Characteristic

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Characteristic 6

• All organisms respond to changes in external
  environment while maintaining constant internal
  environment.

• Inside is controlled chemically and physically.
• External responses
• Skin tans in response to sunlight
• Roots change direction moving towards water
• Dogs pant in the heat

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Evolution

• Change over time

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Charles Darwin

• A naturalist who served aboard research ship
  called The Beagle in 1831
• Observed bird and animal species in Galapagos
• Made observations about species characteristics
• Published On the Origin of Species
• Formulated theory of evolution by natural
  selection

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Darwins Observations

• Birds on different islands had different shaped
  beaks.
• Each beak style seemed perfect for islands food
  supply.
• Darwin speculated that each species of bird had
  adapted to utilize the food in its environment.
• Darwin explained these changes with his theory of
  evolution by natural selection

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Evolution

• Gradual changes in a population or species over
  time
• Natural Selection
• The way these changes occur

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Patterns of Evolution

• Artificial selection
• When humans breed organisms with certain traits
  to produce offspring with those traits.
• Examples dog species, draft horses, garden
  variety flowers

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Artificial Selection
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Dairy cows have been bred by artificial selection
for large udders and high milk production. As a
result, many cows have udders so large that they
cannot walk without swinging their legs out to
the side.
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Patterns of Evolution

• Natural selection
• When organisms that have favorable adaptations
  are selected by nature survive and reproduce.
• Examples colors which blend in with habitat,
  prehensile tail, beaks adapted to local food
  sources

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Adaptations

• Opposable thumb thumb that allows grasping
  and holding

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Evolution by Natural Selection

• In nature, organisms with the best
  characteristics for surviving in an environment
  will live longer and pass those characteristics
  on to more offspring. Eventually more of the
  population will have these adaptive traits.

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In nature, organisms produce too many offspring
for environment to support
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Individuals will have a variety of
characteristics
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• Individuals with good traits for survival will
  live and reproduce more than others, passing on
  the good traits to their offspring.

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• The population will eventually change in
  appearance as this trait becomes more common.

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Two Types of Natural Selection

• Divergent Evolution
• When related
• species become
• more and more
• different due to
• different niches

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Adaptive RadiationOne type of divergent evolution

• One species in a new environment changes into
  many new species, each adapted to a particular
  food source and way of life.

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Divergent Evolution of Hawaiian Honeycreepers

• A small bird migrated to an island
• Island had diverse ecosystem (insects, nuts,
  berries, flowers nectar, worms, leaves

• Eventually, many species of birds evolved
• Each had features adapted for one niche
• Different coloration
• Different beak shapes
• Different anatomical structures

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• Maui Parrotbill
• Breaks apart wood and then pries out insect
  larvae.

• Amakihi
• Eats insects and nectar.

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• Akohekohe
• Feed primarily on insects and nectar from ohia
  blossoms

• Maui Creeper
• Eats insects among the leaves and branches.

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• The Poouli
• Finds insects, spider and snails under leaves and
  bark

• 'I'iwi Honeycreeper
• Eats the nectar stored in deep-throated flowers.

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• Homologous structures
• Structures from related individuals that have
  become modified for a particular environment.
• Usually result from divergent evolution.

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Second Type of Natural Selection

• Convergent evolution
• When two or more
• unrelated species
• become more similar
• due to similar
• environments.

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Organisms that have converged due to similar
environments
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• Analogous structures
• Structures on unrelated species that are similar
  due to similar functions.
• Analogous structures result from convergent
  evolution.

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Analogous Structures

• Fish/shark and Whale
• No common ancestry
• Similar body shape and streamlining due to common
  environment.
• Structures have become similar due to convergent
  evolution.

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Evidence for Evolution and Relatedness of Species

• Types of evidence that shows if species are
  related include
• Fossil evidence
• Comparative anatomy
• Biochemistry
• Chromosomes
• Embryology
• Microevolution

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What are Fossils?

• Fossils - traces of dead organisms
• Fossils can be molds, footprints, imprints, bones
  or entire organisms

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Determining the Age of a Fossil

• Absolute age carbon dating relies on radioactive
  elements, which tell the actual age of the
  fossil.
• Relative age the age of a fossil can be
  predicted by its location in a rock column

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Fossil Evidence

• Fossils can be found in sedimentary rock (mud,
  sand or clay).
• Older fossils are found lower in rock
• Newer fossils are found closer to the surface

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Sedimentary RockGeologic column a tall segment
with many layers of sediment
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Fossils on the bottom of the column are older
than those on the top.

• Oldest Youngest

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Using Fossils to Understand Relationships

• The bone structure in fossils indicates how
  closely related organisms may be
• The sequence of development the horse was
  determined by the location in rock and the
  similarities of the fossils

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• 1. Hyracotherium 2. Orohippus
  3. Mesohippus
• 4. Merychippus 5.
  Pliohippus 6. Modern day Equus

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Comparative Anatomy

• Similar anatomy indicates closer relationships
• Homologous structures show closer relationships

Crocodile forelimb
Bird wing
Whale forelimb
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Vestigial Structures

• Structures present in ancestors but no longer
  needed.
• For example
• - appendix
• - tailbones
• humans (4)
• gorilla (?)
• - ear muscles
• - pelvic girdle
• Snakes
• Whales

Snake Whale
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Biochemistry

• ALL living organisms contain the same genetic
  code
• the same four DNA nucleotides (AGCT)
• The same 20 amino acids
• More closely related species have more similar
• Nucleotide sequences in DNA
• Amino acid sequences in their proteins

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• All life uses the same genetic code
• In every living species, the codon UAC in RNA
  codes for the amino acid tyrosine

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Cytochrome C

• Cytochrome c is an enzyme in the mitochondria of
  the body.
• Humans have 104 amino acids in cytochrome c
• Chimpanzees have the identical aa sequence as
  humans
• Dogs differ in 13 of the amino acids
• Snakes differ by 20 amino acids.
• The more closely related the species, the more
  amino acids they will have in common.

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Chromosomes

• Closely related species have similar gene
  sequences on chromosomes

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• Genetically, chimpanzees are 98.5 percent
  identical to humans.
• However, the differences between the species are
  profound.
• Small gene differences make for huge differences
  in traits

• Genetic Differences between Chimpanzees
  and Humans

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Embroylogy

• Embryos from different species show similar
  features due to shared ancestry
• All vertebrates have
• Tails
• Gill pouch Chick Human

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Microevolutionwatching evolution occur

• Sometimes, evolution occurs on a small scale
  that we can watch over a period of a lifetime

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Microevolution
In England, the industrial revolution resulted in
heavy pollution and soot-covered surroundings.
Eventually the trend was reversed and the
pollution was reduced. Researchers studied how a
species of moth with two forms adapted to its
changing environment.
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In each environment, the form that was best
camouflaged lived longer and had more offspring
than the other, and eventually became the most
common form.
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Microevolutionwatching evolution occur
The Moth study is one example of microevolution
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Physiological adaptations can develop rapidly
Non-resistant bacterium
Antibiotic
Resistant bacterium
When the population is exposed to an antibiotic,
only the resistant bacteria survive.
The bacteria in a population vary in their
ability to resist antibiotics.
The resistant bacteria live and produce more
resistant bacteria.
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Non-resistant bacterium
Antibiotic
Resistant bacterium
Today, penicillin no longer affects as many
species of bacteria because some species have
evolved physiological adaptations to prevent
being killed by penicillin.
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