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. K E Y W O R D S :Artificial selection, genetic correlations, linkage map, sex-specific expression, sexual conflict.

Expansion of the Pseudo-autosomal Region and Ongoing Recombination Suppression in the Silene latifolia Sex Chromosomes

“…latifolia PAR: Unlike the previously published map, which used dominant AFLP markers and inferred two PARs (Scotti and Delph 2006;Delph et al 2010), our map, with a new set of mostly codominant markers, finds only a single PAR. This suggests that more study is needed before the existence of a second PAR is accepted, particularly as cytological studies consistently report terminal pairing of the X and Y chromosomes (e.g., Zluvova et al 2007;Filatov et al 2008), except in chromosome mutants (e.g., Westergaard 1946Westergaard , 1948aZluvova et al 2007).…”

“…Those that have been mapped and sequenced from the X and Y demonstrate the existence of at least two evolutionary strata (Bergero et al 2007). Genic markers are preferable to anonymous ones such as AFLPs, the basis for the only previous dense genetic mapping in this species (Delph et al 2010), because codominant markers, such as SNPs and intron-size variants, are more reliable (e.g., Vekemans et al 2002) and allow integration of maps from both parents of a cross (e.g., Lorieux et al 1995a) and construction of consensus maps from multiple families. It is also easier with codominant markers to map individual loci, even when duplicates exist.…”

The effects of inbreeding, genetic dissimilarity and phenotype on male reproductive success in a dioecious plant

“…Such antagonistic selection has been shown to be common and relatively strong in many species, in particular for reproductive traits [74]. As many quantitative trait loci involved in dimorphic traits are autosomal [75], the alleles will be found in males and in females, facing opposite selective pressures. This will contribute to maintaining a fair level of diversity for these traits.…”

Origin and domestication of papaya Yh chromosome

“…The sex chromosomes in other organisms, such as mammals, are ancient (Veyrunes et al 2008;Bellott et al 2014;Cortez et al 2014), and the genes involved in their initial evolution cannot be identified, because many subsequent changes, including gene gains and losses, have occurred (Hughes et al 2010(Hughes et al , 2012Zhou et al 2014). The younger sex chromosomes of some species of plants, fish, and insects may provide insights into the mechanisms involved in the early stages of the evolution of separate sexes and of sex chromosomes (Delph et al 2010;Zhou and Bachtrog 2012).…”