While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos islands. There, he encountered some unique animals. But these unique creatures were obviously related to ones he knew, namely finches and tortoises. And as he looked closely at them, he noticed they were not as different from each other as they first appeared.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos islands. There, he encountered some unique animals. But these unique creatures were obviously related to ones he knew, namely finches and tortoises. And as he looked closely at them, he noticed they were not as different from each other as they first appeared.
15–1 The Puzzle of Life’s DiversityA. Voyage of the Beagle
Pinta IslandIntermediate shell
Pinta
Isabela IslandDome-shaped shell
Hood IslandSaddle-backed shellHood
Floreana
Santa Cruz
James
Isabela
Tower
B. Darwin’s Observations-Patterns of Diversity-plants and animals adapt over time to their environment. The Galapagos Islands brought this fact home to Darwin.
Living Organisms and FossilsStudying fossils show links between living organisms
and ones long extinct.
15–2 Ideas That Shaped Darwin’s ThinkingA. Hutton and Geological Change-Hypothesized that geological
forces changed the earth over millions of years.
B. Lyell’s Principles of Geology-Past processes that shaped the earth continue today.
Volcanoes continue to erupt throughout
the world, destroying and creating
simultaneously in gigantic explosions
of hot gas and molten rock.
C. Lamarck’s Evolution Hypotheses 1. Tendency Toward Perfection
2. Use and Disuse
3. Inheritance of Acquired Traits
D. Thomas Malthus-Populations grow slowly at first and then exponentially until all available resources are at maximum use. The population will then crash as organisms die off from disease and starvation.
"In October 1838, …I had begun my…inquiry, I happened to read …Malthus on Population, …being well prepared to appreciate the struggle for existence which everywhere goes on… it at once struck me that under these circumstances (what Malthus described)… favorable variations would…be preserved, and unfavorable ones…destroyed. The results…would be the formation of a new species….I had at last got a theory by which to work".
Charles Darwin, from his autobiography. (1876)Quoted to show Malthus tremendous
influence on Darwin’s ideas.
15–3 Darwin Presents His Case
A. Publication of On the Origin of Species-
Published in 1859-28 years after Darwin’s voyage on the Beagle
For those who want to know, here is the link to the on-line text of Darwin’s famous and controversial book.