How evolution works

• Evolution: Change in the genetic makeup of a population of a species in successive generations. If continued long enough it can lead to the formation of a new species.

• Natural selection: Process by which a particular beneficial gene is reproduced in succeeding generations more than other genes. The result is a population that contains a greater proportion of organisms better adapted to certain environments.

Hummingbird species

http://www.pbs.org/wgbh/evolution/library/05/2/quicktime/l_052_04_56.html

1. What is the relationship between the length of the hummingbirds' beaks and the flowers from which they feed?

2. If the size and shape of the flowers available to a group of hummingbirds were to change dramatically over a short period of time, would individual hummingbirds have the ability to change the size and shape of their beaks to adapt?

3. Although individual members of a species may look very much alike, there is often a great deal of variation among them. What role might this variation play in natural selection and evolution?

Evolution of Camouflage

http://www.pbs.org/wgbh/evolution/library/01/1/quicktime/l_011_03_56.html

1. What is the praying mantis's strategy for self-defense?2. The mantis is nearly invisible sitting on a leaf in the forest, but when the

scientist places the insect on his blue shirt, it becomes very obvious. What does this suggest about how well this species of mantis would survive in a different environment -- a desert or a short-grass prairie, for example?

3. Would an individual mantis be able to transform its appearance if it were placed in another type of environment? Why or why not?

4. If the forest were to dry out and turn to grassland, or if this species of mantis began to expand its range to an area with fewer trees, what might happen to the species over time?

Floral Arrangements

http://www.teachersdomain.org/asset/tdc02_vid_floral/1. Some plant species rely on the wind for

pollination. What other pollination strategies do plants use?

2. Insects are often critical to a plant species' survival. What reward do plants usually offer in return for the insects' services?

3. The orchid in the video promises a different kind of payoff. What is that false promise?

Tale of the Peacock

http://www.pbs.org/wgbh/evolution/library/01/6/quicktime/l_016_09_56.html

1. From the research discussed in the video, what appears to be the most important factor in a male peacock's ability to attract mates and successfully reproduce?

2. What happened when the scientists altered the peacocks' tails by cutting them short?

3. Aside from providing the egg, what role do peahens play in the reproductive success or failure of a would-be mate?

4. How might this trait have begun, and how might it have evolved over millions of years?