Think about sustainable management even at the level of your own backyard, even if it is a small yard. What does your household do with organic waste? Do you have a compost pile or would you or your family consider starting one? What kinds of trees and shrubs are planted in your yard? Are they native or introduced species? Drought-tolerant? Research some of the vegetation you can plant that will attract native bird, mammal, and other species. Put out bird feeders, especially in the winter in areas where birds may have trouble finding food, but make sure you keep the feeders well-stocked with food. Similarly, bird baths are useful, especially when temperatures get warm and during dry periods. Use organic or natural pesticides and fertilizers.
Remember that in addition to all the actions you can take, even learning about biodiversity and ecology is an important part of valuing and protecting the diversity of life. Pass on what you learn to others.
Lesson Summary
There are a number of causes of habitat destruction, including clearing of land, introduction of invasive species, overfishing, mining, pollution, and storm damage.
Habitat destruction threatens species through pollution, eliminations of niches, availability of fewer resources, and introduction of new species.
Some habitats affected by destruction include tropical rainforests, wetlands, and coral reefs.
Introduction of invasive species have caused harmful effects on native species, sometimes resulting in extinction
Other causes of extinction include pollution, global climate change, and overpopulation.
Biodiversity is important because it directly affects humans as well as ecosystem benefits and benefits to other species.
Economically, biodiversity diversifies our food supply; increases resources for clothing, shelter, and energy, and medicines; inspires new technologies; supplies models for medical research and an early warning system for toxicity.
Because of the importance of biodiversity and habitats, it is vital to do what we can do as citizens to protect habitats; these include continued protection in national parks, reserves, and other green areas; creation of new areas; communicating with representatives about these issues; volunteering with local organizations which have these goals in mind; and practicing sustainable practices, even at the level of your own backyard! Most importantly, educate others about the importance of habitat protection.
Review Questions
What is the largest cause of deforestation today?
How can habitat destruction through pollution kill a species over a long period of time?
Why do introduced exotic species have unexpected and negative effects in the new ecosystems?
Why are so many exotic species now being introduced either accidentally or intentionally to native habitats?
Explain how biological magnification played a role in the disappearance of the peregrine falcon from the eastern U.S.
Loss of biodiversity limits our ability to increase the genetic diversity of crops. What is the advantage of producing hybrids of crop species with wild species adapted to local climate and disease?
What are some of the things you can do to have a sustainably managed backyard?
Further Reading / Supplemental Links
Unabridged Dictionary, Second Edition. Random House, New York, 1998.
http://www.fws.gov/endangered/kids/index.html
http://www.blm.gov/education/LearningLandscapes/students.html
http://www.epa.gov/owow/oceans/kids.html
http://www.biodiversityproject.org/biodiversity.htm
http://ology.amnh.org/biodiversity
http://www.biodiversity911.org
http://en.wikipedia.org
Vocabulary
biodiversity
The number of different species or organisms in an ecological unit (i.e. biome or ecosystem).
biological magnification
The process in which synthetic chemicals concentrate as they move through the food chain, so that toxic effects are multiplied.
bionics
Engineering which uses the design of biological organisms to develop efficient products.
desertification
A process leading to production of a desert of formerly productive land.
extinction
The cessation of existence of a species or group of taxa.
genetic pollution
Hybridization or mixing of genes of a wild population with a domestic population.
habitat
The ecological or environmental area where a particular species lives and the physical environment to which it has become adapted and in which it can survive.
habitat destruction
The process in which a natural habitat is made functionally unable to support the species originally present.
invasive species
Exotic species, introduced into habitats, which then eliminate or expel the native species.
slash-and-burn agriculture
A method of agriculture in the tropics in which the forest vegetation is cut down and burned, then crops are grown for a few years, and then the forest is allowed to grow back.
tallgrass prairies
Native prairie ecosystems with thick fertile soils, deep-rooted grasses, and other characteristic species.
wetlands
A habitat that has a defined soil with characteristic vegetation and hydrology.
Points to Consider
Global warming and climate change are frequently in the news these days, with reports of glaciers melting, and possible effects on species, such as the polar bear. Keep aware of these news trends and learn what you can about what species are becoming threatened.
Our purchasing decisions may affect biodiversity: be more aware of the natural resources used to make and transport any product you buy; Buy recycled products whenever possible; when you buy fish for food, check to be sure that commercial species are not from overharvested areas.
Chapter 26: Appendix: Life Science
Investigation and Experimentation Activities
The following activities are based on information provided within this FlexBook or taken directly from the Teacher Edition.
