Research on plant speciation with adaptive radiation in New Zealand.

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One of the modes of speciation, an adaptive radiation is a speciation in which some species have derived from single ancestral species with ecological adaptation to diversified environments. This process generally has occurred within short times, and relatively small numbers of mutation could be responsible to large changes in their morphology and ecological characteristics. New Zealand has been isolated from the adjacent landmass by the ocean, and thus for the plants, it is very hard to migrate from the other landmass. New Zealand is located in high latitude, and in glacial ages, a large part of the land had been covered with glaciers. Thus, the flora of New Zealand is a good model for studying plant adaptive radiation. We examined the mode of speciation in New Zealand for Celmisia (Asteraceae) and Hymeonophyllaceae (Pteridophyte), both of which includes many species endemic to New Zealand.In Celmisia, an ancestral plant, which had estimated to be belong to one group of Olearia, could be migrated from Asustralia, and then diversified in New Zealand. Then, from this group, the ancestors of Celmisia would be derived with following large scale of adaptive radiation. The Australian species of Celmisia, consisting about 10 species, are estimated to be derived from the single ancestor species migrated from New Zealand.On the other hand, in Hymenophyllaceae, some species had been branched at base in their phylogenetic tree, and the others are derived relatively recently.