title: The origins and evolution of the genus Myosotis L. (Boraginaceae).
abstract: Although morphologically well defined, the phylogeny and taxonomy of Myosotis has been uncertain. In particular it has been unclear whether the genus had a Northern Hemisphere or Australasian origin. However, separate analyses of the ITS and the 3' region of matK, as well as a combined analysis of ITS, 3' matK, the psbA-trnA spacer, and 3' ndhF regions indicate that several distinct lineages exist within Myosotis and strongly support a Northern Hemisphere origin for the genus. Further, the observed transoceanic distributions and levels of genetic divergence between lineages indicate that long distance dispersal has been important for establishing the current geographic range expansion of Myosotis. Our molecular data also suggest that the diversification of Australasian Myosotis has occurred since the late Tertiary and is largely due to radiation within and from New Zealand. This inference is consistent with the findings of recent phylogenetic studies on other New Zealand alpine genera. Our results highlight the important role played by late Tertiary and Quaternary climate change in explaining current floristic diversity. The genetic relationships reported here also suggest that the current infrageneric taxonomy of Myosotis does not fully reflect the evolution of the genus.
authors.affiliation: Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand. richard.winkworth@yale.edu
authors.forename: Richard C
authors.initials: RC
authors.lastname: Winkworth
authors.forename: Jürke
authors.initials: J
authors.lastname: Grau
authors.forename: Alastair W
authors.initials: AW
authors.lastname: Robertson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lockhart
mesh_terms: D024509:3' Flanking Region; D001315:Australia; D005075:Biological Evolution; D028082:Boraginaceae / Q000502:physiology*; D002736:Chloroplasts / Q000235:genetics; D021901:DNA, Intergenic; D018744:DNA, Plant; D004722:Endoribonucleases / Q000235:genetics; D014644:Genetic Variation; D009245:NADH Dehydrogenase / Q000235:genetics; D009520:New Zealand; D009713:Nucleotidyltransferases / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D045332:Photosystem II Protein Complex; D010802:Phylogeny; D010940:Plant Proteins; D017422:Sequence Analysis, DNA
chemical_list: D021901:DNA, Intergenic; D018744:DNA, Plant; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; C489904:NdhF protein, plant; D009245:NADH Dehydrogenase; D009713:Nucleotidyltransferases; C034038:mRNA maturase; D004722:Endoribonucleases