Transcript Evolution Notes

Five Fingers of Evolution - video
1. Direct Observation
 2. Fossil record
 3. Homologous structures
 4. genetic/and or biochemical similarities


Evolution of drug resistant viruses and
antibiotic resistant bacteria

Peppered moths during Industrial
Revolution.
Peppered Moth Video
A.
Early Life Forms: Fossils

Fossil = a trace of a long-dead
organism, found in layers of sedimentary
rock; hard minerals replace tissues of
organism
Types of Fossils
Mold = imprint in rock
 Cast = a mold filled with hard minerals


Trace Fossils = signs of life
(footprints, burrowing, etc.)

Resin Fossils = organisms
that have been preserved
nearly perfectly in plant
resin (amber)

“Living Fossils” = any living
species that is nearly
identical to species
previously known only from
fossils
A
C
B
D
• Wet lowlands, slow moving
streams, lakes, shallow seas, near
volcanoes
• Upland forests, mountains,
grasslands, deserts
• Dead bodies may be eaten or
scattered (scavengers)
• Decay
• Hard exoskeleton vs. soft-bodied
organism
How do we determine the age of fossils?

Relative Age – the approximate age
based on position in the layers of
sedimentary rocks

Absolute Age – the exact age of a fossil
based on Radioactive Dating (carbon-14)

Which is older… a fossil found in layer 2
or 4?
when “isotopes” of atoms in fossils decay
into other “isotopes”
 Remember: isotopes are the same atom
with different numbers of neutrons
 Measured in half-lives (how long it takes
for one-half of a sample of an isotope to
decay)


Example: Carbon Dating (C-14C-12)
If the half life of C-14 is 15 years, meaning
half a sample of C-14 will decay into C-12
in
15 years…
 How much C14 (in a fraction) remains
after 45 years?
 How old is the sample if only 1/16 of the
carbon is in the C-14 form?
You need to add this to the back of your notes
packet!
B. Comparative
Anatomy

Comparative
Anatomy – compare
structures found in
modern organisms
with those from
ancient times
Homologous Structures:
inherited from a common
ancestor, changed due to
different environments
Similar structure; different
function
Ex: Limb bones of whale,
bat, human, etc.
1)
Analogous Structures:
similar in purpose, but not
inherited from a common
ancestor
Different structure; similar
function
Ex: Wings of insects vs. bird
2)
C. Vestigial Structures

Features/structures that were useful to an
ancestor but are no longer useful
Ex: Whale pelvis,
Human tailbone +
appendix
Similar structure in
embryos of related
organisms.
Tail
Buds which will become
limbs
Pharyngeal pouches (gills)
Finding similarities in
embryos ; organisms
sharing a recent ancestor
have more similar embryos
(discovered by Ernst
Haeckel)
E. Comparative Biochemistry
 Finding similarities in protein and DNA
sequences to look for relatedness
Below is a DNA sequence in several
different organisms…which organisms
are the most related?
Human
CCA TAG CAC CTA
Pig
CCA TGG AAA CGA
Chimpanzee
CCA TAA CAC CTA
Cricket
CCT AAA GGG ACG
Nature Chooses: Individuals that survive
in nature will live long enough to
reproduce.
 This means that they are the ones that
get to breed and their characteristics
(being good survivors) are inherited by
their offspring.

Types of Natural Selection:
A) Stabilizing Selection = individuals with the
average form of a trait have the highest
fitness. It is favored and most common
B) Directional Selection = one extreme form of
trait is more successful
C) Disruptive Selection = BOTH extreme forms
are more successful than the average. The
most extreme form of a trait is favored and
becomes most common.
Evolution in the Big City
D) Sexual Selection
 Females choose mates
based on certain traits
 Males with these
traits have higher
fitness (reproductive
success)
http://www.youtube.com
/watch?v=gqsMTZQpmE&feature=fvwrel
Video
Humans Choose: Individuals that are
allowed to breed are chosen by humans.
 These individuals have the characteristics
that humans want.
 This process produces animals that
express specific characteristics.

Is there “unnatural selection?”
Artificial Selection = humans
“select” certain characteristics
in plants, dogs, etc., that they
find favorable
These organisms may not
necessarily survive and
reproduce better in nature

It has led to offspring through successive
generations that can be very different in
appearance and behavior from their
distant ancestors.

Organisms with certain traits are bred
repeatedly until population has only that
trait

Example- Dogs, Corn, Broccoli, Cows, etc.
Creating the Perfect Pet - Video
These chickens cannot stand or move.
Cow selectively bred for extra meat (muscle). Usually cannot stand for
more than a few minutes or walk more than a few steps.
Selective Breeding - Video

First off, how do we define a species?

Morphological Species Concept – internal
and external structures are used to group
organisms into species

Biological Species Concept– defines a
species as a population of organisms that
can successfully interbreed

Speciation = formation of
a new species

Reasons for Speciation
1) Geographic Isolation
2) Reproductive Isolation
-prezygotic (before
fertilization)
-postzygotic (after
fertilization)
There are two models of speciation, or how
populations change over time
Model #1: Gradualism (change happens
slowly, and new species are made at a
constant rate)
Model #2: Punctuated Equilibrium (there
are times of little or no change followed
by times of rapid change – often due to
major changes in the environment)
Stephen Jay Gould came up with this
model!
Gradualism
Punctuated Equilibrium
A) Coevolution = change of two or more
species in response to one another. Two
species evolve together in response to their
environment.
(Ex: predator/prey relationships;
hummingbird beak/trumpet flower;
dogs/humans)
Orchid Fly
B) Convergent Evolution = organisms with
different ancestors (not related) become
very similar due to environment (Ex:
sharks and dolphins)
C) Divergent Evolution = two or more
related populations/species become
different (Ex: Darwin’s finches)
Divergent
Evolution
Convergent
Evolution
D) Adaptive
Radiation = an
extreme form
of divergent
evolution
where many
related species
evolve from a
single ancestor
species