Possible Solutions
Just as there are many reasons why the sixth mass extinction is upon us, there are a variety of ways to potentially prevent another mass extinction. Rachel Carson, an environmentalist and author, who began the conservation movement with her 1962 book Silent Spring said, “One way to open your eyes is to ask yourself, “What if I had never seen this before? What if I knew I would never see it again?”26 I want my students to not only understand methods to help endangered species, but also to think critically about the pros and cons of each method.
Through my reading and research, it is clear that people believe biodiversity is a good thing. During the seminar that led to this curriculum unit, Yale University professor, Paul Turner posed the question, “Why is biodiversity good?” Is it because people want to see a variety of species? Is it beneficial to have more species? Will one produce a lifesaving medicine? Do people just enjoy a greater variety of bird calls when walking through the park?
Biodiversity seems to be a common way to examine the health of an ecosystem. The stability of an ecosystem depends on biodiversity. In an ecosystem, each species has a special role or a niche that it fills. Let’s say organism A is a food source for organism B. If organism A is reduced or disappears, then organism B will have to find another food source. As a result, organism B may become less healthy since it is not adhering to its regular diet, in addition to possible competition with other organisms for the same food source. As a result, neither organism may have enough to eat. These species may become weaker or even die. The ripple effect continues through the ecosystem. Thus, this process can reduce the health of the ecosystem and potentially decrease the biodiversity within the ecosystem.
Controlling invasive species
Research seems to indicate that preventing the introduction or establishment of non-native species is the best way to limit their impact on an ecosystem.27 Quarantining is one strategy used to prevent the establishment of an invasive species. An example is the story of the citrus long-horned beetle in Washington. The beetle was discovered in a nursery in 2001, and the owner brought a specimen to the U.S. Department of Agriculture Plant Inspection Station at Sea Tac Airport, where the beetle was identified as a threat. The Washington Department of Agriculture was alerted and was able to isolate the source of the infestation. It was discovered that several beetles had escaped. Fortunately, this particular beetle is slow to reproduce. In an effort to prevent the establishment of the citrus long-horned beetle, trees were cut down, pesticides administered, an education plan was launched to residents, and restoration was funded by the Department of Forestry. In 2006, the quarantine was lifted after data collected over several years indicated favorable results.28 This particular example exemplifies the quick action, the cooperation of a variety of agencies, the understanding of the threat, and the education of the public that was necessary to eradicate the citrus long-horned beetle before it could become an established non-native species. Controlling invasive species is costly in terms of money and resources, but the consequences of failing to control invasive species are costlier.
Reintroduce species
Another technique to increase biodiversity is to reintroduce species. The story of the Florida panther, Puma concolor coryi portrays this technique. The Florida panther was endangered due to humans hunting deer, which was their food source and reducing their habitat with development. After searching, a small population of panthers was discovered. The population was isolated and genetically similar, which are characteristics of inbreeding. The panthers exhibited poor physical fitness, many kittens were dying, and males were reproductively compromised. The panthers were projected to go extinct within forty years.29 A group of scientists met to develop a plan. The group determined that the best course of action would be to bring wild panthers from another location to Florida, to increase the size and variation or the gene pool. So, in 1995, eight panthers from a different subspecies, Puma concolor stanleyana, were captured in Texas and released into the wild in Florida.
Apparently, there is some debate over the different subspecies of the North American panthers. It involves the number of subspecies and whether or not the species in Florida really is a different subspecies from the one in Texas. Some believe they are all the same, Puma concolor cougar.30
Regardless, the goal was to increase the genetic variation and improve the survival rate of panthers in Florida. The plan worked! Of the eight female cougars introduced, three died before producing offspring. The other five however, produced 20 kittens. None of the eight translocated panthers remain in the Florida population today. Two more died, and the remaining three were moved to captivity once a significant number of offspring was produced. Based on a report from February 2017, it is estimated that there are about 120-230 adult and subadult panthers, which is an increase from 100-180 adult and subadults in 2014.31 These counts do not include kittens still dependent on their mothers. Today, Florida has the only known breeding population of panthers on the east coast.
Habitat Preservation
While the Florida panthers’ population is on the rise, the fact that their habitat is so limited is concerning. They are relegated to a small sliver of their former habitat and are surrounded by an ever-increasing population of people. “Although conservation efforts focused on individual endangered species have yielded some successes, they are expensive – and the protection and restoration of whole ecosystems often represents the most effective way to sustain genetic, population, and species diversity.”32
Kolbert raises an important question, “How can humans coexist with species in the modern world when our existence and their survival are pitted against each other?”33 This idea is the crux of the problem. Panthers once roamed from South Carolina to Louisiana, but currently live in less than five percent of their historic range in southern Florida.34
Humans want to help the animals, but as a species, humans are quite narcissistic. While humans may want to help preserve ecosystems, I don’t believe many humans are willing to prioritize saving the environment above their own needs. I don’t think humans are concerned enough to preserve large swaths of land, when it can be used for homes, factories, shopping malls, office buildings, roads, and other capitalistic ventures that make life easier.
