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Unveiling Evolution: Evidence and Principles

Exploring evidence of evolution like fossils, geographical distribution, embryo structures, and DNA analysis. Learn the 4 principles of natural selection and discover the origins of vestigial structures.

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Unveiling Evolution: Evidence and Principles

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  1. EVIDENCE OF EVOLUTION!

  2. 1. FOSSIL RECORD! • Fossils in older layers are more primitive (older) than those in the upper layers. • Fossil records document the course of life through time

  3. Fossil Record • The oldest known bird fossil is the Archaeopteryx • It is intermediate between bird and dinosaur • Possesses some ancestral traits and some traits of present day birds • Archaeopteryx was first found in 1859

  4. Question! • After examining the fossil record, scientists have determined that scorpions today are much smaller than their extinct ancestors. For example, Jaekelopterus rhenaniae, a giant scorpion species that lived 255 million to 460 million years ago, was 2.5 meters long. Which of the following conclusions is supported by this information? • A. Scorpions living today have increased their numbers since they first appeared. • B. Scorpions in the fossil record are smaller than their descendants are. • C. Scorpions have changed as a result of natural selection. • D. Scorpions do not appear in their original state in the fossil record.

  5. 2. GEOGRAPHICAL DISTRIBUTION! • Organisms adapt according to where they live. • The study of geography provides evidence of evolution. • island species most closely resemble nearest mainland species • populations can show variation from one island to another

  6. similar embryos, diverse organisms 3. EMBRYOLOGY!

  7. Molefoot Batwing Human hand • Structural patterns are clues to the history of a species. A. Homologous Structures 4. HOMOLOGY & ANALOGY • Same origin but differ in function. • Share a common ancestry or origin. • http://evolution.berkeley.edu/evolibrary/article/0_0_0/similarity_hs_02

  8. B. Analogous Structures • Structures that look similar • Same function • Different structure & development

  9. C. Vestigial structures • Remnants of organs or structures that had a function in an early ancestor. • They have changed (evolved) over time by diminishing in size or function so as to become functionless, or near functionless compared to its original use • Structures that are USELESS and JUST TAKING UP SPACE!

  10. TONIGHTS HOMEWORK: RESEARCH ONE VESTIGIAL STRUCTURE. (in any organism) • WRITE 10 COMPLETE SENTENCES ABOUT IT. (HANDWRITTEN OR TYPE-WRITTEN) • What was its purpose? Why is it not used anymore? • MUST INCLUDE PICTURE/DETAILED DRAWING • DUE ON THURSDAY

  11. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Birds and insects both have wings, but they developed in completely different ways. ANALOGOUS

  12. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Snakes don’t have legs, but they do have hip and leg bones. VESTIGIAL

  13. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • The human appendix – a small organ next to the intestines – doesn’t seem to do anything at all. VESTIGIAL

  14. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Cat embryos and human embryos both have tails. HOMOLOGOUS

  15. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Dolphins and sharks both have fins, but they evolved completely differently. ANALOGOUS

  16. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Alligators and bats have the same bone structure in their forelimbs (front legs for alligators, wings for bats). HOMOLOGOUS

  17. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Humans have wisdom teeth (third molars), even though they are not needed to chew up food. VESTIGIAL

  18. Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Humans and squids both have eyes, but they evolved in completely different ways. ANALOGOUS

  19. TONIGHTS HOMEWORK: RESEARCH ONE VESTIGIAL STRUCTURE. (any animal) • WRITE 10 COMPLETE SENTENCES ABOUT IT. (HANDWRITTEN OR TYPE-WRITTEN) • What was its purpose? • INCLUDE PHOTO. • DUE ON WEDNESDAY

  20. 5. DNA Analysis • Similar GENES shows common ancestry.

  21. The 4 Principles of Natural Selection • Individuals in a population have VARIATIONS • Variations are INHERITED • Not all offspring produced can survive • Variations that increase reproductive success will have a greater chance of being passed on

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