Higher-level relationships among the eucalypts are resolved by ITS-sequence data

Abstract

This expanded survey of ITS sequences represents the largest analysis of molecular data ever attempted on Eucalyptus. Sequences of the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA were included in an analysis of 90 species of Eucalyptus s.s. and 28 species representing eight other genera (Allosyncarpia, Angophora, Arillastrum, Corymbia, Eucalyptopsis, Stockwellia, Lophostemon and Metrosideros). The results of the study indicate that Angophora and Corymbia form a well-supported clade that is highly differentiated from Eucalyptus s.s. Corymbia species are divided between two clades, one of which may be the sister to Angophora. Allosyncarpia, Arillastrum, Eucalyptopsis and ‘Stockwellia’ are also highly differentiated from Eucalyptus s.s. If the genus Eucalyptus is to be expanded to include Angophora and Corymbia(sensu Brooker 2000), ITS data suggest that Allosyncarpia, Eucalyptopsis, ‘Stockwellia’ and potentially Arillastrum should also be included in Eucalyptus s.l. The ITS data suggest that subg. Symphyomyrtus is paraphyletic and that subg. Minutifructus should be included within it. Within subg.Symphyomyrtus, only sect. Maidenaria appears to be monophyletic. Sections Adnataria and Dumaria are probably monophyletic; sections Exsertaria and Latoangulatae are very close and probably should be combined in a single section. Section Bisectae is polyphyletic and is divided into two distinct lineages. The phylogenetic groups depicted by ITS data are consistent with the frequency of natural inter-specific hybridisations as well as data from controlled crosses within subgenus Symphyomyrtus. The ITS data illustrate that subg. Idiogenes and western Australian monocalypts are early evolutionary lines relative to E. diversifolia, E. rubiginosa (monotypic subg. Primitiva) and the eastern monocalypts and that subg. Primitiva should be sunk into subg. Eucalyptus. Subgenus Eudesmia may be monophyletic, grouping with subgenera Idiogenes and Eucalyptus. Further work is required to confirm the phylogenetic positions of the monotypic subgenera Alveolata, Cruciformes, Acerosae and Cuboidea.

Phylogenomics of the green ash eucalypts (Myrtaceae): a tale of reticulate evolution and misidentification

“…Although only a few taxa from the present study were included in more recent phylogenies, the relationships found here were generally consistent with the findings of Steane et al (1999Steane et al ( , 2002Steane et al ( , 2011, for the relationship of Eucalyptus obliqua and E. regnans) and Bayly and Ladiges (2007, for the close relationship of E. triflora, E. spectatrix and E. paliformis). The results from the present study support many of the relationships proposed by Ladiges et al (1989), Hill (2002) and Brooker (2000).…”

“…The phylogenies produced here were more resolved than were previous phylogenies of subgenus Eucalyptus using traditional one-region sequence data (e.g. Steane et al 1999Steane et al , 2002Bayly and Ladiges 2007). These findings demonstrate that phylogenetic analyses based on DArT markers can provide insights into evolutionary relationships among Table 2 (Column 6).…”

“…The development of sequence datasets has enhanced our understanding of relationships between eucalypt genera and major subgenera (e.g. Udovicic et al 1995;Steane et al 1999Steane et al , 2002Udovicic and Ladiges 2000;Whittock et al 2003;Parra-O. et al 2006Parra-O.…”

Phylogeny and classification of Eucalyptus subgenus Eudesmia (Myrtaceae) based on nuclear ribosomal DNA, chloroplast DNA and morphology

“…Although based on a small sample of eudesmid species, analyses of Sale et al (1993, chloroplast DNA) and Udovicic and Ladiges (2000, chloroplast and nuclear DNA) provided further support for the monophyly of the subgenus, in addition to morphology discussed above. In a large sample of ITS nuclear rDNA sequences for species of Eucalyptus, including six eudesmids, Steane et al (2002) also found subgenus Eudesmia to be monophyletic, and related to subgenus Eucalyptus (the 'monocalypt' clade) and E. tenuipes (Maiden & Blakely) Blakely & C.T.White, although nodes lacked bootstrap support.…”

“…Outgroup taxa included were E. curtisii Blakely & C.T.White (monotypic subgenus Acerosae), E. tenuipes (subgenus Cuboidea) and E. cloeziana F.Muell. (monotypic subgenus Idiogenes) based on previous eucalypt studies Sale et al 1996;Steane et al 2002). As indicated by their treatment as subgenera by Brooker (2000), there is evidence from morphology and molecular data that these species are outside the main clades of Eucalyptus (subgenera Eudesmia, Eucalyptus and Symphyomyrtus) and therefore they are useful as outgroups.…”