The human population is projected to reach nine billion people within the next 30 years. Thus, increasing our need for housing, food, and goods and services, which will only compound our inability to preserve natural habitats for the earth’s flora and fauna. The best strategy for saving a species is to protect them in their native habitat. This strategy is called in situ conservation.
Captive Breeding and Reintroduction
The next method, captive breeding, is one type of ex situ conservation. This is when an endangered species is taken out of its natural habitat. With ex situ conservation, the species could be moved to another habitat in the wild, a zoo, or a preserve. Captive breeding programs are a last-ditch effort to keep a species that is in imminent danger from going extinct. The goal is to eventually re-establish a wild population. “An estimated 4,000 to 6,000 vertebrate species will need captive breeding over the next 200 years in order to mitigate extinction threats.”35
Captive breeding programs face several challenges. They are not always successful with the intent to have individuals mate and breed and can face a lack of genetic variation due to inbreeding among close-relatives. In some cases, zoos are able to relocate a suitable mate to increase genetic variation for breeding purposes. Once raised in captivity, survival in the wild becomes more challenging. Training is necessary to teach species the survival skills prior to their release into the wild. In the case of the California condor, some died once they were released as a result of crashing into power lines. Subsequently, California condors were trained to avoid the power lines.36
The California condor, the black-footed ferret, the golden lion tamarin, and the red wolf are some species that were recent successes of captive breeding programs. Captive breeding is expensive as 35 million dollars was spent between 1987 and 2009 to reintroduce the California condor.37 Another success story is with great apes. In captive breeding programs, great apes experience good health, readily reproduce, and live 10 or more years longer than their peers that are not raised in captivity.38
Education
Educating my students about the importance not only of caring for endangered species, but also of taking care of the earth is important so they will hopefully become good stewards of the earth. With the sixth mass extinction underway, time is of the essence. My students may one day play a vital role in the future of endangered species and the possible de-extinction of species.
My students need to be made aware of the role genes and the genome will play in the future of science. I recently caught up with an old friend. As I described my curriculum unit, he shared with me a latent effect of Jurassic Park. Upon further research, I discovered an NPR story that says fossil-evidence of a new dinosaur species is discovered every ten days. Some of the Jurassic Park generation are graduating from Ph.D. programs and bringing their talents to the field. Ari Shapiro, the host of the NPR segment, says, “Many people who work in paleontology think what's happening today is tied to a summer blockbuster that hit movie theaters 25 years ago.”39
After reading a chapter in The Rise of the Necrofauna, a book by Britt Wray about reviving extinct species, I took note when she mentioned that two production companies had approached her about turning the book into a film. She also mentioned other films that are in the works related to species resurrection. Perhaps my curriculum unit and future films will inspire the next generation of scientists to study genes and the genome.
Science changes rapidly. The ability to map genomes continues to become more readily available and less expensive. Colin Tudge states in his book, The Impact of the Gene, “We need to know which species are most endangered and in the greatest need of immediate help. We can’t make that judgement without knowledge of genes.”40 His idea connects education and the next four methods of supporting endangered species and the possible de-extinction of species.
Genetic Assistance, Gene Editing, CRISPR, and Cryo
Going back to Jurassic Park, the idea of genetically engineering dinosaurs seemed far-fetched in the 1990’s, but today the concept of resurrecting more-recently extinct fauna is moving closer to becoming a real possibility. I want my students to realize that we already live in a genetically modified world. Much of our food, manufacturing of medical products such as insulin, and even our pets are obtained from genetic modification.
Genetic assistance relates to techniques used to rescue endangered species. Britt Wray describes genetic assistance as three layers. The first layer is the discovery of what is going on with the species. Researchers collect and analyze genetic information in an effort to determine what is making the species vulnerable and susceptible.
The second layer involves editing the genome to reduce the vulnerability. One example would be a species that is susceptible to a particular disease, and the possibility of replacing the compromised gene with one that has pathogen-resistance. This is one way that gene editing could be used to help save endangered species before they disappear.
The third layer is essentially the resurrection of an extinct species. The idea is to take genes that define the species and put them into the genome of the closest living relative. Ben Novak, a scientist at a company called Revive and Restore, is working to resurrect the passenger pigeon. He sequenced its genome and analyzed it to determine the key aspects that distinguish a passenger pigeon from its closest living relative, the band-tailed pigeon. The passenger pigeon was a keystone species. Robert Paine, an ecologist who worked at the University of Washington in Seattle, first coined the term keystone species in 1966. According to a National Geographic website, “A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.”41 National Geographic then explains that the ecosystem is unable to fill the niche when a keystone species disappears.
The woolly mammoth is a keystone species that Professor George Church from Harvard University is working to resurrect. As I spoke to people regarding my ideas for the curriculum unit and the notion of bringing back the woolly mammoth, people seem a little shocked. I get the sense they were thinking, “Why would we want to do that?” The thought of bringing back a prehistoric beast does seem more daunting to me than resurrecting a passenger pigeon, which was more recently driven extinct. As I searched around trying to find out more about keystone species, I found the answer.
