Unit 5: The Sixth Extinction
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This page first made public: Apr 20, 2017
In this unit, students will prepare by reading a couple of articles describing the causes and rates of mass extinctions, including the current "Sixth Extinction," and why conservation is important to society. After an introduction to species conservation approaches, students will participate in an exercise in which they 1) evaluate various criteria for setting biodiversity conservation priorities, 2) apply criteria to potential conservation projects in order to make a recommendation to the board of directors of a large, international conservation organization, and 3) as homework, write a letter to potential donors of the organization about the current loss of biological diversity, ecosystem health, and societal impacts.
- Students will be able to explain the impacts of humans on biological diversity.
- Students will be able to compare and contrast the causes and rates of the sixth extinction with previous mass extinctions as documented by the fossil record.
- Students will evaluate criteria for setting species conservation priorities.
- (Optional): Students will be able to distinguish between ex-situ and in-situ species conservation approaches.
Overarching Module Goals
This unit directly supports multiple InTeGrate guiding principles and addresses grand challenges by having students explore one of the grand challenges facing society: loss of biological diversity and ecosystem functioning. They are also exposed to some of the Big Ideas of Earth Literacy. For example, students engage in the methods of geoscience by evaluating the current extinction crisis in the context of the geologic record (Big Idea #1.5). Students will also use interdisciplinary concepts from biology, geography, and geology to consider the causes (human activities) and potential solutions to biodiversity loss (Big Idea #9). The unit will also show that the biodiversity crisis is a complex problem that cannot be solved with a single, simple solution.
Context for Use
This unit is designed as the culminating activity of the Changing Biosphere Module, but could be used on its own. The unit could be incorporated into any introductory geology, geography, biology, or integrated-science class. It can be used for a variety of class sizes and should take approximately 50 minutes for the introduction, group work, and discussion. Students will be expected to do online reading prior to class. A follow-up homework report may be assigned if desired.
Description and Teaching Materials
Before class, students should:
Review The Biodiversity Crisis – Are Humans Causing a Sixth Mass Extinction? by Holmgren (2017) and the associated Study Guide from Unit 1. The study guide can also be downloaded: Study Guide (Word) (Microsoft Word 2007 (.docx) 20kB Jan16 17) Study Guide (PDF) (Acrobat (PDF) 52kB Jan16 17)
Read the "Why Conserve Biodiversity" section in Conservation of Biodiversity from The Nature Education Knowledge Project (students will need to scroll down to this section of the reading, which is about halfway down the page).
If Unit 1 of the Changing Biosphere module was completed, students will have read the first article previously and should review it here. If this unit is being used on its own, students will be reading the article for the first time. In more advanced courses where an examination of the methods used to calculate numbers of species and extinction rates is desired, the Barnosky et al., 2011, Ceballos et al., 2015, and/or Pimm et al., 2014 reference articles could also be assigned.
If you want to assess their reading comprehension, or want them to self-assess it, you can give students access to a reading quiz, either as a printout or through a course management system like Blackboard or Moodle:
- Student version: Unit 5 - Reading Quiz (Word) (Microsoft Word 2007 (.docx) 18kB Jan16 17) Unit 5 - Reading Quiz (PDF) (Acrobat (PDF) 55kB Jan16 17)
- Instructor version:
Introduction: Conservation Approaches and Priorities (15 min)
Introduce biodiversity conservation, ex-situ and in-situ conservation approaches (optional — see Tips for Teaching below. If not using, omit slides 5–8), and potential criteria for setting conservation priorities using the PowerPoint file:
- Intro to Biodiversity Conservation (PPT) (PowerPoint 2007 (.pptx) 1.2MB Jan16 17)
- Intro to Biodiversity Conservation (PDF) (Acrobat (PDF) 1.3MB Jan16 17)
The question "Why should we conserved biodiversity?" on Slide 4 is best used as a think-pair-share opportunity. Give students a minute or two to answer the questions on their own, then another minute to discuss their answers with a partner, then ask students to share answers with the class. Give students a chance to provide multiple answers before covering the topic/answers. In longer class periods, instructors may choose to spend additional time discussing reasons for conserving biodiversity, including more complex issues such as competing values or the cost of replacing ecosystem services with technology.
Evaluating Criteria for Conservation Priorities (10 min)
PowerPoint slides 13 & 14 in the PowerPoint file above serve as a prompt for this activity.
Use a think-pair-share strategy to have students evaluate criteria for deciding on conservation priorities. Ask students to think alone for a minute or two to come up with their top five criteria from the list on the slide that they think should be the most important for deciding which species or habitats to protect. Next, ask students to form a group of 3–4 and share ideas. Have them choose their top three priorities as a group and write a short justification for each. Finally, have each group share one or two (depending on class size/number of groups) of their top priorities and justification with the class.
Applying Criteria for Conservation Priorities (20 min)
PowerPoint slide 15 serves as a prompt for this activity. The activity includes ~15 minutes for students to work in groups, plus 5 minutes for reporting recommendations to the class.
Distribute the following handout:
- Conservation World Student Handout (Word) (Microsoft Word 2007 (.docx) 607kB Jan18 17)
- Conservation World Student Handout (PDF) (Acrobat (PDF) 395kB Jan18 17)
Instruct students to work in their groups (3–4 people) for 15 minutes to evaluate and rank the potential conservation projects described in the handout. The first page provides discussion prompts. Encourage students to use the space provide to take notes, make marks if a criteria is met, etc. This will help them with their choice, justification, and homework letter. Next, they should provide their ranking and a short justification for their top choice in the space provided on the second page of the handout. Finally, have the groups share their recommendation and justification with the class.
