Michael Vella & Sumit Dohle: Population Genetics of Gene DrivesA gene drive biases inheritance of a gene so that it increases in frequency within a population even when the gene confers no fitness benefit. There has been renewed interest in environmental releases of engineered gene drives due to recent proof of principle experiments with the CRISPR-Cas9system as a drive mechanism.With the tremendous potential of gene drives to alter natural populations, there have been calls to minimize risks associated with the release of gene drives. Two ways of reducing risks are to make gene drives that are reversible and will remain localized.Several methods of reversing and localizing drives have been proposed with optimistic predictions about efficacy, but expected dynamics are often not analyzed in detail.Michael Vella will discuss theoretical analysis of gene drive countermeasures that could be used to reverse a CRISPR-based homing drive.Countermeasures include synthetic resistance alleles, reversal drives, and immunizing reversal drives. Unexpected dynamics arise in some cases, and each countermeasure has advantages and disadvantages that would need to be considered before use.Sumit Dhole will then discuss a comparative analysis of three gene drives that have been proposed for localized population alteration – the one- and two-locus underdominance drives, and therecently proposed daisy-chain drive.Related PublicationsInvasion and migration of self-limiting gene drives: a comparative analysisDhole, S., Vella, M.R., Lloyd, A.L., Gould, F., doi: 10.1101/159855http://www.biorxiv.org/content/early/2017/07/06/159855Evaluating Strategies For Reversing CRISPR-Cas9 Gene DrivesVella, M., Gunning, C., Lloyd, A.L., Gould, F. doi: 10.1101/144097http://www.biorxiv.org/content/early/2017/08/10/144097