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Evolution Notes
1. Evolution: Process of change that happens to organisms over time.
a. Other definitions
i.
The process of change by which new species develop from preexisting
species over time
ii.
The process in which inherited characteristics within populations change
over time.
2. Evolution Fact or Fiction?
a. Facts
i.
The earth is changing and has changed
ii.
Life and organisms are changing and have changed
1. Look at the dogs of today vs Dogs of the past (400 different breeds)
2. Look at the corn we eat today vs the black and colored corn the
pilgrims ate
b. Fiction and Falsehoods
i.
Individual evolve
ii.
Jean Baptists de Lamark (1809) Evolution Theory
a. The animals wanted to. They desired to change
b. Used or disused effect organs or structures
c. Passed on acquired traits
Giraffes
stretched
their
necks to get leaves at the top of the tree. By the end of its life
This
its neck would be longer. They would pass that longer neck to its offspring. Over time
is BS
they ended up with very long necks.
c. Theory (not fact, but has evidence to make you believe it’s true)
i.
Some organisms change so much they become a new species
ii.
How and what causes those changes.
3. Newest and best theory about evolution - Darwin's Evolution by Natural Selection
a. Charles Darwin
www.aboutdarwin.com
Naturalist from England (1809-1882). Developed the theory of evolution after taking a 5
year world tour on the ship HMS Beagle (1831). He visited many remote Islands and collected
many animal and plant specimens. After studying his many books of notes and his large
collection of specimens for 30 years he wrote his book that describe his theory of evolution. The
book was called "Origin of Species by means of Natural Selections" Published in 1859.
4.
Important idea’s about nature Charles Darwin learned
a. Diversity of Life (Biodiversity)
i.
3 to 20 million living species are believed to be in the world today.
ii.
Most of the species of the world are extinct (99.99%)
iii.
That means several hundred million species have come and gone in the
world.
b. Organisms have fitness
i.
Fitness: the physical traits and behaviors that help an organism survive
and reproduce in its environment.
ii.
Organisms with the best adaptations or the most fitness are able to survive
and reproduce.
1. Adapting: the ability to change to fit new environmental pressures
2. Adaptation: Inherited characteristic that helps an organism to survive
in it's environment.
- Long necks of giraffe,
- Wings on a bird, - Warm fur on a beaver
5. Basic Principles of Evolution by Natural Selection
a. Step 1 - Overproduction
i.
Reproducing organism make more offspring than the environment can
support. (So many usually most will die)
1. fish will lay millions of eggs and only a few will grow to adulthood.
2. A population of rabbits will have 200 baby bunnies; the environment
will only support 10 more rabbits. 190 will die. What 10 will live?
b. Step 2 - Variations
i.
Reproducing organisms produce offspring with variations due to the mixing
of genes or mutations.
ii.
when you dogs have puppies they are all a little bit different
iii.
Some bunnies are bigger and faster, some are smaller and slower
c. Step 3 – Selection (Survival of the Fittest)
i.
The bunnies or the organisms that have the best variations or traits have a
better chance to survive and reproduce passing those traits on.
1. the bunny that is the fastest can get away from predators better.
2. the bunny that can hide the best can avoid the predator.
d. Step 4 - Adaptation
i.
Organisms with the best traits survive and pass those traits on to their
offspring
6.
Important Information about the Earth that supports Evolution
a. The Earth is 4.6 Billion years old
b. Based upon fossils the first life showed up on earth 3.5 billions years ago.
i.
See Geological Time Scale on pages 453
c. Radioactive Dating: Method of measuring rates of decay of radioactive materials
to determine how a fossil or rock is.
Half life: Time required for half of the radioactive sample to decay.
Radioactive element
Half-life
Decayed Element
Carbon-14
5770 years
Nitrogen-14
Potassium-40
1.3 Billion years
Argon-40
Uranium-235
713 Million years
Lead-206
If we find a fossil that is missing 2 of it=s carbon-14 it is 5,770 years old.
If we find a fossil that is missing 3/4 of it=s carbon-14 it is 11,540 years old.
If we find a fossil and it is missing 100% of it=s carbon-14 what do we do?
7. Fossil: Preserved remains or trace evidence of life from the past.
8. Fossil Record: The history of life on earth. Shows us that the earth is dynamic (always
changing)
a. Sharks teeth in Arizona
b. Mountains of Utah made of limestone with fossils of sea life
c. Tropical plants in Canada
9. Paleontologist: Scientist uses fossils to study life of the past.
10. How fossils are formed
a. Buried by sediments
b. Trapped and frozen in ice
c. Buried in peat bogs, tar pits, quick sand
d. Trapped in tree sap (amber)
11. Steps to make a fossil
a. Covered or buried in some type of sediments
b. Pressure turns sediments into stone
i.
if it happens quick enough the organisms get preserved
ii.
usually only hard parts are preserved
c. Sometimes minerals replace the organic materials of the organism and it turns into
stone
i.
Petrified wood, or petrified bones
ii.
12. Problems with fossil record
a. Most organisms are not fossilized
b. Most of the organisms that are fossilized are destroyed or never found
c. When we do find them, they are in fragments.
13. Other Evidence that supports Evolution
a. Embryo similarities - Organism in it=s early stages of their development have
similar appearances.
i.
Their head, tails, limbs, right and left sides are all in the
same arrangement
ii.
All vertebrates develop a notochord, body segments,
pharyngeal gill pouches, and a post-anal tail. These
fundamental similarities indicate a common evolutionary
history.
14. Homologous Structures: Anatomically similar
structures inherited from a common ancestor.
- Structures found on different organisms that
are in a similar location but does different
functions.
-People arm, frog arm, dogs front leg, whale
flipper, chicken wing
- all of these structures have almost the
exact bone arrangement
15. Vestigial Organs: Structure that have become smaller or reduced in function and are
merely traces of the same organ in other species.
- Leg bone in python - leg in other species
- Tail bone in people - tail in monkeys
- Appendix in people - extra stomach in a cow
- Hip bone on a whale – hip on a wolf
16. Chemical Compound such as DNA or RNA and protein are found in all living things
a. 99% of DNA is just like Chimps DNA
b. DNA found in frozen mammoths and living elephants are so similar scientist are
trying to clone a mammoth using elephant cells
c. Organisms that produce hemoglobin are closer related to each other that organisms
that don’t
i.
Based on hemoglobin mice are closer to people than chickens (page 384)
How do we go from same organisms with varied traits to a whole new organism ?
17. Natures Rule: No two species can occupy the same niche in the same location for a
long period of time
a. Niche: an organism job or it’s where and what an organism does to survive.
i.
a frogs niche is to live in the pond and eat flies
ii.
a bobcats niche is to live in the forest and eat rabbits
1. if something steals your niche you become extinct
18. Speciation: Evolutionary process of making a new species.
i.
Species: group of organisms that share similar characteristics and can
mate and have fertile offspring.
Step 1 Reproductive isolation: a population (a group of organisms of the same
species) becomes separated from the other species. The two separated species can
no long interbreed and share genes.
- new river is formed
- new mountain is made
- new island is made
Step 2 - Change in the Gene Pool
Populations become adapted to the needs of their environment. Their traits
and gene change and become different.