2Charles Darwin and Evolution “from so simple a beginning, endless forms most beautiful and most wonderful have been, and are being, evolved.” – Origin of Species
3I. Darwin’s Travels 1. In 1831, Charles Darwin traveled on the HMS Beagle (a ship) around the world from England. One specific place he went was to the Galapagos Islands off of Ecuador Along the way, he made observations of many plants and animals and collected specimens. This evidence led him to propose a revolutionary hypothesis on evolution.
5Evolution is basically change over time Evolution is basically change over time. It is the process by which modern organisms descended from ancient ones.
6II. Darwin’s Observations He asked questions II. Darwin’s Observations He asked questions! - Why aren’t there any rabbits in Australia even though climate is right? - Why are there no kangaroos in England? - Why is there such variety in living things, i.e. biological diversity. - How are species so well suited to their habitats? - Why had so many species disappeared? - How are they related to living ones?
7Fossils would be the answer to many of his questions Fossils would be the answer to many of his questions. Fossils are the remains of ancient organisms.Some ancient fossils resemble modern living organisms.Some fossils didn’t look like ANYTHING he’d seen before. WHAT HAPPENED?
8Why were there so many different types of tortoises, finches etc Why were there so many different types of tortoises, finches etc. Why not just one type since they all lived on the Galapagos Islands?–Islands are far apart w/ different climates, different species.
10The tortoises varied in predictable ways from one island to another The tortoises varied in predictable ways from one island to another. Shell shape and neck length could identify the island the tortoise came from.
11The finches on the different island had different beaks for different foods. The changes in beak shape were driven by competition for food.•Common ancestor???
13III. Darwin’s Conclusions/Hypothesis •These separate species of animals must have come from one common ancestor!
14IV. Ideas that Shaped Darwin’s Thinking A. At this time people thought:1. World and life were created 1000 yearsago!2. Nothing had changed since then!
15V. New Ideas Hutton and Lyell: Geologists 1. Through fossils and geologic formations showed Earth was millions of years old and that it was constantly changing over time.
16This all influenced Darwin… a. If Earth could change over time, couldn’t living things?????b. IF Earth were old (like they are saying) it would give time for organisms to change!!
17VI. LamarckA. His Ideas:Jean-Baptiste Lamarck said (before Darwin) that by using something a lot or not using something, an organism acquired or lost traits during their life. These traits could be passed on to the babies. “Use it or lose it” theory.
18Ex. Lamarck thought that if a giraffe stretched its neck, it could pass this longer neck onto its baby. (Acquired = gained)
19Ex. Or, say a swimmer builds up large strong shoulders, he/she would pass large shoulders on to their child.
20B. Lamarck didn’t quite get it right B. Lamarck didn’t quite get it right. He didn’t know that an organism’s behavior doesn’t influence what traits are passed on to offspring. He did not know about genes.Still, he was one of the first to develop a theory of evolution and recognize that organisms are adapted to their environments. He paved the way for Darwin!
21VII. Darwin Speaks Out A. On the Origin of Species He didn’t publish the book for 25 years! (A little afraid of what would happen!) ….i.e. “dangerous” idea.His theory was Natural Selection AKA “Survival of the Fittest”In sum: the organisms best suited to their environment will survive and reproduce.
22Artificial Selection: •Farmers, Breeders pick the “best” to breed/survive!This Chihuahua mix and Great Dane show the wide range of dog breed sizes created using artificial selection.Pigs are artificially selected by man to produce the largest amount of meat.