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EVOLUTION:
CHANGE OVER
TIME
In Biology…evolution refers to:
• Changes in SPECIES
over time
• A species is a group of
similar organisms that
can breed and produce
fertile offspring.
CHARLES DARWIN
• Proposed the theory of
evolution
• He made observations on
his voyage around the
world…collecting evidence
to develop his theory.
• On the Origin of Species
(Book—1859)
IMPORTANT OBSERVATIONS
1. Noticed a great diversity
among a number of
species.
2. Plants and animals were
suited to the environment
in which they lived.
3. Different species lived in
similar ecosystems.
FOSSIL RECORD
• A fossil is the
preserved remains of
ancient organisms.
–Some looked like
modern animals
–Some looked different
than any modern
organisms
The Galapagos Islands
• Very close to one
another…but their
climates differed greatly–Low elevation: very dry,
hot, sparsely vegetated
–Higher elevation: a lot of
rainfall, more diverse
plant life
The Galapagos Islands
Galapagos Tortoises
Saddleback
Domed
FITNESS
• Organisms compete to
survive and reproduce
• Organisms best suited
to their environments
are most likely to
succeed
FITNESS is attributed to:
• Adaptations
–Any inherited trait that
increases an organism’s
chance of survival
NATURAL SELECTION
• SURVIVAL OF THE
FITTEST—
–Those that are able to
survive will be able to
reproduce and pass on
their adaptations to the
next generation
NATURAL SELECTION
(4 Principles)
1. VARIATION
EXISTS WITHIN
POPULATIONS
NATURAL SELECTION
(4 Principles)
2. ORGANISMS
COMPETE FOR
LIMITED
NATURAL
RESOURCES
NATURAL SELECTION
(4 Principles)
3. ORGANISMS
PRODUCE
MORE
OFFSPRING
THAN CAN
SURVIVE
NATURAL SELECTION
(4 Principles)
4. INDIVIDUALS
WITH
VARIATIONS
SUITABLE FOR
THEIR HABITAT
SURVIVE AND
REPRODUCE
FINCHES
TWO WAYS EVOLUTION MAY OCCUR
• GRADUALISM
– Occurs over a long period of time
• PUNCTUATED EQUILIBRIUM
– Occurs in spurts
– Caused by:
• Random change in DNA
• Sudden environmental changes
CONTINUITY
OF LIFE
FORMS
OVER TIME
TWO FORMS OF EVOLUTION
• MACROEVOLUTION
– changes that occur on the tree
of life
• MICROEVOLUTION
– Changes that occur within a
population
– (group of individuals of the
same species living in the
same area)
• Genetic variation is caused
by changes in genetic
frequency—there are 5
forces of genetic change:
1. Natural Selection
2. Mutations
3. Gene flow
4. Genetic drift
5. Nonrandom mating
MUTATIONS
• Change in DNA sequence
–Deletion
–Inversion
–Translocation
–Duplication
…however…
MUTATIONS
• To affect evolution,
mutations must be passed
on from one generation to
the next…
• Only mutations in gametes
can be passed on…
• …to affect evolution!
GENE FLOW
• Genes from one population
are introduced into the
gene pool of another
• GENE POOL: combined
genetic info of all members
• Basically affected by
migration
GENETIC DRIFT
• Changing the allele
frequency
• Some individuals may have
more offspring than others
BOTTLENECK EFFECT
• A form of genetic drift
• Sudden and severe
decrease in a population
size that results from
natural disaster, predation,
or habitat reduction.
Bottleneck Effect
FOUNDER’S EFFECT (you’ll have to
add this where you can!)
• A form of genetic drift
• occurs when a new isolated
population is founded by a
small number of individuals
possessing limited genetic
variation
(relative to the larger
population from which they
have migrated)
Founder’s Effect
http://upload.wikimedia.org/wikipedia/commons/2/24/Founder_effect-anim.gif
NONRANDOM MATING
• Not all individuals have the
opportunity to contribute
their genes to the next
generation (decreasing
their allele frequency)
• Courtship rituals, pecking
orders, breeding territories
MECHANISMS OF CHANGE
MUTATIONS
GENE FLOW (MIGRATION)
GENETIC DRIFT
NATURAL SELECTION
NATURAL SELECTION
Peppered Moths
• Number of current
classified species =
• 2.1 million
• Organisms that are not
capable of breeding with
each other belong to a
different species
• What causes new species to form?
»The evolutionary
process called
SPECIATION forms
new species.
»New species evolve
in 3 ways….
1. GEOGRAPHIC ISOLATION
• A population is divided by a
barrier
• Two geographically isolated
populations can no longer reach
each other to breed
• Natural selection on each side
causes the populations to
become genetically different
2. PARAPATRIC SPECIATION
• Two neighboring populations
– One hot and dry
– One cooler and wet
• Natural selection favors
different adaptations in area
– Causing genetic differences
• At the boundary—individuals
breed and make hybrids…
3. BEHAVIORAL ISOLATION
• Differences among
individuals cause them to
choose different mates.
• Continual, nonrandom
mating causes individuals
to become genetically
different.
EXTINCTION
• The death of all individuals
within a species.
• No longer able to survive
changing environmental
conditions
-or• No longer able to compete
EVIDENCE
OF
EVOLUTION
FIELD OF PALENTOLOGY
• Fossils are “dead remains”
that prove organisms
existed
• Give information about the
age of organism (dating)
• PROBLEMS??
