Ramo’s death means that Karana is now totally alone on the island. And as she notes here, it’s impossible to know for sure whether the ship is actually going to come back for her. The fact that the dogs killed Ramo makes it clear that for now, they’re one of the biggest threats to human life on the island—especially now that Karana is all alone. Because of their presence and their willingness to kill humans, the island becomes much less hospitable.