EVOLUTION

1
EVOLUTION

• Unit 5

2
Introduction to Evolution

• Central Ideas of Evolution
• Life has a history
• It has changed over time
• And different
• species share common
• ancestors.

3
Scientific Explanation

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

4
15.1 The Puzzle of Lifes Diversity

• The variety of living things is called
• biological diversity.

5
Charles Darwin1809-1882

• 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.

6
Voyage of the Beagle(5 years)
7
Darwins Observations

• 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.

8
Living Organisms and Fossils

• Darwin also found and
• collected fossils
• He questioned
• Why had so many species
• disappeared?
• How were they related
• to living species?

9
Fossils preserved remains of once living
organisms

• Actual Remains
• - Real tissue or portion of
• once living thing
• Casts
• - Imprint in rock
• Color of imprint
• same as surrounding
• Mineral Replacement
• Organic changed to
• mineral rock

10
Galàpagos Islands

• 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

11
Shell Shape/Neck Length Variedby Habitat

Pinta
Tower
Marchena
Pinta IslandIntermediate shell
James
Fernandina
Santa Cruz
Isabela
Santa Fe
Hood Island Saddle-backed shell
Hood
Floreana
Isabela Island Dome-shaped shell
12
Could Isolation and Habitat Produce New Species?

• Although Darwin
• observed plants and
• animals varied
• noticeably among
• different islands, could
• it be possible they had
• evolved from an
• original South American
• species?

13
Variation within a 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

14
Variation Activity

• 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.