Seasonal Changes Are Impacted by Climate Change

For us humans, especially in urban settings, the seasons come and go with regularity and cause relatively painless changes in our lives — longer days, shorter days, setting clocks forward or backward as we just did. But for most other animal species seasonal changes do not go unnoticed.  Further, when climate change impacts patterns of seasonal change, animals can be affected.

For example, pregnant caribou depend on particular plants to nourish them while they nurse their calves. The spring calving season is short and the window for peak plant nourishment coincides with that short season. However, these plants are emerging or germinating earlier in the season, in response to warmer temperatures, reaching their peak before calving occurs. Thus, nursing caribou are receiving less nourishment, calves are suffering, and mortality rates are increasing, as reported by ScienceDaily. Researchers believe this is just one example of the impact of climate change that will be documented repeatedly in the near future

caribouCaribou are cued to move to new grazing patches by increasing day length. The plants, however, are cued to emerge or germinate by increasing temperature. This causes a “trophic-mismatch.” If the trend continues, caribou will not survive unless they can find a substitute for their nourishment needs. This may be possible in one of two ways. One is an additional plant species, useful to caribou, becomes established in the ecosystem made possible by the longer growing season. The second way caribou could thrive is if the caribou alter their migration patterns to better align calving with plants at their peak nutrition. Doing so would be a case of the caribou population shifting its      range.

According to a second ScienceDaily article, “One of the main predicted effects of climate change is a forced shift in species’ distribution range.” This comment was made in reference to a plankton scientists have decided was able to change its range to further north in the Atlantic after the last warming trend in climate 18,000 years ago. They attribute this ability to a lot of genetic variability within the species and large populations. This, they say, is good news since it indicates the species can react and adapt appropriately in order to survive and avoid extinction. It is also a cause for optimism since plankton is the base of the food chain.

Conversely then, small, less variable populations are at risk of not adapting to and surviving climate change. What if anything can or should be done?

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The National Science Education Standards in life science states students should gain understanding in (1) structure and function in living systems, (2) regulation and behavior, and (3) diversity and adaptations of organisms. Climate change affords opportunities to touch on those areas as well as topics in Science and Society, and Earth Science concepts in climate.

Ask students what caribou are, where they live and how they behave. Or direct students to do their own research. This Natureworks site provides a succinct reference for students.  Most will probably know caribou migrate and live in Alaska, but students may not know they also live in Greenland. Many will say caribou are reindeer. Though they are related, they are different. Reindeer are domesticated and live in northern Asia actually.

Students may know caribou migrate, but they may not be fully aware of the adaptations the caribou have, enabling the thousands of miles of migration accomplished each year. Ask students what cues caribou to migrate north in the spring: increasing day length or increasing temperatures? Since temperatures vary, it is adaptive perhaps that caribou respond instead to increasing day length, which is rather constant in its annual pattern.

Now focus on the plants of the tundra. What signals plants it’s time to emerge? Warming temperatures rather than light. After all, an underground root system or a buried seed cannot sense light. To track average temperatures from 1995-2003, students can access Excel files of the data from the Arctic Long Term Ecological Site. In pairs or groups of three, students can find tundra temperature data for a specific year and then share. They can have the program calculate the average temperature each year for the month of June or the first week in June. Graph the data points. What is the pattern?

Tundra plants are low to the ground and small. Caribou have to do a lot of grazing to meet their needs. Turn student attention to the calving and nursing period. Calves nurse for about one month. Nursing caribou need lots of nutrition during that period. What if calves were born one week after plants had reached their maximum? How might this impact the herd over time? Remind students of the two different cues plant and caribou respond to: light and temperature. How might the plant diversity be impacted by a warming trend?

Share the plankton story with students. In sum, two things can happen in response to climate change: adapt or go extinct. Life on the planet survived the last warming trend; thus it may survive this one too. However, human contributions to this warming trend were not present 18,000 years ago. It remains to be seen what difference that makes.

Here are additional related resources from the Middle School Portal 2: Science and the Polar Regions and The Reason for the Seasons.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published November 5, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

Polar Bears and PCs: Technology’s Unintended Consequences

How Does an iPod Affect a Polar Bear?

Photo courtesy of Amanda Graham (Yukon White Light) via Flickr.

When we talk about the problems of global climate change, we tend to focus on cars and coal-burning power plants as major contributors. Yet there are other significant players, including consumer electronics. The number of cell phones, MP3 players, laptops, and flat-screen TVs is increasing rapidly, and not just in wealthier nations. It is estimated that one in nine people in Africa has a cell phone – and those numbers are expected to continue growing.

