You may be thinking of this passage from "Evolving to Extinction":

The real struggle in natural selection is not the competition of organisms for resources; this is an ephemeral thing when all the participants will vanish in another generation. The real struggle is the competition of alleles for frequency in the gene pool. This is the lasting consequence that creates lasting information. The two rams bellowing and locking horns are only passing shadows.

Best wishes, the Less Wrong Reference Desk.