Transcript Summary Powerpoint of all Evolution chapters

“Evolution is the grand
unifying theory of the
life sciences”
Evolution =
changes over
time
Theory = wellsupported,
testable
explanation
Theory of evolution changes as new
information and additional data is collected.
Why is evolution so important to study?
• Predicts strains of flu for vaccine
• Predicts AIDS & West Nile outbreaks
• Human genome studies (Y chrom. disappearance)
• Bacterial resistance to antibiotics and “super bugs”
• Keep up with insecticides/herbicides for controlling
pests and weeds (malaria)
• Effects of GMOs
• Climate change threatens the existence of many
species
Charles Darwin
• Family of doctors. • Hired as companion
to the captain of the
Darwin disliked
Beagle.
medicine.
• Went to theological • 5 year trip. Darwin
worked as a
school to be a
naturalist.
minister.
Questions Darwin Asked
• Why are there no rabbits in Australia and
no kangaroos in England?
• Observed dinosaur bones – why did they
disappear?
• Had similar animals on different
Galapagos Islands once been members of
the same species?
Darwin’s Observations
1. Diversity –
– very different animals and
plants
– many more species
than he ever thought
– wide variety of
ways to reproduce
Darwin’s Observations
2. Fossils –
– Resemble
organisms alive
today
– Why did they
disappear?
Darwin’s Observations
3. Galapagos –
– Different climates
= different types of
animals
Pinta Island
Hood Island
Darwin’s beliefs before and after:
• Earth is only a few
thousand years old.
AFTER:
• Layers of rock
show Earth
is very old.
• All species on Earth
were placed in their
present forms
without changes.
• Rich fossil records = several
periods of creation and
extinction.
• Rocks and geologic
features were
produced suddenly.
• Many features created slowly
by wind and water erosion, and
rocks (sedimentary) are made
very slowly.
BEFORE:
Lamarck’s Theory of
“use and disuse”
Inheritance of
“Acquired traits”
What’s wrong?
• Changes don’t
usually
happen in just
1 generation as a
result of predicted
need.
Artificial Selection –
Selective Breeding
Page Title
• Note 1
• Note 2
• Note 3
NATURAL SELECTION
1.
Over-production – more offspring are born
than survive
Natural selection
2.
Competition for resources – food, space,
mates
Natural selection
3.
Survival of the fittest – variations within
genes may provide some organisms
with an advantage over others
– “The individual best suited to their
environment will survive to reproduce.”
– Ex – camouflage, efficiency of
photosynthesis, hunting in packs.
– Over time, the population changes the
inherited traits.
Real Life Scenario:
Industrial revolution increases pollution in the
air. The pollution can be seen discoloring the
environment.
Peppered moths saw a big change in favored color.
Before Industrial Revolution
After
Natural selection
3.
Traits are inherited–
–
All organisms are related and have changed
(diverged) over time as the altered trait gets
passed down..
• Bigger and stronger is not
always better!
misconceptions
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
mutation!
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
Generation 3: 0.76 not resistant
0.24 resistant
How natural selection works
Resistance to antibacterial soap
Generation 1: 1.00 not resistant
0.00 resistant
Generation 2: 0.96 not resistant
0.04 resistant
Generation 3: 0.76 not resistant
0.24 resistant
Generation 4: 0.12 not resistant
0.88 resistant
WHY SHOULD WE BE WORRIED ABOUT RESISTANCE?
http://evolution.berkeley.edu/evolibrary/home.php
Peccaries are
great
predators of
cacti
= original cactus
population
= population after
introduction of
peccaries
Observable evidence for
evolution
Pinta Island
1. Fossils
2. Geographic distribution –
diff. species in diff. geographic locations
need different adaptations.
Hood Island
Evidence for Evolution
3. Convergent Evolution - Animals in
similar habitats but different geographic
locations look similar due to similar
needs/food/climate.
Flying
Squirrel
Sugar
Glider
Marsupial Mammals
Convergent
Evolution
Placental mammals
Mammalia
Rat like
common
ancestor
4. COEVOLUTION
5. Biochemical/DNA evidence
• Determines relationships, ancestry and how long ago
organisms diverged.
• Ex – Old World Monkeys & New World Monkeys
Old belief: diverged from common
ancestor 50 million years ago when
African and South American
continents separated.
After DNA testing : much
more recently diverged.
Supported “raft hypothesis”
American vultures, African vultures and storks were originally
classified in the falcon family.
DNA evidence showed that American vultures are actually more
closely related to storks that African vultures.
Did modern birds
descend directly
from the dinosaur?
DNA shows relationships
we would never have
guessed!
6. Homologous body structures
• Anatomical similarities in related
organisms
Human Cat
Whale
Bat
Shows that all 4-limbed animals descended with modifications from
a common ancestor.
7. Vestigial structures
• Little or no function and are reduced in size.
Also: appendix, tail bones, ear
muscles, wisdom teeth
Would the vestigial legs of snakes look more like a rabbit or bird bones?
8. Similar embryology
• Early stages of embryo development in closely related
animals is similar.
• Timing of gene actions is different.
fish
salamander tortoise
chick
pig
cat
rabbit
human
Mechanisms of
Change
• Natural Selection:
adapts a
population to its
environment
Gene Pool
Combined genetic
info. of all
members
Allele frequency is #
of times alleles
occur
(has nothing to do with
dominant or
recessive!)
Isolating Mechanisms cause change
1. Geographic
Isolation –
rivers, mountains,
bodies of water
(roads)
•
Environmentslight
differences may
influence direction
of natural selection
Soloman Flycatchers
Chestnutbellied
flycatcher
(Makira
Island)
Blackbellied
flycatcher
(Santa Ana
Island)
2. Behavioral Isolation – differnces in
courtship rituals
Fig. 23.6
Four species of leopard frogs: differ in their
mating calls. Hybrids do not live.
3. Temporal Isolation
These squirrels live on opposite sides of the Grand
Canyon. This is an example of ________ isolation.
Extinction
•Usually
coincides with
global climate
change
•99% off all
species that
ever lived are
now extinct