Cytogenetic studies in North American minnows(Cyprinidae). VII. Karyotypes of 13 species from the southern united states.

Abstract

Karyotypes of 13 spp. of cyprinid fishes [Semotilus atromaculatus, Dionda episcopa, Notropis atrocaudalis, N. amabilis, N. atherinoides, N. potteri, N. stramineus, N. camurus, Pimephales promelas, Ericymba buccata, Hybognathus nuchalis, Nocomis leptocephalus and Hybopsis amblops] endemic to North America were examined. All 13 have diploid complements of 50 chromosomes. Arm numbers were estimated for 10 spp. and varied from 46-50 (haploid). The pattern and extent of karyotypic diversity among these 13 spp. is typical of all North American cyprinids assayed to date. Almost all species have n = 25 chromosomes and variation in arm number is minimal. The conservatism in gross karyotype among these fishes is not commensurate with their apparently rapid and extensive radiation, and suggests that major chromosomal change has played only a minor role in cyprinid evolution.