A new research paper from Curtin University has traced the evolution of the plant genus, Beauprea, providing evidence to support Antarctica as its place of origin when it was covered in temperate rainforest.
The paper, published in the journal Science Advances, explores the historical prevalence of Beauprea, a member of the Proteacae family, which is currently endemic to the tropical pacific island of New Caledonia.
Lead researcher, Dr Tianhua He, from Curtin University’s Department of Environment and Agriculture, said the research had contributed to an understanding of the evolution of the Proteaceae, one of the most important families in the Australian flora and which includes well-known Australian plants such as banksias, grevilleas, hakeas, waratahs and macadamia.
“Our research shows that Beauprea originated around 88 million years ago in Antarctica-Southeastern Australia and spread throughout the then supercontinent Gondwana before its final breakup,” Dr He said.
“During the time that Gondwana existed, New Caledonia and New Zealand were part of the continent of Zealandia. It was previously thought that since the time of breakup, this continent became fully submerged.
“However, our research shows that Beauprea spread to Zealandia and now only survives in present-day New Caledonia, supporting the theory that the continent did not in fact become fully submerged since separating from Antarctica.
“If Zealandia did become fully submerged, Beauprea could not exist in New Caledonia as it does today, as it has very poor dispersability, for example, its fruits do not float in water,” Dr He said.
The world’s most ancient flowering plant, Amborella, is also endemic to New Caledonia. Other prehistoric Proteaceae species exist on the island, as well as the spider-related group Troglosironidae, Gondwanan moss bugs, the beetle family Passalidae and the saw moth Sabatinca.
“Many of these New Caledonian endemics are traditionally viewed as an inheritance from Gondwana, which points to a hypothesis of vicariance where New Caledonia is perceived as a refuge for these ancient plants and animals,” Dr He said.
The researchers found that the oldest Beauprea fossil pollen record, from 83.8 million years ago, was present in the Otway Basin that stretches from Cape Jaffa in South Australia to north-west Tasmania. Beauprea survived in New Zealand up to one million years ago when it became too cold for it.
“Taking into account the fossil pollen records and the geographical distribution of its pollen, our research suggests that Beauprea was already widespread across Antarctica, Australia and Zealandia before they separated 81 million years ago,” Dr He said.
“While the idea of Antarctica being the centre of origin for certain taxa is not new, our analysis provides the best evidence so far to support a pivotal role for Antarctica in the possible origin and early diversification of some Southern Hemisphere biota.”
The research was supported by the Australian Research Council. The full paper, Pre-Gondwanan-breakup origin of Beauprea (Proteaceae) explains its historical presence in New Caledonia and New Zealand, is available on the Science Advances website.