Darwin’s Theory of Evolution. Chapter 15. The Puzzle of Life’s Diversity 15-1. In 1831, at age 22, Charles Darwin joined the crew of the H.M.S. Beagle as a naturalist for a 5 year voyage around the world. . Darwin went ashore and collected plant and animal specimens for his collection.
Darwin went ashore and collected plant and animal specimens for his collection.
and on Pinta Island, tortoise necks
were somewhere in between
Pinta IslandIntermediate shell
On the desert-like Hood Island,
tortoises had long necks…
…while on the lush rainforest of Isabela Island,
tortoises had short necks…
After his voyage, Darwin spent a great deal of time thinking about his findings.
The male fiddler crab uses its front claw to attract mates and fight off predators.
Through repeated use, the front claw becomes larger.
The fiddler passes on this acquired characteristic to its offspring
1858—Alfred Russel Wallace, another naturalist, publishes an essay describing his work in Malaysia and outlining the same ideas that Darwin had for 25 years!
Selection by humans for breeding of useful traits from the natural variation among different organisms.
Chihuahua – bred from Techichi of Mexico
by Mayans, had religious significance
Saint Bernard – bred by monks around 1050 A.D.
to rescue travelers of mountain passes in the
Swiss Alps between Italy and Switzerland
Irish Wolfhound – bred in Ireland to
hunt wolves and elk
Dachshund – bred in Germany as early
as the 15th century to hunt badgers
4. Individuals with the favorable traits (adaptations) will survive and reproduce more than those individuals without the favorable trait.
= Survival of the fittest
5. The favorable variation will become more common in the population.
2. Geographic Distribution
3. Homologous Body Structures
Ancient lobe-finned fish