Phadnis N, Orr HA (2009) A single gene causes both male sterility and segregation distortion in Drosophila hybrids. Science 323: 376-379. [link]
Segregation distorter (also referred to as meiotic drive) is a selfish genetic element that is preferentially transmitted to subsequent generation by distorting the 50:50 Medelian segregation. If such gene is located on X chromosome, offspring sex ratio of the XY male would be biased toward female. If such alleles spread in the population, suppressors against segregation distortion become easier to spread. So, segregation distorter and its suppressor can be both fixed in the population. In such situation, violation against Mendelian rule can never be observed unless hybridization between different populations occurs.
In the fruitfly Drosophila pseudoobscura, segregation distortion of the X chromosome is observed by hybridization between different subspecies. This is never observed within subspecies.
In this paper, a single gene, called overdrive, was found to cause hybrid male sterility (a kind of post-mating reproductive isolation) between subspecies, and this very gene was also found to cause segregation distortion.
Although this result is not a proof for speciation by the selfish genetic element, such scenario seems very likely.
Readers who are interested in this paper may also be interested in the following paper:
- Bordenstein SR, O'Hara FP, Werren JH (2001) Wolbachia-induced incompatibility precedes other hybrid incompatibilities in Nasonia. Nature 409: 707-710. [link]
