I have to agree with this. There is no "ecosystem". Just a bunch of randomly-chosen animals walking/swimming/slithering around, doing things at random based on a handful of lines of code.
Many of the animals are wildly inappropriate for the biomes in which they are found. Cobras and lions in the Tundra? Bears in the Tropics? Come ONNN... (Sure, it could be argued that the islands and biomes are close enough together on this world for creatures to migrate between them while clinging to flotsam, but that's stretching it.)
Creature AI is bare-bones at best and unrealistic. Ever notice cobras and rattlesnakes aggressively attack everything, and KO other creatures, but never actually EAT them? (Heck, the surest sign there's cobras in the area is the random "Wild sheep (unconscious)" label floating in the near distance.) If they wanted snakes to be realistic, rattlesnakes would only attack larger creatures/people if they got within a meter or so, and cobras would unhinge their jaws and SWALLOW unconscious creatures whole, then lounge around lazily (with comically swollen bellies) for hours, barely able to move. Most other wild creatures seem to make no attempt to eat anything. And wild creatures in general would be leery of humans, tending to wander AWAY instead of TOWARDS us, which would make the passive tames that much harder.