Download Units 8 & 9: Evolution and Classification

Units 8 : Evolution
Explaining how species change
over time and the great extent of
different species on Earth
A. Theory of Evolution
Explains how changes in a species occur
over time
________________ sails around the
world on the HMS Beagle
Make a historical stop over in the
____________________
1. Observations on the Galapagos Islands
a) Islands have very different _______________________
b) Diversity of life
hundreds of plant and animal species so ___________ to
their environment
c) _______ organisms in ________ parts of the world living
in similar habitats were often very __________ from each
other
d) Some living organisms resembled _______________.
Some fossils very different, Some living organisms very
different
2. Publishes: The Origin of Species by Means of
Natural Selection
Darwin explains evolution as a ____________________
3. Theory of Natural Selection
a) ___________________
- Within a population more offspring are produced
than can survive
- There is variation among the offspring
- Darwin could not explain the variation
Where does variation come from?
b) ______________________
- The number of organisms in a population tends to
stay constant generation after generation
- At some level there has to be _________ among the
individuals of a population for ______, ____, _______,
_________
- ________________ – compete for limited resources
c) ______________________
- Those organisms best adapted to the environment are
more likely to survive
- __________ = any inherited characteristic that increases
an organism’s chance of survival
Structural, Behavioral, Chemical
d) _________________
- The organisms with the _____________ survive and pass
their adaptations on to their offspring
- How are adaptations passed on?
e) ________________
- After generations adaptations accumulate in the offspring
as such that the offspring creates a new species
- Species = a group of organisms that can interbreed and
have viable offspring
How did the Giraffe get its long neck?
Overproduction
Variation
Competition
Survival of the Fittest
Reproduction
Speciation
How did the Giraffe get its long neck?
4. Artificial Selection = ____________________
Choosing specific traits in the hope the offspring will have a
combination of the traits.
Done for thousands of years by humans
5. Competing idea of Evolution
Lamarck’s Theory of Evolution
selective __________ of traits led to the change in
a species over time
This theory has been ___________! Don’t mess this up!
Lamarck’s theory
is based on the
idea that evolution
is based on need.
______________
to do with
evolution.
Millions of species
have gone extinct
because they
needed a new
adaptation!
B. Evidence for Evolution
How do we know that Darwin is correct?
1. ___________________
- Theory that Earth formed 4.6 billion years ago
- Radioactive dating of rocks on Earth
- 4.0 billion years ago – Earth begins to cool
Water Vapor condenses and it Rains
Oceans = Primordial Soup
- 3.5 billion years ago – first signs of life
simple single celled organisms
______________________
Heterotroph Hypothesis – 1st organisms on Earth
were anaerobic heterotrophs  autotrophs  aerobic
heterotrophs
- 2.0 billion years ago – first signs of single celled
eukaryotes
- 250 million years ago – age of dinosaurs
- 200,000 years ago – first signs of modern humans
2. ________________
Fossil = organismal remains that have been mineralized
Bones, imprints, amber
Generally:
a) the deeper the layer the ______ the layer  so organisms
found in deep layers tend to be older
b) Older organisms tend to be ______________
c) Upper / newer layers show more _________________ that
have a connection to the older structure  shows change
d) more _______ of organisms tend to show up in the newer
layers
3. Comparative biology
a) Anatomy
1. ___________________ – on the outside the structures
may look different and perform very different functions, but
on the inside the structures are built ________________.
Evidence that the
organisms came from
a _____________ and
adapted to different
environments=
_______________
2. ___________________
perform the same function but built __________________.
Evidence that organisms of different origins ________ to
_____________ = ____________________
3. _______________________
body structure that is reduced in the living organism but __
________________________________ of the organism the
structure had some significance and importance.
Evidence that the organism is now ___________________________
b) _______________________
the more closely related organisms are the _____________
______________________________. Shows the organisms
had a common ancestor.
c) ___________________
The more similar the chemical make up of the organisms the
more closely related they are.
Compare ____________:
Human - Chimp – 98.2%
Human - Gorilla – 97.7%
Human - Orangutan – 96.3%
4. Geographic Distribution of Species
biological diversity results from the descendants of a
local species migrating and adapting to new
environments
C. Mechanisms of Evolution
Populations evolve  not the individual organism
Natural Selection acts upon the phenotypic expression of a
gene in the life time of an individual organism
new features do not evolve in a life time
new adaptations result from mutations and sexual
reproduction
Gradualism
Darwin’s idea of evolution
Slow steady process over millions
Supported by the fossil record
ex: Giraffe, Elephants
Punctuated Equilibrium
Evolution occurs in rapid bursts with long
ofperiods
years of stability in between
Drastic environmental changes occur that
cause extinction or rapid change in species
ex: bacteria resistance, peppered moth
Genetic Drift
- because populations don’t always remain stable
- gene frequencies are changing = evolution is
happening!
1. Stabilizing Selection – evolution that favors the average
individual reduces variation
2. Directional Selection – evolution that favors either of the
extreme forms
3. Disruptive Selection – evolution that favors both of the
extreme forms evolution of new species