Extensive karyotype variability of African fish genus Nothobranchius (Cyprinodontiformes)

Abstract

Karyotypes of 65 species of the genus Nothobranchius Peters, 1868 were reviewed and of those 35 examined first time. The results of present study have shown that fishes of the genus Nothobranchius possessed highly diverse karyotypes. The diploid chromosome number (2n) ranged from 16 to 50. The most frequent 2n was 2n = 36 (in 35 species) while the second one 2n = 38 (in 13 species). Proportion of biarmed chromosomes varied from 0 to 95% between species. Diploid chromosome number variability apparently exists as a result of chromosomal fusions or fissions and extensive karyotypic formula alterations promoting by inversions. Multiple sex chromosomes of system X1X1X2X2/X1X2Y type were found only in karyotypes of 5 species. The extensive karyotype variability, unusual for teleosts, of genus Nothobranchius can be likely associated with the characteristics of its life cycle and inhabiting under unstable environment of East African savannah temporal pools.

Cytogenetics of the small-sized fish, Copeina guttata (Characiformes, Lebiasinidae): Novel insights into the karyotype differentiation of the family

“…CGH focusing on male and female comparison revealed no differences in repetitive DNA accumulations in either sex, suggesting either the absence of a sex-chromosome system in this species or its cryptic nature that might escape recognition due to the limitations in resolution of the method. It would be not surprising as morphologically undistinguishable sex chromosomes may appear in fish lineages where otherwise taxa with multiple sex chromosomes occasionally appear (for example, in annual killifishes of the genus Nothobranchius ; [68,69]). In fact, till now only P .…”

Multiple sex chromosomes in teleost fishes from a cytogenetic perspective: state of the art and future challenges

“…The other orders do not differ significantly from the average. At the genus level, the highest number of multiple sex chromosomes (six) has so far been reported in African annual killifish Nothobranchius ( figure 1 ; electronic supplementary material, table S1; [ 71 , 72 ]). Some not well supported or even inconsistent reports, such as in the goby Awaous flavus and the doryfish Zeus faber (electronic supplementary material, table S1), would benefit from a re-examination, as well as several other speculative cases of putative sex-linked chromosome polymorphisms reported, e.g.…”

Deciphering the Origin and Evolution of the X1X2Y System in Two Closely-Related Oplegnathus Species (Oplegnathidae and Centrarchiformes)

“…Including Oplegnathus , about 60 cases of multiple sex chromosomes have so far been reported across the teleost phylogeny (reviewed in [13], for more recent examples, see [30,31,32,33,34,35,36,37,38,39]). In this context, molecular cytogenetics provides a powerful toolbox for understanding the genome evolution and organization [40,41,42], and many of these approaches have enabled unique insights into the vertebrate sex chromosome evolution.…”