Changes Over Time

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Changes Over Time

• Charles Darwin
• and
• Evolution

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Charles Darwin
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Charles Darwin

• 1831
• When he was 22 years old he set sail aboard a
  British Naval Ship called the HMS Beagle.
• 5 year long trip around the world
• He was a naturalist a person who studies the
  natural world.
• Darwins observations led him to develop one of
  the most important scientific theories of all
  time the theory of evolution by natural
  selection.

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Observations

• During the voyage Darwin observed plants and
  animals he had never seen before.
• He wondered why they were so different than the
  ones he had seen in England.
• He was amazed by the tremendous diversity or
  variety of living things he saw.

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Diversity

• Today scientists know that living things are even
  more diverse than Darwin could ever have
  imagined.
• Scientists have identified more than 1.7 million
  species of organisms on Earth.

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Species

• A species is a group of similar organisms that
  can mate with each other and produce fertile
  offspring.
• What is the difference between a species and a
  breed?

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South America
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The Galapagos Islands
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Finch Beaks
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The Galapagos

• Darwin observed some of the greatest diversity of
  life forms.
• Giant tortoises, land tortoises
• Seals
• Lizards
• Flightless birds
• 13 species of finches

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Island differences

• Darwin observed that you could determine what
  island a tortoise was from based on the shape of
  its shell.
• Finches were noticeably different from one
  island to another. The most obvious difference
  was the various sizes and shapes of their beaks.
• Adaptation a trait that helps an organism
  survive and reproduce.
• The beaks were an adaptation related to the foods
  the finches ate.

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Evolution

• Species gradually changed over many generations
  and became better adapted to the new conditions.
• The gradual change in a species over time is
  called evolution.

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Scientific Theory

• Darwins ideas are often referred to as the
  theory of evolution.
• A scientific theory is a well-tested concept that
  explains a wide range of observations.

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Natural Selection

• In 1858, Darwin and another British Biologist,
  Alfred Russel Wallace, proposed an explanation
  for how evolution occurs.
• The next year Darwin published The Origin of the
  Species.
• Natural selection is 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.

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• http//streaming.discoveryeducation.com/

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Factors that Affect Natural Selection

1. Overproduction
2. Competition
3. Variation

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Overproduction

• Most species produce far more offspring than can
  possibly survive.
• Each year a female sea turtle lays over 100 eggs.
• Why isnt the sea full of sea turtles?

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Competition

• Since food and other resources are limited, the
  offspring must compete with each other to
  survive.
• Only a few turtles will survive long enough to
  reproduce.

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Variations

• A difference between individuals of the same
  species is called a variation.
• For example, some newly hatched turtles are able
  to swim faster than other turtles.
• Some variations make certain individuals better
  adapted to their environment. Those individuals
  are more likely to survive and reproduce.
• Without variation a species can become extinct.
• Extinct meaning no longer and living members of
  that species

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Selection

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

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Speed of evolution

• Gradualism- Described as a slow ongoing process
  by which one species changes to a new species
• Punctuated Equilibrium- One species suddenly
  changes to another.

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What role do genes play in evolution?

• Only traits that are controlled by genes can be
  acted on by natural selection
• Elephant Evolution

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Peppered Moth

• The Industrial Revolution began in England in the
  late 1700s.
• Smoke from the factories blackened the tree
  trunks of trees.
• Light colored moths were no longer camouflaged.
• What color was more suited for the new
  environment?

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How do New Species Form?

• Geographic Isolation
• Continental Drift
• A new species may form when a group of
  individuals remains separated from the rest of
  its species long enough to evolve different
  traits.
• A group is separated from the rest of the species

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Continental Drift
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Pangea
Pangea
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Examples of New species 10,000 years to change

• Kaibab squirrel/Aberts squirrel
• North American White Tailed Deer/Fire Island Deer

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Kaibab Squirrel
Abert's Squirrel
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Aberts Squirrel
Kaibab Squirrel
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Supporting Evidence
Used to determine the evolutionary relationships
among species

• Fossil Records
• Embryology
• Homologous structures
• Vestigial structures

• Fossils
• Body structure
• Early development
• DNA
• Protein structures

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Fossil

• A fossil is the preserved remains or traces of an
  organism that lived in the past.
• A fossil can be formed from parts of live
  organisms, foot prints, or burrows left in mud.
• Actual age of fossils is determined by
  radioactive dating

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How do they form?

• Most fossils form when organisms that die become
  buried in sediments.
• Sediments are particles of soil and rock.
• Over millions of years layers harden to become
  sedimentary rock.
• Some remains get buried in the sediment and are
  actually changed into rock.
• Fossils that form in this way are called
  petrified fossils. Minerals replace all or part
  of an organism

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Preserved Remains

• Ice preservation
• Tar pit
• Tree sap hardens to form amber.
• Imprint fossils
• Cast fossils
• Mineralized fossils

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The Fossil Record

• What can fossils tell you?
• How do they form?

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Branching Trees Cladograms

• A branching tree is a diagram that shows how
  scientists think different groups of organisms
  are related.

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Embryology

• The study of embryos and their development
• The similarities suggest an evolutionary
  relationship among all vertebrate species.

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Homologous Structure

• Birds wing
• Dolphins flipper
• Dogs leg
• All of their bones are arranged in a similar
  pattern.
• These similarities provide evidence that these
  organisms all evolved from a common ancestor.
• Similar structures that related species have
  inherited from a common ancestor are known as
  homologous structures.

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Vestigial Structures

• Structures that dont seem to have a function.
• Example Manatees, snakes, and whales no longer
  have back legs, but, like all animals with legs,
  they still have pelvic bones.
• Humans appendix, tailbone, wisdom teeth, and
  goosebumps