unit 5. central ideas of evolution: ◦ life has a history ◦ it has changed over time ◦ and...

Unit 5

Central Ideas of Evolution:

◦ Life has a history

◦ It has changed over time

◦ And different species share common ancestors.

Science tries to explain the past in terms of events/processes we can observe, measure and replicate today.

The variety of living things is called

biological diversity.

He contributed most to the understanding of evolution Born in England Naturalist on the crew of H.M.S. Beagle (1831) During travels, made numerous observations and collected evidence to propose how life changes over time.

Collected plant and animal specimens at every stop. Well educated and curious Strong interest in natural history Noted more diversity than his native country Collected 68 different beetle species in one Brazilian forest.

Darwin also found and collected fossils

He questioned: Why had so many species disappeared? How were they related to living species?

Actual Remains- Real tissue or portion of once living thing

Casts- Imprint in rock- Color of imprint same as surroundingMineral Replacement- Organic changed to mineral rock

1000 km west of South America

Influenced Darwin the most

Although islands close, they had very different climates. Most fascinated by land tortoises and marine iguanas

Pinta IslandIntermediate shell

Pinta

Isabela IslandDome-shaped shell

Hood IslandSaddle-backed shellHoodFloreana

Santa Fe

Santa Cruz

James

Marchena

Fernandina

Isabela

Tower

Although Darwin observed plants andanimals varied noticeably among different islands, couldit be possible they had evolved from an original South American species?

Darwin also knew that individuals differ from all the other members of its species

Sometimes differences easy to observe Sometimes differences are subtle Variation necessary for evolution by natural

selection

Do Lima Beans Show Variation?Procedure: 1. Count out 10 lima beans and measure the

length of each in millimeters. Record your results in a data table.

2. Combine your data with the data of two other classmates. Place all the data on one graph. Plot the length on the x-axis and the number of beans of each length on the y-axis.

Analyze your data and Make predictions.