You're assuming a binary extant/extinct dichotomy. That may work on the level of an individual species, but not on the colony level. The colony is simply attemp

You're assuming a binary extant/extinct dichotomy. That may work on the level of an individual species, but not on the colony level. The colony is simply attempting to propagate itself. So the utility at a given time could be given by something that measures the current size of the colony, the size of its descendants, and some estimate of how much each colony will further propagate.