The genomic architecture of sexual dimorphism in the dioecious plant Silene latifolia

Abstract

Evaluating the genetic architecture of sexual dimorphism can aid our understanding of the extent to which shared genetic control of trait variation versus sex-specific control impacts the evolutionary dynamics of phenotypic change within each sex. We performed a QTL analysis on Silene latifolia to evaluate the contribution of sex-specific QTL to phenotypic variation in 46 traits, whether traits involved in trade-offs had colocalized QTL, and whether the distribution of sex-specific loci can explain differences between the sexes in their variance/covariance matrices. We used a backcross generation derived from two artificial-selection lines. We found that sex-specific QTL explained a significantly greater percent of the variation in sexually dimorphic traits than loci expressed in both sexes. Genetically correlated traits often had colocalized QTL, whose signs were in the expected direction. Lastly, traits with different genetic correlations within the sexes displayed a disproportionately high number of sex-specific QTL, and more QTL co-occurred in males than females, suggesting greater trait integration. These results show that sex differences in QTL patterns are congruent with theory on the resolution of sexual conflict and differences based on G-matrix results. They also suggest that trade-offs and trait integration are likely to affect males more than females.