Epistasis among Drosophila persimilis Factors Conferring Hybrid Male Sterility with D. pseudoobscura bogotana

Abstract

The Bateson-Dobzhansky-Muller model posits that hybrid incompatibilities result from genetic changes that accumulate during population divergence. Indeed, much effort in recent years has been devoted to identifying genes associated with hybrid incompatibilities, often with limited success, suggesting that hybrid sterility and inviability are frequently caused by complex interactions between multiple loci and not by single or a small number of gene pairs. Our previous study showed that the nature of epistasis between sterility-conferring QTL in the Drosophila persimilis-D. pseudoobscura bogotana species pair is highly specific. Here, we further dissect one of the three QTL underlying hybrid male sterility between these species and provide evidence for multiple factors within this QTL. This result indicates that the number of loci thought to contribute to hybrid dysfunction may have been underestimated, and we discuss how linkage and complex epistasis may be characteristic of the genetics of hybrid incompatibilities. We further pinpoint the location of one locus that confers hybrid male sterility when homozygous, dubbed “mule-like”, to roughly 250 kilobases.

Neighboring genes for DNA-binding proteins rescue male sterility in Drosophila hybrids

“…In effect, hybrid males of D. simulans and D. mauritiana are sterile 15 times over. The factors do not act independently, however: epistasis among incompatibility genes is pervasive (7,29,70).…”

“…Additionally, even when only one sex is sterile or lethal, the number of genes contributing to hybrid incompatibility is usually large and their interactions complex (5)(6)(7)(8).…”

The genetics of speciation: are complex incompatibilities easier to evolve?

“…(), Chang & Noor (), Chang et al . (); 5 Orr & Coyne (), Spicer & Bell (); 6 Mills et al . (), Vigneault & Zouros (); 7 Sawamura et al .…”

The Adaptive Potential of Hybridization Demonstrated with Bacteriophages

“…Heterosis, or hybrid vigor, has been observed in a variety of plant and animal taxa, where hybrids of distinct genotypes or species yield offspring possessing greater fitness than either parent (Chen 2010). In contrast, hybridization yielding low-fitness or inviable progeny (Rokyta and Wichman 2009) contributing to postzygotic isolation has also been well documented in many taxa, and is generally more frequently observed than heterosis (Orr and Irving 2001; Coyne and Orr 2004; Chang et al 2010; Kubo et al 2011; Burkart-Waco et al 2012; Janousek et al 2012). …”

“…One of the primary causes of postzygotic isolation is the effect of the deleterious disruption of epistatic interactions in hybrid backgrounds (Burke and Arnold 2001; Orr and Irving 2001; Presgraves 2007; Rokyta and Wichman 2009; Chang et al 2010; Maheshwari and Barbash 2011). Epistasis can result in hybrids with poor fitness, while heterosis is more likely in cases where hybrid offspring benefit from the segregation of beneficial additive genetic factors and are less subject to debilitating epistatic effects (Burke and Arnold 2001; Barton 2001).…”