Classify the following: Trout, catfish, frog, snake, whale, human, cardinal, turtle, salamander, shark, dolphin, bat, blue jay, - PowerPoint PPT Presentation

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Classify the following: Trout, catfish, frog, snake, whale, human, cardinal, turtle, salamander, shark, dolphin, bat, blue jay,

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Title: Slide 1 Author: Cobb County School District Last modified by: Cobb County School District Created Date: 3/20/2008 7:11:40 PM Document presentation format – PowerPoint PPT presentation

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Title: Classify the following: Trout, catfish, frog, snake, whale, human, cardinal, turtle, salamander, shark, dolphin, bat, blue jay,


1
Classify the following Trout, catfish, frog,
snake, whale, human, cardinal, turtle,
salamander, shark, dolphin, bat, blue jay,
http//www.pbs.org/wgbh/evolution/educators/teachs
tuds/svideos.html
2
  • Did you group them by movement?
  • SWIMMERS FLIERS UPRIGHT
  • Trout cardinal Human
  • Catfish bat
  • Whale blue jay
  • Shark
  • dolphin
  • HOP/CRAWL/SLITHER
  • frog turtle
  • snake salamander

3
  • Or by
  • FISH AMPHIBIANS REPTILES
  • trout frog snake
  • catfish salamander turtle
  • shark
  • BIRDS MAMMALS
  • blue jay whale bat
  • cardinal dolphin
  • human

4
Evidence for evolution
  • Scientists compare these things to determine the
    evolutionary relationships among organisms.
  • 1. body structures
  • 2. development before birth
  • 3. DNA sequences

5
1. SIMILARITIES IN BODY STRUCTURE
  • An organisms body structure is its basic body
    plan (ex. How its bones are arranged.)
  • The 5 classes of vertebrates (fish, amphibians,
    reptiles, birds and mammals) all have a similar
    body structure Internal skeleton w/a backbone.

6
HOMOLOGOUS STRUCTURES similarities in structure
inherited from an early common ancestor
7
2. Similarities in Early Development
  • Scientists can also make inferences about
    evolutionary relationships by comparing the early
    (embryonic) development of different organisms.

8
rat
chicken
turtle
9
3. Similarities in DNA
  • Scientists infer that the species inherited many
    of the same genes from a common ancestor.
  • Genes are made of DNA. By comparing the sequence
    of nitrogen bases in the DNA of different
    species, scientists can infer how closely related
    the species are. The more similar the sequences,
    the more closely related the species are.

10
  • Because of its appearance, the tiny elephant
    shrew was once thought to be closely related to
    mice. DNA analysis shows that they are much more
    closely related to elephants! Ya never know!!

11
Combining evidence
  • Scientists have combined evidence from fossils,
    body structures, and early development, and DNA
    and protein sequences to determine the
    evolutionary relationships among species.

12
  • An example of how scientists combined evidence
    from different sources is shown in the branching
    tree. A branching tree is a diagram that shows
    how scientists think different groups of
    organisms are related.

13
Below image from Prentice Hall Life Science.
Most recent species at top of tree
Time moves from the past at the bottom to
present time at the top to
ForksWhere species began to evolve away from
their common ancestor
Common ancestor at bottom of tree
14
Natural Selection
  • The process by which individuals that are better
    adapted to their environment are more likely to
    survive and reproduce than other members of the
    same species.

15
4 Parts of natural selection
  • 1-overproduction
  • 2-competition/struggle to survive
  • 3-variations
  • 4-selection/successful reproduction

16
1. Overproduction
  • Most species produce far more off spring than can
    possibly survive
  • Often so many are produced that there are not
    enough resources for them all.
  • Ex Sea turtles

17
What would happen if all the young sea turtles
lived?
  • Sea turtles lay 100s of eggsif they all
    survived, the ocean would be full of turtles.

18
Darwin knew better
19
2. Competition
  • Offspring must compete with each other to
    survive.
  • Competition does not necessarily mean physical
    fighting.
  • It is usually indirect

20
For example,
  • Some baby turtles
  • May not be able to find enough to eat.

21
Variations
  • Members of a species differ from each other in
    many of their traits.
  • Any difference in between individuals of the same
    species is called variation.

22
For example
  • Some turtles
  • are able to swim
  • faster than others
  • To escape from
  • predators.

23
  • Remember you dont have to be faster than the
    predator, you just have to be faster than the
    other prey!

24
Selection
  • Over a long period of time, natural selection can
    lead to evolution.
  • Helpful variations gradually accumulate in a
    species, while unfavorable ones disappear.

25
For example
  • A new faster predator moves into the turtles
    habitat.

26
Perhaps a faster breed of shark
27
  • The turtles that are able to swim faster would be
    more likely to escape from the new predator.

28
  • The faster turtles would be more likely to
    survive and reproduce. Over time, more turtles in
    the species would have the fast-swimmer trait.

29
Genes
  • What role do genes have in evolution?
  • Variations can occur due to mutations in genes or
    from the shuffling of alleles during meiosis.
  • Therefore, only traits that are inherited are
    acted upon by natural selection

30
How are new species formed?
  • A new species might form when a group of
    individuals remains separated form the rest of
    its species long enough to evolve different
    traits.
  • This is called isolation or complete separation.

31
Continental drift
  • Millions of years ago on the super continent
    Pangaea, organisms could travel from one part of
    the continent to another.

32
  • Pangaea gradually split apart over millions of
    years in a process called continental drift.
  • As this separation happened, species became
    isolated from one another and began to evolve
    independently.

33
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