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Ch. 7: Regenesis of the Passenger Pigeon Teacher Sheet

Ch. 7: Regenesis of the Passenger Pigeon Teacher Sheet

Introduction

The "Regenesis of the Passenger Pigeon" chapter shares the history of the passenger pigeon and its human-caused extinction. This chapter introduces the efforts to extract DNA from passenger pigeon samples and one day resurrect these birds. This teacher sheet provides background information and answers to the questions on the student sheet.


There are many key terms introduced in this chapter that students may not be familiar with. If there are any terms missing on this sheet that you think the students should know, please add them. Use the resources provided to familiarize yourself with this chapter and the concepts presented. The takeaway points of this chapter include:

  • The passenger pigeons are an example of human-driven extinction. These pigeons were considered keystone species. When they became extinct, their food source, acorns, increased in production and it has been proposed that other acorn consumers, such as mice and deer populations, increased leading to an increase in the tick population and Lyme disease.
  • This chapter delves more into the science of de-extinction and introduces a lot of the prominent groups involved and the future goals. 
  • The technology of CRISPR-Cas9 is introduced here. It is up to you on how much detail you would like the students to understand about this. But a basic understanding is all that’s needed. The use of this technology would allow scientists to take DNA from another pigeon and change any genes on it to reflect that of the passenger pigeon’s DNA. This is a genomic editing tool that uses a protein found in bacteria that can cut specific pieces of DNA out of a genome. Scientists are extracting DNA from frozen tissue samples and sequencing it, meaning they are determining the genetic code of that organism. Then they can take a closely related species and line up the sequenced DNA with that species' DNA to see where the differences lie. In the case of the passenger pigeon, they would take the closest relative, the band-tailed pigeon, and manipulate its DNA to reflect that of the passenger pigeons. 
  • Once a living passenger pigeon is created, Novak goes on to explain how this bird would now have to be taught how to be a passenger pigeon. The take-home message to the students here is that it is going to take more than just making a baby passenger pigeon to truly bring back the species. In the case of de-extinction, there needs to be a surrogate that can give birth to the resurrected species. Another hurdle will also be the habitat, especially when it may no longer exist, and if re-introducing a species back into a habitat would affect the dynamics already there in that ecosystem in a negative way. This goes back to the big questions presented in Ch. 6, "Would an animal born in the laboratory be the same as the animal born from a living one? If the passenger pigeon were resurrected but learned how to be a passenger pigeon from a decoy bird and had to settle into an ecosystem that is different from the one their ancestors lived in, would it still be the same bird?"

Key Terms

  • De-extinction – bringing extinct organisms back to life
  • Genetic rescue – term has expanded to include genomic editing and genomic engineering to bring back an extinct species in addition to translocating populations to offset inbreeding and increase genetic diversity
  • Keystone species – does not have to be the most abundant in an ecosystem but plays a pivotal role in that if they are removed, the ecosystem can collapse. Usually the keystone species keeps a food source in check, such as a sea star keeping the mussel population in low numbers in the intertidal zone to allow room for other species
  • CRISPR-Cas9 – a genomic editing tool that uses a protein found in bacteria that can cut specific pieces of DNA out of a genome

Questions

1. In your own words, explain the dilemma in this chapter.
Answers may vary. Encourage your students to explain their answers.

2. What was one of the most interesting things you discovered?
Answers may vary. Encourage your students to explain their answers.

3. What was confusing?
Answers may vary. Encourage your students to explain their answers.

4. What made the passenger pigeon a keystone species?
The passenger pigeon maintained some forest ecosystems by eating and dispersing seeds. 

5. Briefly describe how the passenger pigeon became extinct.
They were game birds for hunters and were hunted to extinction.

6. Suppose a passenger pigeon chick has hatched, what is the plan to raise it and teach it how to be a passenger pigeon? Why is this step important?
The plan is to paint other birds to look like passenger pigeons and help them establish a migration pattern so the young ones can follow and learn. Even though it is possible to resurrect an extinct species to have the same DNA, some behaviors would need to be taught.

7. In your own words, do you think that resurrecting extinct animals will benefit the conservation effort?
Answers may vary. Encourage students to explain their answers.

8. Does your opinion change knowing that the animal in question became extinct due to humans killing them off? Explain.
Answers may vary. Encourage students to explain their answers.

9. Research any additional information out there on this current de-extinction project. Will these passenger pigeons be brought back to life anytime soon?
Ben Novak is the scientist working on this project. They are still investigating the individual steps to get to the point of resurrection.

This teacher sheet is a part of the Resurrection Science lesson.

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