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 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 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

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.

Project Earth – Making the World a Smaller Place

Project Earth is a global networking website for K–12 educators and the public designed to connect people around the world to help solve environmental problems. Its mission is to generate ongoing conversation and collaboration across national boundaries that collectively lead to positive environmental change. Registration is required and member teachers/schools/classrooms are able to showcase their innovative environmental projects, connect and interact with ecologically-minded people around the world (from Minnesota, to Los Lagos, Chile, to Ulaanbaatar, Mongolia!).  Teachers and students also have the opportunity to participate in environmental contests and earn recognition for efforts.

Last year, Project Earth’s World Environment Day Contest drew winners involved with environmentally conscious projects such as studying how plastic bags affect our environment, and growing food for a school kitchen and composting the waste. Submissions to the 2011 contest are due May 15th. A great project idea for your classroom!

A few  other resources to tap into on this topic include the MSP2 resource guides on Technology and the Environment, Populations and Ecosystems, and Oceans, Climates and Weather.

World Water Day – March 22

International World Water Day is held annually on March 22nd as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. There are lots of ways to make a difference for people who don’t have access to life’s most basic needs – safe drinking water and latrines. To get started, visit Water 1st’s Youth Involvement website and request a DVD to see and hear about water issues in the developing world. Next, you can “adopt a community” in need of clean water infrastructure. Finally, look on the website to learn about what other schools are doing to tackle this issue and come up with your school’s own strategy for making a difference.

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 Post updated 4/18/2012.

Polar Bears and Climate Change

Did you know that polar bears are at high risk of population decline and future extinction in our warming world? Dr. Steven Amstrup, a Research Wildlife Biologist with the United States Geological Survey, discussed the status of the iconic marine mammal in the lecture, “Polar Bear: Climate Change Sentinel.” The lecture was part of the Columbus Zoo and Aquarium’s Conservation Lecture Series. Dr. Amstrup works at the Alaska Science Center in Anchorage and has conducted research on polar bears for the past 28 years. He was part of the research group that prepared reports used in the listing of the polar bear as a threatened species.

Polar bears are the apex predator of the Arctic. They are closely tied to the sea ice, depending on it for mate selection, breeding, caring for young, and most importantly, hunting ringed and bearded seals. Pregnant females come on land in the fall and den for the entire winter to give birth and care for their cubs. The other bears continue to hunt on the sea-ice year round.

Studies have shown that polar bears prefer medium to thick sea ice over the shallower waters of the continental shelf. However, as Arctic sea ice has retreated in past years, bears are forced to travel out further (and over much deeper and less productive water) to hunt from the ice edge. In the West Hudson Bay area, females are coming ashore up to three weeks earlier and thus losing valuable time to feed before denning. In both cases this leads to decreased weight and a decreased survival rate of cubs and older individuals. Years of sea ice decline correlate with population decline in the Hudson Bay and Beaufort Sea areas, trends which are most likely consistent with other polar bear populations around the world.

Based on this data, researchers projected that as a result of global warming and sea ice decline, polar bear populations have a very high risk of extinction within the next century. One particular population in the Canadian archipelago may be able to survive through the end of the century, as the ice there is still thick and covering shallow water. Ice thinning in that area may open up increased hunting opportunities and support a larger population. However, if warming trends persist, this population will also eventually be at risk.

When asked how individuals could help polar bears, Amstrup spoke of immediate changes to reduce our carbon footprint. While large scale action by governments and corporations is certainly necessary, it is worthwhile to remember that changing our individual habits (and encouraging others to do the same) can make a difference.

A study of polar bears and their response to climate change aligns with the Life Science and the Science in Personal and Social Perspectives content standards of the National Science Education Standards.

The entire National Science Education Standards document can be read online or downloaded for free from the National Academies Press web site. Find science content standards in Chapter 6.


Polar Bears International
PBI is nonprofit organization dedicated to the worldwide conservation of the polar bear. Find background information and information about the bear’s listing as a threatened species.

 The Polar Bear Tracker
Follow the movements of polar bears throughout the Arctic. Use the real-time data to explore how global warming is affecting the bears.

Tracking Polar Bears
In this interactive activity adapted from the USGS Alaska Science Center, investigate the migration patterns of polar bears.

Polar Bears Change Diet
This radio broadcast from 2001 explains how polar bears have adjusted their diet due to the climate warming around Hudson Bay, Canada. The ringed seals that polar bears normally eat have been harder for polar bears to get to, due to disappearing ice. This has forced polar bears to begin eating harbor seals and bearded seals. The clip is 4 minutes and 15 seconds in length.

Polar Bears and Climate Change
This video from the World Wildlife Fund addresses the primary threat to polar bears in the Arctic today: global warming. Scientists monitor the effects of climate change on the large predator’s activities and range, study the bears’ physical condition, and explore why the melting of glaciers and reduction of sea ice in the Arctic region may ultimately have dire consequences for the polar bears.

Bearly Any Ice
This game is similar to tag that simulates the prey and predator relationship between polar bears and ringed seals. It demonstrates the drastic impact of global warming by linking the amount of sea ice and length of season of sea ice to the survival of the polar bear.

Science and the Polar Regions
Background information, lessons, resources, and standards alignment for a study of the polar regions.

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 Post
updated 12/07/2011.

Energy Sources

Running on empty? Not yet, but national energy decisions may be a bigger issue in our students’ lifetimes. A number of groups have created appealing web sites to teach young people about sources of energy as well as the environmental and economic pros and cons of relying on them.

Explore More: The Future of EnergyNSDL Annotation
The energy segment from Iowa Public Television’s multimedia Explore More project is a comprehensive examination of the topic, giving profiles of eight energy sources, experts’ viewpoints, many teaching tools, and opportunities for students to express their opinions.

Energy in-Depth: TimelineNSDL Annotation
From the Explore More web site, this timeline highlights important events in the formation, discovery, and uses of each energy source—from 4,300,000 B.C.E. to the 21st century.

Energy StoryNSDL Annotation
A feature of the California Energy Commission’s Energy Quest, this site offers 20 chapters of information about energy sources, from fossils to wind currents. The site also provides science projects, games, and links to dozens of online resources.

What Is Energy?NSDL Annotation
The Kid’s Page from the federal Energy Information Administration web site offers information on renewable and nonrenewable energy, puzzles (including sudoku), science fair projects, and more for teachers and students.

We Need Your Help

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. You can also request email notification when new content is posted (see right navigation bar).

Let us know what you think and tell us how we can serve you better. We want your feedback on all of the NSDL Middle School PortalNSDL Annotation publications. Email us at