Evolution, Natural Selection and the Diversity of Animals

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Evolution, Natural Selection and the Diversity of
Animals
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How do new species begin?

• DNA is instructions for all life
• DNA -? RNA? Protein? Trait
• Mutations MAY cause changes in the production of
  proteins
• New traits can be passed to offspring
• May be helpful, bad or cause no change at all

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Mutations

• Changes in the DNA sequence of nucleotides As,
  G, Cs and Ts
• Sickle cell anemia Harmful? Helpful?
• Albinism
• Cystic fibrosis
• Most diseases and deformities
• Blond or brunette
• 2 legs or 4 legs?
• Fins or flippers?
• Color of skin
• All differences!

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Mutations the good, the bad, and the indifferent

• Point mutations one letter change substitution
• Frame-shift mutations insertion or deletion of
  one or more nucleotides that shifts
  information
• each 3 code for 1 amino acid that makes up a
  protein
• EX cat ate the rat?catatetherat
• caatatetherat? Caa tat eth era t
• Ctatetherat? Cta tet her at
• Not all mutations are bad some make bacteria
  ANTI-BIOTIC RESISTANT.
• Good for the bacteria, not-so-good for you!
• Some mutations result in no change

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Mutations can change a population

• If new traits is advantageous,
• those w/ trrait will have more successful
  offspring than those without it
• Over long periods of time
• populations --? new species
• Fish ? w/ lungs? move onto land? reptile?
  humans!
• Species groups that are so similar they can
  breed with each one another and produce VIABLE
  (capable of reproducing) offspring.

This is Natural Selection.
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New species can develop if

• Members of a populations are separated from each
  other (GEOGRAPHIC ISOLATION)
• Members of two populations can no long breed
  successfully with one another (REPRODUCTIVE
  ISOLATION)
• Having an abnormal number of chromosomes
  (POLYPLOIDY)

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Divergent Evolution

• One ancestral species leads to 2 new species

Marine Iguana
?
DNA
DNA
Land Iguana
Ancestral Green Iguana
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Adaptive Radiation

• One ancestral species leads to 3 or more new
  species

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Types of Evolution

• Two ideas of how new species develop
• Gradualism lots of small changes in DNA over
  long periods of time
• Punctuated Equilibrium fewer, larger changes
  over long periods of time.

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Gradualism Punctuated Equilibrium
10 million years
10 million years
Notice the results of both are the same CHANGE
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Evidence for evolution

• Antibiotic resistant bacteria
• Fossils
• Anatomy
• Embryology
• Biochemistry
• All of these methods are used together to show
  relationships between species

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Fossil Record

• Used to observe early life
• Incomplete only hard parts fossilize in
  specific types of soil
• Like a puzzle overall pattern

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Anatomy

• Similarity in structures suggests relationships
  between animal species
• Homolgous and Analogous structures see diagram
• Vestigial structures whale pelvis

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Homologous and Analogous Structures

• Homologous structures (homosame) alike because
  they are closely related
• Example bird wings, bat wings, your arm and hand
• Analogous structures (not closely related, but
  same function)
• - -bird wings and
• insect wings

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Embryology

• sperm egg fertilization zygote
  (1 cell)
• blastula about 64 cells
• gastrulation when blastula begins to fold in
• Forms opening into gastrula
• gastrula 2 cells layers 2 tissue layers
• archenteron opening into the gastrula

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Protostome vs Deuterostome

• If the archenteron (opening) forms into
• a mouth first PROTOSTOME
• an anus first DEUTEROSTOME
• All invertebrates (no backbone) are protostomes
  except echinoderms
• Vertebrates (w/backbone) and echinoderms
  Deuterostomes
• Humans?

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Living things are grouped according to
similarities

• Embryology
• The more similar the
• embryonic
• development pattern the
• more closely related

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Embryology

• Vertebrate embryos share developmental
  characteristics
• Post anal tails
• Pharyngeal slits or pouches
• Notochords
• Nerve cords
• DNA determines these characteristics!

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Biochemistry

• All organisms have DNA, ATP, and other
  enzymes/proteins in common
• DNA is made of 4 molecules A,T,C, and G
• Similar DNA sequences similar ancestry

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A cladogram is like a family tree showing how
things have changed.
Shows relationships based on specific
characteristics
Point where common ancestors diverged
Everything to the right of this point have
Vertebrae
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Living things are grouped according to
similarities
Taxon Groups

• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Few similarities Largest of organisms Most
similarities Smallest of organisms
Binomial Nomenclature scientific names are Genus
and Species Ex Iguana iguana, Homo sapien
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Living things are grouped according to
similarities
HOMOLOGOUS structures, humans, birds, porpoises
and elephants are considered more closely related
to each other than any are to insects.
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Dichotomous keys

• Species can be identified using a dichotomous key
• Series of either / or questions leading to the
  identification.

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Dichotomous keys
Example 1. Does the flower have white or yellow
petals? -if yellow, it is a sunflower -if
white, go to question 2 2. Does the flower have a
yellow or red center? -if yellow, it is a
daisy -if red, go to question 3