3. Trait remixing: The overall genetic structure of coevolving species continually changes through new mutations, genomic alterations, gene flow among populations, differential random genetic drift among populations, and extinction of local populations that differ in the combinations of coevolving traits they harbor. New genetic material on which natural selection can act can result from simple genetic mutations, chromosomal rearrangements, hybridization between populations, or whole genome duplications (polypoloidy). These processes contribute to the shifting geographic mosaic of coevolution by continually altering the spatial distributions of potentially coevolving genes and traits.