Should scientists ever use genetic engineering to save an imperiled species?
Marjorie Matocq and her colleagues were recently discussing how they might use material held in the biological collections of various museums to study how wildlife populations have responded to environmental change over time.
Marjorie and her colleague Gary Roemer from New Mexico State University had convened scientists from across the Western U.S. in a workshop sponsored by the National Science Foundation (Tri-State EPSCoR program). In attendance were representatives from various major museums and repositories of plant and animal specimens - including the Museum of Southwestern Biology at the University of New Mexico, the University of Utah's Natural History Museum of Utah, and Cal's Museum of Vertebrate Zoology.
The main topic was to consider how biological collections can help us understand how organisms have adapted to environmental change through time. By comparing specimens collected many decades ago to those more recently collected, a wide variety of critical questions can be addressed. Have the ranges they occupy changed? Have they shifted their habitat use? Has their physical appearance changed? Have they become larger or smaller? By understanding how animals and plants have responded to environmental changes of the past, we might be able to predict how they will respond to changes in the future. Because DNA is also preserved in the specimens held in collections, it will be possible to examine how the genes that underlie the traits of interest changed over time as well.
The workshop discussion then turned to considering how scientists could use such information to conserve biodiversity. Specifically, would scientists ever consider using genetic engineering to save a species that is threatened with extinction? For instance, if a small set of genes increases tolerance to high water temperatures, should wildlife managers ever consider inserting these adaptive gene variants into a native trout population that is known to be declining and facing extinction because of increasing water temperatures?
"Given how fast technology is advancing, it is not too early to begin discussing these issues and to debate if and when such approaches might be used in conservation," says Matocq, an associate professor of wildlife genetics with CABNR's Department of Natural Resources and Environmental Science.
Their discussion resulted in a commentary article titled "Ecology: Gene Tweaking for Conservation" in the journal "Nature," an international weekly journal of science. Matocq collaborated on the piece with five of her workshop colleagues - Michael Thomas of Idaho State University; Roemer; C. Josh Donlan, a visiting fellow at Cornell; Brett G. Dickson of Northern Arizona University; and CABNR postdoctoral associate Jason Malaney.
The article, published Sept. 25 this year, discusses the pros and cons of various, sometimes very controversial, methods of helping wildlife that are facing extinction due to environmental change. Conservative estimates are that 15 to 40 percent of living species today will be effectively extinct within 36 years as a result of climate change. To address these challenges scientists are examining various approaches including moving populations to track hospitable habitats, reinstating keystone species into areas where they have disappeared, and the revival of species that have recently gone extinct.
The article suggests that an "increasingly viable (and potentially less risky) option" for intervening on behalf of a wildlife population is an approach that the authors call "facilitated adaptation," which involves rescuing a population or species via genetic engineering. This would involve introducing to the population adaptive alleles - gene variants - that would allow it to withstand the outside pressures that threaten its existence. Matocq said the goal of the commentary in Nature was to get scientists talking about genetic engineering, how it could be used in conservation, and the need to establish a decision-making framework that considers the scientific and ethical implications of these approaches.
"The technical expertise to genetically engineer organisms is moving rapidly, but we still know very little about which genes underlie particular traits of interest in natural populations," Matocq says. "Being able to consider adaptive genetic variation in our management plans, let alone manipulation of this variation, will require a great deal of research into identifying the relationship between genes and traits of interest."
Matocq says scientists will have to have thorough knowledge of how gene variants function within organisms before there could be consideration of moving these variants into a natural population. The same allele that helps an animal tolerate more heat or drier conditions may also control other critical traits. The relationship between genes and the traits they determine need to be thoroughly understood before an informed decision could be made about whether moving particular variants into a population would have a chance of augmenting population persistence.
Matocq notes that people have been manipulating traits and the underlying genetic variation that determines those traits for generations through the process of selective breeding. Dog breeders and farmers, for instance, have long encouraged certain traits to become more common in order to achieve a certain color of fur, or a shorter tail, or a plant that uses half as much water or produces prettier flowers.
Rather than achieving these alterations through selective breeding, newer technology allows particular gene variants to be directly inserted into the genomes of organisms. The Nature article noted that genetically modified crops are now grown on 12 percent of the world's arable land and that the market for genetically modified seed is now $15 billion.
Matocq and her colleagues note that facilitated adaption could be achieved through a variety of approaches, including the process of interbreeding or hybridization such as when an endangered Florida panther population was aided through hybridization with a related subspecies. Similarly troubled populations could be bolstered by breeding plants or animals from threatened populations with those from better-adapted populations. Using a more targeted approach, alleles from a well-adapted population could be inserted into the genomes of a closely-related but threatened population, or alleles could even be transferred among species.
How would all this work? According to the authors, potential donor populations could be screened for their individuals who exhibit the characteristics needed by the threatened plants of animals, such as resistance to heat or disease. Some amphibians, for instance are resistant to chytridiomycosis, a fungal disease that has caused several extinctions. "If one or a few genes are found to increase resistance," the authors said, "they might make excellent targets for transfer."
While encouraging discussion on the topic, Matocq and her co-authors freely admit that facilitated adaptation is fraught with questions. But the biggest threat, the authors say, is doing nothing. If people think that genetic engineering will "rescue biodiversity" they may be less inclined to address the causes of environmental change. Even in cases where facilitated adaptation would be deemed appropriate, habitat conservation and reduction of other environmental stressors will be needed.
"Before genetic engineering can be seriously entertained as a tool for preserving biodiversity, conservationists need to agree on the types of scenarios for which facilitated adaptation, managed relocation and other adaptation strategies might be appropriate, and where such strategies are likely to fail or introduce more serious problems," the article concludes. "For some species, facilitated adaptation could turn out to be the only viable remedy."
Matocq graduated for California Polytechnic State University in San Luis Obispo in 1992 and earned a master's degree from San Francisco State in 1996. She earned her Ph.D in 2000 from the University of California, Berkeley and was a Postdoctoral Fellow at the Smithsonian Institution.