Evolution

What is it?

Changes that occur in a population over time, in response to

the environment.

Lamarck

• Acquired characteristics can be passed down form generation to generation

• Organisms evolve over time due to the impact of the environmental factors acting on them

Darwin• Natural Selection: organisms best suited to

survive will pass their traits down

1. Survival of the fittest2. Struggle for existence (competition for resources,

produce more young than can survive)3. Variation and adaptation

The Giraffe, Darwin and LamarckLamarck Darwin

Use and disuse

Passing on of acquired characteristics

Increasing complexity

No extinction

Variation

Inheritance

Differential Survival

Extinction

Lamarck: long necks of giraffes due to reaching for higher levels…offspring would inherit the trait…Darwin: longer necks were a result of adapting to the environment…short neck giraffes died off

BREED ORGANISMS FOR PARTICULAR TRAITS

Selective Breeding

FossilsThe preserved remains of plants and

animals

Aging a Fossil

• Carbon dating• Measure the amount

of C-14 (an isotope of Carbon) remaining in the fossil

• Calculate according to half life ( the time it takes for half the amount of a substance to degrade)

Vestigial Organs• Served a prior purpose• Organism has evolved

and no longer serves a purpose

• Example: human tail bone, snakes have tiny pelvic bones with limb bones, blind salamanders having eyes

Vertebrates• All vertebrates shared a

common ancestor. • How do we know this? • What evidence is there

for this? • They have evolved from

common ancestry, sharing certain inheritable traits.

• The backbone is the most evident.

Mutation

• Permanent changes to the DNA sequence resulting in structural changes in a gene

• Peppered Moths: occurred over last two hundred years