Threespine stickleback, which occupy lakes across the northern latitudes, are a tiny fish with an outsize impact on evolutionary research. These sticklebacks thrive in both marine and freshwater habitats and exist in most of the inland waters that dot the northern coasts of North America, Europe, and Asia. Significant to scientists, the species has a conspicuously variable trait governed by a single gene: the amount of bony plating, or “armoring,” on their bodies. Variations in this gene in this tiny fish species have the potential to alter the broader aquatic ecosystem, according to new research led by University of Pennsylvania postdoctoral researcher Seth Rudman. His work appears in the journal Ecology Letters.