Board Thread:Warhammer 40k General Discussion/@comment-6589306-20130228113457/@comment-24944355-20150111221758

As I said above part of the ancient bio ships cortical node survived the destruction of the ship itself. Somehow the current era Tyranids were aware of the ancient nodes existence even when it was frozen & went all out to destroy it. This gave the defenders the idea to defrost it (they were getting desperate) & they discovered that attacks by the current era Tyranids immediately lost cohesion. The defenders detected the telepathic signal the node was giving off & theorized that it was somehow disrupting the current era hive minds control. The defenders used an astropath to project that signal throughout the system where it completely disrupted the Tyranid hive fleets cohesion allowing the beleaguered imperial fleet to destroy or drive off the tyranid bio ships.

All this seems to indicate that Tyranids from separate hive minds cannot coexist due to the disrupting effect of clashing telepathic signals. Which also indicates that all current incursions come from the same source ruled by the same hive mind & that if fleets from another hive mind entered our galaxy the result would be all out Tyranid civil war as the conflicting hive minds battled for dominance & survival.