Biodiversity and evolution of terrestrial flora in Antarctica.

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Growth environment, geohistory, morphological diversity, and molecular systematics were investigated on mosses in Syowa station area, Antarctica, especially on aquatic mosses at the bottom of lakes.Water temperature at the lake bottom was +7℃ in austral summer, and +7℃ even in winter. Because of little snow accumulation in this region, the sun light easily permeate through surface ice cover to plants growing at the lake bottom, strongly enough for photosynthesis between October to April. Salinity of lake water was variable among lakes, and nutrients are quite low. Flora in Antarctic lakes was characterized by little amount of plankton and rich benthic vegetation a the bottom. Most part of the lake bottom was covered with population of filamentous cyanobacteria and some green algae and diatoms. Sediments of these plants and sands were analyzed to clarify the age of lakes and history of lake environments.Molecular systematic study was carried out on two aquatic mosses, Bryum sp. and Leptobryum sp. Aquatic Bryum was thought to originated from terrestrial B.pseudotriquetrum, but terrestrial B.pseudotriquetrum itself must be changed its name to B.pallescens distributing in Antarctic peninsula and out of Antarctica. Genetic diversity of aquatic Leptobryum was included in wide diversity range of L.pyriforme known as weedy species in all around the world.