Pest demography critically determines the viability of synthetic gene drives for population control

• Published in: Mathematical biosciences 2018-11, Vol.305, p.160-169
• Main Authors: Wilkins, Kym E., Prowse, Thomas A.A., Cassey, Phillip, Thomas, Paul Q., Ross, Joshua V.
• Format: Article
• Language: English
• Subjects: Animal populations; Animal reproduction; Animals; Biodiversity; Breeding; Carrying capacity; Computer Simulation; CRISPR; Demographics; Demography; Deoxyribonucleic acid; DNA; Eradication; Female; Fertility; Gene drive; Genes; Genes, Synthetic; Genetics, Population; Heredity; Homologous recombination; Homology; Introduced Species; Invasive species; Male; Mathematical Concepts; Mating system; Mice; Models, Genetic; Nonnative species; Nucleotide sequence; Pest Control, Biological - methods; Pest Control, Biological - statistics & numerical data; Pest eradication; Pests; Polygyny; Population control; Population Control - methods; Population Control - statistics & numerical data; Population Density; Population genetics; Population modelling; Pregnancy; Reproduction; Rodents; Synthetic biology; Viability
• ISSN: 0025-5564; 1879-3134
• DOI: 10.1016/j.mbs.2018.09.005

•Mass-action reproduction is unsuitable for modelling gene drives in vertebrates.•The evolution of resistance threatens the viability of gene drives for pest control.•Reproductive Allee effects could assist gene drives to eradicate invasive species.•Pest species’ demography must be understood to inform applied modelling efforts. Synthetic gene drives offer a novel solution for the control of invasive alien species. CRISPR-based gene drives can positively bias their own inheritance, and comprise a DNA sequence that is replicated by homologous recombination. Since gene drives can be positioned to silence fertility or developmental genes, they could be used for population suppression. However, the production of resistant alleles following self-replication errors threatens the technology’s viability for pest eradication in real-world applications. Further, a robust assessment of how pest demography impacts the expected progression of gene drives through populations is currently lacking. We used a deterministic, two-sex, birth-death model to investigate how demographic assumptions affect the efficiency of suppression drives for controlling invasive rodents on islands, for two different gene-drive strategies. We show that mass-action reproduction results in overly optimistic eradication outcomes when compared to the more realistic assumption of polygynous breeding. When polygyny was assumed, both gene-strategies failed due to the evolution of resistance unless a reproductive Allee effect (reduced reproductive rates at low population density) was also included; although model outcomes were highly sensitive to the strength of this effect. Increasing the size of the initial gene-drive introduction (up to 10% of carrying capacity) had little impact on population outcomes. Understanding the demography of a population targeted for eradication is critical before the viability of gene-drive suppression can be adequately assessed.