EVIDENCE THAT SUPPORTS EVOLUTION

Definition of Evolution Evolution: Change in heritable traits of biological populations over successive generations. “Descent with modification”

Phylogenetic Tree: A diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor.

Pillar #1: The Fossil Record

What is a fossil? The remains or evidence of an organism Fossilized bone, wood, shell, or dung Casts, imprints, or molds Amber or tar entrapments Imprints of footprints or borings

Organism trapped in amber Original Remains Replacement Organism trapped in amber Recrystallization Carbonization

Original Remains preserved by ice Footprints are Trace Fossils

Fossil Facts Most are found in sedimentary rock. The fossil record shows that life has changed over time. The fossil record is very incomplete. Fossils give us a glimpse into the morphology of organisms now extinct. Show Whale Video Clip and Do Whale exercise

Interpreting Fossil Evidence Relative Dating – the age of a fossil is estimated by comparing it to other fossils in rock layers Rock layers form in order of age – the oldest layers are on the bottom

Interpreting Fossil Evidence Radioactive Dating – using radioactive decay to assign absolute ages to fossils A half-life is the length of time required for ½ of the radioactive atoms in a sample to decay

Step 2: What do you want to solve? Underline the question. If 100 g of Carbon-14 decays until only 25 g of carbon is left after 11, 460 years, what is the half-life of carbon-14? Step 1: Pull out what you know from reading: Step 2: What do you want to solve? Underline the question. Step 3: Solve

Thallium-208 has a half-life of 3. 053 minutes Thallium-208 has a half-life of 3.053 minutes. How long will it take for 120 g to decay to 7.5 g? Step 1: Pull out what you know from reading: Step 2: What do you want to solve? Underline the question. Step 3: Solve

Step 2: What do you want to solve? Underline the question. Gold-198 has a half-life of 2.7 days. How much of a 96g sample will be left after 8.1 days? Step 1: Pull out what you know from reading: Step 2: What do you want to solve? Underline the question. Step 3: Solve

Archaeopteryx (late Jurassic- 150 MYA)

Transitional Whale Fossils ~60 mya ~50 mya ~45 mya ~35-45 mya

Pillar #2: Structural Similarities Among Organisms

Homologous Structures Structures that have similar characteristics but may or may not have similar functions. Ex: forearms of vertebrates

Homologous : Similar structures, NOT similar functions

Vestigial Structures Structures that are diminished in size and/or function. Ex: eyes of moles Ex: human appendix

Whale Vestigial Structure: Pelvis, Femur, leg bones.

Homologous & Vestigial structures give evidence of DIVERGENT EVOLUTION. They suggest that descendants DIVERGED (became different) as the distance from the common ancestor increased.

Analogous Structures Structures with the same function in organisms that are not closely related. Ex: the wings of birds and the wings of insects. Ex: thorns of the rosebush and the quills of the porcupine.

Analogous structures suggest CONVERGENT EVOLUTION. Organisms did not descend from a common ancestor, they independently evolved similar adaptations to survive in similar environments.

Pillar #3: Biogeography The Geographic Distribution of Organisms

What is biogeography? The study of. . . Where species live on earth and why How organisms are adapted to their environment Considers plate tectonics – shifting and movement of tectonic plates

Pillar 4: Embryological Similarities

Scientists study the Biological development from time of conception (i.e. morphology of Embryo) The fate of particular embryonic tissue

Pillar #5: Molecular Similarities

All organism have… The same “Genetic Code” 4 DNA nucleotides Same 64 mRNA codons that code for the same amino acids Ribosomes as the site of protein synthesis ATP as the energy currency Plasma membranes that consist of a phospholipid bilayer w/ imbedded proteins Unity of composition suggests common descent

Compare common proteins Count and compare how many of the amino acids differ Compare the nucleotide sequences of DNA the closer the DNA sequences, the more closely related the organisms are. Show hemoglobin phylogenetic tree.

Molecular Comparisons

Pillar #6: Direct Observation

Examples of OBSERVED Natural Selection Example 1: DDT Resistant Mosquitoes Example 2: Antibiotic Resistant Drugs Example 3: Darwin’s Finches

resistant to insecticide Example 4: Insects resistant to insecticide