Tetraploid Origin of the Karyotype of Catostomid Fishes

Catostomid fishes appear to have 2n(→4n?) ≃ 100 chromosomes. The Cyprinidae, from which catostomids probably diverged before the Eocene, usually have 2n = 48 or 50 chromosomes. Preliminary cytophotometric measurements indicate an approximate doubling of DNA content of cells among catostomids.