Portal de Periódicos da CAPES

Three New Intergeneric Hybirds of Cyprinid Fishes from Western Montana

1955; University of Notre Dame; Volume: 53; Issue: 2 Linguagem: Inglês

10.2307/2422076

1938-4238

George F. Weisel,

Genetic and phenotypic traits in livestock

It has become well established that distinct species and genera of fishes hybridize naturally, particularly in the freshwater families Cyprinidae, Catostomidae, and Centrarchidae. The information accumulating about these crosses is helpful in determining the natural relationship of species, and is finding application in such fields as genetics, speciation, and wildlife management. There is a sizeable literature on fish hybrids. For treatment in detail of American cyprinid hybrids, see especially Hubbs and Schultz (1931), Shultz and Schaefer (1936), Raney (1940a, 1940b), Hubbs and Miller (1943), Hubbs (1951), and Hubbs and Bailey (1952). For catostomid hybrids see Hubbs, Hubbs, and Johnson (1943), Hubbs and Hubbs (1947), wand Hubbs and Miller (1953). For centrarchid hybrids see Radcliffe (1914), Hubbs (1920), Hubbs and Hubbs (1931, 1932, 1933), Thompson (1935), and Bailey and Lagler (1938). Among the fishes collected during two years in the Columbia River drainage of western Montana are three intergeneric minnow hybrids that have hitherto not been recorded. They are the crosses Mylocheilus caurinum x Ptychochadlus oregonense, Ptbychocheilus oregonense x Richardsonius balteatus, and Rhinichthys cataractae x Richardsonius balteatus.1 The hybrids were recognized as such by their intermediacy in characters that differentiate their parental species, and this was confirmed by other criteria, such as those discussed by Hubbs, Hubbs, and Johnson (1943). Their identifications were generously verified by Dr. Reeve M. Bailey of the University of Michigan Museum of Zoology. Most of the measurements and counts in the comparing of the hybrids with the parental species were taken according to methods outlined by Hubbs and Lagler (1947). Procedures that do not follow the system of these authors are noted in the tables. The ratios of all measurements were made by mathematical division rather than by stepping over the surface. The hybrid index used in the tables and discussions is a means introduced by Hubbs and Kuronuma (1942) to express simply the relationship of the traits of the hybrid to those of the parental species. Each value for the one parental type is set at 0, and that of the other at 100. A Hybrid index of 50 denotes exact intermediacy between parental types. The recommendation is to set at 0 the value for the presumably more primitive of the parental species. Mylocheilus seems more primitive than Ptychocheilus, Richardsonius more so than Ptychocheilus, and Rhinichtbys more so than Richardsdnius.