The Scientific Method
Through this discussion, students will understand scientific tools and technology necessary to perform tests, collect data, analyze relationships, and display data, they will understand sources of unavoidable experimental error and reasons for inconsistent results, and how to formulate explanations by using logic and evidence.
The Five-legged Frog
Here is an example of a real observation made by students in Minnesota (Figure below). Imagine that you are one of the students who discovered this strange frog. As you go through this discussion, determine the tools necessary to collect and analyze the data. Also take not of potential places for expeerimental errors. Lastly, develop a fictional set of data based on the experiments proposed in this discussion, analyze the data and present the data to the class.
Figure 26.1
A frog with an extra leg.
Imagine that you are on a field trip to look at pond life. While collecting water samples, you notice a frog with five legs instead of four. As you start to look around, you discover that many of the frogs have extra limbs, extra eyes or no eyes. One frog even has limbs coming out of its mouth. You look at the water and the plants around the pond to see if there is anything else that is obviously unusual like a source of pollution.
The next step is to ask a question about these frogs. For example, you may ask why so many frogs are deformed. You may wonder if there is something in their environment causing these defects. You could ask if deformities are caused by such materials as water pollution, pesticides, or something in the soil nearby.
Yet, you do not even know if this large number of deformities is “normal” for frogs. What if many of the frogs found in ponds and lakes all over the world have similar deformities? Before you look for causes, you need to find out if the number and kind of
deformities is unusual. So besides finding out why the frogs are deformed, you should also ask:
“Is the percentage of deformed frogs in pond A (your pond) greater than the percentage of deformed frogs in other places?”
No matter what you observe, you need to find out what is already known about your topic. For example, is anyone else doing research on deformed frogs? If yes, what did they find out? Do you think that you should repeat their research to see if it can be duplicated? During your research, you might learn something that convinces you to alter your question.
Construct a Hypothesis
A hypothesis is a proposed explanation of an observation. For example, you might hypothesize that a certain pesticide is causing extra legs. If that's true, then you can predict that the water in a pond of healthy non deformed frogs will have lower levels of that pesticide. That's a prediction you can test by measuring pesticide levels in two sets of ponds, those with deformed frogs and those with nothing but healthy frogs. A hypothesis is an explanation that allows you to predict what results you will get in an experiment or survey.
The next step is to state the hypothesis formally. A hypothesis must be "testable."
Example:
After reading about what other scientists have learned about frog deformities, you predict what you will find in your research. You construct a hypothesis that will help you answer your first question.
“The percentage of deformed frogs in five ponds that are heavily polluted with a specific chemical X is higher than the percentage of deformed frogs in five ponds without chemical X.”
Test Your Hypothesis
The next step is to count the healthy and deformed frogs and measure the amount of chemical X in all the ponds. This study will test the hypothesis. The hypothesis will be either true or false.
An example of a hypothesis that is not testable would be: "The frogs are deformed because someone cast a magic spell on them." You cannot make any predictions based on the deformity being caused by magic, so there is no way to test a magic hypothesis or to measure any results of magic. There is no way to prove that it is not magic, so that hypothesis is untestable and therefore not interesting to a scientist.
Analyze Data and Draw a Conclusion
If a hypothesis and experiment are well designed, the experiment will produce measurable results that you can collect and analyze. The analysis should tell you if the hypothesis is true or false.
Example:
Your results show that pesticide levels in the two sets of ponds are statistically different, but the number of deformed frogs is almost the same when you average all the ponds together. Your results demonstrate that your hypothesis is either false or the situation is more complicated than you thought. This gives you new information that will help you decide what to do next. Even if the results supported your hypothesis, you would probably ask a new question to try to better understand what is happening to the frogs and why. When you are satisfied that you have accurate information, you share your results with others.
Hypothesis vs. Theory
From this activity, students will understand the difference between a hypothesis and a scientific theory.
Develop a Research Plan
In chapter 1, the example of a plastic vs. wood cutting board is given. Ask students to develop a research plan involving other everyday items. First, students must develop a hypothesis, then formulate a plan to test their hypothesis. They may base their research plan around different brands of medicine (such as Tylenol vs. Advil) or different brands of food (such as soda), or other items they can think of.
Develop a list of student hypotheses on the board. Hypothetically, assume all the hypotheses proved true. Have the class develop a scientific theory based on these hypotheses. Discuss with the class the difference between the theory and the individual hypotheses, as well as the limitations of the theory.
