Duplicate gene expression in tetraploid fishes of the tribe Moxostomatini (Cypriniformes, Catostomidae).

1. Karyotypically tetraploid fishes of the catostomid tribe Moxostomatini were electrophoretically examined to ascertain in the genetic control of 14 enzyme systems (21 loci in dipoid Cypriniformes). 2. The Moxostomatini have become functionally diploid at 50% or more of their loci since the original polyploidization event in the catosomid line. 3. The subgenera Megapharynx and Moxostoma s.s. (genus Moxostoma) are recognized as comprising a single lineage on the basis of synapomorphic diploidization at the G-3-pdh-A locus. 4. Thoburnia s.l. is allied with the genus Hypentelium on the basis of synapomorphic diploidization at the M-Aat-A locus supporting separate generic status for Thorburnia s.l.