Transcript Theory of Evolution

Theory of Evolution
“Nothing in biology makes
sense EXCEPT in the light of
evolution.”
-Theodosius Dobzhansky
Early Evolutionary
Thought
 James
Hutton
 Gradualism
 Gradual
change over
time  species formation
http://lhs2.lps
.org/staff/spu
tnam/Biology/
U6Evolution/g
radualism.gif
Early Evolutionary
Thought
 Gould
and Eldredge
 Punctuated
A
Equilibrium
successful species may stay
unchanged
 Environmental changes cause
evolution in spurts
http://lhs2.lps
.org/staff/spu
tnam/Biology/
U6Evolution/g
radualism.gif
Early Evolutionary
Thought
 Jean-Baptiste
 Law
Lamarck
of Use and Disuse
 Understood
change over time
 Organisms Change Size Or
Shape Of Organs By Using
Them Or Not
 Adaptations are acquired during
organism’s lifetime
http://www.princesslei
a.com/images/MyImage
s/essays/giraffe_lamark
.jpg
Early Evolutionary
Thought
 Charles
Darwin
Traveled around the
world
 Galapagos Islands
 where he made his
Theory of “Descent
with Modification”.
*Glencoe

The Galapagos Islands
Darwin studied the animals
on islands
 Tortoises
 Iguanas
*Glencoe
 Finches
Natural Selection

Descent with Modification AKA:
“Natural Selection”



*Glencoe

Organisms best adapted 
Most likely to survive 
Reproduce & Pass on adaptations
to offspring
Ex:

Artificial Selection

Breeding
Evidence of Evolution
 Anatomy
 Homologous
Structures
 Structural
features with
a common evolutionary
origin
*Glencoe
Evidence of Evolution
 Analogous
Structures
 Similar
function but
no shared
evolutionary origin.
*Glencoe
Evidence of Evolution
 Vestigial Structures
 Body structure in a present-day
organism no longer useful
 But useful to an ancestor.
*Glencoe
Evidence of Evolution
 Embryology

The embryos of a fish, a
reptile, a bird, and a
mammal have:
A
Post anal tail
 Pharyngeal gills

Suggest evolution from a
distant, common ancestor
Pharyngeal
pouches
Tail
Fish
Tail
Reptile
Bird
Mammal
*Glencoe
Pharyngeal
pouches
Evidence of Evolution

Biochemistry

Species with common ancestor
more recently have similar
hemoglobin (hemo – blood)
amino acid sequences.
Adaptations
 Mimicry
 Enables one species to resemble
another species.
 Ex. Coral snake which has a
powerful neurotoxin that
paralyzes the breathing muscles.
 The common Milk snake is
harmless
“Red and black, friend to Jack; red and yellow kill a fellow”
*Wikipedia
Adaptations
 Camouflage
 Adaptation
that enables
species to blend with
their surroundings
*Wikipedia
Adaptations
 Physiological Adaptations
 Changes in an organism’s
metabolic processes
 Much Faster

Antibiotic Resistance

Ex. Antibiotics developed during
the twentieth century are no longer
effective
*Glencoe
Speciation
New species form
 Reproductive Isolation

Organisms of the same species
no longer breed b/c:
 Geographic separation
 Difference in mating periods
 Genetic
differences
increase and new species
are formed