A recent report from the International Energy Agency (IEA) estimates that new devices such as MP3 players, cell phones, and flat-screen TVs will triple energy consumption. Two hundred new nuclear power plants would be needed just to power all the TVs, iPods, PCs, and other devices expected to be used by 2030.

For example, consider televisions. The IEA estimates that 2 billion TVs will soon be in use across the world (an average of 1.3 TVs for every household with electricity). TVs are also getting bigger and being left on for longer periods of time. IEA predicts a 5 percent annual increase in energy consumption between 1990 and 2030 from televisions alone.

While consumer electronics is the fastest growing area, it is also the area with the least amount of policies to control energy efficiency. Total greenhouse gas emissions for electronic gadgets is currently at about 500 million tons of carbon dioxide per year. If nothing is done, the IEA estimates that the figure will double to about 1 billion tons of carbon dioxide per year by 2030. However, the agency says that existing technologies could reduce this figure by 30-50 percent at little cost. Allowing consumers to regulate energy consumption based on the features they actually use, minimum-performance standards, and easy-to-read energy labels can help consumers make smarter energy choices about their personal electronics.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

This story connects to two National Science Education Standards domains: Science and Technology and Science in Personal and Social Perspectives. The Science and Technology content standard states:

Technological solutions have intended benefits and unintended consequences. Some consequences can be predicted, others cannot.

The Science in Personal and Social Perspectives content standard includes resource use and depletion, human-induced and naturally occurring hazards, and science and technology in society.

Ask students to consider electronic gadgets – cell phones, digital cameras and video cameras, MP3 players, flat-screen TVs, laptops, and so forth. Have students brainstorm the benefits of these devices. Easier communication, access to data, entertainment, and mobility will probably come up. Then ask students to brainstorm “costs” or negative characteristics. Expense will certainly be mentioned, but will the energy cost?

If you have access to an electric power monitor such as a Kill-a-Watt, you can have students plug in different gadgets and compare power consumption. This simple activity can give rise to a number of inquiry-based investigations, such as: What’s the most energy-efficient MP3 player?; Do laptops and desktops consume the same amount of power?; Does screen size (on an MP3, cell phone, laptop, or TV) affect power consumption?; and so on.

Share some of the figures from the IEA report with students. Discuss the idea that making technology (cell phones, laptops and Internet access) available to more people is a good thing, but there are intended and unintended consequences. Greater access to technology enables widespread communication and promotes education, but also requires more energy – most of which comes from fossil fuels. Burning those fossil fuels releases more greenhouse gases into the atmosphere, accelerating climate change and causing Arctic sea ice decline. So all those iPods do impact polar bears after all.

Rather than leave students discouraged, present them with a challenge. Remind them of the many benefits of technology and acknowledge that electronic gadget use will continue to grow rapidly. How can science and technology address the unintended environmental consequences of these tools? Assign small groups of students a particular piece of technology and have them brainstorm ideas that would promote energy efficiency – either on the part of the consumer or the manufacturer, or both. Have groups present their solutions to the class and discuss them. What common solutions were raised? What can students and their families do now to use their electronic devices in a responsible manner?

Here are some related resources from the Middle School Portal 2: Energy Sources, The Power of Electricity,  What is Happening to Polar Bears? Real Data, Claims, and Evidence. The October 2008 issue of the free online magazine Beyond Penguins and Polar Bears included articles about natural resources, the NEED project, and energy efficiency activities for home and school.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Jessica Fries-Gaither and published June 1, 2009 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

Why Did the Anasazi Abandon Mesa Verde

Many middle school curricula include attention to ancient American people and their cultures. This blog entry may be helpful in making connections to the nature of science and scientific enterprises as part of an integrated approach in studying the Anasazi or ancient Pueblos. The story titled “Vanished: A Pueblo Mystery,” published in the New York Times, April 8, 2008, enlightens readers regarding the science of archaeology.

Archaeologists rely on empirical evidence to reconstruct past events. However, this empirical evidence does not normally emanate from controlled laboratory experiments, conceived of and performed at the scientists’ will. Rather, archaeologists use evidence left by the activities of not only people that lived long ago but other organisms as well. They must be skilled observers.

The graphic accompanying the article shows where the Anasazi migrated from–what is now southwestern Colorado–and where they migrated to–what is now the Davis Ranch and Tucson, Arizona, area. There is also a slide show of images of dwellings among other relevant artifacts. For archaeologists interested in this part of the world and these people, the article states, “the most vexing and persistent question in Southwestern archaeology [is]: Why, in the late 13th century, did thousands of Anasazi abandon Kayenta, Mesa Verde and the other magnificent settlements of the Colorado Plateau and move south into Arizona and New Mexico?”