Answers will vary, but justifications will likely include the following criteria.
- Sebangau = existence of an iconic/flagship species, existence of endemic species, ecosystem goods and services provided, high levels of biodiversity, conservation status/extinction risk, reasonable likelihood of success, cost, etc.
- Guadalupe Island = existence of an iconic/flagship species, existence of endemic species, existence of ecologically important keystone predator, economic & recreational value, reasonable likelihood of success, cost, etc.
- Lake Titicaca = existence of endemic species, ecosystem goods and services provided, high levels of biodiversity, cultural value/indigenous population use, expected increase in threat in future, cost, etc.
- Scimitar-horned oryx = it is an iconic/flagship species, it is a large, land-demanding species, conservation status/extinction risk (extinct in wild), reasonable likelihood of success, cost, etc.
Note: these in-class activities in which students informally present and discuss answers are designed to provide formative assessment, so no points are assigned. Individual instructors may choose, however, to have groups turn in the ranking and justification page of the handout and/or assign grades for group participation.
Wrap up and Assign Homework (5 min)
Wrap up by asking the class to vote on a conservation target based on the recommendations. This is a good time to reiterate that there is no single, simple answer for conserving biological diversity or setting priorities for doing so. It will instead require a variety of criteria and approaches, and there will always be trade-offs. As a reflective prompt, ask students if any of their criteria changed while evaluating the potential conservation projects.
Hand out the homework write-up and accompanying rubric:
- Letter to Donors Homework (Word) (Microsoft Word 2007 (.docx) 18kB Jan16 17) Letter to Donors Homework (PDF) (Acrobat (PDF) 52kB Jan16 17)
- Homework Rubric (Word) (Microsoft Word 2007 (.docx) 16kB Jan16 17) Homework Rubric (PDF) (Acrobat (PDF) 59kB Jan16 17)
The homework asks students to write a letter to potential donors summarizing the sixth extinction and possible solutions. This is to be completed as an individual homework assignment. This should be graded using the rubric, which should be given to students along with the homework assignment.
Teaching Notes and Tips
You will need to have PowerPoint capability.
Learning Goal #4 is optional and can be incorporated into longer (60-minute or more) classes. For 50-minute classes, you will want to omit this goal and PowerPoint slides 5-8.
Modification for larger classes:
For larger classes, there will not be time for all groups to share their top criteria/justification in the Evaluating Criteria activity or their recommendation/justification in the Applying Criteria activity. Instead, a sampling of 3–5 groups can be selected to report out to the class for the Evaluating Criteria activity. For the Applying Criteria activity, 3–5 groups can again be selected to share their answers with the class. Try to select different groups to share answers for each activity to increase engagement. Another alternative for the Evaluating Criteria activity is for the instructor to ask all groups that selected the first project to raise their hands and then ask a few of those groups to explain their choice, then doing the same with the second project, etc.
Assessment on Student Reading:
Use Unit 5 - Reading Quiz (Word) (Microsoft Word 2007 (.docx) 18kB Jan16 17) Unit 5 - Reading Quiz (PDF) (Acrobat (PDF) 55kB Jan16 17). If you want to give this quiz to persuade the students to do the reading carefully before this class, administer it online through your course management system or have them do it as homework. It could also be given as a student self-assessment. Specific questions from the quiz related to the learning outcomes are:
Learning Outcome #1: Students will be able to explain the direct and indirect impacts of humans on biological diversity.
1) Approximately how many species have been driven to extinction in the last 500 years?
6) What is the greatest human-driven threat to biodiversity right now?
Learning Outcome #2: Students will compare and contrast the causes and rates of the sixth extinction with previous mass extinctions from the fossil record.
1) Approximately how many species have been driven to extinction in the last 500 years?
3) What percentage of Earth's species died out during each of the five most severe mass extinctions in the fossil record?4) According to the study cited in the article you just read, how much greater is the current extinction rate than the average background extinction rate of the last 542 million years?
5) Unlike the five big mass extinctions in the geological record, the current wave of extinctions is caused by _________________?
Letter to Potential Donors Assessment:
Learning Outcomes #1, 2, 3. Letters should be graded using the Homework Rubric (Word) (Microsoft Word 2007 (.docx) 16kB Jan16 17) Homework Rubric (PDF) (Acrobat (PDF) 59kB Jan16 17) that was given to students. Instructors can modify this rubric to assign point values in a manner that is consistent with their course grading scheme.
Possible exam questions:
Learning Outcome #3. List 5 different criteria used for setting conservation priorities. Circle the one you think is most important and explain why you think it is the most important criteria.
Learning Outcome #4. Explain the difference between ex-situ and in-situ conservation and give an example of each.
The reading quiz questions above could also be used as exam questions.
References and Resources
References for Instructors on Biodiversity Loss and Conservation:
- Brooks, T.M., Mittermeier, R.A., da Fonseca, G.A.B., Gerlach, J., Hoffmann, M., Lamoreux, J.F., Mittermeier, C.G., Pilgrim, J.D., Rodrigues, A.S.L. 2006. "Global biodiversity conservation priorities." Science 313, 58-61.
- Maxted, N. 2001. Ex-situ, in-situ conservation. Encyclopedia of Biodiversity, Volume 2. Academic Press.
- Wanjui, J. 2013. "Biodiversity conservation needs and method to conserve the biological diversity." Journal of Biodiversity & Endangered Species 1, 113.
Additional Resources for Instructors and Students: