Analogous and Vestigial Structures

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Analogous and Vestigial Structures
Write in complete sentences! Dont talk during
the Catalyst!

• Catalyst
• Cougars eat Bucaneers, which have decreased in
  population over the past few years. What is the
  environmental pressure?
• Humans and cows both have hearts with four
  chambers.
• What type of structure is this?
• Describe what it tells us about how humans and
  cows evolved.
• What are two things ALL animal embryos have in
  common? What does this tell us about how animals
  evolved?

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Objectives

• By the end of today, all SWBAT
• Explain how analogous structures support the
  theory of evolution
• Explain how vestigial structures support the
  theory of evolution

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Agenda

• Review
• Structures
• Analogous
• Vestigial
• Guided Practice
• Independent Practice/Homework
• Closing
• Exit Questions

4
Catalyst Review

• Cougars eat Bucaneers, which have decreased in
  population over the past few years. What is the
  environmental pressure?
• The environmental pressure is the decrease in
  population of the Bucaneers.
• WHY?

5
Catalyst Review

• Humans and cows both have hearts with four
  chambers. What type of structure is this, and
  what does it tell us about how humans and cows
  evolved?
• Human and cow hearts are homologous structures.
• This shows that humans and cows evolved from a
  common ancestor with a four-chambered heart.

6
Catalyst Review

• What are two things all animal embryos have in
  common? What does this tell us about how animals
  evolved?
• All animal embryos have gill slits and tails.
• This is evidence that all animals evolved from
  the same common ancestor.

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Homework Review

1. What are homologous structures? Provide two
   examples of homologous structures.
2. What is an embryo?
3. What is a common ancestor? Give an example.
4. All animal embryos start off looking very
   _______________. For example, they all have
   _______________ and _______________. These traits
   are examples of _______________ structures.

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Homework Review

• Lions and tigers have similarly structured tails.
  What type of structures are these? EXPLAIN how
  these structures support the theory of evolution.
  (Hint use the phrases evolve and common
  ancestor!)
• How can we use the appearance of cat and horse
  embryos to support the theory of evolution?
  (Hint use the phrases evolve and common
  ancestor!)

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Comparative Anatomy

• Scientists can compare the anatomy of different
  organisms to figure out how closely they are
  related.
• Anatomy body structure

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Analogous Structures

• Analogous structure Parts of different species
  that have the same function, but EVOLVED
  SEPARATELY
• Key Point 1 Analogous structures show that
  unrelated species will evolve similar
  adaptations in response to similar environmental
  pressures
• Natural selection selects for (keeps around)
  mutations that increase fitness in the specific
  environment.
• If organisms they live in similar environments,
  they will evolve similar structures.

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Insect, bird, and bat wings evolved completely
separately. Unrelated organisms will evolve
similar adaptations in response to similar
environmental pressures!

• No recent common ancestor!!!

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Seals and penguins both have streamlined bodies,
and store fat to keep them warm in the cold
water. Unrelated organisms will evolve similar
adaptations in response to similar environmental
pressures!
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Vestigial Structures

• Vestigial structure Part of an organism that is
  no longer used for anything
• Key Point 2 Vestigial structures show that a
  species used to live in a different environment.
• Organism moved into a new environment, where the
  vestigial structure decreases fitness
• No longer needed, waste of energy
• Risk of disease

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Letter c hind legs of a baleen whale skeleton

• Vestigial no longer used!!!

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Blind salamanders have eye sockets!?!?
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So, what about me?
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Guided Practice Notes Reflection

• How do analogous structures provide evidence for
  evolution?
• Analogous structures show that unrelated
  organisms will evolve similar adaptations in
  response to similar environmental pressures

ADD IT!!!
If you cant find the answer
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Guided Practice Notes Reflection

• How do vestigial structures provide evidence for
  evolution?
• Vestigial structures show that the species used
  to live in a different environment
• Organism moved into a new environment where the
  vestigial structure decreased fitness so it
  started to degrade

ADD IT!!!
If you cant find the answer
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Study!

• This practice will cover yesterdays lesson
  (homologous structures) as well as todays
  (analogous and vestigial structures).
• Take three minutes to study your notes from
  yesterday and refresh your memory before we
  proceed.

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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Human embryos and cat embryos both have gill
  slits.

HOMOLOGOUS
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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Birds and insects both have wings, but they
  developed in completely different ways.

ANALOGOUS
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Guided Practice (GP)
Is this structure (A) Homologous, (B) Vestigial,
(C) Analogous?

• Snakes dont have legs, but they do have hip and
  leg bones.

VESTIGIAL
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Guided Practice (GP)
Is this structure (A) Homologous, (B) Vestigial,
(C) Analogous?

• The human appendix a small organ next to the
  intestines doesnt seem to do anything at all.

VESTIGIAL
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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Cat embryos and human embryos both have tails.

HOMOLOGOUS
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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Dolphins and sharks both have fins, but they
  evolved completely differently.

ANALOGOUS
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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Alligators and bats have the same bone structure
  in their forelimbs (front legs for alligators,
  wings for bats).

HOMOLOGOUS
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Guided Practice (GP)
Is this structure (A) Homologous, (B) Vestigial,
(C) Analogous?

• Humans have wisdom teeth (third molars), even
  though they are not needed to chew up food.

VESTIGIAL
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Guided Practice (GP)
Are these structures (A) Homologous, (B)
Vestigial, (C) Analogous?

• Humans and squids both have eyes, but they
  evolved in completely different ways.

ANALOGOUS
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Independent Practice (IP)

• Get an early start on the homework.

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Key Point Wrap-Up

• Key Point 1 Analogous structures show that
  unrelated species will evolve similar
  adaptations in response to similar environmental
  pressures
• Key Point 2 Vestigial structures show that a
  species used to live in a different environment.
• Organism moved into a new environment, where the
  vestigial structure decreases fitness

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Exit Question Choose one optionWrite in
complete sentences!

• All humans have a tail bone, but we dont have
  tails.
• What type of structure is this?
• EXPLAIN how this structure provides evidence for
  evolution.

• Dogs and alligators both have long snouts that
  allow their jaws to open wide. However, they
  evolved in completely different ways.
• What type of structure is this?
• EXPLAIN how these structures provide evidence for
  evolution.