Floral specialization and angiosperm diversity: Phenotypic divergence, fitness trade-offs, and realized pollination accuracy

Plant reproduction by means of flowers has long been thought to promote the success and diversification of angiosperms. It remains unclear, however, how this success has been come about. A recent review by Scott Armbruster published in AoB PLANTS considers the role of reproductive factors in the evolutionary success of flowering plants, with emphasis on flowers and pollination. Flowers are complex structures that have varying degrees of integration of parts and surprising evolutionary lability. Diversification of floral form usually accompanies plant diversification by speciation. This correlation has traditionally been interpreted as the result of floral specialization increasing speciation rates. However, another possibility is that species diversity generates selection for divergent specialized flowers when related species occur together, thereby reducing extinction rates.