Analysis on the character evolution in Australian Asteraceae based on molecular phylogenetic tree

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The generic circumscription and intra-generic relationships of the Australian genera of Calotis (Astereae) and Gnephosis sensu lato (Gnaphalieae) with various chromosome numbers were examined by the comparison of the sequences of the internal transcribed spacers(ITS) of nuclear ribosomal DNA and the matK gene of chloroplast DNA. Of the aligned 251 sites of ITS 1 Region, 75 sites were variable and 39 of them were phylogenetically informative among 16 species of Calotis. Of the aligned 1206 sites of total matK gene, 22 sites were variable and 5 sites of them were phylogenetically informative. The DNA data sets analyses displayed the 18 most parsimonious trees for the ITS 1 data and three trees for the matK data selected Brachyscome decipiens as outgroup. The monophyly of the genus Calotis was supported with high bootstrap values by both trees. The character reconstruction based on these trees shows that the reduction in chromosome number from n=8 to n=7, 5 and 4. Of the aligned 260 sites of ITS 1 region, 117 sites were variable and 50 of them were phylogenetically informative among seven species of Gnephosis sensu lato, Tricanthodium skirrophora and Epitriche denissus. Molecular phylogenetic tree selected Millotia myosotidifolia as outgroup showed that the genus Gnephosis was not monophyletic and it needed further taxomical re-examination. The reduction in chromosome number from Gnephosis drumondii (n=12) to G. tenuissima (n=6) has been occurred.