Transcriber's Note
The follow suspected error has been corrected in this text: On page 3, C. erythogaster changed to C. erythrogaster.
University of Kansas Publications
Museum of Natural History
Volume 13, No. 1, pp. 1-18
June 1, 1960
Five Natural Hybrid Combinations
in Minnows (Cyprinidae)
BY
FRANK B. CROSS AND W. L. MINCKLEY
University of Kansas
Lawrence
1960
University of Kansas Publications,Museum of Natural History
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson
Volume 13, No. 1, pp. 1-18
Published June 1, 1960
University of Kansas
Lawrence, Kansas
PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1960
28-3424
Five Natural Hybrid Combinations
in Minnows (Cyprinidae)
BY
FRANK B. CROSS AND W. L. MINCKLEY
The hybrid fishes described herein are Chrosomus erythrogaster(Rafinesque) × Notropis cornutus frontalis (Agassiz), C. erythrogaster× Semotilus atromaculatus (Mitchill), Campostomaanomalum plumbeum (Girard) × S. atromaculatus, Gila nigrescens(Girard) × Rhinichthys cataractae (Valenciennes), and Notropisvenustus venustus (Girard) × Notropis whipplei (Girard). Twoof the combinations have been reported, without descriptions, inliterature (citations below), and Hubbs (1955: Fig. 3) graphicallyindicated hybridization between the same genera with which thispaper is concerned, but did not designate the species involved.
All specimens of C. erythrogaster × N. c. frontalis, C. erythrogaster× S. atromaculatus, C. a. plumbeum × S. atromaculatus,and N. v. venustus × N. whipplei were taken in a period ofsevere drought in Kansas and Arkansas. All were from small,spring-fed streams that support large populations of fishes. Thatthe drought of 1953-1956 had pronounced effects on stream habitatsin Kansas has been documented by Minckley and Cross (1959).Satisfactory sites for spawning may have been few, but an abundanceof adult fishes persisted from earlier, wet years. Unusualcrowding of spawning fishes would increase the opportunity forfertilization of the eggs of one species by sperm from anotherspecies. We think that the hybrids reported here (excepting G.nigrescens × R. cataractae) are explainable on the basis of crowding;we have no information about stream-conditions where thelast-named hybrid was found. Generally, hybridization of fishesseems most common in areas that have been subject to radicalclimatic change in the past 20,000 or fewer years (Hubbs, 1955:18-19),and in streams that have been altered recently by theactivities of man (Hubbs and Strawn, 1956:342, and others).Streams from which we report hybrids probably were affectedby overgrazing of their watersheds; overgrazing was unusuallysevere in the drought.
Most of the hybrids were recognized as unusual at the timeof capture, and were saved as part of numerically selective samples[Pg 4]from the streams (rather than being discovered in the laboratory,in random samples)