1. Evolution:
A Beginning

2. Evolution: A Beginning
Evolution – change over time; modern organisms have descended from ancient organisms
Lamarck & Darwin – 2 important scientists for evolution

3. Lamarck’s Theory of Evolution - 1809
Recognized that living things change over time
One of the first scientists to suggest evolution
****By selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime. These traits could then be passed on to their offspring. Over time, this process led to change in species.****

4. Lamarck’s Theory of Evolution (continued)
Tendency toward perfection
All organisms have an innate tendency toward complexity and perfection = change features to help them adapt
Ex. Urge to fly = wings

5. Lamarck’s Theory of Evolution (continued)
Use and disuse
Organisms alter size and shape of organs by using bodies in new ways
Ex. No flying = smaller wings

6. Lamarck’s Theory of Evolution (continued)
Inheritance of acquired traits
New traits acquired during lifetime could be inherited
Ex. Lift weights to build muscle = children will inherit muscles

7. Lamarck’s Theory of Evolution

8. Lamarck’s Theory of Evolution
Is Lamarck’s theory legit?
Why or why not?

9. Darwin
1831, traveled around the world on HMS Beagle. During his travels, Darwin made many observations and collected evidence that led him to propose a revolutionary hypothesis about evolution…

10. Darwin’s Travels

11. Patterns of Diversity
Organisms well suited to environments they inhabited

12. Living Organisms and Fossils
Collected fossils that resembled organisms that were still alive and those that were completely different

13. Galapagos Islands
1000 km west of South America

14. Galapagos Islands These islands influenced Darwin greatly
Differences in tortoises from island to island due to different environments

15. Galapagos Islands Tortoises
Pinta
Tower
Pinta Island Intermediate shell
Marchena
James
Fernandina
Santa Cruz
Isabela
Santa Fe
Hood Island
Saddle-backed shell
Floreana
Hood
Isabela Island
Dome-shaped shell

16. Galapagos Islands
Differences in beaks of finches due to different foods eaten
Were these animals once members of the same species….?

17. Darwin’s Theory Darwin hypothesized that
present-day species are the descendents of ancient ancestors that they still resemble in some ways and
change occurs as a result of “descent with modification,” with natural selection as the mechanism.

18. Darwin’s Theory
Natural selection is a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are individuals with other characteristics.
As a result of natural selection, a population, a group of individuals of the same species living in the same place at the same time, changes over generations.

19. Darwin’s Book: On The Origin of Species
Darwin made two main points in The Origin of Species.
Organisms inhabiting Earth today descended from ancestral species.
Natural selection is the mechanism for descent with modification.