Download Intro to Evolution ppt

Which Came
First?
 Geologic evidence: Earth is old
 Fossil evidence: Life is old & 99% species are extinct
 Fossil evidence: Life today resembles life of the past
 Conclusion: Life on Earth has changed over time
 HOW?
 Mechanism: Natural Selection
 Natural Selection
 Organisms better suited to the environment are more likely to
survive & reproduce than organisms less suited to the
environment.
 All life shares a universal common ancestor
 Natural selection is the mechanism to describe unity
 Artificial Selection:
 humans modify species over generations by selecting &
breeding individuals with desired traits
 http://www.hhmi.org/biointeractive/evolution/dog_breeding.html
 https://www.youtube.com/watch?v=aDmzzREXI_g
 Individuals are born with variable DNA from parents
 Environment pressures the fitness of individual
 Fit individuals pass on successful DNA to offspring
 Over time, mutations build within a population
 Evolution is a result of changes at the population level
 Amniotic egg: ~300,000,000 years ago
 Chickens: ~6,000 years ago
 At no point in history can you specifically point to the
first chicken or egg, evolutionary change was at the
population level not the individual level of life!