Molecular phylogenetics of Fouquieriaceae: evidence from nuclear rDNA ITS studies

Abstract

Molecular sequence data from the 18S-26S rDNA internal transcribed spacer (ITS) region support the monophyly of Fouquieria sensu lato (Fouquieriaceae) and the three subgenera (subg. Fouquieria, subg. Bronnia, subg. Idria) previously recognized within it. Resolution within subg. Fouquieria differs somewhat between parsimony and maximum likelihood (ML) trees. Section Fouquieria and sect. Ocotilla within subg. Fouquieria are not well supported as monophyletic groups. Uncertainty regarding placement of the root within Fouquieriaceae makes discussion of character evolution within the family difficult. Three root positions are consistent with rate-constant evolution of ITS sequences: (1) along the branch to subg. Idria, (2) along the branch to subg. Bronnia, and (3) along the branch to subg. Fouquieria. The first root position listed is equivalent to an outgroup rooting. The third root position listed is equivalent to a midpoint rooting. Of the three root positions above, only the third is along a branch that may be sufficiently long to act as a long-branch attractor. The first two root positions would result in character reconstruction suggesting that succulent growth forms and white floral pigmentation are ancestral within the family, with shifts to woody growth forms and to red floral pigmentation. The third root position results in equivocal reconstruction of the ancestral growth form, equivocal reconstruction of ancestral floral pigmentation in parsimony trees, and a suggestion of white floral pigmentation as ancestral in ML trees. Two previous hypotheses of polyploid origins are compatible with the molecular data presented here: (1) origin of the tetraploid F. diguetii from F. macdougalii, and (2) allopolyploid origin of the hexaploid F. burragei from the tetraploid F. diguetii and a diploid species similar to F. splendens. Direct descent of the hexaploid F. columnaris from the subg. Bronnia lineage is not supported by our data. An amphiploid origin of F. columnaris involving a member of the subg. Bronnia lineage and an extinct taxon outside subg. Bronnia, however, cannot be ruled out.

Diversification of the Perognathus flavus species group in emerging arid grasslands of western North America

“…Presumed paleoendemics restricted to the Mexican Plateau are known in other animal and plant taxa. For example, the ocotillo species Fouquieria shrevei, a sister lineage to the widespread warm-desert species F. splendens (Schultheis and Baldwin 1999), is restricted to gypsum soils within the Bolson de Mapimi. The xantusiid lizards Xantusia bolsonae, X. extorris, and X. sanchenzi form a deeply divergent clade (also including X. gilberti from the Cape Region of the Baja California Peninsula) restricted to rock and plant habitats within the Bolson de Mapimi or trans-Mexican Volcanic Belt (Sinclair et al 2004).…”

Wood Anatomy of Fouquieriaceae in Relation to Habit, Ecology, and Systematics; Nature of Meristems in Wood and Bark

“…Terminology that of the IAWA Committee on Nomenclature (1964), except for the terms pervasive axial parenchyma, ray-adjacent axial parenchyma, and vasicentric tracheid, which are in accordance with Carlquist (1988). The sequence of the species in Table I is the same as given above, and represents the sequence of subgenera and sections of Schultheis and Baldwin (2000), with species arranged alphabetically within each infrageneric group.…”

From famine to feast? Selecting nuclear DNA sequence loci for plant species-level phylogeny reconstruction

“…Soltis et al 1999;Savolainen & Chase 2003;Futuyma 2004;Yates et al 2004). Phylogenetic trees provide not only the basis for classification, but also studies of character evolution (Schultheis & Baldwin 1999), hybridization (e.g. Hughes et al 2002;Linder & Rieseberg 2004), polyploidy (e.g.…”