Each of the 49 colonies carries a csd allele inherited from one of the founder breeding lines. Queens mate with drones drawn partly from a curated, diverse drone-mother pool and partly from the local uncontrolled gene pool — the drone control slider sets that mix, which sets the effective number of drone contributors N꜀: Nₑ = 4·N꜀·Nf / (N꜀ + Nf) where Nf is the number of active queen lines. A small Nₑ means strong genetic drift each generation (a Wright–Fisher resample of 2·Nₑ gene copies) — rare alleles get lost and the surviving allele frequencies pᵢ concentrate. Because a fertilised egg homozygous at the csd locus becomes a diploid drone that workers eat, producing the classic "shotgun" brood pattern, the population's brood loss is loss = Σ pᵢ² (Hardy–Weinberg homozygosity). Fresh stock introduction occasionally injects a brand-new, biosecurity-checked allele back into the pool, the real-world antidote to a narrowing gene pool.