Phylogenetic systematics of Gilia section Giliandra.

Abstract

Nuclear ribosomal internal transcribed spacer (ITS) DNA sequences are used to (1) estimate the phylogeny of thirty-six members of Polemoniaceae and (2) estimate the phylogeny of twenty-five populations, representing fifteen named species of Gilia section Giliandra. Analyses evaluating robustness estimations suggest that the earliest branching events are not resolvable using ITS sequences. Evidence is presented to suggest that the genus Gilia, as currently interpreted, is polyphyletic, comprised of at least three independent lineages. Species currently included in Gilia sect. Giliandra represent a monophyletic lineage, independent of the "true Gilias," but sharing common ancestry with G. latifolia. The evolution of reproductive systems is evaluated, using a phylogeny of the fifteen diploid species of Giliandra, derived from a combined sequences and morphological data. Although P/O differs significantly between autogamous and xenogamous classes of species, there is no major changes in P/O associated with the transition from xenogamy to autogamy relative to changes in P/O within xenogamous and autogamous lineages. There is a major decrease in pollen production associated with this transition. It is also shown that changes in pollen and ovule production are uncorrelated.