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_0
4_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_0
3_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?