Nearly all of these genotypes have been observed in field collected flies, although others exist as well (Hamm et al. 2005; Hamm and Scott 2008, 2009). In theory, any of the five autosomes could exhibit these genotypes and produce the same proportion of male offspring (e.g., III^M/III^M or V^M/V^M both produce only male progeny in the absence of Md-tra^D).