Angiosperm diversification

Crane P.R., Lidgard S. (1989) Angiosperm diversification and paleolatitudinal gradients in Cretaceous floristic diversity. 

Crane, P. R. (1987) Vegetational consequences of angiosperm diversification. In The Origins of Angiosperms and their Biological Consequences (ed. E. M. Friis, W. G. Chaloner and P. R. Crane). Cambridge University Press, Cambridge, pp. 107-144. 

Friis, E. M., Pedersen, K. R. and Crane, P. R. (1999) Early angiosperm diversification The diversity of pollen associated with angiosperm reproductive structures in Early Cretaceous floras from Portugal. Annals of the Missouri Botanical Garden, 86 259-296. 

One of the hypotheses regarding evolutionary aspects of flavonoid diversification concerns the concept of flavonol accumulation in basal Angiosperms versus flavone accumulation in advanced families. Recently, some further efforts have been made towards defining the flavone/flavonols ratio in Dicotyledonae and their relation to lignification, indicating an increased tendency towards flavonol accumulation in lignified plants, whereas herbaceous species tend to accumulate more of the flavones. From the presented entries, it appears that flavone derivatives are more abundant in Lamiaceae than flavonols. In the Asteraceae, however, more data concern the flavonols. Both families are more or less herbaceous and members of the more advanced Angiosperms. 

In order to understand fully the importance of these chemical factors, it is necessary to consider the processes which are probably responsible for their diversification. A mechanism of coevolution of insects and plants was set forth eloquently by Erlich and Raven (4). According to their hypothesis, angiosperms produced a series of chemical compounds which were not directly related to their basic (or primary) metabolic pathways, but which were otherwise not harmful to the plants growth and development. 

Cretaceous 138 Ma Most continents widely separated continued radiation of dinosaurs angiosperms and mammals begin diversification mass extinction at end of period... 

The origin and diversification of angiosperms. American Journal of Botany, 91, 1614-1626. 

Molecular mechanisms underlying origin and diversification of the angiosperm flower. Annals of Botany, 100, 603-619. 

Specht, C. D. and Bartlett, M.E. (2009). Flower evolution the origin and subsequent diversification of the angiosperm flower. Annual Review of Ecology and Systematics, 40, 217-243. 

TRACING THE EARLY EVOLUTIONARY DIVERSIFICATION OF THE ANGIOSPERM FLOWER 89... 

TRACING THE EARLY EVOLUTIONARY DIVERSIFICATION OE THE ANGIOSPERM FLOWER 103... 

Tracing the early evolutionary diversification of the angiosperm flower, pp. 85-117 in Wanntrop, L., Ronse De Craene, (eds.). Flowers on the Tree of Life. Cambridge Cambridge University Press. 

The undoubted pleurocarps, however, are almost absent or at least extremely rare in earlier deposits. This fact, along with the other evidence, leads to the tentative conclusion (e.g.. Buck, 1991), that the evolution of pleurocarps followed the habitat diversification of the angiosperms, i.e., occurred in the Cretaceous. At the same time, an analysis of fossil data lead Krassilov and Schuster (1984) to the conclusion that the pleurocarpous mosses appeared no earlier than the Jurassic. 

The appearance of pleurocarpy was dated at 194-161 mya, significantly earlier than the radiation of the majority of pleurocarp lineages about 165-131 mya. This radiation coincides with the diversification of the angiosperms in the Early Cretaceous, but predates appearance of complex angiosperm forests in the early Cenozoic. The hypothesis that pleurocarpous mosses evolved to exploit the angiosperm forests is modified — pleurocarpous mosses diversified in the same time frame as the early angiosperms and the recovered pattern suggests a putative correlation of these diversification events. 

Estimates of species-, genus- and family-level diversity in different lineages are summarized in Table 17.3, with classification based in part on that of Gofflnet and Buck (2004), and in part on Crosby et al. (1999). Temporal variation in rates of diversification was evaluated in a LTT plot and reported in Figure 17.2. The plot is calculated across all age estimates obtained for the 100 trees randomly drawn from the posterior distribution. For comparison, corresponding curves calculated for angiosperms and polypod ferns by Schneider et al. (2004) are included in Figure 17.2. 

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