杜鹃花科白珠树属分子系统学和生物地理学研究进展

白珠树属(Gaultheria) 在杜鹃花科(Ericaceae)系统演化中占有十分重要的地位, 其系统位置和演化关系一直备受争议。最近的分子系统学研究认为, 白珠树属已经不再属于传统上的越橘亚科(Vaccinioideae)的綟木族(Andromedeae), 而是与一些相关属组成了白珠树族(Gaultherieae)。对白珠树属产于美洲的类群和相关类群的分子系统学的初步研究则表明, 该属与Diplycosia、Tepuia和Pernettya等属(均为“常绿类群”)关系密切, 可能应将这几个属并入到白珠树属中, 但其属下分类系统关系还需要对产于亚洲的类群进行深入的研究后才能确定。白珠树属与其近缘属的进化历史和生物地理学关系较为复杂, 与杜鹃花科其他大多数属不同, 白珠树属为典型的环太平洋分布。关于白珠树属的起源问题存在两种不同的推测: 一种观点认为该属起源于南半球的冈瓦纳古陆; 另一种观点则认为其起源于北半球的劳亚古大陆。本文概述了近年来白珠树属的分子系统学和生物地理学研究进展, 并对该属尚存的一些问题进行了讨论。

Advances in Molecular Phylogenetics and Biogeography of Gaultheria (Ericaceae)

The genus Gaultheria has played an important role in the evolution of the family Ericaceae. However, agreement is lacking on the systematic position and relationships of and within Gaultheria. On the basis of molecular data, Gaultheria is not a member of the tribe Andromedeae in which it was traditionally treated but is in a tribe of its own, Gaultherieae, along with other related genera. Molecular analyses of samples of the genus from America and related genera have revealed that Gaultheria could be considered paraphyletic if the closely related genera of the “wintergreen group”, i.e., Diplycosia, Tepuia and Pernettya, are excluded. These genera should be treated as part of Gaultheria; however, an infrageneric system of the genus may not be well established without sampling the Asian members of the genus. Phylogenetic analyses have revealed that the evolutionary history and biogeography of Gaultheria and its allied genera are fairly complicated, because Gaultheria is widespread, being a typical amphipacific genus, in terms of the modern geographic disjunction. Speculating on the origin of Gaultheria, two different hypotheses were suggested, one of Gondwanan origin, and the other of Laurasian origin. In the present paper, recent advances in molecular phylogenetics and biogeography of Gaultheria are summarized and some problematical issues within the genus discussed.