Transcript Evidence for Evolution - Ms. Nevel's Biology Website

Evidence of
Evolution
Blue-footed booby
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)
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)
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– 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
# of amino acid differences between
human hemoglobin and other organisms
H: Human Chromosome
C: Chimp Chromosome
Evidence for Microevolution
Evolution Observed
Evolution of pesticide resistance
in response to selection.
Evidence for Evolution – Evolution Observed
Evolution of drug-resistance in HIV
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-togeneration) that change the genotypes and