Transcript Evidence Supporting Biological Evolution

Biological Evolution
• concerns changes in living things
during the history of life on Earth.
• Explains that living things share
common ancestors.
• Over time, biological processes
such as natural selection give rise
to new species. Darwin called this
process "descent with modification"
Biological Evolution
• Natural selection: Environment
impacts who lives to produce
offspring
• Survival of the fittest: Lion King
Evidence Supporting
Biological Evolution
The fossil record
Age of the Earth
Homologous or Common Structures
Distribution of Species
Similarities during development (embryos)
DNA and Molecular Evidence
Evolution
Descent with modification
A long path leads from the origins of
primitive "life," which existed at least
3.5 billion years ago. This path is best
understood as a product of evolution.
Eye Evolution
Evolution’s Key
“Small change over unimaginable
blocks of time”
-Darwin
The Fossil
Record
The fossil record
thus provides
consistent evidence
of systematic
change through
time of descent with
modification.
The Fossil
Record
The fossil record
clearly shows that
change followed
change on Earth.
So critters also had to
change along with the
Earth, or go extinct.
The Missing Link
Many pieces of the fossil record are
missing…why?
It is unusual for organisms to
fossilize
It is difficult to find and preserve
those fossils that do exist most
organisms die and leave no
trace.
Life Form
Millions of Years Since
First Known Appearance
(Approximate)
Microbial (procaryotic cells)
3,500
Complex (eucaryotic cells)
2,000
First multicellular animals
Shell-bearing animals
Vertebrates (simple fishes)
Amphibians
Reptiles
Mammals
Nonhuman primates
Earliest apes
Australopithecine ancestors of
humans
Modern humans
670
540
490
350
310
200
60
25
4
0 .15 (150,000 years)
Age of the Earth
4.5 billion years
Centuries of Earth’s layers
Homologous Structures
Con’t Structures
Look at differences and
similarities among the skeletons
Homologous structures - parts of
different organisms, often quite
different, that developed from
the same ancestral body parts.
Homologous structures
Other Structures
Vestigial organs - structure that
serves no useful purpose or function
in an organism.
Why do organs become vestigial?
Mutation
Why would those changes be passed
on?
Didn’t harm the organism
The Distribution of Species
Life on the separate Continents
Evolved differently
Australian animal life is very different
Galapagos Finches
The Distribution of
Species
Similarities
During
Development
Embryology
Similarities
During
Developmen
t
what does this mean?
Early stages of development
are repeated
Whales evolved from a
land mammal
DNA and Molecular Biology Evide
DNA and
Molecular
Biology
Evidence
ATP is the energy carrier
found in ALL living
organisms
DNA and
Molecular Biology
Evidence
ALL LIVING
ORGANISMS USE
DNA AND/OR RNA
THE DNA BASE
SEQUENCES ARE
VERY SIMILAR FOR
SIMILAR SPEICES
DNA and
Molecular
Biology
Evidence
A wide variety of
complicated proteins (like
cytochrome C) are shared
by many organisms.
ALL living things are
carbon based.
Creationism and the Evidence
for Evolution
Is life a tree
with a
common
ancestor for
the trunk?
Evolution: Online Lessons for
Students: Activity 2- Evidence
for Evolution WebQuest
Evidence Supporting Biological
Evolution | Science and Creationism:
A View from the National Academy
of Sciences, Second Edition
Essay Exam
http://www.pbs.org/wgbh/evolution/index.html
Areas of Interest on the Site
Darwin
Change
Extinction
Survival
Sex
Humans
Religion
Student Lesson/Online Lessons
(Use Quicktime for Videos)
Evolution: Survival: Microbe
Clock
Darwin Observed
Nature
Darwin’s Premises
• Individuals vary
• Organisms produce more offspring
than will survive
• Population remains fairly constant
• Environment is constantly changing
Darwin Concluded
• Competition: only some survive
• Most fit traits survive &
reproduce
• The genetic variation that
increases fitness will eventually
appear in the whole population
Hardy Weinberg
• No change in the gene pool
if……
Hardy Weinberg
• Mating is random
• Mutations do not occur
• No immigration or emigration
• Large population or allele
frequency is high
• Natural selection is not
operating