BIODIVERSITY – WHY IS IT IMPORTANT? INTRODUCTION When scientists speak of the variety of organisms (and their genes) in an ecosystem, they refer to it as biodiversity. Genetic diversity plays a very important role in the survival, sustainability, and adaptability of a particular species or variety of species in an ecosystem or habitat. A species that has a large degree of genetic diversity among its population will have more variations from which to choose the most fit individuals. Increase in genetic diversity is also essential for an organism to evolve. Species that have very little genetic variation are at a great risk. With very little gene variation within the species, healthy reproduction becomes increasingly difficult, and offspring often deal with similar problems to those in inbreeding. The vulnerability of a population to certain types of disease can also increase with reduction in genetic diversity. The same is true with biodiversity within a habitat or ecosystem. A biologically diverse ecosystem, such as an old growth forest or tropical rainforest, is healthy, complex, and stable. Nature tends to increase diversity through the process of succession. The opposite of biodiversity is referred to as monoculture, or the growing of one species of organism, such as a lawn, a wheat field, or a cornfield. Because all of the species are identical, there are few complex food webs and disease can spread quickly. Agricultural Relevance When humans initially started farming, they used selective breeding to pass on desirable traits of the crops while omitting the undesirable ones. Selective breeding leads to monocultures: entire farms of nearly genetically identical plants. Little to no genetic diversity makes crops extremely susceptible to widespread disease. Bacteria morph and change constantly. When a disease causing bacterium changes to attack a specific genetic variation, it can easily wipe out vast quantities of the species. If the genetic variation that the bacterium is best at attacking happens to be that which humans have selectively bred to use for harvest, the entire crop will be wiped out. In this simulation, your first card represents the monoculture of second growth forests. In this case, Douglas Fir trees were planted after an old growth forest was cut down. A disease kits one of the Douglas Firs and because of the proximity of the other Douglas Firs, disease spreads quickly. On the second card, a biologically diverse community (old growth forest) is symbolized. In this scenario, a Douglas Fir still gets a disease, but this time it does not spread because the other Douglas Firs are few and far between.

OBJECTIVES • •

The student will be able to understand the relationship between biodiversity and spread of disease and population sustainability The student will be able to explain biodiversity in terms of monoculture and polyculuture and relate these to biological succession

PRE-LAB QUESTIONS 1. What does biological diversity mean? 2. Why should we care about monocultures and polyculuture in a habitat or ecosystem?

MATERIALS • •

Index Cards Writing utensils

Credits: Original lab adapted from Kathy Paris’ activity accessed at http://www.accessexcellence.org/AE/ATG/data/released/0534KathyParis/ and the modified by Amy Moore

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PROCEDURE Simulation #1 1. Each student receives one card marked with D to represent Douglas Firs 2. Each person is to meet three other people and write their names on the card. 3. All are to remain standing after they write down the names. 4. The teacher symbolizes the disease and will touch one of the students. That person will sit down (because he or she is “dead”) and read the names on his/her card. As the names are read, those students sit as well because they have been “touched” by the disease. 5. Ask another one of those sitting (dead) to read the names on their card, and all those students named will sit. Continue until all those sitting have read the names on their cards. 6. Number of students left standing: ________________ Simulation #2 1. Each student will receive a card that is marked with a letter that represents a particular species of tree: 2 with D for Douglas Firs, the rest with other letters: N for Noble Fir, C for Western Red Cedar, M for Vine Maples, H for Western Hemlocks, W for White Fir, L for Lodge Pole Pine, WP for Western White Pine, B for Bigleaf Maple, WD for Western Dogwood. 2. Repeat steps 2-6 as for Simulation #1. This time, only those students that are the same variety as the diseased tree that touched them will sit. Different variety trees don't sit (don't die) even if they were touched by a diseased tree. 3. Number of students left standing: _______________

POST-LAB QUESTIONS 1. What does biological diversity mean? 2. Why didn't all the different trees get the disease? 3. Why didn't the disease spread as fast among the Douglas Firs in Simulation #2 as it did in Simulation #1? 4. In which forest would you need to use more chemicals to control disease: the Douglas Fir forest of the more diversified, old growth forest? Why? 5. Summarize what this simulation symbolized. 6. Which forest would have more diversity of wildlife? Why? 7. If you cut down the variety in a piece of forest you owned and replanted with one type of tree, what will happen to much of the wildlife that was adapted to the forest? (Hint: they cannot just move elsewhere. If other habitats are good, they will probably be near carrying capacity already.) 8. Will this fate happen to all the wildlife? Explain. 9. Many species can only live/reproduce in one type of forest. The spotted owl is an example: it can only live and successfully reproduce in old growth forests (big, old cedars, hemlocks, etc.). If these old growth forests are cut down, it’s unlikely this owl will survive. Environmentalists call it an “indicator species.” What does this mean? Why be concerned about one species? 10. Growing one plant, as is the case of growing only Douglas Fir, is called monoculture. Give examples of monocultures: a. in your home b. in agriculture 11. Why would you need to use more insecticides in monoculture? Is this good or bad? 12. If you wanted to help wildlife, what would you do with regards to the landscaping of your own home?

Credits: Original lab adapted from Kathy Paris’ activity accessed at http://www.accessexcellence.org/AE/ATG/data/released/0534KathyParis/ and the modified by Amy Moore

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D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir   131

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir   132

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir  

D  

D  

Douglas  Fir  

Douglas  Fir   133

N  

N  

Noble  Fir  

Noble  Fir  

N  

N  

Noble  Fir  

Noble  Fir  

C  

C  

Western  Red  Cedar   Western  Red  Cedar  

C  

C  

Western  Red  Cedar   Western  Red  Cedar  

M   Vine  Maples

 

M   Vine  Maples

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M   Vine  Maples

  H  

M  

 

Vine  Maples

 

  H  

 

Western  Hemlocks Western  Hemlocks

 

 

 

  H  

  H  

Western  Hemlocks Western  Hemlocks

  W  

  W  

White  Fir

 

White  Fir

 

White  Fir

 

White  Fir

 

  W  

  W  

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L  

L  

Lodge  Pole  Pine

 

Lodge  Pole  Pine

Lodge  Pole  Pine

 

Lodge  Pole  Pine

 L  

  WP  

 

 L         WP       WP       B    

Western  White  Pine   Western  White  Pine  

  WP  

Western  White  Pine   Western  White  Pine  

  B  

Bigleaf  Maple  

Bigleaf  Maple  

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B  

B  

Bigleaf  Maple  

Bigleaf  Maple  

Western  Dogwood  

Western  Dogwood  

Western  Dogwood  

Western  Dogwood  

  WD     WD    

  WD       WD      

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