Genome-wide sequence divergence of satellite DNA could underlie meiotic failure in male hybrids of bighead catfish and North African catfish (Clarias, Clariidae).

Hybrid sterility, a hallmark of postzygotic isolation, arises from parental genome divergence disrupting meiosis. While chromosomal incompatibility is often implicated, the underlying mechanisms remain unclear. This study investigated meiotic behavior and genome-wide divergence in bighead catfish (C. macrocephalus), North African catfish (C. gariepinus), and their sterile male hybrids (important in aquaculture). Repetitive DNA analysis using bioinformatics and cytogenetics revealed significant divergence in satellite DNA (satDNA) families between parental species. Notably, one hybrid exhibited successful meiosis and spermatozoa production, suggesting potential variation in sterility expression. Our findings suggest that genome-wide satDNA divergence, rather than chromosome number differences, likely contributes to meiotic failure and male sterility in these catfish hybrids. • This study identifies meiotic failure as the primary cause of sterility in bighead catfish-North African catfish hybrids. • Chromosomal incompatibility likely causes hybrid sterility due to partial or complete absence of homologous chromosome synapsis. • Divergence in satellite DNA, like bighead catfish satDNA in a North African catfish, suggests repetitive DNA's role in reproductive isolation. • Interspecific satDNA transfer indicates possible limited genetic exchange events between these catfish species. [ABSTRACT FROM AUTHOR]