Evolution Slow change over time 3 5 billion

Evolution: • Slow change over time – 3. 5 billion years

New Traits • Mutations and genetic recombination during meiosis and fertilization of sexual reproduction can give rise to new traits. • Mutations are only heritable if they occur in the sex cells (gametes)

• In sexually reproducing organisms, there is a lot of genetic variation. • Genetic variation within a species increases the chances that someone will survive!

Resistance • An insect may become resistant to pesticides. • A pesticide might kill 99% of insects • The other 1% had the genes to survive and will reproduce and pass on their traits. • Overtime, there will be a population of strong, pesticide resistant insects

Resistance: • A drug might kill 99% of bacteria. • The 1% that had the genes to survive will reproduce and create a population of resistant bacteria

Natural Selection • An adaptation is a trait that helps you survive in a particular environment. • Organisms that are better adapted, or most fit, will survive and reproduce more. • Organisms that are less fit are unable to compete for finite resources.

• In nature, organisms reproduce as much as possible, but the resources needed for life are finite – Limited space, food, shelter, sunlight, water, mates etc. • Because resources are finite, only the best competitors will survive.

• Overtime, the population of the better adapted organisms will increase. • Overtime, the population of the less fit species will decrease, and possibly go extinct.

Extinction • Extinction happens when the environment changes and a species is no longer adapted to survive in that environment – Climate changes, availability of resources changes, population changes • New species moves in who is a better competitor

• Extinction is COMMON!!!! • Earth is 3. 5 billion years old • MOST species that were once living are now extinct and no longer living

• The most important sources of evidence for evolution is the fossil record. • Scientists study the organisms from long ago by looking at fossils.

Present Day Species… • We can compare their structural characteristics – Bones, colors, petals, leaves, seeds, skin, fur, scales, teeth, etc.

Paper Chromatography • A technique used to separate pigments

Modern Science: • Because of DNA technology, we can compare the relatedness of PRESENT DAY SPECIES by comparing their DNA.

Gel Electrophoresis • Scientists use an ENZYME to cut DNA into fragments. • Scientist load the pieces of DNA into a gel • The gel machine separates DNA fragments according to SIZE!!!!!

• The SMALLEST, SHORTEST fragments will travel the farthest from the well! • The biggest fragments will travel the least distance from the well • Species will the most similar bands are the most closely related!!!!