Transcript Evolution pres Bio 1 (design 2)

EVOLUTION
Theory of Evolution
-Evidence for Evolution
-
Part 1
Theory of Evolution and Selection
Evolution is a Theory
In common usage, people use the word theory to mean a
guess. In science, does the word theory mean a guess?
Name some additional theories.
Evolution is a Theory
Name some additional theories:
Cell Theory-cell is the basic unit of living things
Quantum Theory-describes very small particles
Germ Theory- microbes cause disease
Plate Tectonics- continental plates are shifting
Heliocentrism-sun is the center of the universe, which
superseded geocentrism
Theory of Evolution
How has evolution risen in status to the level of THEORY,
the same level as gravity or plate tectonics?
Through repeated observations from many areas of life
sciences.
Charles Darwin (Slide 1)
Who is Charles Darwin?
What was his profession?
Where did he travel?
What did he learn?
What is his famous idea?
Charles Darwin (2)
Who is Charles Darwin? World
renowned
Naturalist-before there was Biology.
Born Feb 12, 1809, same day as
Lincoln. What a day!!!
What was his profession? Ship’s Naturalist
Where did he travel? All over the world. He is
remembered most for his observations
in the Galapagos Islands.
 What did he learn? That
organisms change
over long periods of time, evolution.
 What idea is he famous for? The Theory of
Evolution by Natural Selection
Variation among organisms
Describe how each can vary…
Tortoises
Saddle shaped shell for reaching higher vegetation or
dome shaped shell if vegetation is more abundant.
Also an intermediate form
Bird beaks
In finches, many varieties of beak shape to correspond
to habitat.
Lamarck (1)
Describe John Baptiste-Lamarck
Why is he such an important figure in modern biology?
Lamarck (2)
Describe John Baptiste-Lamarck
He was a French naturalist. He published his hypothesis the
year Darwin was born.
He proposed the concept of Use and Disuse and Inheritance
of Acquired Traits
Why is he such an important figure in modern biology?
Although his hypothesis hasn’t been supported by data, his
groundbreaking thoughts influenced future naturalists like
Darwin. Plus, as we learned in “Ghost in Your Genes”, he
was not completely wrong.
Selection
Discuss in your own words what is meant by selection.
Give an example of natural selection.
Give an example of artificial selection.
Darwin’s Theory of Natural
Selection
1. There is variation among organisms
2. More offspring are produced than can survive.
3. There is competition for limited resources
4. Natural Selection: Individuals best suited for their
environment survive and pass down their traits.
Descent with modification
Race to the Finish
 Alfred Russell Wallace – Was thinking of
the very same ideas at the same time.
 When Wallace sent him an essay about his
hypothesis, Darwin quickly published the
work he had been accumulating for 25
years.
Darwin’s Influences
 Hutton– Proposed that the earth is in a
constant state of change.
 Lyell- Proposed that these changes occur as
a result of events such as earthquakes and
volcanoes.
Artificial Selection
Give 2 examples of artificial selection…
Page 379
Selection Ponderables
 Does selection act directly on genotypes or phenotypes?
 Which is more likely to be selected against, deleterious
mutations that are dominant or those that are recessive? Why?
 Can selection create perfect organisms?
Human’s backs are evolved from 4-legged ancestors and not
fully compatible w upright posture, so many [older or very
tall] people have back problems).
Humans have a blind spot that even the octopus doesn’t have.
-Blind Spot Test
Part 2
Evidence for Evolution
Early Clues
What is probably the first clue that living things have changed
over time?
Fossils
Fossil Evidence
There is a story about the history of life
written in rock.
Relative dating--layers of rock (index
fossils)
Absolute dating--uses radioactive
isotopes (half-life)
How can the age of fossils be determined?
Carbon dating—all living things made of carbon
Carbon-14 has a half-life of 5730 years
If a fossil has ¼ of its original C-14, how old is it?
See page 445 for graph and add’l problem
Piecing the evidence together
What other evidence has contributed to our current
understanding?
Geographic Distribution
Island Patterns
Tortoises and finches from mainland are adapted to fit
their new island environment.
Ex: necks and shell in tortoises.
Similar Environments
Organisms that live in similar environments often come to
have similar adaptations. These are called analogous
structures.
Darwinian Prediction
 Darwin found an orchid whose reproductive
organs were 30 cm deep inside the flower.
 Darwin postulated that a pollinator would
be found with a 30 cm proboscis.
 It took 40 years, guess what scientists
found!...
Darwinian Prediction
 Xanthopan morganii
praedicta
– The Hawk Moth
– Guess the length of the
proboscis?
– Notice its last name?
– What kind of logic?
• Inductive or deductive?
Anatomical Evidence
Homologous structures
Structures that have different functions but arrived from
same body part.
Human arm, bird wing, turtle leg, alligator leg derived
from an ancient, lobed fish (page 384)
Evidence- Homologous Structures
Anatomical Evidence
Embryological Development
Developing human embryo displays features from ancestors
• Gill pouches
• Tail
• 3 sets of kidneys in humans
http://www.pbs.org/wgbh/nova/odyssey/clips/
Which Embryo is Which? Click Link:
http://www.explora
torium.edu/exhibits
/embryo/embryofla
sh.html
Anatomical Evidence
Did you know there are pelvic bones in snakes? In
whales? Why?
They are vestigial structures
What vestigial structures do humans have?
Appendix
Analogous Structures
 The wing of a bird and the wing of an insect
are not homologous. They do not arise from
a common structure.
 They are analogous structures.
 They are two structures that have evolved
separately to do the same job.

