Evolution!

Charles Darwin In 1831, Darwin set sail for a voyage around the world. Makes hundreds of observations and collects evidence. Comes up with hypothesis about the way life changes over time: Evolution.

Darwin’s Observations Plants and animals are well suited to wherever they live. Similar habitats separated by oceans had very different animals. Collected fossils (preserved animal remains) that looked like living creatures. Galapagos Islands.

Evidence of Evolution #1: Natural Selection Survival of the fittest: Strongest and best survive. Organisms compete for resources. Key factor is how well organism is suited for its environment: Like having fur or a beak that can crush seeds. Fur would be an adaptation, which is an inherited characteristic that increases a organisms chance for survival.

The birds look the same, but have different beaks. Why?

What adaptations make this polar bear best suited to her environment?

Evidence of Evolution #2: Fossil Record Fossils are remains of ancient life. Different layers of rock formed at different times during Earth’s history. By comparing older fossils to newer fossils, gradual change over time can be seen.

Evidence of Evolution #3: Geographic Distribution Similar animals in different locations. Came from common ancestor.

Evidence of Evolution #4: Homologous Body Structures Structures that have different mature (fully grown) forms but develop from the same embryonic tissues are said to be Homologous Body Structures.

Evidence of Evolution #5: Similarities in Embryology Early stages, or embryos, of many animals with backbones are similar.

Terminology Natural Selection Artificial Selection Adaptation Nature picks who lives and who dies. The strongest or most fit survive. Artificial Selection We pick who survives. Adaptation Inherited characteristic that increased chance for survival.