Written by Samantha O’Loughlin, Target Malaria
(This is the fourth of a series of six posts about common gene drive misconceptions)
Gene drive can become a useful tool to reduce biodiversity loss and control vector-borne diseases. In the process of researching gene drive, we’re not only looking at the benefits (i.e. what it could do that would be useful) but also we’re trying to understand the potentials risks involved, including the impacts they may have on other species.
So could a gene drive organism lead to a species’ extinction? As I mentioned in the post Gene drive myth-busting: Gene drive will spread globally, gene drives can be designed so that they will not spread through an entire species. There are also regulations and guidance in place to make sure gene drive organisms will be kept in laboratories and tested thoroughly before they would be considered for use in the environment. Gene drives that are being developed with the aim of spreading and reducing the numbers of a species (such as mosquitoes) could, in theory, result in local extinctions of the target species, but computer models show that there is a very low likelihood that gene drive could crash an entire species.
This is due to factors such as barriers to spatial spread, differences in fitness of gene drive carrying individuals (compared to the wild type), and the eventual development of resistance. In the case of malaria, a common misconception that I have heard is that we are trying to eradicate mosquitoes. In fact, we are able to target a gene drive so that it only affects a few species of malaria carrying mosquitoes (and leaves all the many other mosquito species alone). The aim is to reduce their numbers to a low level so that the disease transmission cycle is broken. Eradicating malaria does not require eradicating the mosquitoes that transmit it.