Evolution

Word is used in many ways: –Cosmic evolution of the universe –Biochemical evolution of the 1 st life –Biological evolution of the species

Outline for Notes: 1.Definition of Evolution 2.People: a)James Hutton b)Charles Lyell c)Lamark d)Charles Darwin 3.Natural Selection

Evolution Change over time The theory explaining how modern organisms have descended from ancient organisms

History of the Current Theory

James Hutton (1795) – Charles Lyell (1833) Geologists Proposed –earth is millions of years old –Same processes you see now are ones that were there in the past

James Hutton Proposed layers of rock, mountains, valleys form slowly – so earth is very old

Charles Lyell Processes which shape the earth now must be the same ones that shaped the earth in the past

Providence Canyon, Georgia How old is it? a) 150 yearsb) 15,000 years c) 15 million years

Lamarck WRONG Inheritance of acquired traits Gain/lose traits through usage

Charles Darwin Voyaged on Beagle Wrote On the Origin of the Species proposing a theory where all the different species came from: natural selection

Example: the Galapagos turtles What kind of variations might exist in this turtle species?

Natural Selection –Variation exists in nature –Struggle for existence – compete for resources –Survival of the fittest – the strongest survive to pass their genes on –Descent with modification – each living species has descended with changes from other species

variation: neck length Compete for food (tall shrubs) Long necked turtles more fit long neck turtles survive to pass on the long neck trait

Natural Selection –Variation –Struggle for existence –Survival of the fittest Which would survive best as a seed eater? Insect eater?

This is the part that is controversial: Descent with modification

Outline for Notes Fossils a)What is a Fossil? b)What are the Four Common Fossil Types? c)How do Fossils Form? d)How Are Fossils Dated? a)Absolute Age b)Relative Age e)What are fossil used for?

What is a Fossil? Remains of ancient life

4 Types of fossils Body fossils – actual parts (a tooth) Molds – hollowed out rock Casts – solid forms of plant/animal when mold fills up Prints – impressions formed in mud that harden (footprint)

How do fossils form? 1. Animal dies and is QUICKLY buried 2. Soft body dissolves leaving a mold 3. Minerals replace bone/shells

How are fossils dated?

Method 1: Relative Dating Compare fossils to other fossils in layers of rock Oldest fossils are in lowest strata

Method 2: Radioactive Dating Absolute dating based on remaining radioactive isotopes C-14 for previously living organisms that are “young” Must assume that all things have remained constant over history of earth

Example AmountHalf-livesTime

Fossils show change over time…

…but they form an incomplete record of life…

Outline for Notes: Evidences Cited for Evolution 1.Fossils 2.Homologous Structures 3.Biochemical Comparisons 4.Antibiotic Resistance

Fossils show change over time Controversy comes with the missing links

Homologous Structures Perform related functions in different species

Biochemical Comparisons Compare amino acid sequences in proteins Compare nucleic acid sequences in genes

Antibiotic Resistance Bacteria develop the ability to “resist” antibiotics

Today: A.Rates of Evolution B.Geological Time Periods C. What does Evolution Require?

Rates of Evolution 2 popular theories: (1) Gradualism: SLOW and steady (2) Punctuated equilibrium: long periods of no change with a sudden period of rapid change Both take a LONG time

Geological Time Periods Mass extinctions often mark divisions

Evolutionary Change Requires Changes in Genetic Information

Changing the allele frequency 50/50 A selecting factor 80/20

SPECIES evolve, not individuals

Cladogram Diagram showing how organisms are related based on shared, derived characteristics such as feathers, hair, or scales

Michael Behe

Intelligent Design Bacteria flagellum 25 different proteins uses an electrochemical ion gradient to drive rotation speeds of up to 300 Hz.

Origin of Eukaryotic Cells