Download Evidence for Evolution

Evidence of
Evolution
Blue-footed booby
Five Fingers of Evolution - video
Part 3: Evidence of Evolution
What supports the Theory of
Evolution…..
Evidence of evolution
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Fossil Record
Anatomy
Embryology
Biochemistry
• Evidence in microevolution
Fossil evidence
• Fossils → remains of ancient life
– Fossils arranged according to age
show a progression of changes
– The Law of Superposition → a
layer of rock is older than the layer
above
Mold Fossil
• Fossils can be arranged by relative age
– Radioactive Dating → naturally
occurring radioactive substances
decay at a known rate
• Transitional forms of fossils
are evidence for evolutionary
change
Preservation (insect
in amber)
Reasons Why a Fossil Might Not
Form
• Dead bodies may be eaten or
scattered (scavengers)
• Decay
• Hard exoskeleton vs. soft-bodied
organism
Anatomy evidence
• Evolution works primarily by modifying
pre-existing structures
• Homologous structures: parts came from
the same origins, but now may have different
function
– e.g., forelimbs of all mammals contain the same
pattern of bones, although the bones now carry
out a variety of functions
• horse leg, bat wing, human arm, whale flipper
Anatomy evidence
• Analogous
structures: parts
came from
different origin,
but now have
same function
Anatomy evidence
Vestigial structures:
parts have no current
function (had a
function in ancestors)

– Examples in humans:
wisdom teeth, erector
pili, coccyx, ear
muscles, appendix
Embryology evidence
• Closely related organisms develop similarly,
especially in early fetal stages
• This suggests that these organisms are
related to other forms.
– Mammal embryos (including humans) have fishlike gill slits, tail
Biochemistry evidence
• All organisms share certain biochemistry
– Genetic code for building amino acids
– All organisms use ATP for energy
– Plasma membranes of all organisms consist of a phospholipid
bi-layer
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
# of amino acid differences between
human hemoglobin and other organisms
Evidence for Microevolution
Evolution Observed
Evolution of pesticide resistance
in response to selection.
Evolution in Action
Macroevolution
Large scale changes
that take place over
a long period of
time that create and
eliminate species.
Microevolution
Short time scale events (generation-to-generation) that change
the genotypes and phenotypes of populations.
Part 4: Types of Natural
Selection
Example of Natural Selection
• 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)
• Male birds show off
their beauty to attract
females
Video
Example of Artificial Selection
• 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
Artificial Selection
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.
Artificial Selection
Selective Breeding - Video