This is not the first time this question has been asked or that an answer has been proposed based on evidence. For example, drought has been documented during this time, providing a seemingly good explanation for the migration. However, evidence suggests many people were able to survive the drought. That fact casts doubt on drought as the only cause for the migration. Further, the area the Anasazi migrated to was actually drier than that which they migrated from.

An alternate hypothesis is based on the pollen record. “Measurements of the thickness of pollen layers, accumulating over decades on the bottom of lakes and bogs, suggest that growing seasons were becoming shorter.” Even this fact in combination with the relatively short drought does not convince many archaeologists these were the reasons for the migration. Why did the Anasazi never return, even when the drought ended? Evidence suggests they did not leave in a hurry, but planned their exit as if they intended to return.

Even more interesting hypotheses are presented regarding the role of religion in the migration. Donna Glowacki, an archaeologist at the University of Notre Dame, cites evidence that suggests the early culture of the group, prior to the migration, included a tradition where only a select, privileged few had access to the largest, most well-equipped dwellings. She asserts a change can be detected after the migration in the southern villages. There evidence indicates fewer of these select kivas are found, suggesting there was less reverence for a select few. The article indicates this change could be analogous to the Protestant reformation.

So who’s right? Well, no one knows for sure, but the Village Ecodynamics Project is set to bring together these various hypotheses to see if a coherent, though probably somewhat complex explanation, or theory, can be constructed. The researchers will use evidence of “rainfall, temperature, soil productivity, human metabolic needs and diet, gleaned from an analysis of trash heaps and human waste” to reconstruct events and come to conclusions.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

The article illustrates well the nature of science. Our understanding of the Anasazi migration is undergoing revision in light of new evidence and reinterpretation of existing evidence from new perspectives. It calls attention to the various scientists working on the same project, each contributing unique expertise and building new knowledge. The article conveys several possible hypotheses, all of which need to be thoroughly investigated to see if any can be discarded. It underscores that scientists don’t have definitive, pat answers, only best guesses based on reasonable interpretations of much evidence. Several kinds of, or sources of, evidence are identified giving readers an indication of the nature of archaeology in particular.

Ask students to describe archaeology. Affirm their responses and ask them to elaborate as much as they can. They should use terms like ancient, culture, science, observation, inference and reconstruct. Ask students what kind of knowledge or skills a good archaeologist needs. They should include knowledge of anatomy, plants, and history, and excellent observational skills. Archaeologists need to be global thinkers, able to see relationships among seemingly disparate observations. They should be good team players. If needed, ask leading questions such as: What other fields of science might be related to archaeology? They should include botany, zoology, and anthropology even if they don’t use those names for them.

Explicit connections to life science and earth science can be made, particularly to botany and climate. Ask students how knowledge of the growing season can be inferred from the pollen record. How can inferences regarding wet or dry years be obtained from tree rings?

Here are some additional resources related to the nature of science and fields of science: Science Sampler: Jumping to the Right Conclusions, Inferences, and Predictions;  Presenting a Logical and Reasonable Case Using Logical and Reasonable Arguments; Frequently Asked Questions: Questions about Paleontology.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published April 11, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

Mechanism for Antibiotic Resistance Discovered

Those of us born after World War II have take antibiotics for granted. Strep throat? Ear infection? Acne? Bronchitis? Not a problem. Take the full prescribed antibiotic dose and you are cured. The reality of antibiotic resistant bacteria however, disrupts that scenario. No longer can we always trust in a full recovery from a bacterial infection after completing the antibiotic regimen. Rather than continuing to create new and different antibiotics, the trend in research is to discover the mechanisms of antibiotic resistance in order to neutralize it.

How Some Bacteria Survive Antibiotics from ScienceDaily describes how researchers at the University of Illinois, Chicago, studied bacterial action in the presence of erythromycin and related antibiotics. These drugs incapacitate the bacterial protein factories, ribosomes. All cells have ribosomes which are the site of translation in protein synthesis. Erythromycin prevents newly synthesized proteins from detaching from the two subunits of the ribosome, thus preventing the bacteria from thriving. The researchers discovered, however, that these drugs can signal the bacteria to switch a bacterial gene on that enables bacterial release of newly synthesized proteins from the ribosomes. Thus, they effectively resist the drug in a process known as inducible antibiotic expression.

