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Evolution - PowerPoint PPT Presentation

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Evolution. The Earth has been home to living things for about 3.8 billion years. Evidence. Fossils – the remains of once living organisms preserved in the Earth Types of fossils: Hard Body parts (such as bones, teeth, shells ) Imprints in Sedimentary Rock. W hich rock layer is the oldest?.

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The Earth has been home to living things for about 3.8 billion years.

  • Fossils– the remains of once living organisms preserved in the Earth
  • Types of fossils:
    • Hard Body parts (such as bones, teeth, shells)
    • Imprints in Sedimentary Rock
mass extinction
Mass Extinction
  • A period when large number of species became extinct at nearly the same time.
  • Permian Era- 225 mya: 90% of marine life when extinct
  • Cretaceous Era – 65 mya. Disappearance of dinosaurs

How did new species arise on Earth?

  • Evolution- the change of a species over a LONG period of time.

We know today that the changes arise from genetic mutations or variations that are passed down from generation to generation.

  • But where did this idea come from?
2 theories of evolution
2 Theories of Evolution
  • 1. Theory of Acquired Characteristics
  • The idea that a species can “get” a trait by passing it on to the next generation.
  • Lamarck!

Lamarck thought that if an animal

acquired a characteristic during its

lifetime, it could pass it onto its offspring.

charles darwin
Charles Darwin
  • Naturalists who published The

Origin of Species after studying

a variety of species on his voyage.

2 theory of natural selection
2. Theory of Natural Selection
  • Natural Selection – the best trait that is suited for the environment will allow a species to survive and reproduce at a higher rate
the galapagos island
The Galapagos Island

(just read…)

  • Darwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos.
  • Giant tortoises varied in predictable ways from one island to another.
  • The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.
the galapagos islands
The Galapagos Islands
  • Darwin collected the preserved remains of ancient organisms, called fossils.
  • Some of those fossils resembled organisms that were still alive today.
the journey home
The Journey Home
  • Darwin Observed that characteristics of many plants and animals vary greatly among the islands
  • Hypothesis: Separate species may have arose from an original ancestor
discovery of genetics
Discovery of Genetics?!?!?
  • From 1856-63, a monk called Gregor
  • Mendel cultivated 29,000 pea plants
  • to investigate how evolution worked
  • i.e., how characteristics were passed
  • down the generations.
  • He figured out the basic principles of
  • genetics. He showed that offspring
  • received characteristics from both
  • parents, but only the dominant
  • characteristic trait was expressed.
  • Mendel’s work only came to light in
  • 1900, long after his death

Mendel and his peas

four factors that support natural selection
Four Factors that support Natural Selection
  • Adaptation- trait that allows species to survive and reproduce in a particular environment.
  • Selection– organisms with particular adaptations are most likely to survive and reproduce.
  • Overproduction– an abundance of offspring are produced, but not all survive.
  • Variation- results from mutations and increases the variety of traits in a species
evolution by natural selection
Evolution by Natural Selection
  • The Struggle for Existence-members of each species have to compete for food, shelter, other life necessities
  • Survival of the Fittest-Some individuals better suited for the environment
  • Where food was limited, competition meant that only the fittest would survive.
  • This would lead to the natural selection of the best adapted individuals and eventually the evolution of a new species.
welcome to shark tank
Welcome to Shark Tank!
  • Which shark is the fittest?
natural selection
Natural Selection
  • Over time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment
evidence of evolution
Evidence of Evolution
  • Fossilized Evidence
  • Similarities in Early Embryonic Development
  • Geographic Distribution of Living Things
  • Homologous Body Structures
evidence for evolution
Evidence for Evolution
  • Vestigial organs - physical structures that were fully developed and functional in an ancestral group of organisms, but is reduced and unused in the later species.
  • So basically… organs that serve no useful function in an organism
  • i.e.) appendix, miniature legs, arms
homologous structures
Homologous Structures
  • Similar structures that are related species have inherited from a common ancestor.
  • Ex- the bones in a bird’s wing, dolphin’s flipper, dog’s leg, human’s arm
works cited
Works Cited
  • http://www.pbs.org/wgbh/evolution/change/family/index.html
  • http://www.ucmp.berkeley.edu/education/explorations/tours/Trex/index.html
  • What did T-Rex taste like?
  • http://www.the-brights.net/images/TeacherRequest%20Form.pdf
  • http://www.nclark.net/Evolution#Activities


Natural Selection in the Peppered Moth