Transcript The Theory of Evolution

The Theory of Evolution
Evolution
The change of populations
over time.
Charles Darwin
• The father of
evolution.
• Published book, On
the Origins of the
Species, in 1859
Darwin’s studies
• Began on the
Galapagos Islands
• He noticed many
species of animals
that were unique to
each island, but
similar to species
elsewhere.
Darwin’s four basic thoughts:
One Very Crazy Saying
1. Overproduction of offspring:
• Species produce
more offspring than
can survive.
• Example- fish lay
millions of eggs at a
time.
2. Variation:
• In any population,
individuals have
variations
(differences).
• Size, speed, color,
etc.
3. Competition:
• Individuals compete
for a limited amount
of resources
• Such as food, shelter,
protection, from
predators, mates, etc.
4. Survival:
• Certain individuals
survive, based on
variations.
• The individuals that
survive pass on their
genes, producing
generations full of
individuals with those
helpful genes.
These four steps make up
Darwin’s theory of Evolution
Natural Selection
• The mechanism for
change in populations
• Change is considered
a mutation.
• Mutations can be
good and/or bad.
• Mutations occur in the
organism’s?
DNA
Artificial Selection:
• Purposely breeding
organisms with
specific traits in order
to produce offspring
with identical traits.
• A.K.A. Selective
Breeding
Evidence for Evolution
Adaptations-Changes in species
that occur over time.
1. Structural Adaptations
• Change in an
organisms body parts
that help an individual
survive in their
environment.
• Examples: coloring,
teeth, claws, etc.
• These adaptations
happen over millions
of years
Examples of Structural
Adaptations:
A. Mimicry- a structural
adaptations that
allows one species
to resemble another
species.
• A harmless species
will resemble a
harmful species
A. Mimicry
• A predator that avoids
the harmful species
will also now avoid
the harmless species
out of a fear that it is
the harmful one.
B. Camouflage
• A structural
adaptation that allows
a species to blend
into their
surroundings.
• Species is then not
easily found by its
predators.
2. Physiological Adaptations
• Changes in an
organisms metabolic
processes.
• These adaptations
happen very quickly.
• Examples- Weeds
becoming resistant to
pesticides.
• Bacteria becoming
resistant to
antibiotics.
Other Evidence for Evolution
1. Fossils
• Scientists use fossils
to form timelines from
one species to
another that evolved
from it.
2. Anatomy
Physical structure of an organism
A. Homologous
structures
• Structural features
with a common
evolutionary origin.
• Example- Whale fin,
Crocodile limb, bird
wing, human arm
• Evidence that
organisms evolved
from a common
ancestor.
B. Analogous Structures
• Body parts of
organisms that do not
have a common
ancestry, but do have
similar functions.
• Example- Bird wing
and Butterfly wing.
• Evidence that species
adapted
independently to
similar ways of life.
C. Vestigial Structures
• A body structures that
has no present day
use, but was useful to
an ancestor.
• The body structure
became vestigial due
to lack of use.
• Example- Ostrich
forelimbs, Human
appendix.
3. Embryology
• Comparing Embryos
of different species for
similarities.
Embryology
• Compare an adult
mammal, fish, reptile,
and bird.
• Do they look alike?
• NO
Embryology
• Compare the
embryos of these
species
• Do they look alike?
• YES
• All have gill slits, and
tails when they are
embryos, but as they
develop, you start to
see differences.
• This provides
evidence that they all
evolved from a
common ancestor.
4. Biochemistry
• Comparing the DNA
and RNA of different
species is the best
way to determine the
relationships of
organisms
Biochemistry
• Humans and bananas
have
• 50% same DNA
Word Bank
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Variation
Evolution
Overproduction
Survival
Competition
Mimicry
DNA
Camouflage
Fossils
Homologous
structures
Analogous
structures
Biochemistry