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Whole-genome duplications are radical evolutionary events that have driven speciation and adaptation in many taxa. Higher-order polyploids have complex histories often including interspecific hybridization and dynamic genomic changes. This chromosomal reshuffling is poorly understood for most polyploid species, despite their evolutionary and agricultural(More)
We explored the idea that sex ratio represents a unique context for selection on attractive traits by manipulating sex ratio and pollinator abundance in experimental populations of a gender-dimorphic wild strawberry Fragaria virginiana. We found that increasing the frequency of functional males (the pollen-bearing morph) increased the frequency of(More)
Sex chromosomes differ from other chromosomes in the striking divergence they often show in size, structure, and gene content. Not only do they possess genes controlling sex determination that are restricted to either the X or Y (or Z or W) chromosomes, but in many taxa they also include recombining regions. In these 'pseudoautosomal regions' (PARs),(More)
The number of ovules per flower varies over several orders of magnitude among angiosperms. Here we consider evidence that stochastic uncertainty in pollen receipt and ovule fertilization has been a selective factor in the evolution of ovule number per flower. We hypothesize that stochastic variation in floral mating success creates an advantage to producing(More)
Hyperaccumulation is the phenomenon whereby plants take up and sequester in high concentrations elements that generally are excluded from above-ground tissues. It largely is unknown whether the metals taken up by these plants are transferred to floral rewards (i.e., nectar and pollen) and, if so, whether floral visitation is affected. We grew Streptanthus(More)
■ Abstract Quantifying the extent to which seed production is limited by the availability of pollen has been an area of intensive empirical study over the past few decades. Whereas theory predicts that pollen augmentation should not increase seed production, numerous empirical studies report significant and strong pollen limitation. Here, we use a variety(More)
Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved. In fact, males and females are determined by diverse mechanisms that evolve rapidly in many taxa. Yet this diversity in primary sex-determining(More)
To understand how genetic constraints may limit the evolution of males and sexual dimorphism in a gynodioecious species, I conducted a quantitative genetic experiment in a gynodioecious wild strawberry, Fragaria virginiana. I estimated and compared genetic parameters (narrow-sense heritabilities, between-trait and between-sex genetic correlations, as well(More)
Gynodioecy is a sexual system wherein females coexist with hermaphrodites. It is of interest not only because male-sterile plants are advantageous in plant breeding but also because it can be a crucial step in the evolutionary transition to entirely separate sexes (dioecy) from a hermaphroditic ancestor. The gynodioecious diploid wild strawberry, Fragaria(More)
Gynodioecious plants exhibit modest sexual dimorphism in vegetative and phenological traits, which stands in stark contrast to pronounced dimorphism in reproductive traits. I evaluate the roles of limited genetic variation, negative genetic covariation (within and between sex morphs), and lack of gender-differential selection in contributing to minimal(More)