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9 Cards in this Set

  • Front
  • Back
What is Darwin's major contribution to evolution?
Not descent with modification but the mechanism behind evolution: Natural selection.
What is artificial selection?
Darwin first began theorizing by observing artificial selection by breeders who practiced this for thousands of years. They selected and mated domestic animals that had desirable traits. Doing so repeatedly created animals with the desired trait.
What did domestication of the cabbage create?
Artificial selection can change more than size. In the case of domesticating vegetables, wild cabbage was bred to form broccoli, kohlrabi, cabbage, and brussel sprouts.
Darwins 4 postulates that lead to natural selection.
If the following 4 postulates are true than natural selection will occur in a population. 1. Individuals in a population have variation in their traits. 2. Some of these variations can be passed down to offspring. 3. Some individuals in every generation will be more sucessful at surviving and reproducing than others. 4. Individuals with variations best suited to the environment will be those that reproduce most sucessfully.
To biologists, what is an "adaptation"?
An adaptation is a trait that increases the fitness of an organism relative to other organisms without the trait.
What is fitness and how is it measured?
Fitness is measured in passing genes from one generation to the next. Fitness is relative to others in the population.
Evolution of Snapdragons by bumblebees
There were 48 snapdragons. 75% white with yellow nectar guides and 25% yellow. Postulates 1 and 2 were assumed to be true. Postulates 3 and 4 needed to be tested to see if natural selection by bumblebees causes evolution of the plant. Plants were grown in pots in Colorado. Bumblebees were allowed to pollinate. Reproductive sucess was measured in ability to be pollinated and number of seeds produced. Sucess in pollination was measured by the number of bees that visited the plant. Seed production was measured by counting seeds. Jones and Reithal in 2001 did not know which flower would have more reproductive success. It was found that the white flower attracted more bees and produced more seeds than the yellow flower. It was found that the next generation of snapdragons had a greater number of white flowers and thus evolution had occured.
What is a cladogram?
A phylogenetic tree created by clustering synapomorphies together
What is monophyletic group?
All the descendents of a common ancestor. (clade)Synapomorphies define a clade.