– Still missing links
– Haven’t found all remains
FIELD OF BIOGEOGRAPHY
• Geographic distribution of
organisms
• Grouped according to the
needs of habitats,
resources
• Similar organisms will
arise in the same
geographic location
Rhea (South America)
Ostrich (Africa)
Emu (Australia)
FIELD OF BIOCHEMISTRY
• All living things have DNA
• Organisms that show
close relationships have
similar protein and DNA
structures
BIOCHEMISTRY
BIOCHEMISTRY
FIELD OF ANATOMY
1. Homologous structures
–Have similar construction
–Example:
• Human arm
• Cat leg
• Whale flipper
• Bat wing
ANATOMICAL HOMOLOGY
FIELD OF ANATOMY
2. Analogous structures
–Serve the same purpose
–BUT not designed in
same way
–Example:
• Bird wing
• Insect wing
• Bat wing
ANALOGOUS STRUCTURES
FIELD OF ANATOMY
3. Vestigial structures
–Seen in organisms of
today but not used
–Example:
• Appendix
• Tail bone
• Whale legs
• Snake legs
VESTIGIAL STRUCTURES
FIELD OF EMBRYOLOGY
• (embryo development)
• Very early stages of
development in animals
are hard to distinguish
between different animals
EMBRYOLOGICAL HOMOLOGY
IDENTIFY THE ORGANISMS
EMBRYOLOGICAL HOMOLOGY
HOW ABOUT NOW?
EMBRYOLOGICAL HOMOLOGY
EMBRYOLOGICAL HOMOLOGY
MARCH 16, 2011
BIOLOG: Without
using notes, write a
paragraph explaining
evolution providing
evidence to support
your explanation.
PATTERNS
OF
EVOLUTION
COEVOLUTION
• Change in two or more
species in close association
with each other
• Change occurs to benefit
each other
• EXAMPLE:
– Animals and their plants
– Hummingbird and trumpet flower
COEVOLUTION
DIVERGENT EVOLUTION
• Two or more related
species become different
CONVERGENT EVOLUTION
• Ancestors were different
and become similar
DIVERSITY
DIVERSITY
• TAXONOMY
–Science of naming and
then classifying living
things
• CLASSIFICATION
–Systematic grouping of
organisms based on
common characteristics
•
•
•
•
•
•
•
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kids Prefer Cheese Over Fried Green Spinach
• Scientists attempt to
understand the
evolutionary
relationships among
organisms…
• PHYLOGENETICS
–Studies the
relationships among
organisms
• PHYLOGENETIC TREE:
– Diagram that represents
the evolutionary history of
a species
PHYLOGENETIC TREES
ARE USED TO CLASSIFY:
• Organisms into major taxa
(groups) based on
evolutionary relationships
• Species in the order in
which they descended
from a common ancestor
using physical
characteristics
PHYLOGENETIC TREE
PHYLOGENETIC TREE
PHYLOGENETIC TREE
PHYLOGENETIC TREE
• Which groups are most closely
related?
• Which groups are least closely
related?
• Which group diverged first
(longest ago) in the lineage?
Charles Darwin
• Discuss Darwin’s contributions to how living things
change over time.
• Discuss evidence for how living things change over
time—including homology, biogeography and fossil
record.
• Discuss the five conditions preventing living things from
changing over time (Hardy-Weinberg). What
conclusions can you draw based on this information?
• There are several agents (mechanisms) for how living
things change over time, focus your research on the
following: genetic drift (including the founder’s effect
and bottleneck effect) and gene flow.
• There are several agents (mechanisms) for how living
things change over time, focus your research on the
following: natural selection and mutations.
• What misconceptions did you have prior to your
research? What are your conclusions?
Hardy-Weinberg
• What Is Hardy-Weinberg?
• How does it work?
Hardy-Weinberg Conditions
1. No Genetic Drift (Infinite Population Size)
2. No Migration (No Gene Flow)
3. No Mutation
4. No Selection (No Differential Selection)
5. Random Mating (No Differential Reproduction)
Founder’s Effect
SURVIVAL OF THE FITTEST
All blue-eyed people can be traced back
to one ancestor who lived 10,000 years
ago near the Black Sea
By MICHAEL HANLON
Everyone with blue eyes can be traced back 10,000 years to the Black Sea
region. Throughout history they have been the eyes that are prized. Frank
Sinatra's were legendary, Paul Newman's melted a million hearts while
Cameron Diaz's dazzle in modern Hollywood.
But how - and why - blue eyes arose has always been something of a
genetic mystery. Until now.
According to a team of researchers from Copenhagen University, a single
mutation which arose as recently as 6-10,000 years ago was responsible
for all the blue-eyed people alive on Earth today.
The team identified a single mutation in a gene called OCA2, which arose
by chance somewhere around the northwest coasts of the Black Sea in
one single individual, about 8,000 years ago.
The gene does not "make" blue in the iris; rather, it turns off the
mechanism which produces brown melanin pigment. "Originally, we all
had brown eyes," says Dr Hans Eiberg, who led the team.
And most people still do. The finding that a rare mutation, probably
dispersed in the rapid wave of colonization that followed the end of the
last ice age, highlights one of the great mysteries of human evolution: the
oddness of Europeans.
One theory is that Europe's cold weather and dark skies played a part.
Fair skin is better at making Vitamin D from the 8 per cent of the world's
population have blue eyes weak sunlight found in northern latitudes.
Perhaps the most plausible theory is that blonde hair and blue eyes arose
because of a mechanism called sex selection.
This is where males and females choose as their mates those who have
one unusual physical characteristic, not necessarily associated with
"fitness" per se but simply something unusual.
The gigantic (and otherwise useless) tail of the peacock is the best
example.
VARIATION
THE NEW
FACE OF
AMERICA
November 18, 1993
IMAGES
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ANATOMICAL HOMOLOGY
EMBRYOLOGICAL HOMOLOGY
VARIATION
MECHANISMS OF CHANGE
NATURAL SELECTION
FINCHES
GIRAFFES
THE NEW FACE OF AMERICA
BLUE EYES
FROGS