DO NOW In box on note sheet Why is variation important? Which does NOT cause evolution? In order for mutations to be heritable, where must they occur?

Extinction Phylogenetic Trees Evolution Extinction Phylogenetic Trees

Evolution Evolution is the slow change of species over time Factors that cause evolution, or change to happen: Competition for finite resources Sexual reproduction Genetic Recombination- Meiosis and Fertilization Mutation Natural selection Environment Variation / Diversity

The idea of evolution is that all modern day species evolved from a common ancestor The first life form was most likely a simple, single-celled organism Over billions of years, life slowly become multicellular and more complex

Scientists estimate that the world is 3.5 billion years old Many organisms that lived long ago are no longer present today Extinction occurs when the adaptations of a species are no longer fit for the environment

The fossil record indicates that many organisms have gone extinct. Extinction is common. Most of the species that lived in the past are no longer present today.

All organisms on earth are related and share common ancestors. The majority of evidence for evolution is from the fossil record. Scientists try to piece together the history of species by looking at fossils.

Present-day organisms evolved from and branched away from other species. Present-day organisms descended from other species. Scientists represent the evolution of species with branching trees.

Species present in modern times are adapted to today’s environments. Species not seen in the present are extinct.

Modern scientists determine the relatedness of species by comparing molecular and structural evidence Molecular evidence- DNA analysis

Gel electrophoresis- Scientists use an enzyme to cut DNA into fragments. Fragments are separated by size.

Structural evidence- physical traits and characteristics (body parts, bones, colors, etc.)

Regents Practice