evolution. what is it? changes that occur in a population over time, in response to the environment
TRANSCRIPT
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