Transcript Understanding Evolution

Understanding Evolution
An Introduction to Evolutionary Theory
What Is Evolution?
• Descent with modification.
• Descent?
– Reproduction
– Creation of new individuals from old
– Continuity (connection) between generations
through inheritance (heredity, genetic information)
• Modification?
– To change or alter
Where did this idea come from?
• Though not the first to propose the theory,
evolutionary theory in its modern form was
made famous by Charles Darwin (1809-1882).
• For 5 years in the 1830s Darwin sailed on the
HMS Beagle – a ship charting the coast of
South America.
• Darwin, a naturalist, was invited to come on the
voyage to keep the captain company at dinner.
Darwin’s Travels
Darwin’s Observations
Extinct & Modern Forms
• Observed exposed fossils of
extinct mammals in cliff faces.
•Where did the unknown forms
originate?
•Observed similarities between
extinct and living forms
(morphology & distribution).
•Could there be a link?
Darwin’s Observations
Different But Similar…
•Observed great diversity of
living things.
•Observed differences in
species that had been
separated on various
Galapagos islands.
•However forms were
similar enough to infer
common ancestry.
Darwin’s Dangerous Idea
• Why did some species survive while others
became extinct?
• An excerpt from the biographical film…
• Darwin's Dangerous Idea
But How Does It Work?
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Natural Selection! - ‘Survival of the fittest’.
Struggle for survival (environmental pressures)
Individual variation in phenotype.
Inheritance (heredity)
Differential success of certain phenotypes.
Consequently, certain adaptations enable organisms to
become better suited to their environment…
• And living things EVOLVE…
Darwin observed that on different islands, different finches had
been ‘successful’ (survived and reproduced in abundance) by
developing different adaptations that suited the environment.
Natural Selection in Action
• Natural Selection in Action
Natural Selection In Action
• Natural selection of the woolyboogers.
• Get into groups of 5-6 and number off.