In the case of human knowledge, the variation is by Conjecture, and the selection is by Criticism and experiment. In the biosphere, the variation consists of mutations (random changes) in genes, and natural selection favors the variants that most improve the ability of their organisms to reproduce, thus causing those variant genes to spread through the population.
Both sources are abstract replicators which means they're forms of information that are embodied in a physical system and tend to remain so (in DNA strands, books, hard-disks etc).
But the two sources have some key differences. Evolution is bounded and parochial. It tends to make slow iterative changes. People's creativity is unbounded and has Reach.