Chapter 10 Darwin’s Theory of Evolution

I. Charles Darwin A – 1882 B. Came from a family of doctors C. Realized he did NOT like blood or surgery without anesthetic and dropped out. D. His father enrolled him in school to become a clergyman E. Darwin finished 10 th in his class but did not become a minister.

F. Darwin’s favorite subject was natural science. G.He joined the crew of the H.M.S. Beagle and sailed around the world. H. The trip took 5 years and he collected plants and animals at every stop to study while at sea.

II. Darwin’s Observations A. Noticed that the organisms he collected seemed well suited to the environment he found them in. B. Collected fossils – preserved remains of ancient organisms. C. Liked the Galapagos islands the most. GlyptodonArmadillo

D. The islands were close together but had different climates and elevations. E. This led to a variation of species on each island. (see tortoises on p.452) F. The most famous were the finches.

G. Each island had a species of finch but they all had different beaks suited to the environment.

Was it possible that each finch or tortoise type were all related to a South American ancestor at one point, but were changed when landforms shifted and they became isolated? ktime/e_s_2.html

II. Pangaea A. Means “all land” B. It is a theory about the appearance of the land that existed during the Mesozoic (dinosaur) era that included most of Earth’s present day continents. C. Based on fossil findings and knowledge of plate tectonics

10.1 Ideas That Shaped Darwin’s Thinking

I. Before Darwin there was… A.1785 James Hutton- hypothesized that the Earth is millions (not thousands) of years old and it changed very slowly over time = Gradualism The Grand Canyon was formed by erosion of rock layers by the Colorado River at a rate of 0.3 meters per millennium (pretty quick for erosion!). The deepest point is 1800 meters. At this rate how long did it take for the river to erode the Grand Canyon to this depth?

B. Charles Lyell- English Geologist Theory of Uniformitarianism Lyell stated “the present is the key to the past” –Geologic processes that shape the earth are uniform throughout time. Conditions of the past can be explained by geological conditions today.

C. Georges Cuvier- French zoologist –Didn’t think species could change, but could go extinct. –Theory of Catastrophism = natural disasters (floods, volcanic eruptions, etc.) during earth’s history shaped landforms and caused some species to become extinct. –Cuvier said the appearance of new species in each rock layer resulted from other species’ moving into the area from another location after a catastrophic event.

B Thomas Malthus – 1. predicted the human population would grow faster than the space and food supplies needed to sustain it. 2. war, famine, and disease were the only things balancing out birth and death rates 3. also applied to trees and animals since one adult tree could produce thousands of seeds a year and one animal could produce a litter of offspring.

C Jean-Baptiste Lamarck- First to recognize things changed over time and all species came from other species. His ideas were on the right track but flawed…

1. He proposed that organisms acquired or lost traits based on whether they used them or not. 2. He believed that since all organisms want to be perfect, they constantly change and acquire features that help them survive.

3. Lamarck’s examples of use choose one to write in your notes Ex. a – all birds have had the urge to fly so over many generations they kept trying to fly. This increased their wing size and eventually they flew and would pass this onto offspring. Ex. b- If a water bird needs long legs to wade deep in water, it can acquire them by making an effort to stretch and use its legs in new ways. This trait can be passed on to offspring. Ex. c – Birds strained their feet while trying to swim creating webbed feet over generations.

Ex. d – Giraffes had short necks but needed to stretch to reach the leaves on the tops of trees. This gave them longer necks which they passed on to their offspring.

Ex. a – snakes moved faster when they lifted their legs and slithered so they’re offspring were born without legs Ex. b – Penguins preferred to swim then to fly, over time their wings grew smaller. 4. Lamarck’s examples of disuse choose one to write in your notes