Molecular biology has become extremely useful for plant systematists and population biologists, providing an additional source of taxonomic characters. This study used deoxyribonucleic acid sequencing to construct two molecular phylogenies at the intrafamily and intrageneric levels within the Rutaceae family, to determine if molecular biology supported the existing taxonomy. In addition inter-simple sequence repeats (ISSRs), random amplified polymorphic DNA (RAPDs) and isozymes have been used at the intraspecific level in Rutaceae to examine population structure in F. brayleyana.
Analysis of trnL-trnF sequence data for five Rutaceae sub-families showed that there was no molecular support for the current sub-family classifications within the Rutaceae. The Dictyolomatoideae and Spathelioideae sub-families belonged to a clade separate from the clades containing the remaining Rutaceae sub-families. Rutoideae and Citroideae did not form discrete clades suggesting a reassessment of the sub-family classification is necessary, particularly as Ruta (Rutoideae), falls within the majority Citroideae clade. Flindersiodeae formed a clade within the Rutaceae and did not form a separate family or form a clade with Meliaceae. This molecular phylogeny of Rutaceae does not concur with morphological based phylogenies.
Unlike the Rutaceae sub-families, the internal transcribed spacer (ITS1) and trnL-trnF sequencing of 17 Flindersia species produced a similar phylogeny to that proposed by morphological methods, with two exceptions. The molecular phylogeny indicated that F. amboinensis was associated with F. fournieri and F. laevicarpa and, in addition, F. oppositifolia and F. pimenteliana were found to be genetically indistinguishable. Results also indicated that the centre of origin for Flindersia was likely to have been Australia, with multiple dispersal events to the Pacific islands.
ISSR, RAPD and isozyme markers were used to estimate genetic variation in the timber species Flindersia brayleyana F.Muell.. The ISSR and RAPD marker data were combined to measure the association between geographic distribution and genetic diversity for this species. Analysis showed that there was only limited correlation of geographic distribution to genetic diversity within F. brayleyana.