Phylogenetic Relationship Among Fifteen Kobresia Species Based On Random Amplified Polymorphic DNA

The Kobresia are dominant species in alpine meadows of the Himalayas and adjacent areas, and are an important forage grass of high economic as well as ecological value. Additionally, the genus occupies an important phylogenetic position in the tribe Cariceae. However, many of the earlier studies are based only on a limited number of herbarium specimens that do not sufficiently reflect the natural variation in populations. Also the previous studies are derived from morphological characters that can be greatly affected by environmental conditions. Because of the limitations in sampling and the variability in morphology, Phylogenetic relationships of Kobresia species have not been well resolved and may be inaccurate. In contrast to morphological traits, molecular makers are not directly influenced by environmental effects and can provide substantial amounts of information. Here we examine 47 accessions of the 15 Kobresia species to estimate genetic relationships in the genus and to reexamine previous phylogenetic efforts using RAPD markers. Simultaneously, phylogenetic position in the tribe Cariceae and infrageneric system of kobresia are evaluated by virtue of previous studies of others.The main conclusions are as follows: (1) RAPD markers are effective in constructing phylogenetic relationships among Kobresia species. (2) K. maquensis has been previously classified as an independent species, our results suggest that it should be considered a synonym of K. setchwanensis. (3) According the dendrogram, fourteen kobresia species formed two main groups. One of which comprised three species (K.kansuensis, K.stenocarpa and K.royleana) of section kobresia together with the three species (K.humilis,K.setchwanensis and K.capillifolia) of section Elyna and three species (K.pygmaea, K.graminifolia and K.vidua) of section Hemicarex, and the other group only included the five species (K.robusta, K.tibetica, K.littleda, K.cuneata and K.myosuroides) of section Elyna. (4) The majority using infrageneric systems of kobresia are inaccurate. The present results are more approached to the infrageneric system established by Ivanova in 1939. (5) NJ analysis is suggested in the subsequently study compared UPGMA for more profitably interpreting the present query of kobresia. (6) Phylogenetic relationships among the five genera of tribe Cariceae maybe incorrect and need to be studied. (7) The share characters of open perigynia and rudimentary rachilla, which have been used as evidences of close relationship, are likely plesiomorphic or homoplastic and not direct evidences of close relationship among the genus of the tribe Cariceae. Moreover, Schoenoxiphium, Kobresia, Uncinia and Cymophyllus might have evolved in parallel from that certain species of Carex what are those common relative genres.