1. KEY CONCEPT Evidence of common ancestry among species comes from many sources.

2. Evidence for evolution in Darwin’s time came from several sources.
Fossils:
Fossils provide evidence of evolution.
Fossils in older layers are more primitive than those in the upper layers.
Extinct Fossils resemble modern animals. This shows a common ancestry.

3. There are several types of fossils.
Permineralization occurs when minerals carried by water are deposited around a hard structure.
b) A natural cast forms when flowing water removes all of the original tissue, leaving an impression.
c) Amber-preserved fossils are organisms that become trapped in tree resin that hardens after the tree is buried.
d) Preserved remains form when an entire organism becomes encased in material such as ice, ash,etc.

4. Dating Fossils

5. Relative dating estimates the time during which an organism lived.
It compares the placement of fossils in layers of rock.
Scientists infer the order in which species existed.

6. Isotopes are unstable in their nuclei, so they decay
Radiometric Dating
Isotopes: atoms of the same element with differing neutrons
Ex: 12C and 14C
12C = 6 protons + 6 neutrons
14C = 6 protons + 8 neutrons
Isotopes are unstable in their nuclei, so they decay
Isotopes have a known half life (rates of decay are known).
Half life = number of years it takes for half of the isotopes to decay
14C has a half life of 5700 years, and 14N is a decay product
Age determined by comparing ratio of 14C to 14N
Wider ratio = older samples

8. 2. Geography
The study of geography provides evidence of evolution.
island species most closely resemble nearest mainland species
populations can show variation from one island to another

9. Embryology provides evidence of evolution.
identical larvae, different adult body forms
similar embryos, diverse organisms
Shows common ancestry
Larva
Adult barnacle
Adult crab

10. flipper leg wing arm flight walking swimming grasping 4. Anatomy
The study of anatomy provides evidence of evolution.
Homologous structures are similar in structure but different in function.
Homologous structures are evidence of a common ancestor.
flipper
leg
wing
arm
flight
grasping
walking
swimming

11. Homologous structures are different than Analogous Structures
Analogous structures have a similar function.
Human hand
Bat wing
Mole foot
Fly wing
Analogous structures are not evidence of a common ancestor.

12. Structural patterns are clues to the history of a species.
Vestigial structures are remnants of organs or structures that had a function in an early ancestor.
Examples include ostrich wings, human appendix, and wisdom teeth, whale and snake pelvis/hind legs.

13. Pythons have tiny femurs (leg bone)

14. 5. Molecular and Genetic Evidence
AKA Biochemical Evidence
Two closely-related organisms will have similar DNA, RNA, and protein (amino acid) sequences.
This also gives evidence of a common ancestor.

15. Evolution Results from FOUR Factors!
These are four factors to Darwin’s Theory of Natural Selection
Overproduction - the potential for a species to increase in number.
The more of a species there is, the more chance of survival.

16. 2. Inherited Variation – the heritable genetic variation of individuals in a species due to mutation and sexual reproduction. DNA replication errors, environmental mutations, and independent assortment all aid in variation for survival.

17. 3. Struggle to Survive – competition for limited resources
3. Struggle to Survive – competition for limited resources. When a species has to compete for resources, the ones most suited for that situation and environment will survive. This is called survival of the fittest.

18. 4. Successful Reproduction – the increase in number of those organisms that are better able to survive and reproduce in the environment. Being able to reproduce means that a species can survive longer and will not become extinct.

19. Examples of the process of evolution:
Rabbits evolved longer ears to be able to detect predators and keep cool. They are timid animals that frequently did not survive when danger approached. Their ears have a lot of blood vessels which give off heat.
In an ecosystem, some giraffes have long necks and others have short ones. If something caused low-lying shrubs to die out, the giraffes with short necks would not get enough food. After a few generations, all the giraffes would have long necks.
Deer mice that migrated to the sand hills of Nebraska changed from dark brown to light brown to better hide from predators in the sand.

20. More examples
Galapagos finches all have different types of beaks. During drought, the finches with the larger beaks survived better than those with smaller beaks. During rainy times, more small seeds were produced and the finches with smaller beaks fared better.
Peacock females pick their mate according to the male’s tail. The ones with the largest and brightest tails mate more often. Today, males that do not have bright feathers are very rare.
The peppered moth used to be a light color with black spots. When the atmosphere in London became filled with soot because of the Industrial Revolution, the white trees became darker and light colored moths were eaten by birds more readily. Within months, moths became darker and lighter moths were rare. After the Industrial Revolution, light colored moths were found in greater numbers.

21. A few more examples:
Bacteria have become resistant to antibiotics and this can happen very quickly, since bacteria can produce several generations within one day. The strongest bacteria are the last to die and the antibiotics sometimes do not kill all of them. (This is why you keep taking antibiotics even after you feel better.)
Sharks are colored white on the underside and blue or gray on the top. This is their camouflage as the top blends with the water color to someone looking down into the water and the bottom blends with the light coming through the water from above.