CONTI, ELENA* AND SYLVIA KELSO. Institute for Systematic Botany, , University of Zurich, 8008 Zuerich, SWITZERLAND, , Colorado College, Colorado Springs, CO, 80907, USA. - Phylogenetic relationships and character evolution in Primula L.: Results from ITS sequences.
The main goals of this research are to reconstruct the intrageneric
phylogeny of the genus Primula based on both nuclear and
chloroplast DNA sequences and to use the resulting phylogenies to
elucidate the evolution of breeding systems, morphological characters,
chromosome number, and biogeographic distribution in the genus. In
this paper we present the results of a pilot study based on the
nuclear ribosomal Internal Transcribed Spacer (ITS) region. ITS
sequences from 21 taxa produced a number of variable characters
sufficient to resolve relationships among sections. The resulting
phylogeny confirmed the monophyly of sections Auricula and
Aleuritia. Sections Armerina, Proliferae,
Crystallophlomis, Parryi, and Auricula, with a
base chromosome number of x = 11, and sect. Aleuritia, with a
base chromosome number of x = 9, formed two well supported clades.
The ITS topology also suggested that leaves with revolute vernation,
previously believed to be a derived state, might represent the
ancestral condition in Primula, with later reversals to the
involute condition. Finally, this initial ITS tree lent preliminary
support to the proposed role of the widespread, diploid and
heterostylous P. mistassinica as having given origin to the
polyploid, homostylous P. incana and P. laurentiana.
Key words: Breeding systems, heterostyly, homostyly, ITS phylogeny, polyploidy, Primula