system
Given the following post, respond as if you're commenting on Reddit:
human
[Dungeons And Dragons] How does the world of Torill have such incredible biodiversity

Seriously, there's over 100 sentient races, hundreds of apex predators. how does the world support this level of biodiversity?
gpt
Alien invasions and immigrations mostly. Mindflayers, everything fae related, Dragons, Genasi, and many others come from other worlds or realities.  Others like Gnomes were artificially created. 

A lot of flora and fauna also comes from other realities as well. Just glancing through the Monster Manuals you'll see some cone from the Faewild, others from the Far Realm, others from Elemental Planes, and so on.