Linking genomic variation to floral trait adaptation across species boundaries

Flowers are highly diverse in shape, scent, and colour and may differ strikingly even among closely related species. Floral traits experience correlational selection favouring trait combinations that maximise plant reproduction, leading to outstanding questions on how floral trait divergence evolves in closely related species. In this review, we take a quantitative genetic perspective and ask whether and how the genetic architecture of floral trait divergence depends on adaptation to specific pollination systems and how it informs on the dynamics of the assembly of floral traits during divergence. After reviewing results from studies mapping divergent floral traits in closely related species, we emphasise the value of combining trait mapping approaches with approaches that identify genomic variation differentiating species boundaries. We show how the combination of these approaches has been successful in recent studies and how it could improve our understanding of floral diversification.