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10.4 Evidence of Evolution EVIDENCE OF EVOLUTION! 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution 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 found in 1859 first Question! 10.4 Evidence of Evolution • 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. 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution 3. EMBRYOLOGY! – similar embryos, diverse organisms 10.4 Evidence of Evolution 4. HOMOLOGY & ANALOGY • Structural patterns are clues to the history of a species. A. Homologous Structures – Same origin but differ in function. – Share a common ancestry or origin. Human hand Mole foot Bat wing • http://evolution.berkeley.edu/evolibrary/article/0_0_0/si milarity_hs_02 10.4 Evidence of Evolution B. Analogous Structures • Structures that look similar • Same function • Different structure & development 10.4 Evidence of Evolution 10.4 Evidence of Evolution 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! 10.4 Evidence of Evolution Practice! Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Human embryos and cat embryos both have gill slits. HOMOLOGOUS 10.4 Evidence of Evolution Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Birds and insects both have wings, but they developed in completely different ways. ANALOGOUS 10.4 Evidence of Evolution Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Snakes don’t have legs, but they do have hip and leg bones. VESTIGIAL 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Cat embryos and human embryos both have tails. HOMOLOGOUS 10.4 Evidence of Evolution Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Dolphins and sharks both have fins, but they evolved completely differently. ANALOGOUS 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution Are these structures… (A) Homologous, (B) Vestigial, (C) Analogous? • Humans and squids both have eyes, but they evolved in completely different ways. ANALOGOUS 10.4 Evidence of Evolution • 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 10.4 Evidence of Evolution 5. DNA Analysis • Similar GENES shows common ancestry. 10.4 Evidence of Evolution 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 10.4 Evidence of Evolution