C. C. Davis, P. K. Endress, and D. A. Baum. 2008. “
The evolution of floral gigantism.” Curr Opin Plant Biol, 11, Pp. 49-57.
AbstractFlowers exhibit tremendous variation in size (>1000-fold), ranging from less than a millimeter to nearly a meter in diameter. Numerous studies have established the importance of increased floral size in species that exhibit relatively normal-sized flowers, but few studies have examined the evolution of floral size increase in species with extremely large flowers or flower-like inflorescences (collectively termed blossoms). Our review of these record-breakers indicates that blossom gigantism has evolved multiple times, and suggests that the evolutionary forces operating in these species may differ from their ordinary-sized counterparts. Surprisingly, rather than being associated with large-bodied pollinators, gigantism appears to be most common in species with small-bodied beetle or carrion-fly pollinators. Such large blossoms may be adapted to these pollinators because they help to temporarily trap animals, better facilitate thermal regulation, and allow for the mimicry of large animal carcasses. Future phylogenetic tests of these hypotheses should be conducted to determine if the transition to such pollination systems correlates with significant changes in the mode and tempo of blossom size evolution.
PDF C. C. Davis. 2008. “
Floral evolution: dramatic size change was recent and rapid in the world's largest flowers.” Curr Biol, 18, Pp. R1102-4.
AbstractRecent studies clarifying the closest relatives of the world's largest flowers, Rafflesiaceae, whose floral diameters range from approximately 11 to approximately 100 cm, indicated that they evolved from tiny-flowered ancestors in a burst of floral gigantism. New data now suggest that floral size evolution within Rafflesiaceae may be more dynamic than expected, with both recent and rapid changes in flower size.
PDF C. G. Willis, B. Ruhfel, R. B. Primack, A. J. Miller-Rushing, and C. C. Davis. 2008. “
Phylogenetic patterns of species loss in Thoreau's woods are driven by climate change.” Proc Natl Acad Sci U S A, 105, Pp. 17029-33.
AbstractClimate change has led to major changes in the phenology (the timing of seasonal activities, such as flowering) of some species but not others. The extent to which flowering-time response to temperature is shared among closely related species might have important consequences for community-wide patterns of species loss under rapid climate change. Henry David Thoreau initiated a dataset of the Concord, Massachusetts, flora that spans approximately 150 years and provides information on changes in species abundance and flowering time. When these data are analyzed in a phylogenetic context, they indicate that change in abundance is strongly correlated with flowering-time response. Species that do not respond to temperature have decreased greatly in abundance, and include among others anemones and buttercups [Ranunculaceae pro parte (p.p.)], asters and campanulas (Asterales), bluets (Rubiaceae p.p.), bladderworts (Lentibulariaceae), dogwoods (Cornaceae), lilies (Liliales), mints (Lamiaceae p.p.), orchids (Orchidaceae), roses (Rosaceae p.p.), saxifrages (Saxifragales), and violets (Malpighiales). Because flowering-time response traits are shared among closely related species, our findings suggest that climate change has affected and will likely continue to shape the phylogenetically biased pattern of species loss in Thoreau's woods.
PDF