Code from: Sex-biasing gene drives for island mouse eradications: Modeling dispersal and mating behavior for improved risk assessment preparedness
Data files
Jun 30, 2026 version files 2.91 MB
-
GDShredMus_Functions.R
95.46 KB
-
GDShredMus_XSensAnGlobal_LHS.R
2.81 KB
-
GDShredMus_XSensAnGlobal.R
6.34 KB
-
GDShredMus_YSensAnGlobal_LHS.R
3.23 KB
-
GDShredMus_YSensAnGlobal.R
18.10 KB
-
README.md
4.64 KB
-
XShred_d0025_fail.gif
1.37 MB
-
XShred_dA03_success.gif
1.41 MB
Abstract
Invasive rodents remain a major source of environmental damage worldwide. Sex-biasing gene drives may provide an alternative to toxicant-based eradication strategies. Risk assessments for gene drives will rely partially on models, which must account for intraspecific variation in the ecological and life history characteristics of target populations. Dispersal patterns and mating system characteristics in particular are expected to impact drive spread and suppression outcomes, though empirical data on natural populations are lacking.
We developed a stochastic metapopulation model implemented using numerical simulations that simulates the introduction and spread of male-biasing X-Shredder or female-biasing Y-Shredder gene drives to suppress an island population of house mice (Mus musculus). Our model includes parameters for mating system complexity, sperm competition, dispersal frequency and distance, as well as several features related to release strategy and drive efficiency (shredding efficiency for both drives, homologous site cutting efficiency for Y-Shredder drives).
We found that both drive strategies are capable of complete population eradication within ~15 - 35 years depending on parameterization. Drive efficiency had the strongest impact on eradication probability and timing across both drive types. Increasing dispersal frequency usually improved the probability of successful eradication and reduced the time required to achieve eradication, though we identified several exceptions to this trend. Polyandrous mating limited the success and speed of X-Shredder drives, while the effect of polygynous mating varied for Y-Shredder drives, improving eradication probability across certain parameter combinations at lower dispersal frequencies when cutting efficiency exceeded shredding efficiency and shredding efficiency remained above a minimal threshold.
Across parameter space and drive strategies, ‘chasing’ events, in which wildtype individuals repeatedly recolonize eradicated areas, were common and often prevented successful eradication at low dispersal frequency. Dispersal behavior exhibited a strong influence on the spatial characteristics of recolonization and chasing events.
Synthesis and applications: Though drive efficiency was highly influential to model outcomes, such parameters will likely be known prior to any experimental gene drive introductions. We conclude that understanding the ecological and life history characteristics specific to target populations will be critical to accurately predicting gene drive outcomes and informing risk assessments.
Functions and scripts for running X-Shredder and Y-Shredder gene drive simulations for an island population of Mus musculus
Functions: all functions found in GDShredMus_Functions.R
Yshred
Simulates demographic, dispersal, and Y-Shredder gene drive processes across time steps. Requires input parameters and starting abundances for each sex-age-genotype combination.
Yshred.v2
Same as Yshred except juvenile dispersal rate is set to the same value as adult dispersal rate. Used for initial set of simulations in manuscript.
Yshred.v2.chase
Same as Yshred.v2 except max distance between patches with wildtype individuals and the nearest gene drive-harboring patch is recorded
Xshred
Simulates demographic, dispersal, and Y-Shredder gene drive processes across time steps. Requires input parameters and starting abundances for each sex-age-genotype combination.
Xshred.v2
Same as Xshred except juvenile dispersal rate is set to the same value as adult dispersal rate. Used for initial set of simulations in manuscript.
Xshred.v2.chase
Same as Xshred.v2 except max distance between patches with wildtype individuals and the nearest gene drive-harboring patch is recorded
calculateCentroids
Calculates XY position of patch centroids within square patch lattice. This function is implemented within the natMigration function.
natMigration2
Determines destination patch for each migrant and final abundance in each patch following migration.
Requires a distance threshold of permissible difference between dispersal distance and distance between starting location and centroids of possible destination patches.
randBirthYS
Determines the discrete number of births of each potential genotype in the Y-Shredder system using weighted sampling.
randBirthXS
Determines the discrete number of births of each potential genotype in the X-Shredder system using weighted sampling.
randpois
Determines discrete numbers of individuals experiencing dispersal or demographic processes for each patch, given relevant parameters and patch abundances.
randpoisLitter
Determines the discrete number of individuals in each litter, capped at minimum and maximum values for house mice.
MatedFemByPoly
Determines the number of mated females in each patch given male availability and mating system characteristics (i.e., max number of male mates, probabilities of female mating with 1 - n mates).
minCheck
Determines minimum value. Used to determine number of mated females.
dist2GdPatch
Calculates the minimum, maximum, and average distance between patches with wildtype individuals, and the nearest gene drive-harboring patch is recorded.
Scripts
GDShredMus_XSensAnGlobal_LHS.R
Script to generate parameters for global sensitivity analysis of X-Shredder system using Latin hypercube sampling. Note that the parameters CSV file generated by this script must be combined with static parameters in the correct column order before use. Complete list of columns and static values for the complete parameter array provided.
GDShredMus_XSensAnGlobal.R
Script to run global sensitivity analysis of X-Shredder gene drive. Note that the parameter CSV file that must be imported includes the parameters generated in the LHS script, with additional static parameters added to generate a complete parameter array.
GDShredMus_YSensAnGlobal_LHS.R
Script to generate parameters for global sensitivity analysis of Y-Shredder system using Latin hypercube sampling. Note that the parameters CSV file generated by this script must be combined with static parameters in the correct column order before use. Complete list of columns and static values for the complete parameter array provided.
GDShredMus_YSensAnGlobal.R
Script to run global sensitivity analysis of Y-Shredder gene drive. Note that the parameter CSV file that must be imported includes the parameters generated in the LHS script, with additional static parameters added to generate a complete parameter array.
Animations
XShred_dA03_success.gif
Example animation from a successful eradication using an X-Shredder gene drive system in which the mouse population dispersal frequency parameters were set to 0.3.
XShred_d0025_fail.gif
Example animation from a failed eradication using an X-Shredder gene drive system in which the mouse population dispersal frequency parameters were set to 0.025.
