Change Over Time …

Evolution Objectives: 1.Define evolution. 2.How do we know the living world has changed over time? 3.What can you learn from fossils? 4.Define natural selection.

Why Change? Changes in the environment can have an impact on living organisms Three options: Adapt – change and find a way to survive in the new situation Move – migrate to a new location; either temporarily or permanently Extinction – failure to adapt

Evolution The process of biological change over time Organisms of the present differ from ancestors of the past Charles Darwin

Evolution – How do we know? 1.Some organisms evolve or change very quickly and can be observed 2.Examples: bacteria and insects 3.Fossils are evidence of past life 4.Examples: bones, teeth, footprints, shells, feather impressions, etc.

Fossils Early organisms were simple in form Organisms became more complex over time The diversity of life has increased over time New organisms appear and others die off (extinct)

Evolution – How do we know? Hyracotherium – “early horse” 20 cm tall 55 million years ago Equus – “modern horse” 300 cm tall Today

Why do living things evolve? Response to changes in the environment Ex. changes in climate, vegetation, or introduction of new organisms Some organisms have variations that allow them to adapt to changes Ex. genetic mutations

Natural Selection Organisms with favorable variations are more likely to: survive reproduce produce offspring with these variations

Artificial Selection Human beings have been using evolution for centuries!! Thousands of years ago wolves were taken as pets by humans. Each culture had specific traits they wanted these animals to have. Today we have hundreds of different types of dogs that are extremely different from one another