Research on plant speciation with adaptive radiation in New Zealand.

作为物种形成的一种模式，适应性辐射是一种物种形成，其中一些物种是由生态适应多样化环境的单一祖先物种衍生而来的。这一过程通常发生在很短的时间内，相对较少的突变可能导致它们的形态和生态特征的巨大变化。新西兰被海洋与邻近的陆地隔绝，因此对于植物来说，很难从另一个陆地上迁徙。新西兰地处高纬度，在冰河时代，大部分土地都被冰川覆盖。因此，新西兰植物区系是研究植物适应性辐射的良好模式。我们研究了卫矛科(Asteraceae)和凤尾蕨科(Hymeonophyllaceae)在新西兰的物种形成模式，这两种植物都包括许多新西兰特有的物种。在卫矛科，一种被估计属于一个组的原始植物可以从菊科迁徙到新西兰，然后在新西兰多样化。然后，从这个群体中，凯尔米西亚的祖先将在随后的大范围适应性辐射中衍生出来。凯尔米西亚的澳大利亚种约有10种，估计是从新西兰迁徙而来的单一祖先种衍生而来。另一方面，在膜藻科中，一些种在其系统发育树上已经在底部分枝，另一些种则是较新的。

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.