D.Mauritiana D.Simulans hybrid
We explored the relation between Y chromosome rapid divergence during evolution and hybrid male sterility. The mechanism of how divergent Y chromosomes may lead to male sterility is not clearly understood. By performing total RNA-sequencing on male hybrids between D. simulans and D. mauritiana, we show that hybrids fail to express Y-linked genes required for fertility. These Y-linked fertility genes possess gigantic introns ranging from kilobases to megabases, which diverge considerably between species. We propose that failure to splice these introns leads to the defective expression of fertility genes and thus hybrid male infertility.