Some scientists think that resurrecting the woolly mammoth may help to revive the “mammoth steppe,” a grassland-tundra ecosystem which played a key role in driving climate. Modern steppe ecosystems have already been created in Sweden and the Siberian Arctic, with the idea that these ecosystems could help lessen the effects of global warming.42 Church explains, “Today they (tundras) are melting, and if that process continues, they could release more greenhouse gas than all the world's forests would if they burned to the ground.”43 Church and his lab are working on editing some woolly mammoth traits into Asian elephants. The main traits to edit-in are subcutaneous fat, woolly hair, and sebaceous glands. These are the traits that help the mammoth to survive in the cold climate. The theory is that the woolly mammoth will eat the dead grass which will foster the growth of spring grass. The spring grass will help prevent erosion with its deep roots. The woolly mammoth will take down trees thus increasing the amount of reflected light. Also, the woolly mammoth will poke holes in the ice allowing freezing air to reach the soil which will enable deeper freezing of the permafrost layer (Figure 3). The increased grasslands will better insulate the permafrost layer in the summer thus preventing emissions of greenhouse gases.44
Figure 3: Woolly mammoths near the Somme River, American Museum of Natural History mural. (Public domain)
CRISPR
CRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR is a cutting-edge gene editing technology. In my research, I read the book A Crack in Creation by Jennifer A. Doudna and Samuel H. Sternberg. It is basically a memoir telling the story of how Doudna first learned about CRISPR and her journey to become one of the leading scientists studying CRISPR today.
Jennifer Doudna, a professor at the University of California Berkeley, describes her feelings early in her journey. She said, “These bits of information sent a little shiver of intrigue down my spine; if CRISPR was present in so many different species, there was a good chance that nature was using it to do something important.”45
As Doudna worked more with CRISPR and other top scientists around the world, she came to understand and explain in her book that CRISPR basically is the equivalent of an immune system that allows bacterial cells to fight bacteriophages, or bacteria-specific viruses. Doudna had been working on Type I CRISPR when she was introduced to Emmanuelle Charpentier, a French biologist, who was working with Type II CRISPR which uses the Cas9 protein. Basically, CRISPR finds the target sequence in the DNA, the Cas9 protein cuts the DNA, and then the new DNA sequence is inserted. As of now, CRISPR can edit genes and turn off genes. The recent discoveries with CRISPR make it feasible for this technology to help in efforts for resurrecting species such as the passenger pigeon and the woolly mammoth. So Doudna, Emmanuelle, Martin Jinek and Michi Hauer from Doudna’s lab and Krzysztof Chylinski who had previously worked in Emmanuelle’s lab began collaborating across the globe. Bit by bit they figured out more of the CRISPR puzzle.
Doudna described the feeling, “How incredible that bacteria had found a way to program a warrior protein to seek and destroy viral DNA! And how miraculous, how fortunate, that we could repurpose this fundamental property for an entirely different use.”46
Cryo
There are about a dozen locations around the world that are freezing cells and DNA of endangered species. They have various names such as: The Frozen Zoo at the San Diego Zoo, the Cryobiobank at the Cincinnati Zoo, the Frozen Ark at the University of Nottingham in England, and the Ambrose Monell Cryo Collection at the American Museum of Natural History (AMNH) in New York City. The AMNH has one of the largest collections of frozen tissues. The idea is that this is like a lending library and the samples can be sent to any scientist anywhere in the world. From the literature I read, cryo repositories are an attempt to catalogue as many species from around the world so that future generations potentially can figure out what to do with them. Embedded in the mission statement of the Ambrose Monnell Cryo Collection it states, “In a time of massive species loss, such efforts are essential in order to preserve as comprehensive a record as possible of the earth’s biodiversity.”47
With the development of CRISPR and gene editing technology, the “future” of using the cells and DNA stored in the cryo banks is literally right around the corner. Fortunately, scientists had the foresight to plan for the future. One question that will continue to be debated is whether a woolly mammoth or a passenger pigeon is really the same species if it did not develop in its natural habitat.
Once again, I will return to Jurassic Park, now that the gene-editing techniques have been explained. I may even replay the clip where the scientists go out and find the dinosaur eggs which was a supposed impossibility because the dinosaurs were designed to be incapable of reproduction. This will encourage my students to consider possible intended and unintended consequences of bringing back the passenger pigeon or other extinct species when the consequences are not known.
Introducing a de-extinct species could have the same effect as an invasive species. So, while it could initially increase the biodiversity, in the long term it may actually decrease it. As discussed in our seminar, another consequence is we really do not know what will happen if we start tinkering with the genome. While we do not fully understand how all genes work, we are figuring out that many genes can play a role in a single trait, such as height in humans.48 Another concern is that if a gene is turned off, others may turn on to make up for it. What effect will replacing genes in a species have on the species, on other species, or on the environment over time? If we use gene editing to help an endangered species be more resistant to a pathogen, will another more virulent pathogen replace the pathogen?
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