EVIDENCE OF EVOLUTION Chapter 15-2

Evolution defined Change of heritable traits within a population through gradual modifications over generations (descent with modification)

Common Ancestor All organisms share a common ancestor and have deviated from that ancestor over time

1. Homologous Structures Homologous Structures: body parts that are similar in structure may have different functions Indicating at in the past they did the same job and came from a common ancestor

2. Analogous Structures Analogous Structures: same functions but different development Indicates that different populations evolved to be better suited to the same environment

3. Vestigial structures Vestigial structures- remnants of organs or structures that had a function in an early ancestor Shows that these organisms are descendants from organisms that used them Ex: (tailbone coccyx or hip bones in whales)

4. Fossils Fossils provide geologic evidence of evolution since newer species are modified versions of older species Fossil record contains the intermediates and transitional species that are now extinct

5. Biogeography Geographical distribution of living things The continents have not always been in the position they are now

Similar species are found in similar places showing common ancestry Fossils of the same ancient species have been found on different continents providing evidence that they were once connected