Species delimitation

Conservation efforts in Australian plant communities are often plagued by difficult and unresolved taxonomy, so there is a pressing need to do the hard work of disentangling species complexes and deciding which entities deserve to be named species.


Xerochrysum alpinum rosettes, Cradle Mountain, Tasmania.

What is a species? Varying answers to this question continue to influence evolutionary biology (e.g. see the debate on what defines hybrid speciation). Views seem to range from “complete reproductive isolation must be demonstrated” to “any discrete population should be a species”. Somewhere in between is a defensible hypothesis of evolutionary independence and genetic stability based on multiple lines of evidence, much as de Queiroz proposed. To conclude that lineages are evolutionarily independent may require different criteria and different data for different taxa. For instance, Eucalyptus species rarely show monophyly at any single gene, but can be morphologically stable and genetically isolated nonetheless. For reliable molecular evidence of species boundaries, we need highly multilocus datasets coupled to high quality herbarium specimens and field data.

With collaborators at UNE, CSIRO and RBG Sydney, our group is tackling the question of what defines a species in several native plant groups: everlasting daisies, native mint and desmids (plants in the broad sense).

Golden everlasting daisies, Xerochrysum and Coronidium


Xerochrysum subundulatum, near Cradle Mt, Tasmania


Project Title: Integrative taxonomic revision of the everlasting daisy genera Xerochrysum and Coronidium (Asteraceae, Gnaphalieae)

PhD student: Tim Collins

Collaborators: Prof. Jeremy Bruhl (CI – UNE), Dr Alexander Schmidt-Lebuhn (CSIRO) and Dr Ian Telford (UNE)

Funding: Australian Biological Resource Study

We are applying modern, integrative approaches to delimitation of species in the everlasting daisy genera Xerochrysum and Coronidium, as well as their close relative, Helichrysum leucopsideum. The most recent molecular taxonomy, by Schmidt-Lebuhn et al. (2015), found a lack of monophyly at the genus level, as well as at the species level, prompting this taxonomic revision. Quantitative analysis of morphology, genomic level data and cytology will provide multiple lines of evidence to study evolution and speciation in this genus, and to test for polyploidy. A robust phylogeny will underpin a taxonomic revision of Xerochrysum and most Coronidium and the production of tools for interactive identification. The phylogeny will highlight the most genetically distinct taxa and will thus inform conservation decisions and biodiversity management, as well as . Although yellow paper daisies of the X. braceatum assemblage are widely cultivated commercially, those cultivated are neither the most ornamental nor likely the best to grow/harvest/transport.

Tim Collins has embarked on a superhuman effort to sample all putative taxa Xerochyrsum and the Coronidium complex that it appears entwined with. See photos of the field trip in Tasmania on Rose’s twitter feed. Day 1, Day 2, Days 3-6, Days 7-9.

Prostanthera cineolifera, a native mint that smells like Eucalyptus

Student: Ruth Palsson, Masters student


Prostanthera spp. propagated for morphological analysis.

Collaborators: Prof. Jeremy Bruhl (CI – UNE), Dr Ian Telford (UNE) and Trevor Wilson (National Herbarium of NSW)

Project Title: Taxonomic and conservation assessment of Prostanthera cineolifera

Prostanthera cineolifera is listed as vulnerable both in NSW and federally, and was known from only four populations. However, morphologically similar populations have been variously classified as P. ovalifolia and P. lanceolata. Confusion amongst these morphologically similar species necessitates a better understanding using tools capable of resolving the differences among the study group presented here. Resolving the taxonomy of P. ovalifolia assemblage is outside the scope of the current project. We will focus on determining the limits and status of P. cineolifera to underpin its conservation and management.

Using morphology, phytochemistry and next-generation sequencing, we aim to clarify the boundaries between the species, as well as assessing the conservation status of P. cineolifera.

Desmid diversity of the New England Tablelands

Student: Alex Kenins, Masters student

Collaborators: Prof. Jeremy Bruhl (UNE)

Alex is an experienced desmid biologists, who is also a UNE student. For the major project of his Masters, Alex is conducting extensive sampling of the sphagnum bogs of the New England Tablelands, which preliminary work has shown to hold a diverse desmid flora. Components of the desmid community are new to science, and he will conduct detailed morphological descriptions. We hope this will lay the groundwork for further study of the ecology and phylogenetic diversity of the desmid flora of New England.