Evidence of Evolution Bellwork Explain the difference between

Evidence of Evolution

Bellwork �Explain the difference between a scientific theory and a hypothesis. �Give an example of a scientific theory and a hypothesis.

Objectives �Explain how the various disciplines of biology support the Theory of Evolution

Key Terminology �Biogeography �Fossil record �Comparative anatomy � Homologous structures � Vestigial Organs �Comparative embryology �Molecular Biology �All support Darwin’s idea of descent with modification

Evolution is a Scientific Theory not an Educated Guess �Definition of a Scientific Theory �A well-tested explanation that unifies a broad range of observations collected from hundreds of experiments

Criteria to be a scientific theory § More general than hypothesis § General explanation of important natural phenomena § Derived from inductive reasoning § make specific observations draw generalizations § Supported by empirical data § Theory continually tested § If Data contradict theory § Modify theory to satisfy all the data

Think-Pair-Share Identify whether the following is a scientific theory or educated guess? � Hannah will wear a polka dotted bikini to the beach in July. � All living things are made of cells � Infectious diseases are caused by different microorganisms called germs � It will be 100°F in Tucson by May 15 th. PROPERTY OF PIMA COUNTY JTED, 2010 3

Biogeography �Definition: Geographic distribution of species �Key observations �Species on islands more closely related to species on nearest mainland than a distant mainland �Example: Organisms found on the Galapagos Islands more closely related to organisms on the South American coastline than the African coastline �Conclusion: Modern species evolved from geographical regions nearby their current residence

Fossil Record �Definition of a fossil �Preserved remains of once living organisms �Scientists who study fossils are paleontologists �Fossils created: �Organisms become buried in sediment �Calcium in bone and other hard tissue mineralize �Surrounding sediment hardens and forms rock

Process of fossilization a rare event - Why? �Animal/plant life decay or are eaten before fossilization can begin �Fossils occur in rocks inaccessible to scientists �Destroyed by erosion or other natural processes before collected �Result: We have fossils for only a fraction of Earth’s organisms

Fossil Record �Sufficient evidence from fossil record to show evolution over time �From fossil record shown: �Bacteria appeared on Earth 3. 5 billion years ago �Plants/animals appeared 500 million years ago �Chronological appearance of vertebrates � Fish amphibians reptiles birds mammals

Think-Pair-Share Why is the fossil record considered evidence of Evolution? Why are the gaps in the fossil record not a good argument against Evolution? PROPERTY OF PIMA COUNTY JTED, 2010 3

Comparative Anatomy Homologous structures Definition: similar bones with different functions Ex. forelimb of vertebrates Conclusion: Vertebrates evolved from a common ancestor.

Comparative Anatomy (cont) �Vestigial Structures �Structures that have no modern function but did have function in presumed ancestor �Example �Vampire bat has molar teeth

�Pelvic Bone in whales

Comparative Anatomy Embryology similar early embryo anatomy in vertebrates Conclusion: Vertebrates descended from a common ancestor

Think-Pair-Share How do Homologous Structures, Vestigial Organs and Embryos support the idea that vertebrates descended from a common ancestor? PROPERTY OF PIMA COUNTY JTED, 2010 3

Comparative Biochemistry �Examine evolution at a molecular level �Macromolecules often compared between different organisms include �DNA �RNA �Protein

Comparative Biochemistry �Number of mutations determines how closely related: �Close relative � sequence of nucleotides or amino acids similar � very few or no mutations � Diverged more recently �Distant relative � Sequence of nucleotides or amino acids different � more mutations � Diverged long ago

Molecular Connections

3 Minute Summary The various disciplines of biology all support the Theory of Evolution. Why is this stronger than if only one discipline supported Evolution?