Non-equilibrium dynamics and floral trait interactions shape extant angiosperm diversity.

Why are some traits and trait combinations exceptionally common across the tree of life, whereas others are vanishingly rare? The distribution of trait diversity across a clade at any time depends on the ancestral state of the clade, the rate at which new phenotypes evolve, the differences in speciation and extinction rates across lineages, and whether an equilibrium has been reached. Here we examine the role of transition rates, differential diversification (speciation minus extinction) and non-equilibrium dynamics on the evolutionary history of angiosperms, a clade well known for the abundance of some trait combinations and the rarity of others. Our analysis reveals that three character states (corolla present, bilateral symmetry, reduced stamen number) act synergistically as a key innovation, doubling diversification rates for lineages in which this combination occurs.

Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora.

Background: The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora--South Africa's biodiversity hotspot--through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years.

Floral organogenesis and the developmental basis for pollinator deception in the asiatic dayflower, Commelina communis (Commelinaceae).

The upper half of flowers in Commelina communis deceptively lures potential pollinators with its showy petals and staminodes on the false promise of abundant pollen. This paper presents evidence that staminodization in the upper half is associated with a severe retardation of the entire upper floral hemisphere early in development. Possible consequences of this developmental retardation are seen also in the gynoecium, where the upper carpel of the three-carpellate ovary is underdeveloped and sterile at maturity.

Intraspecific variability and timing in ancestral ecology reconstruction: a test case from the cape flora.

Thamnochortus (ca. 32 species) is an ecologically diverse genus of Restionaceae. Restionaceae comprise a major component of the southern African Cape flora, wherein eco-diversification might have been important in the generation of high levels of species richness.

Taxon sampling effects in molecular clock dating: an example from the African Restionaceae.

Three commonly used molecular dating methods for correction of variable rates (non-parametric rate smoothing, penalized likelihood, and Bayesian rate correction) as well as the assumption of a global molecular clock were tested for sensitivity to taxon sampling. The test dataset of 6854 basepairs for 300 terminals includes a nearly complete sample of the Restio-clade of the African Restionaceae (272 of the 288 species), as well as 26 outgroup species. Of this, nested subsets of 35, 51, 80, 120, 150, and the full 300 species were used.