Postgraduate Profiles

Timothy Andrew Hammer

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Thesis: Molecular systematics and drivers of diversification within Ptilotus R.Br. and the aervoids (Amaranthaceae)

Ptilotus (Mulla Mulla) is a large genus of showy wildflowers in the amaranth family native to arid Australia, commonly occurring on nutrient-poor soils. Approximately 90% of its diversity is present in Western Australia, especially the Pilbara. Previous research has indicated that Ptilotus may have diversified rapidly from the aervoid clade of Amaranthaceae, which is distributed throughout Africa and Asia. Physiological studies have shown that some species are hyperaccumulators of phosphorus, which is often in limited supply where it grows. My research is focused on (1) producing a phylogeny of this group using next generation sequencing to resolve its taxonomy and for use in subsequent analyses, (2) assessing the diversity of phosphorus accumulation and metabolism strategies, (3) analyzing the evolution of pollination syndromes, and (4) synthesizing this information using biogeographic and analyses to work out how and under what selection pressures Ptilotus diversified and evolved over time and how pollinator shifts and environmental changes, including poor soils and aridification, may have spurred the rapid diversification of this group in Australia.

Why my research is important

Ptilotus has the potential to give insights into the evolution of the arid Western Australian biota, including how and when groups of plants dispersed to Australia from Asia, and how these plants responded to aridification and ecological changes in their new environment. This can help us to understand how invasive plants may respond to similar events in the future. Documenting the evolution of and variation in pollination syndrome and pollinator specificity will aid in our understanding of how native pollinators have shaped our flora and how a loss of these pollinators may impact native vegetation. Due to Ptilotus’ nearly unique ability to uptake large amounts of phosphorus in its tissues without suffering P-toxicity (growing well in both low and high P settings), it may also have applications for bioremediation and sustainable agriculture.

Funding

Ptilotus noblis (Lindl.) F.Muell. growing in the Pilbara, Western Australia

Jul 2015

Jul 2018

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