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Evolution
• Change in populations
overtime
• specifically a change in
the gene pool
• Populations change, NOT
individuals
•
http://www.youtube.com/watch?v=faRlFsYmkeY&feature=related
Charles Darwin
•The Father of Evolution
•Coined the term
“Natural Selection”
Natural Selection
• Natural Selection: Organisms
with certain variations
survive, reproduce, and pass
their variations to the next
generation
• Organisms without these
variations are less likely to
survive and reproduce
Natural Selection EX:
• 1) There is a variation in
traits (some brown and
green beetles)
• 2) Green beetles are more
easily seen, and are
therefore more likely to be
eaten
• 3) Brown color is an
advantageous trait,
therefore they are
better able to survive
• 4) End result: Brown
Beetles reproduce
brown beetles
Artificial Selection
• How humans influence evolution
• AKA selective breeding
• Humans pick and choose what
organisms can and will
reproduce
• EX: Domesticated animals and
crops
Sexual Selection
• It’s an organisms ability to
obtain a mate
• It is powerful enough for the
male to produce features that
are harmful to its ability to
survive, but are appealing to
a female
The “Prettier” the male the
more likely a female will
choose
it.
Female
Which
one
should I
choose?
?
How does Evolution occur?
• Evolution can happen
gradually or in rapid bursts
• 1) Gradualism
• 2) Punctuated Equilibrium
Gradualism
• Species evolves
through a SLOW
change of
adaptions
• Some evidence in
fossil record
supports it
EX: Camel
Punctuated Equilibrium
• Punctuated Equilibrium:
Speciation occurs through
rapid bursts with periods of
genetic equilibrium
• These rapid bursts are due to
environmental changes
• EX: Elephants
Punctuated Equilibrium
Gradualism
Vocabulary
• Natural Selection
• Artificial Selection/Selective Breeding
• Sexual Selection
• Gradualism
• Punctuated Equilibrium
STOP
Warthog do now
• warthog
Anatomy: Indirect Evidence of
Evolution
• 2 kinds of anatomy
evolutionary biologists look
at
• 1) Homologous Structures
• 2) Analogous Structures
Homologous Structures
• Structural features with a
common evolutionary origin
• Have a similar structure, but
different function
• Demonstrates organisms
evolved from a common
ancestor
Homologous Structures
Divergent Evolution
• Have a common ancestor, but
have developed different
traits to adapt to their
environment
• EX: Bat and human
Analogous Structure
• Body parts of organisms that
DO NOT have a common
evolutionary organism
• BUT, have a similar function
• EX: bird and butterfly wing
Analogous Structures
Convergent Evolution
• Unrelated species evolve
similar traits but are NOT
related
• Has to do with the
environment
• EX: Shark and Dolphin
Convergent Evolution
FINS EVOLVED INDEPENDENTLY of EACH OTHER,
but THEY ALL NEEDED FINS TO BE ABLE TO SWIN
STOP
Video on Sickle Cell Anemia
• Sickle Cell Video
Population Genetics & Evo
• Populations evolve, not
individuals
• Evolution occurs in a
populations genes, and the
frequency of those genes
change over time
Gene Pool
• All of the alleles of the
populations
• Wait, what’s an allele
again?
• An allele has different
forms of gene
• EX: T= tall, t= short
Allelic Frequency
• Allelic Frequency
is the percent of
any specific allele
in the gene pool
• There is an 80%
chance a baby
frog will be green
Genetic Equilibrium
• Frequency of alleles that remains
the same over generations
Change in Genetic Equilibrium
• In order to evolve, something
needs to change the allelic
frequency in the gene pool
• If there is a change in the
gene pool, evolution can
happen
4 ways Evolution can happen
• Natural Selection
• Mutation
• Genetic Drift
• Gene Flow
Natural Selection
• Is the result of variations
among offspring, struggle for
survival, and adaptive value of
advantageous traits
• The diversity of life today, is a
result of natural selection
Mutation
• Mutations and genetic
variation occur through the
recombining and sorting of
meiosis
• What cell does a mutation
need to occur in, in order to
be passed on to its offspring?
Genetic Drift
• When the chance of allele
frequency changes
• Happens when populations
become isolated, and an
allele will appear more
frequently because the
population is small
Ex: Polydactyl in Amish
Gene Flow
• The movement of genes in and
out of a population (Migration)
• With the movement of people,
genes can move in and out of
a gene pool
• Evolution is like
the growth of a
tree
• Some branches die
out, some survive
and never change,
and other continue
to give rise to
other branches
DO NOW:
WHICH ORGANISM IS BEST
ADAPTED FOR A COLD CLIMATE?
Furless Rabbit
Rabbit W/
Fur
• Genetic Drift
• Genotype
• Gene pool
• Phenotype
• Gene Flow
• Allele
• Allelic
Frequency
• Artificial
Selection
• Homologous
Structure
• Analogous
Structure
• Comparative
Embryology
• Comparative
Anatomy
• Fossils
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Adaptive Radiation
• When an ancestral specie
evolves into an array of
species to fit a number of
diverse habitats
• It is a type of Divergent
Evolution
• Ex: Darwin’s Finches
Adaptive Radiation
Speciation
• Speciation- the evolution of
new species
• How does it happen?
• When a member of similar
species can no longer
interbreed to produce fertile
offspring
3 ways Speciation Happens
• 1) Physical Barrier
(Geographic Isolation)
• 2) Reproductive Isolation
• 3) Change in chromosome
number