Phylogenetic relationships in Fagales based on DNA sequences from three genomes

Nucleotide sequences of six regions from three plant genomes - trnL-F, matK, rbcL, atpB (plastid), matR (mtDNA), and 18S rDNA (nuclear) - were used to analyze inter- and infrafamilial relationships of Fagales. All 31 extant genera representing eight families of the order were sampled. Congruence among data sets was assessed using the partition homogeneity test, and five different combined data sets were analyzed using maximum parsimony and the Bayesian approach. At the familial level, the same phylogenetic relationships were inferred from five different analyses of these data. Nothofagus, followed by Fagaceae, are subsequent sisters to the rest of the order. Fagaceae are then sister to the core "higher" hamamelids, which consist of two main subclades, one being Myricaceae (Rhoipteleaceae (Juglandaceae)) and the other Casuarinaceae (Ticodendraceae (Betulaceae)). The combined data sets provide the best-supported estimate of evolutionary relationships within Fagales. Our results suggest that the combination of different sequences from several species within the same genus representing a terminal taxon has little influence on phylogenetic accuracy. Inclusion of taxa with some missing data in combined data sets also does not have a major impact on the topology.

Duke Scholars

Author Paul S. Manos Biology