Paleopolyploidy

Paleopolyploidy is the result of genome duplications which occurred at least several million years ago (mya). Such an event could either double the genome of a single species (autopolyploidy) or combine those of two species (allopolyploidy). Because of functional redundancy, genes are rapidly silenced and/or lost from the duplicated genomes. Most paleopolyploids, through evolutionary time, have lost their polyploid status through a process called diploidization, and are currently considered diploids (e.g. baker's yeast, Arabidopsis thaliana, and perhaps humans).