evidence of evolution n.
Skip this Video
Loading SlideShow in 5 Seconds..
EVIDENCE OF EVOLUTION PowerPoint Presentation
Download Presentation


160 Vues Download Presentation
Télécharger la présentation


- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript


  2. INTRODUCTION • Evolution: change in a species over time • Organic Evolution: changes in living things Data from organic evolution explains two things: • Differences in structure, function, and and behavior among living things • Changes in characteristics in populations over time

  3. WHAT INFLUENCES EVOLUTION? Factors influencing evolution include: • Potential for a species to increase its numbers • Genetic variability of offspring due to mutations and recombination of genes • Finite supply of resources required for life • Environmental selection of offspring better able to survive and reproduce

  4. GEOLOGIC TIME • Definition: time from beginning of the world until today • It is assumed that the Earth is at least as old as the oldest rocks and minerals composing its crust—about 4.5 billion years old • The oldest living thing is estimated to be a bacteria-like organism that is 3.4 billion years old

  5. FOSSILS • Definition: remains or traces of organisms that have been preserved by natural processes • Important to evolution because scientist can compare remains of ancient organisms with modern-day organisms to determine if organic evolution occurred

  6. FOSSIL FORMATION • Fossils are typically found in sedimentary rock Formed as follows: • Rock particles, silt, and mud are deposited in layers • Time, pressure, and heat harden the sediment into rock, forming layers • Animal and plant remains get trapped in the sediment layers, forming fossils

  7. AGE OF ROCK LAYERS • In undisturbed rock layers, the oldest fossils are found on the bottom • Fossils in the upper layers resemble fossils on the bottom, but are more complex—this provides evidence for evolutionary relationships

  8. TYPES OF FOSSILS Whole organisms can be preserved in one of the following ways: • Amber: yellowish-brown sap secreted by pine trees that traps insects and other organisms • Ice: cold temperatures preserves flesh, skin, and hair of organisms

  9. MOLDS & CASTS • Molds: indentation in rock shaped like an organism • Casts: formed when a decayed organism forms a mold, and the mold becomes filled with minerals

  10. PETRIFICATION • Definition: process by which tissues of organisms are slowly replaced by minerals • Preserve the original form of the organism

  11. IMPRINTS • Definition: occur when a print is made in soft sediment, such as mud, that later turns to rock