Students compare blade size of leaves from one species and between closely related species.
Evolution through natural selection accounts for the diversity of species developed through gradual processes over many generations. Biological adaptations include changes in structures, behaviors or physiology that enhance survival and reproductive success in a particular environment.
Before the Activity
To prepare your own set of leaves, randomly collect 10 leaves from the same tree on a day that is not real humid or after a rain. Place the leaves between layers of newspaper, and then cover the top with a heavy book. Keep in a dry place.
After 2-3 days, the pressed leaves are ready to be mounted. Use clear contact paper and poster board for mounting. Write the name of the species and the number of the specimen on each card.
Students can also be required to make their own sets.
During the Activity
Complete attached activity.
Students will need sets of leaves and a metric ruler.
Suggested specimens include:
Acer saccharum and Acer saccharinum
Quercus alba and Quercus macrocarpa
After the Activity
Activity extensionsChoose a third closely related species, i.e., Acer rubrum and compare the data among the three species.
Choose a cultivar, a closely related species that horticulturists have artificially selected and compare its data to its native species. Discuss the traits that horticulturists choose when designing cultivars. Then continue your discussion with genetic engineering. What traits would genetic engineers choose to incorporate into the tree’s genome?
Predict if any relationship exits between leaf blade width and height, or between leaf blade height/width and petiole (stem) length. Graph the data on a scattergram and perform a regression to determine which relationship if any exists.