From a Usenet newsgroup:

You seriously think two[1] of every species[2] fitted in there for months on end (with no food or waste disposal systems)? [1] and seven of some

[2] or it is two of every 'kind', today?

She has previous stated that they were "kinds". The example she gave was that there were two 'felines' on board which evolved (oops, changed by small increments within a kind) into all the cats on the planet today. Lions, tigers, tabbies, etc. Of course this all had to take place between Noah and Daniel, as we know there were fully "changed" lions in the den. About 1000 years.