1. Introduction to change in organisms
Lamarck vs. Darwin
Introduction to change in organisms

2. What is a theory?
The most probable explanation for a large set of data based on the best available evidence
Summarizes a hypothesis or group of hypotheses that have been supported with repeated testing

3. What is a species? What is a population?
Species – group of a single type of organisms that interbreed and are reproductively isolated
White-tailed deer
Population – refers to a group of organisms of a particular species living in a certain area.
White-tailed deer on Mt. Nebo

4. Lamarck’s Theory Jean Baptiste Lamarck: 1800’s Believed:
Change Occurs Over Time
inheritance of acquired characteristics
acquired changes were passed to offspring
Law of Use and Disuse
If a body part were used, it got stronger
If body part NOT used, it deteriorated
Examples: Body builders or pierced ears

5. Lamarck’s Theory of Evolution
Giraffes all had SHORT necks originally
Giraffe’s Necks got LONGER from stretching for food
“Acquired” trait (long necks) then passed to offspring
Giraffe population became long-necked

7. Lamarck’s Theory of Evolution
More examples
Traits Acquired During Ones Lifetime Would Be Passed To Offspring
Clipped ears and tails of dogs could be passed to offspring!

8. Lamarck’s Mistakes Was he correct?? NO!
Traits are passed down from one generation to the next by GENES, not by an individual’s life experiences or activities
Lamarck did NOT know how traits were inherited (Traits are passed through genes)
Genes Are NOT Changed By Activities In Life
Change Through Mutation Occurs Before An Organism Is Born

9. Voyage of the Beagle Charles Darwin Born Feb. 12, 1809
Joined Crew of HMS Beagle, 1831
Naturalist
5 Year Voyage around world
Astounded By Variety of Life

10. Voyage of the Beagle
During His Travels, Darwin Made Numerous Observations And Collected Evidence That Led Him To Propose A Revolutionary Hypothesis About The Way Life Changes Over Time

11. Darwin’s Belief’s Survival of the fittest OR natural selection
Food and resources are limited
So organisms have to COMPETE to get them (lions fight for food, space, mates …)
OVER PRODUCE too many organisms
Not all offspring will survive only the MOST FIT (not always the strongest!)

12. What happened to the giraffe’s?
Survival of the fittest or natural selection
Natural selection said the giraffes with short necks had less food to eat
Why?
the food resources changed to leaves only on the upper branches
What happened?
short necks could not reach upper branches and did not survive (couldn’t pass on genes)
Long neck giraffes survived & reproduced because they were able to reach the food

14. Evolution is
the slow, gradual change in a population of organisms
over time…
a looooooooong time!

15. Where do we see this change?
When there is an unequal ability of individuals to survive and reproduce …
This leads to a gradual change in a population with favorable characteristics accumulating over generations
Most fit “naturally” selected
New species evolves

16. Natural Selection How does Selection occur?
Selection of the most fit can occur from several factors:
Variations exist among individuals in a population
Competition for limited resources
Overpopulation
Predation/Disease

17. Example of Natural Selection
A classic example of natural selection is the Peppered moths during Industrial Revolution in Europe