Most genes have a 50% chance of being inherited by offspring. Gene drives are inherited at higher frequencies, sometimes close to 100%. This type of genetic construct could be useful in disease prevention or conservation, as it could allow managers to purposefully spread a desired gene into a wild population, even when that gene imposes a fitness cost on the individual. Because such a technology could cause widespread, irreversible damage to natural ecosystems, a 2016 report by the National Academies of Science, Engineering, and Medicine titled Gene Drives on the Horizon recommended a cautious, phased approach for developing, studying, and adopting gene drives.
I have contributed to several projects where we attempt to understand the potential conservation applications of gene drives. In particular, I am interested in the ecological risks and uncertainty of gene drives in the wild. Below, I summarize some of these projects with links to related research.
If you are also interested in a broad overview of gene drives and their applications, please consider reading these following papers from other researchers.
I have contributed to several projects where we attempt to understand the potential conservation applications of gene drives. In particular, I am interested in the ecological risks and uncertainty of gene drives in the wild. Below, I summarize some of these projects with links to related research.
If you are also interested in a broad overview of gene drives and their applications, please consider reading these following papers from other researchers.
- Emerging technology: Concerning RNA-guided gene drives for the alteration of wild populations (Esvelt et al. 2014)
- Regulating gene drives (Oye et al. 2014)
- Cheating evolution: engineering gene drives to manipulate the fate of wild populations (Champer et al. 2016)
- Is it time for synthetic biodiversity conservation? (Piaggio et al. 2017)
Island Mice: Conserving Biodiversity
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As part of an NSF-funded Integrative Graduate Education and Research Traineeship (IGERT), I collaborated with an interdisciplinary cohort of graduate students to explore the hypothetical strategy of eradicating an invasive species through genetic engineering. We created a website where we synthesize these ideas, presenting these ideas to a non-academic audience. Specifically, we want to reach a potential future stakeholders who might be interested in or reluctant about the intersection of conservation biology and biotechnology. In other words, we wrote the website for the open-minded skeptic with agency as well as anyone else who might be interested. Throughout, we highlight the ethics and history of invasive species and eradication, describe a hypothetical example of genetic engineering for eradication, and discuss potential societal implications.
Find the website here: https://research.ncsu.edu/islandmice/ Also see: Genetic Biocontrol of Invasive Rodents |
Developing gene drive technologies to eradicate invasive rodents from islands
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.Elaborating on the ideas that we initially proposed in the previous website, we explain how gene drive technology could be used to eradicate invasive rodent species. Because of their remoteness, unique species live on islands throughout the world. Rodents do not naturally occur on many of these islands, so they become invasive after they are introduced, often causing the extinction of those unique species. Past efforts to remove these rodents from island ecosystems involved dropping large amounts of toxicants onto the islands to kill the rodents. One proposed alternative is to use gene drive technology. The idea is to genetically engineer mice that only produce male offspring and release them onto the island. Over time, the population should decline until there are no more females left. Gene drives present ecological and social risks that we need to evaluate and compare with traditional toxicant-based methods before this technology can or should move forward.
Find our 2018 paper [Free access] in the Journal of Responsible Innovation or email me for a copy. This was developed from an interdisciplinary workshop, summarized here. If you're interested in learning more, you should also consider these papers from other researchers |
Genetic engineering to eradicate invasive mice on islands: Modeling the efficiency and ecological impacts
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To eradicate invasive rodents from islands, we could develop genetic constructs like drives that would alter the sex ratio of wild rodent populations. By releasing a mouse that carries a sex-ratio-altering gene construct into a wild population, an invasive population would be eradicated after there are no remaining females. Before we can seriously consider developing gene drives or releasing them into the wild, we need to know whether they spread, how they spread, and how they can eliminate an entire population. We developed and analyzed a mathematical model to determine how a sex-ratio-altering genetic construct might spread through a wild population over time. Under most conditions, the genetic construct can only spread through a population if it is released repeatedly. The population is eradicated quicker if more genetically altered mice are released, but more mice in the wild could negatively effect the ecosystem. We also identified a possible (though unlikely) scenario where the genetic construct could give a competitive advantage to mice that carry it. In this case, the gene construct might spread even if it is not repeatedly released.
Find the 2016 paper [Free access] in Ecosphere or email me for a copy. If you're interested in learning more, you should also consider these papers from other researchers.
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Threshold-dependent gene drives in the wild: Spread, controllability, and ecological uncertainty
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Threshold-dependent gene drives are those that spread when they exist in a wild population above some critical frequency. If there aren't many in the population, the gene drive should be lost over time. However, if there are many, the gene drive spreads until most of the population carries it. Because of this, they are often considered to be local gene drives as they can are not expected to spread into a new population if only a few migrating individuals reach an unintended location. The threshold frequency that determines whether the gene drive can spread depends on several factors, including inherent genetic characteristics, ecological dynamics, and behavioral dynamics. Each of these factors are veiled in some uncertainty and the relative ecological fitness of organisms carrying the gene drive is very difficult to predict without extensive field experiments. We describe how ignoring this ecological uncertainty could lead to unexpected spreading behavior. Unlike many simpler gene drives, threshold-dependent drives do show a lot of promise in allowing managers to control spreading dynamics, but a considerable amount of ecological uncertainty suggests that local spreading dynamics are context-dependent.
Find the 2019 paper [Free access] in BioScience or email me for a copy. I also talk about this paper on the BioScience Talks podcast with my co-author Jason Delborne. If you're interested in learning more, you should also consider these papers from other brilliant scientists.
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