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Introduction to Evolution

Introduction to Evolution. SBI 3U Ms.Zafar. Brief Introduction. Life is united and has descended from organisms that appeared early in Earth’s history Fossils: preserved remains or markings left by organisms. For example …. The Polar Bear. One of the world’s newest mammals

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Introduction to Evolution

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  1. Introduction to Evolution SBI 3U Ms.Zafar

  2. Brief Introduction • Life is united and has descended from organisms that appeared early in Earth’s history • Fossils: preserved remains or markings left by organisms

  3. For example … • The Polar Bear. • One of the world’s newest mammals • Transparent fur  helps with blending in • Compare Arctic animals to Desert animals  how have each adapted to their respective environment? • Around the world there is an enormous diversity of life, and each species has its own set of characteristics  what is a species?

  4. Evolution is a theory … • Recall, a theory is a set of statements that explains a group of facts or phenomena • Charles Darwin  developed a theory to explain the diversity of life and how all organisms are related to one another AND to the environments in which they live  Darwin’s theory explained evolution

  5. What is Evolution? • Evolution the idea that all species are descendents of ancient species that were different from modern-day species • The biological history of Earth

  6. Before Darwin, it was believed that … • Species were fixed permanent • That Earth was less than 10,000 years old

  7. Changing Ideas About the Natural World • James Hutton  Scottish Geologist. Proposed that rock formations are continually being formed. Studied present-day erosion and the thickness of sedimentary rock  and what did he conclude? • Charles Lyell  Popularized and expanded upon Hutton’s ideas in the 183os. Found more evidence to support the idea that rock formations were formed by very slow processes

  8. Changing Ideas About the Natural World • Georges Cuvier  French naturalist. Compared elephant bones with mammoth fossils. Concluded that mammoths were very different and a different species

  9. Jean Baptiste Lamarck • Species are not permanent. They adapt to their environment. • Three ideas: • By using or not using certain body parts, an organism develops certain characteristics. Ex: giraffes • These enhanced characteristics would be passed on to the offspring - Inheritance of acquired characteristics • All organisms have a tendency towards perfection *We now know that Lamarck’s hypotheses do not stand true. Because of our knowledge of DNA

  10. Darwin’s Observations • 1831  HMS Beagle set out to study the South American coastline • Darwin  Naturalist. Collected lots of samples and maintained journals • Observed 3 patterns: • Species vary globally • Species vary locally • Species vary over time

  11. Species Vary Globally • Distantly related animals living in different places but similar habitats  looked similar and acted similar!

  12. Species Vary Locally • Related animal species that occupied different habitats within a local environment had different features • Most obvious on the Galapagos Islands • Ex: tortoises and rainfall levels -Isabela Island  more rainfall  tortoises get to vegetation close to land -Espanola Island  Dry and barren  tortoises have longer necks and notches in shells to allow them to reach high for food

  13. Species Vary Over Time • Species living today were descended from ancestral species • Example: Armadillo and Glyptodon

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