2-Evolution (Chapter 22-25)

2-Evolution (Chapter 22-25) - Evolution, Part 1 1 BIOL 112...

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Unformatted text preview: Evolution, Part 1 1 BIOL 112 Evolution Chapters 2225 BIOL 112 The Scientific Method Two major aspects: Observations Facts What we see Interpretations Theories What it means A good theory does two things: Explains what happens Predicts what will happen, if certain conditions are established. (Not fortune-telling, but expected data from specified situation: experiment) BIOL 112 Evolution: Major Biological Paradigm Evolution: a change in population of organisms over long period of time Basis of change change in genetic composition of population. Genetic changes produce: Change in biochemistry Change in morphology Change in behavior Any other aspects of organisms under genetic control BIOL 112 Observations of Evolution Fossil Record Anatomical Homologies Vestigial Organs Embryological Development Molecular (Sequence) Homologies BIOL 112 Fossils From the Greek: dug up Preserved parts of plants or animals that were once alive Hard parts have highest chance of being preserved: bones, teeth, wood, shells Soft parts found less frequently: skin, feathers, leaves, flowers; rarely, even cell structures are found Organic materials usually replaced by inorganic materials (stone) BIOL 112 Evolution, Part 1 2 BIOL 112 BIOL 112 BIOL 112 BIOL 112 BIOL 112 BIOL 112 Evolution, Part 1 3 BIOL 112 BIOL 112 BIOL 112 BIOL 112 Hyracotherium (Eohippus) Skull, 60 m.y. b.p. Horse Evolution Series Horse Evolution Series BIOL 112 Hyracotherium foot: 5 toes BIOL 112 Orohippus, 45 m.y. b.p. Evolution, Part 1 4 BIOL 112 Mesohippus, 35 m.y. b.p. Note foot: 3 toes BIOL 112 Merychippus, 26 m.y. b.p. BIOL 112 Pliohippus, 3 m.y. b.p. BIOL 112 Prezwalskis Horse ( Equus ferus przewalskii ) Eurasian wild horse until early 1800s; now found only in zoos BIOL 112 Modern Horse ( Equus caballus ) This breed selected for small size BIOL 112 Horse Lineage Macroevolution Shows general trends over past 60 million years Increasing body size Shift of toe structure from many digits to one (hoof) Change in diet/dentition from soft leaves to hard grasses Branching speciations followed by selective survival Evolution, Part 1 5 BIOL 112 BIOL 112 Horse Evolution Showing a series of divergences and extinctions with geological ages, and marking the change in food behavior, to modern form. From: MacFadden (2005) Science 307 BIOL 112 How Old are Fossils? Dating methodologies Relative dating; stratigraphy Distinguishes older from younger Absolute dating, usually by radioactive decay Gives an estimate in years BIOL 112 BIOL 112 BIOL 112 Relative Dating Index fossils, common forms unique to a particular geologic period and world-wide in distribution Using index fossils as markers, can reconstruct a whole history of strata from different locations in the world into one sequence Assembled strata sequence is geologic time scale Need to apply dates to time scale using absolute dating Evolution, Part 1...
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This note was uploaded on 03/27/2008 for the course BIOL 112 taught by Professor Vaughn during the Spring '08 term at Texas A&M.

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2-Evolution (Chapter 22-25) - Evolution, Part 1 1 BIOL 112...

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