The article quotes one of the researchers

Combining biochemical data with the knowledge of the structure of the ribosome tunnel, we were able to identify some of the key molecular players involved in the induction mechanism. . . .We only researched response to erythromycin-like drugs because the majority of the genetics were already known. There may be other antibiotics and resistance genes in pathogenic bacteria regulated by this same mechanism. This is just the beginning.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

A manifestation of evolution, antibiotic resistance aligns with the Life Science standard of The National Science Education Standards, “Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.” Also related is the structure and function section of the standard: prokaryotic cell structure, the ribosome, and protein synthesis.

Ask students if they have ever had an ear infection or strep throat. What did they do about it? Lead them to disclose that they went to the doctor, were prescribed an antibiotic and took it for the full course, often 10 days. Ask if they were cured then, or did anyone suffer a recurrence within the next week or so? If yes, why? Then what did they do? Lead them to articulate the concept of bacterial resistance. Consider showing visuals of a typical animal eukaryotic cell side by side with a bacterial cell. This will highlight the size and structural difference, and enable student comprehension of how bacterial cells can colonize a eukaryotic cell. Make sure they understand the activity of the millions of bacteria cells a) consumes nutrients needed by one’s own healthy cells and b) produces waste that makes one sick.

If you’ve already discussed the characteristics of living things, cell theory and cell structure, lead students to recall the importance of ribosomes to all living cells. Ask, what might happen if the function of the ribosomes were disrupted? Students should reason that protein production would stop and the cell would die for lack of needed proteins. Inform them that this is the way some antibiotics work; they interfere with the bacterial cells’ ribosome function. (Prokaryotic and eukaryotic ribosome structure varies slightly allowing the eukaryotic ribosomes to remain unaffected.) Ask, what if the presence of the antibiotic signaled the bacteria to produce a protein (turn a gene on) that interfered with the drug’s ability to disrupt the ribosome’s work? Allow plenty of wait time for them to think this through logically. They should arrive at the idea of antibiotic resistance, even if they don’t use that phrase.

Allow students to read the first three paragraphs above and follow the links. The protein synthesis link however, is probably too advanced for middle school students and can be eliminated. Have them read the article How Some Bacteria Survive Antibiotics. Assess: what is an antibiotic? How do drugs like erythromycin work? What is inducible antibiotic expression? How might it be helpful to know the mechanisms by which bacteria resist antibiotics? Describe how antibiotic resistance is an example of evolution.

Here are some additional resources from the Middle School Portal 2 related to antibiotic resistance and bacteria: Introduction to Bacteria; Microbes: Too Smart for Antibiotics?; Microbes: What They do and how Antibiotics Change Them; and What’s making you sick?

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published May 9, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.

How Is Species Defined and Why Does It Matter? The Politics of Conservation

This post focuses on the definition of species and its implications beyond science content knowledge—specifically, how the definition is related to species conservation and protection.

For example, the brown bear of the Iberian Peninsula is a different species compared with other European brown bears because it is geographically isolated, right? According to a press release, New Study Changes Conditions for Spanish Brown Bears, published by AAAS’s EurekAlert! there are just two small populations of this bear and they are threatened. One idea to help bolster their population size is to introduce brown bears from other European populations. However, this may cause hybridization and eventual loss of the Iberian Peninsula brown bear species. Further, what makes conservation biologists think the two different bears will interbreed successfully?

According to the Life Science content standard of the National Science Education Standards, middle school students should be learning concepts associated with structure and function in living systems; reproduction and heredity; regulation and behavior; populations and ecosystems; diversity and adaptations of organisms. All of these areas of study are related to the concept of species. That is, discussions in any of these areas will necessarily be founded on an understanding of the term “species.”

Can we take for granted that middle school students have developed an accurate concept of species on their own, through personal experience? Because they can distinguish cat from dog, a rose from a maple tree, and a human from an ant, is it safe to assume they have a good grasp of the concept? Not if we wish to facilitate and broaden students’ conceptual understandings to progressively more sophisticated levels.

Students understand that cats and dogs, roses and maple trees, and humans and ants do not interbreed. Thus, they have an understanding of the biological definition of species. But things can get complicated and this definition does not always fit. Another perspective assumes reproductive isolation defines species. That is, if two populations are physically or temporally isolated preventing interbreeding, then they are considered separate species. That works well conceptually for most middle school students’ experience, but what about when individuals from one geographically isolated population are introduced to another, either intentionally or unintentionally, and they successfully interbreed?

