Strain leaking. Relatively a hidden system and one players wont ever directly interact with unless they have prior knowledge of it beforehand.

Upon a strain being introduced into any dimension it may begin “leaking.” When a strain begins leaking into a dimension its eventually added to that dimensions spawn pool and can begin having naturally occurring hives with that strain.

Not only does this apply to base strains. (Nethermorph, Aberrant) It also applies to genetically modified ones, and as a result causing your creation to grow naturally across the dimension.

For example, when a player introduces a base strain into the nether it may begin leaking into the nether and as a result causing base strain xenomorphs to begin creating hives within that dimension. The same applies for introducing Nethermorphs into the overworld.