Evaluation of Fossil Evidence
In this activity, students will analyze the time intervals associated with the succession of species in an ecosystem.
Have students critique the figure below, describing and evaluating the changes that occur at each evolutionary step depicted.
Figure 26.2
Evolution of the horse. Fossil evidence, depicted by the skeletal fragments, demonstrates evolutionary milestones in this process.
Accumulation of Scientific Evidence
In this activity students will understand the cumulative nature of scientific evidence.
Evolution is a Scientific Theory
Evolution by natural selection is supported by extensive scientific evidence. Have the class view the following video.
PBS Evolution: Library: Isn’t Evolution Just a Theory? http://www.pbs.org/wgbh/evolution/library/11/2/real/e_s_1.html 6 minute RealPlayer video
Follow with a class discussion. Point out that no evidence has been found on earth that is not explained by evolution. Discuss how much evidence has been discovered, why evolution is such a widely-held scientific theory, and what future discoveries may show.
Evolution as a theory does not simply mean a guess; it has been tested and supported by massive amounts of biological evidence from the fossil record and living species. Evolution can explain all evidence from the past two centuries of searching. In the future, we may find more about new species and their genomes from the fossil record, rainforests, and oceans.
Is it the data or the theory?
Jean-Baptiste Lamarck proposed the idea that evolution occurs, but he did not suggest how it occurs. Darwin's theory of evolution by natural selection did discuss how evolution occurs. Though Darwin agreed with Lamarck that evolution occurs, he differed with Lamarck on several other points. Lamarck proposed that traits acquired during one’s lifetime could be passed to the next generation. We now this is does not occur.
Discuss with the class how some data may not agree with an accepted scientific theory because sometimes the data is mistaken or fraudulent. Other times the theory may be wrong.
Science and Society
In this activity students will investigate a science-based societal issue by researching the literature, analyzing data, and communicating the findings. Students should incorporate concepts from biology and ecology into their responses.
Habitat Destruction
Ask students if they understand that habitat destruction and biodiversity are related. How do they think these concepts might be intertwined? Begin discussion and accept all answers, writing some notes on the board.
Have students research this topic, analyzing available date and presenting their findings to the class.
Students may choose to research the consequences of:
clearing habitats of vegetation for purposes of agriculture and development
habitats destruction by natural causes (lightning, earthquakes, fires, hurricanes, ice storms)
habitats destruction by humans
within the past 100 years, the significant increase in the area of cultivated land worldwide
the destruction of habitats on the species living in the habitats.
Science and Math
The Hardy-Weinberg Equation
Using a hypothetical rabbit population of 100 rabbits (200 alleles), determine allele frequencies for color:
9 albino rabbits (represented by the alleles bb) and
91 brown rabbits (49 homozygous [BB] and 42 heterozygous [Bb]).
The gene pool contains 140 B alleles [49 + 49 + 42] (70%) and 60 b alleles [9 + 9 + 42] (30%) – which have gene frequencies of 0.7 and 0.3, respectively.
Solution
If we assume that alleles sort independently and segregate randomly as sperm and eggs form, and that mating and fertilization are also random, the probability that an offspring will receive a particular allele from the gene pool is identical to the frequency of that allele in the population:
BB: 0.7 x 0.7 = 0.49
Bb: 0.7 x 0.3 = 0.21
bB: 0.3 x 0.7 = 0.21
bb: 0.3 x 0
.3 = 0.09
If we calculate the frequency of genotypes among the offspring, they are identical to the genotype frequencies of the parents. There are 9% bb albino rabbits and 91% BB and Bb brown rabbits. Allele frequency remains constant as well. The population is stable – at a Hardy-Weinberg genetic equilibrium.
A useful equation generalizes the calculations we’ve just completed. Variables include
p = the frequency of one allele (we’ll use allele B here) and
q = the frequency of the second allele (b in this example).
We will use only two alleles (so p + q must equal 1), but similar equations can be written for more alleles.
Allele frequency equals the chance of any particular gamete receiving that allele. Therefore, when egg and sperm combine, the probability of any genotype is the product of the probabilities of the alleles in that genotype. So:
Probability of genotype BB = p X p = p2 and
Probability of genotype Bb= (p X q) + (q X p) = 2pq and
Probability of genotype bb = q X q = q2
We have included all possible genotypes, so the probabilities must add to 1.0. In our example 0.49 + 2(0.21) + 0.9 = 1. Our equation becomes:
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