Could a species erase all other lifeforms and live independently, thus becoming the ultimate living being? And then can an individual of that species kill all other members and live as an immortal organism?
For now I think that the only species capable of doing this is the homo sapiens, but are there other organisms (fungi?) which potentially could do it. I say fungi because they seem the only pathogens which are enough complex and with enough adaptability to do the task.