When discussions around Mendelian genetics occur, the concept of hybrid is introduced. Plants do this all the time. Is the hybrid a new species? They often can and do interbreed. Are the offspring a new species? Most would hesitate to say yes. Then do we revise our definition of species? Those reproductively isolated populations really are the same species after all?

Contrary to what most people believe, the concept of species seems to be a moving target in terms of pinning a definition on it. As such, it is open to criticism from people who believe science is supposed to be definitive. This presents an opportunity for teachers to reinforce the nature of science, and life science particularly. Living systems, from a single cell to a biome, are dynamic and not entirely definitively understood. (If they were, conservation would probably not be an issue!)

Assuming a fixed definition of species may be unreasonable. One’s definition of species is contextual, dependent upon the current issue under consideration. It is important that discussants have a common definition of species in these instances. Why? Because the focus of and outcomes of species-related discussions can determine political policy, such as what gets listed as a threatened or endangered species and receives federal funding for protection from habitat destruction or hunting.

DNA sequencing allows for almost unequivocal determination of whether individuals from two different populations are the same species, and consequently subject to the same political treatment. In the case of the Spanish brown bears, DNA sequencing suggests they are not a distinct species from other European brown bears. That means introducing bears from other populations will not supplant the Iberian Peninsula brown bears. The proposed conservation strategy is a viable one. Scientists are confident that the introduced bears will successfully interbreed with the Spanish brown bears due to the genetic similarity. This constitutes a prediction, and its accuracy will be determined only after bears are introduced into the area.

How to Turn This News Event into an Inquiry-Based, Standards-Related Science Lesson

Consider the American Bald Eagle. It is cited as a success story of the Endangered Species Act (ESA). It has recovered from its endangered status and was delisted in 2007. This means the bird is no longer protected under federal law in terms of some kinds of hunting and habitat protection. States are free to make their own regulations regarding hunting and protection of the species.

More recently, the Northern Rocky Mountain population of gray wolf was delisted. The Western Great Lakes grey wolf population was also delisted. States that are host to these two populations have the power to regulate hunting and management of the animals. However, any wolves on National Park Service land or outside the two areas mentioned above, are under federal government protection.

How is species defined? Ask students if dogs and wolves are separate species. How do they know? Accept all reasonable responses. Are lions and tigers? Are saber toothed cats and Bengal tigers? Lead students to define species in terms of (a) macroscopic anatomy, (b) geographic isolation (lions and tigers), and (c) temporal isolation (extinct and extant cats). This discussion should highlight the difficulty in pinpointing a definition. None is incorrect, yet none is fully sufficient. This is acceptable in classroom discussions, but when conservation groups discuss species, they have to be specific. For example, in delisting the Rocky Mountain gray wolf, the documents specify the geographic region that defines the population. Individual animals falling outside the defined geographic range are not delisted and remain protected by the ESA.

Can students imagine that features other than those immediately visible could be considered in determining who is different and who is the same species? For example, in Batesian mimicry two species are physically similar, but one is poisonous to predators while the other is not. Lead students to understand that there are microscopic or chemical means of determining similarity and differences. Conversely, two populations can appear to be quite different but are chemically quite similar. (This may explain the original assumption that the Spanish brown bear was a separate species from other European brown bears.) The morphological difference is attributed to environmental influences, not genetic differences, and so it is predicted the two populations could interbreed successfully. That’s often good news for conservation management.

What do students think the Endangered Species Act is? Why is it needed? Allow them to brainstorm. Then show them pages from http://www.fws.gov/endangered/about/index.html to either confirm their list or amend it. Can they name any organisms on the list now? Call attention to species other than mammals, including plants. How do students suppose an organism gets listed/delisted? Have students investigate this question at http://www.fws.gov/endangered/species/us-species.html. Facilitate student discovery that the process is not neat and easy necessarily. Rather it can be emotional and partisan. Why?

Here are some additional resources from the Middle School Portal 2 related to conservation and wildlife management: Natural Resources, the Environment, and Ecosystems; and DDT Quest.

We Want Your Feedback

We want and need your ideas, suggestions, and observations. What would you like to know more about? What questions have your students asked? We invite you to share with us and other readers by posting your comments. Please check back often for our newest posts or download the RSS feed for this blog. Let us know what you think and tell us how we can serve you better. We appreciate your feedback on all of our Middle School Portal 2 publications. You can also email us at msp@msteacher.org.

This post was originally written by Mary LeFever and published March 26, 2008 in the Connecting News to the National Science Education Standards blog. The post was updated 4/23/12 by Jessica Fries-Gaither.