Evolution

Evolution

• Word is used in many ways:–Cosmic evolution of the universe

–Biochemical evolution of the 1st life

–Biological evolution of the species

Outline for Notes:

1. Definition of Evolution

2. People:a) James Huttonb) Charles Lyellc) Lamarkd) 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 years b) 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

Amount Half-lives Time

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

CladogramCladogramDiagram showing how organisms are related based on Diagram showing how organisms are related based on

shared, derived characteristicsshared, derived characteristics such as feathers, hair, or such as feathers, hair, or scalesscales

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