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A Darwin Voyage
• Evolution– A change over a
period of time
• Charles Darwin; 22– Voyage on the Beagle
• 1831– 5-year trip around the
world
– Started in England
Living Diversity
• Diversity– The variety of living
things on earth
• Scientists estimate…– Between 5-50 million
living species on earth right now
• Quite a guess!!!
Fossil Diversity
• Fossils give us a glimpse into the past
• Extinction– 99.9% of all species
that have ever lived are now extinct
Adaptations
• Physical and behavioral traits– Enable organisms to
survive• Catch food• Withstand conditions• Reproduce
Fitness
• The ability of an individual to survive & reproduce
• To successfully pass on its genes to its offspring
The Galapagos Islands
• 1000 kilometers west of S. America – 600 miles
• Small & short islands– Dry & hot
• Larger & taller islands– More lush
Giant Tortoise Shells
• Tortoises from different islands had different shells
• Ah, hah!!!!– Natural Selection
• Survival of the fittest– Evolution!!!
Homologous Structures
• Develop from similar tissues in the early development stages of the organism
Arguments for an Ancient Earth
• River Valleys– Carved by glaciers over 100,000’s years
• Shells found in high elevation mountains– Plate tectonics!!!
Problems with Reproduction
• Extinction– Birth Rate < Death Rate
• Over Population– Birth Rate > Death Rate
• Disease• Famine• War
Peppered Moths
• Before the industrial revolution, England– Trees were light in
color from lichen growing on them
• After the pollution from Ind. Rev.– Lichen died, leaving
just the dark bark
Helpful Mutations
• Increases fitness– more offspring than others in population
• Becomes more common in the population
Species
• A group of similar-looking organisms that can breed with one another and produce fertile offspring– Bobcat & Lynx
Natural Selection
• The struggle for existence selects only the fittest individuals to survive in nature– Generation after generation
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