Download Homologous Structures and Speciation

Bell Ringer:
1.
2.
3.
4.
Define Adaptation
Define Natural Selection
Define Fitness
What will eventually happen to a species
that is not “fit” for it’s environment?
5. “Secretariat” was an example of what?
6. What is another name for “Survival of the
Fittest?”
Homologous Structures
and
Speciation
Joke of the Day:
Homologous Structures
• Structures in different species that are
similar because of common ancestry.
Homologous Structures
Turtle
Alligator
Typical primitive fish
Bird
Mammals
Homologous Structures are of the same basic structure
but used differently in the adult organism.
Humerus
Ulna
Radius
Wrist
Homologous Structures Activity
Speciation
Speciation
• The origin of new species in evolution.
– Example: Darwin’s Galapagos Finches
• The Theory……
• The 13 species of Darwin's finches descended from an
ancestral pair of South American finches that landed
there accidentally over 100,000 years ago?
• This pair found an area free of predators and probably
adapted to the various unfilled niches.
Speciation Flow Chart
Process
Founders Arrive
Geographic isolation
Changes in the gene pool
(adaptations)
Reproductive isolation
Ecological competition
How It Leads to Speciation
A population arrives in a new place
Populations are separated by a
geographic barrier and do not
share a gene pool.
Populations evolve new traits in
response to natural selection in
their environments.
Populations reproduce only within
their own group, leading to the
development of new species.
Species evolve in a way that
reduces competition between them
Homologous Structure Activity
and
Beak of the Finch Activity