Ex: Bird’s wing; insect’s wing

Pouch of kangaroo; pouch of oppossum
Piecing the evidence together
What about our new understanding of genetics? How does
this impact our model of evolution?
Molecular Record Evidence
The more amino acid (or DNA base pair) differences, the
greater the evolutionary distance.
Cladogram
Cladogram (page 384, page 660)
Evolutionary Tree--The ‘trunk’ of the tree represents
similar traits or molecules (depending on how tree was
made). Each branch represents a divergence.
See page 452-- CLADOGRAM
What is the common ancestor for the crab, barnacle and
the limpit?
Which of the above animals are most closely related,
according to the cladogram (not the appearance).
Modern Examples
Are there any real life examples of evolution in modern time?
Peppered moth story
Bacteria superbugs (MRSA and TB)
Human size and development
Resistance to pesticides.
Remember DDT?
There are rats in England that no longer even get sick
from 5 times the dose of pesticide that once killed
most rats
Industrial Melanism
Peppered moth story
See peppered moth sim
See details of how the experimental method was
implemented.
How does this relate to the Clean Air Act?
What types of selection can you attribute this to?
Where did life come from?
 First- read pages 424-428

 First Organic Molecules
 Puzzle of Life’s Origin
 Free Oxygen
 Origin of Eukaryotic Cells
Origin of Life
Miller-Urey Experiment
Conditions of Early
Atmosphere of Earth
(Before Life)
Products of Experiment
Origin of Life
Miller-Urey Experiment
Conditions of Early
Atmosphere of Earth
Before Life
Products of Experiment
Flask with H, methane,
ammonia, H20 (no free
oxygen! O2)
Spark (to represent
lightning)
Some amino acids, and
cytosine and uracil
Miller-Urey Conclusion
What is the main idea of this experiment?
How organic molecules (ex: protein or DNA) might have
arisen from simpler molecules
Biogenesis
This is a good time to review Biogenesis.
Compare biogenesis to abiogenesis.
Describe the experiments that proved biogenesis.
Redi, Pasteur
Building Complexity
How might cells with organelles have first come about?
What is the evidence that some cell parts arose in this way?
Building Complexity
How might cells with organelles have first come
about?
Endosymbiosis-one prokaryotic cell engulfed
another, and they remained in this symbiotic
relationship.
What is the evidence that some cell parts arose in
this way?
The membranes, circular chromosomes,
ribosomes and cell division by binary fission of
mitochondria and chloroplasts resemble today’s
prokaryotes.