1 / 17

Evidence for Evolution by Natural Selection

Evidence for Evolution by Natural Selection. What is evolution?. Evolution is the gradual change in a species over time. Isn’t evolution just a theory?.

orson-cote
Download Presentation

Evidence for Evolution by Natural Selection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Evidence for Evolutionby Natural Selection

  2. What is evolution? • Evolution is the gradual change in a species over time.

  3. Isn’t evolution just a theory? A theory is a ____________, _______, explanation of phenomena that have occurred in the natural world, like the theory of __________________, ________, and _____________. well-supported testable gravitational attraction cell theory atomic theory http://www.avgoe.de/StarChild/DOCS/STARCH00/questions/apple_falling.gif http://sixthsense.osfc.ac.uk/chemistry/atomic_structure2/atom.gif

  4. Evidence supporting evolution • Fossil record • Anatomical record • Molecular record

  5. 1. Fossil record Fossils show a series of organisms have lived on Earth over a long period of time

  6. Fossils tell a story… the Earth is old Life is old Life on Earth has changed

  7. Evolution of birds Today’s organisms descended from ancestral species Fossil of Archaeopteryx • lived about 150 mya • links reptiles & birds

  8. ? ? ? Complete seriesof transitionalfossils ? We found the fossil! Land Mammal Where are theintermediate fossils? Someone’s idea of a joke! Ocean Mammal But the joke’s on them!!

  9. 2. Anatomical record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

  10. How could thesevery different animalshave the same bones? Compare the bones • The same bones under the skin • limbs that perform different functions are built from the same bones

  11. Homologous structures • Structures that come from the same origin • homo- = same • -logous = information • Forelimbs of human, cats, whales, & bats • same structure • on the inside • different functions • on the outside • evidence of common ancestor

  12. Vestigial organs • Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Because they used to walk on land!

  13. Vestigial organs • Structures on modern animals that have no function • remains of structures that were functional in ancestors • evidence of change over time • some snakes & whales have pelvis bones & leg bones of walking ancestors • eyes on blind cave fish • human tail bone

  14. Comparative embryology • Development of embryo tells an evolutionary story • similar structures during development all vertebrate embryos have a “gill pouch” at one stage of development

  15. Dog Human Macaque Bird Frog Lamprey 8 32 45 125 67 0 10 20 30 40 50 60 70 80 90 100 110 120 3. Molecular record • Comparing DNA & protein structure • everyone uses the same genetic code (DNA)! • compare common genes • compare common proteins

  16. Building “family” trees Closely related species are branches on the tree — coming from a common ancestor

  17. Rate Yourself • 4 Apply concepts of natural selection and evolution by creating a scenario that demonstrates the ideas • 3Explain how natural selection leads to evolution. • 2Describe how the evidence supports evolution. • 1 Identify evidence for evolution.

More Related