|General aims and suggestions for classroom use |
This fact sheet for middle school to high school students is appropriate for several topics, including plant reproduction, plant diversity, and plant-animal interactions. Page one introduces flowers as adaptations to attract animal pollinators, and leads students to make a prediction about plant and pollinator associations. Page two focuses on the North American example of yucca plants and yucca moths to illustrate the key biology concepts of coevolution, mutualism, and obligate mutualisms.
Suggestions for using this fact sheet in conjunction with plant reproduction and plant diversity:
- Provide students with a diagram of a typical flower and a variety of flowers (some with petals united into a corolla and extended stamens, some open, some with large lower petal, some with nectar spurs, etc.). Have students draw and label the reproductive and nonreproductive parts of the flowers, and identify similarities and differences among them.
- Use the colorful and fragrant petals as a chemistry connection in your biology lesson. For example, the blues and purples and many reds come from anthocyanin pigments, yellows to whites from anthoxanthin pigments. The ?flowery? to fetid flower scents are due mixtures of organic compounds.
- Ask your students to suggest some plants that have wind-pollinated and water-pollinated flowers, and adaptations those flowers might have.
- Present students with representative images of angiosperms, gymnosperms, ferns, and mosses that grow in your region. Have students design and complete a chart contrasting patterns of species diversity (number of species) and reproduction (pollination system) among those plant groups.
- Introduce students to the extraordinary diversity of the earliest animal pollinators ? beetles (~350,000 species worldwide, ~30,000 species in North America). Have students research the link between angiosperm diversity and insect diversity.
Suggestions for using this fact sheet in conjunction with pollination ecology and coevolution:
- Have students model the effectiveness of bird beaks (or insect proboscis) of different lengths to reach a nectar reward from flowers varying in lengths of their corollas (see, for example, Coevolution---A simulation and story http://biology.arizona.edu/sciconn/lessons2/Roxane/co_eval.htm). Building on that experience, ask students to describe generalist and specialist pollination systems.
- Once yucca moths reach adulthood, they do not eat and live only a few days. Have students suggest benefits yucca moths might receive from pollinating yucca plants. Use this discussion to present other pollination systems without an immediate food reward; for example, some flies are lured into fetid-smelling flowers, such as the skunk cabbage (Lysichiton americanus), where they lay their eggs but receive no food reward. Many specialist pollination systems provide rewards related to successful reproduction of the pollinator. Ask students to develop hypotheses to explain this observation.
- Does the word pollen make your students think of allergies? Ask this question to jumpstart a brainstorming session on differences between wind and animal pollination. Then, have students suggest an experiment to determine that yucca (or any other animal-pollinated plant) is not wind pollinated, and to identify its potential pollinators over a 24-hour cycle.
- Focus on declining pollinator populations in a "science and society" discussion. Farmers in America are particularly concerned about reduced numbers of the honeybee, a European species introduced to pollinate 100s of food crops. Native pollinator populations also are declining due to habitat destruction, pesticides, and introduced species. Have students predict what would happen to the yucca moths if the yucca population declined or died out, and visa versa. Then, have them predict what would happen in a generalized pollination system.
The reproductive lives of many plants are intimately entwined with numerous animal species. Consider using the following case studies of North American plant-animal mutualisms (see sources below).
- Pinyon pine (Pinus edulis) and whitebark pine (Pinus albicaulis) rely on pinyon jays (Gymnorhinus cyanocephalus) and Clark's nutcrackers (Nucifraga columbiana) to disperse their wingless seeds.
- In the Organ Pipe Cactus National Monument, the organ pipe cactus (Stenocereus thurberi) is pollinated primarily by the migrating lesser long-nosed bat (Leptonycteris curasoae) but in Mexico hummingbirds and insects provide those services. (This case study is particularly useful for introducing the fact that pollinators may vary over space and time.)
Nonflying mammals pollinate plants many regions around the world: Central and South America-primates, procyonids, marsupials, & rodents; Africa-primates, rodents, & viverrids; Asia-primates, rodents, viverrids, & treeshrews; and Australia-marsupials.
Plants and animals, mainly ants and mites in tropical regions, form positive associations for protection against herbivory. In return, plants provide the ants or mites a place to live and sometimes food.
Animals aren't the only players in positive interactions with plants (or plant-like organisms).
- Most vascular plants have mutualistic associations with fungus, which form special structures on the plant roots called mycorrhizae
- The mutualistic association between fungi and green algae or cyanobacteria is so close we recognize them as one dual organism, a lichen. Visit http://mgd.nacse.org/hyperSQL/lichenland/ or http://www.lichen.com/ to learn more.
Links to more pollination facts and fun
Yucca Pollination in Action - Otto Pellmyr?s lab website has a movie of yucca pollination and more.
The Arizona-Sonora Desert Museum, Migratory Pollinators Program - The Desert Museum has a broad plan to study and conserve migration corridors used by North American birds, bats, and insects.
North American Pollinator Protection Campaign - Promoting stable pollinator populations is the aim of the Coevolution Institute and the National Fish & Wildlife Foundation?s collaboration.
Pollination - The Ecological Society of America and the Union of Concerned Scientists provides fact sheets, case studies, and references in their "Communicating Ecosystem Services Project."
Buchmann, S. L. and Nabhan, G. P. 1996. The Forgotten Pollinators. Island Press.
Carthew, S. M. and Goldingay, R. L. 1997. Non-flying mammals as pollinators. Trends in
- Ecology and Evolution 12(3): 104-108.
Farrell, B. D. 1998. "Inordinate fondness" explained: Why are there so many beetles?
- Science 281: 555-559.
Fleming, T. H. and Valiente-Banuet, A. (eds.) 2002. Columnar Cacti and Their Mutualists:
- Evolution, ecology, and conservation. The University of Arizona Press
Herrera, C. M. and Pellmyr, O. (eds.) 2002. Plant-Animal Interactions: An Evolutionary
- Approach. Oxford University Press.
Hess, W. J. and Robbins, R. L. 2003. Yucca. In: Flora of North America, volume 26, pages 423-
- 439, Oxford University Press.
Kearns, C. A., Inouye, D. W., and Waser, N. 1998. Endangered mutualisms: The conservation
- of plant-pollinator interactions. Annual Review of Ecology and Systematics 29: 83-112.
Pellmyr, O. 2003. Yuccas, yucca moths, and coevolution: A review. Annals of Missouri
- Botanical Garden 90: 35-55.
Raguso, R. A., Levin, R. A., Foose, S. E., Holmberg, M. W., and McDade, L. A. 2003. Fragrance
- chemistry, nocturnal rhythms and pollination "syndromes" in Nicotiana. Phytochemistry
- 63: 265-284.
Vander Wall, S. B. 1990. Food Hoarding in Animals. University of Chicago Press.