Threespine Stickleback Fish

Ten thousand years ago, glaciers retreated across North America and left behind thousands of freshwater lakes. Marine threespine sticklebacks colonized them and evolved the same adaptations independently, over and over: reduced armor, smaller size, different pigmentation. This is parallel evolution at massive scale - the same genetic solution arising in lake after lake.

Here's the twist: the variation wasn't new. Genomic studies revealed that low-armor alleles already existed as standing genetic variation in the marine population, including epigenetically controlled variants. The ocean population was a reservoir of cryptic variation - traits that were neutral or disadvantageous in salt water but adaptive in fresh water. When the environment changed, selection didn't wait for new mutations; it amplified existing variation that had been hiding in the population all along.

The strategic insight is counterintuitive: Successful adaptation often requires maintaining apparently useless variation. Sticklebacks demonstrate that the fastest adapters aren't those with the highest mutation rates - they're those with the deepest reserves of dormant capabilities. Organizations that eliminate all slack and variation optimize themselves into evolutionary dead ends.