A flexible short read simulator. ShotGun generates sequence data with user-specified read length and average depth, accommodates to cycle specific sequencing error rates, allows the read depth distribution to be either the ideal Poisson or Negative Binomial to model the overdispersion observed with real sequencing data. In addition, ShotGun performs computationally efficient Single Nucleotide Polymorphism (SNP) discovery using a statistic aggregated across all sequenced samples.