Social parasite polymorphism

In the queenless clonal raider ant, Oocerea biroi, a rare mutant lineage of ants exhibits queen-like morphology at worker-like body size – akin to a social parasite. Using a combination of long-read assemblies and genome resequencing, we demonstrated that this polymorphism was caused by a 2.3Mb loss-of-heterozygosity mutation. We then used a combination of genomics techniques and fluorescent in situ hybridization to prove that this mutation confers the parasitic polymorphism through changes to a developmental hormone pathway. This work identifies the first genetic caste differentiation polymorphism and provides a novel insight into the evolution of social parasitism.