The Theory of Evolution
Darwin's Theory of Evolution by Natural Selection
Darwin was a naturalist who
observed many species.
He is famous for his trips to the Galapagos Islands,
his observations of the finches (and other animals)
He wrote:
"The Origin of Species:
1. Variation exists among individuals
in a species.
2. Individuals of species will compete for resources (food and space)
3. Differential survival and reproduction
4. Adaptation: Individuals that had advantageous variations are more likely to survive
and reproduce.
V.I.D.A
This process he describes came
to be known as Natural Selection
The favorable variations are called Adaptations
Darwin's
Finches:
Darwin noted that all the finches on the galapagos island looked about the same except for the shape of their beak. His observations lead to the conclusion that all the finches were descendents of the same original population. The shape of the beaks were adaptations for eating a particular type of food (Ex. long beaks were used for eating insects, short for seeds)
Evidence of Evolution
1. Fossil Evidence
- Carbon dating--gives an age of a sample based on the amount of radioactive carbon is in a sample.
- Fossil record---creates a geologic time scale.
- Fossils reveal existence of transitional species
2. Homologous Structures-
- -structures that are embryologically similar, but have different functions, the wing of a bird and the forearm of a human
3. Vestigial Structures
- Organs or parts that have no current function
- Examples include pelvic bones in whales
4. Biochemistry and DNA
- DNA of closely related species have similar sequences
- Proteins and other biochemicals are similar across related species (Cytochrome C)
5. Embryological development
- Embryos follow similar patterns of development
- Early embryos of different species look very similar
6. Direct Observation
- Antibiotic resistance in bacteria
- Rock Pocket mice coloration
- Tuskless elephants
Evolution Activities
Galapagos Finches (HHMI Video)
Evolution by Natural Selection (VIDA) Elephants
Evolution of Rabbits and Wolves (VIDA)