A study of evolution of plants in South Pacific islands

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The purpose of the present study is to contribute to better understanding of evolution and reproductive mechanisms of plant species growing in South Pacific islands. Our output is as follows.1. We presented the first embryological study of Amborella trichopoda representing the first branch of angiosperm evolution, which is an endemic species in New Caledonia. Compared to already known information on Nymphaeales and Illiciales which represent branches next to Amborella, symplesiomorphies of embryological characters were clarified. (Tobe et al. 2000).2. We presented the first karyotype analysis in Amborella trichopoda. It has 2n=26 with x=13. Based on analyses, we discussed that the chromosome number of Amborella is likely to have been derived from x=14 and that a primitive chromosome number of angiosperms is likely to be x=7. (Oginuma et al. 2000).3. A review of embryological studies on Laurales which are distributed worldwide in tropics of Old and New World including South Pacific isla … More nds was presented on the basis of a literature survey. In addition, in the light of molecular trees available for the Laurales, we tried to discuss an evolution of embryological characters, and simultaneously clarified what plant groups and what embryological characters need investigations. (Kimoto and Tobe 2001).4. An overall phylogenetic study of Casuarinaceae that are distributed in South Pacific islands (and Australia) was conducted for the first time using chloroplast DNA sequences of rbcL and matK. Results showed relationships like (Gynmostoma (Ceuthostoma (Allocasuarina Casuarina))). (Sogo et al. 2001).5. We analyzed floral scent in 8 species of 8 genera growing hi mangrove of Iriomote islands, Japan for the first time. We found 61 chemical compounds and discussed relationships with polinators. (Azuma et al. 2002).6. Fourteen species of Begonia from Taiwan were analyzed with respect to karyotypes of their somatic chromosomes for the first time. Based on results, we discussed their evolution, and clarified that 5 new species exist in Taiwan. (Oginuma and Peng 2002). Less