Example: Honey Bees
Honey bees cannot reproduce, but provide for the Queen-bee so she can populate the hive.
They do everything that doesn't involve reproduction such as: food, maintenance, and defense.
Mating is the only reason for existence of the Drone bee.
Maintains the population and reproduces.
They always have one that stands guard that signals when there is some kind of threat.
They share food with the ones who cannot get their own.