Download Homologous Structures - Jefferson School District

How to set up your notebook
Left side
• For examples and
think/pair/write
Right Side
• Notes – you will be writing the
notes today
GOAL: To see how comparing
anatomy can support the theory
of evolution by natural selection.
Homologous Structures
RIGHT
• DEFINITION: Parts of organisms that are
similar in origin and structure are called
homologous structures.
• INFORMATION:
– Are the result of evolution
– Can indicate how closely two or more
species share common ancestors
– Not all structures are homologous.
6.2 Biological Evidence
Homologous Structures Examples
The bones in the upper
limbs of these animals
are homologous
structures.
LEFT
Think, Pair, Write:
What do you
notice?
Homologous Structures Examples
LEFT
Think, Pair, Write:
What do you notice?
Quick questions
• What is a homologous structure?
• What is an example of a homologous
structure?
6.2 Biological Evidence
Vestigial Structures
RIGHT
• DEFINTION: structures that have no
function in their present-day form.
• INFORMATION: Scientists hypothesize
that the structures once functioned in an
ancestor.
Vestigial Structures
• EXAMPLES:
– Pelvic bones in whales
– Pelvic spurs in boas and pythons
– Eyes in cavefish
– Tail bones in humans
– Who knows of any other?
LEFT
Quick questions
• What is a vestigial structure?
• What is an example of a vestigial
structure?
6.2 Biological Evidence
Embryology
• DEFINTION: The science of
the development of embryos
from fertilization to birth is
embryology.
• INFORMATION: The more
closely related species are, the
more features they share during
development.
RIGHT
LEFT
Think, Pair, Write:
What do you
notice?
Another example
• Tunicates
LEFT
Think, Pair, Write:
What do you notice?
Tunicates are
thought to be
related to
vertebrates
because they
have proto
backbone
during
development
but then lose it.
Quick questions
• What is a is embryology?
• What is does embryology help us
understand?
• What was the main goal for today?