossil record

14. 2 Patterns of Macroevolution
Species will diversify when introduced to a new environment or become extinct.
2 Patterns of Macroevolution

15. 1. Divergent Evolution (adaptive radiation)
When species evolves into diverse new species
B/c different environments
Have homologous structures
Ex: polar vs. brown bear, Hawaiian honeycreeper

17. 2. Convergent Evolution
Distantly related (or unrelated) organisms evolve similar traits
B/C similar environments
Have analogous structures

18. Examples
Dolphin, penguin, fish - Streamlined shape b/c need to move thru water efficiently
Bird, bat, butterfly

19. Extinctions:
1. Background extinction - normal extinction rate, species that go extinct simply because not all life can be sustained on Earth and some species simply cannot survive.  2. Mass extinction  - widespread event that wipes out the majority (over 50%) of living plants and animals.

20. Coevolution - the process by which two or more interacting species evolve together, each changing as a result of changes in the other or others
Beneficial relationships
ex. Acacia plant and stinging ant
Competitive relationships
Crabs and murex snails
Evolutionary arms race newt & snake 2:20-8:26min
Bull horn acacia and ants have a mutualistic relationship with many facets: a. large thorns provide nesting for ants, b. Beltian bodies (and nectar) provide food for ants, c. ants swarm to defend anything eating the tree, and d. the ants also clear an area around the base of the tree to reduce competition for nutrients. Artist: Emily Harrington. 
For example, many molluscs, such as Murex snails, have evolved thick shells and spines to avoid being eaten by animals such as crabs and fish. These predators have, in turn, evolved powerful claws and jaws that compensate for the snails' thick shells and spines.