REPRODUCTIVE EVOLUTION AND PHYLOGENY OF THE LECYTHIDOIDEAE (LECYTHIDACEAE)
Lecythidoideae, the New World Lecythidaceae, comprising of 10 genera and ca. 200 species, are an important woody group of the flora throughout the northern part of South America. Various aspects of this subfamily have been intensively studied in the last 30 years mainly by Dr. Scott Mori from the New York Botanical Garden and his collaborators, including the author; however, the phylogeny of this subfamily is obscure and the circumscriptions of a few genera are still problematic. Lecythidoideae are famous for their extraordinary and complex floral morphology, the remarkable monosymmetric androecium is unique in the angiosperms.
In an attempt to clarify the taxomonic problems and intergeneric relationships, floral organogenesis by using SEM and DNA sequence analysis are concurrently applied to all the 10 genera of the subfamily. A four-leveled phylogenetic scheme is highly supported and many important floral features show compatible evolutionary trends with the scheme. The basal group of the subfamily, level 1, comprises the polysymmetric Grias and Gustavia. Transition of floral conformation to monosymmetric pattern was established in level 2 by the evolving of abaxial superiority and the prominent androecial hood, which was firstly expressed in Couroupita. In level 3, the androecium further developed disc-like rim at the adaxial side, as seen in Couratari. In level 4 the monosymmetry was reinforced by the evolving of median depression of the receptacle; in addition, not only XY plane but also Z plane were involved in the establishment of the floral monosymetry. The most specialized features are to be found in Corythophora, Eschweilera, and Lecythis. It is suggested that the diversified fauna of pollinators has played a crucial role in evolution of Lecythidoideae.
PHYLOGEOGRAPHY OF EURYA (TERNSTROEMIACEAE) FROM TAIWAN AS INFERRED FROM ITS SEQUENCES
Eurya is the largest genus among the five genera of Ternstroemiaceous in Taiwan. In an attempt to understand the interspecies relationships and the major phytogeographical events of the 14 Eurya species in Taiwan, 115 samples from 33 Eurya species, including all the Eurya species occurring in Taiwan and samples from the Ryukyus, continental China, and Southeast Asia, were sequenced at the nuclear ITS region. Species of five other genera of Ternstroemiaceae were also incorporated. Molecular phylogenetic trees show that the Eurya species studied form a monophyletic group. These 33 Eurya species are clustered into five clades with geographical constraints. Among them, Eurya species from the Ryukyus and Taiwan all together constitute two coherent but distantly related clades: the RT (Ryukyu-Taiwan) endemic clade stands at a basal position, which includes E. glaberrima, E. gnaphalocarpa, E. rengechiensis, E. strigillosa and E. yaeyamensis, they are probably Tertiary elements of northern China or their direct descendants. The other clade, the RT (Ryukyu-Taiwan) dominant clade, is the most derived among the five clades; its strong affinity to the current Eurya in southeast China suggests that the members are probably originated from the Quaternary flora of southeast China. Two major phases of floristic acquirement in Taiwan are proposed, i.e., the early Pleistocene and the late Pleistocene. Spatial isolation between closely related species pairs and ecological partitioning are thought to be two major mechanisms for the endemism of Eurya species in Taiwan and the Ryukyus.
Tsou, C.-H., and Fu, Y. L. 2002. Pollen tetrad formation in Annona (Annonaceae): proexine formation and binding mechanism. Amer. J. .Bot. 89: 734-747.
Tsou, C.-H., and Mori, S. A. 2002. Seed coat anatomy and its correlation with seed dispersal in the subfamily Lecythidoideae of Lecythidaceae (the Brazil nut family). Bot. Bull. Acad. Sinica 43: 37-56.
Wu, C.-C., Hsu, Z.-F., and Tsou, C.-H. 2003. Studies of Eurya (Ternstroemiaceae) in Taiwan (1), a new endemic species, Eurya septata. Bot. Bull. Acad. Sinica 44: 67-72.
Tsou, C.-H., and Johnson, D. M. 2003. Comparative development of aseptate and septate anthers of Annonaceae. Amer. J. Bot. 90: 832-848.
Shih, M. D., Lin, S. C., Hsieh, J. S., Tsou, C.-H., Chow, T.-H., Lin, T.-P., and Hsing, Y.-I. C. 2004. Physiological and biophysical characteristics of a novel soybean maturation gene, GmPM16. Plant Mol. Biol. 56: 689-703.
Tsou, C.-H., and Fu, Y.-L. 2005. Octad pollen formation in Cymbopetalum (Annonaceae): The binding mechanism. Pl. Syst. Evol. (under revision).
