Evolution A process of change through time in which a new species comes about from a preexisting species

Indirect vs. Direct Evidence Indirect Evidence: 1.Fossils: the remains and traces of organisms that once lived. It shows that through time organisms have changed from one form to another. Suggesting a common ancestor.

Formed by: Preservation: Iceman Tar Pits

Actual Skeletons:

Imprints:

How are Fossils Formed? Sedimentary Rock – Tiny grains of eroded rock and other materials that settle –

Two Types of Dating 1.Relative Dating: – Comparing the stratum of sedimentary rock with other strata. Oldest?? Most complex??

The Grand Canyon Gradualism: Punctuated Equilibrium:

2.Absolute Dating: – Radioactive Dating: estimation of the actual age of a fossil by measuring how fast radioactive elements break down into nonradioactive elements. – Carbon 14 Dating Only for fossils that contain Carbon. 60,000 years and younger.

How is Carbon 14 produced?

2. Darwin's Finches

The Galapagos Islands Finches from the South American mainland were blown off course to the Galapagos Islands.

Correlation of species to food source Seed eaters Flower eaters Insect eaters Finch population adapted to a variety of food sources generating different beak morphology

(a) Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. (c) Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses its narrow, pointed beak to grasp insects. Beak variation in Galapagos finches Conclusion: Suggests a common ancestor. The Beak of the Finch.

3. Comparative Anatomy

Comparative Anatomy: Study which compares body parts from different species – Homologous Structures: Similar structure, different function. (Suggests a common ancestor)

Analogous structures Similar function, different structure. Solving a similar problem with a similar solution

4. Vestigial organs These are remnants of structures that were functional in ancestral species Suggests common ancestry.

5. Comparative Embryology Organisms are similar to each other early in their development, slowly differing. Indicating a common ancestor.

LampreyFrogBird Dog MacaqueHuman What causes the Hemoglobin to be different?  compare common genes  cytochrome C (respiration)  hemoglobin (gas exchange)  compare common genes  cytochrome C (respiration)  hemoglobin (gas exchange) Mutations in the DNA!! Comparative hemoglobin structure 6. Comparative Biochemistry Comparing the differences between Protein or DNA Sequences Genetic differences are interpreted as indication of how much evolution has taken place.

Cytochrome c (104 Amino Acids)Hemoglobin (146 Amino Acids)

7. Geographic Isolation: Species have been isolated by a physical barrier and cannot interbreed any more. Indicating slow change.

Albert and Kaibab Squirrels

Direct Evidence for Evolution 1. Peppered Moth Coloration fluctuated over 100 years due to environmental change in tree trunks. Year% dark% light

Peppered moth What was the selection factor? – early 1800s = pre-industrial England low pollution lichen growing on trees = light colored bark – late 1800s = industrial England factories = soot coated trees killed lichen = dark colored bark – mid 1900s = pollution controls clean air laws return of lichen = light colored bark – industrial melanism B. Kettlewell

2. Antibiotic Resistance: Bacteria become resistant to antibiotics over a short period of time.

Resistance… NOT immunity ! 3. Insecticide resistance Insects become resistant over a short period of time  insecticide didn’t kill all individuals  resistant survivors reproduce  resistance is inherited  more of population is resistant Insecticide becomes less and less effective.

Age determined by half-life The time it takes for ½ of a radioactive material to decay to its nonradioactive form. Carbon Half-life = 5730 years. Full Amt. ½ left ¼ left 1/8 left 1/16

Half – Life of other Substances Uranium 238 – Lead 206 Uranium 235 – Lead 207 Carbon 14 – Nitrogen 14 Oxygen 19 – Oxygen 16 Potassium 40 – Argon Billion Years 713 Billion Years 5730 Years 19 Seconds 1.5 Billion years m&m Half-Life Activity!!

Activity