Follows its 4a merge survivor H-3, which 4b dropped: the natural-bat-reservoir claim is compatible with every member of HC-1 (natural evolution then market spillover, or natural evolution then collection and lab escape), so it is background rather than a competing answer to the route question; its discriminating natural-vs-engineered content is scored once inside H-5.
Absorbed into H-3 at 4a (state was `merged`); re-dispositioned to `dropped` when 4b dropped H-3, since a `merged` node must resolve in one hop to an `active` survivor. Original 4a merge recorded in `former_merged_into` and in H-3's `merged_from`.