Cycads in central Australia are not ancient relics

Aug 06, 2012
Cycadophyta. Image: Wikipedia

(Phys.org) -- An ancient plant isolated in the heart of Australia, more than 1200km from its coastal cousins, is now believed to have arrived inland far more recently than initially thought.

Researchers from The University of Queensland (UQ), the Queensland Herbarium and The Australian National University have found that Macrozamia, a of cycad found only in Australia, arrived in central Australia millions of years earlier than the 30 million years initially believed.

The research team found this known as the MacDonnell Ranges cycad (Macrozamia macdonellii) was too similar to its more than 1200 km away in eastern and coastal Australia to have been isolated in central Australia for 30 million years.

James Ingham of UQ, a PhD candidate on the team, said comparisons between the plants revealed little difference.

“Some of the central Australian plants have chloroplast DNA with an identical sequence to those in eastern Australia,” said Mr Ingham.

“This is much too similar for the plants to have been isolated in central Australia since the Eocene period, instead suggesting that Macrozamia in central Australia has only become isolated sometime in the past couple million years.”

“In contrast, plants from Western Australia have been isolated from plants in eastern Australia for much longer, possibly for as long as ten million years or more.”

Macrozamia cycads occur in south-west Western Australia, central Australia and along the east coast, including Queensland and New South Wales, but nowhere in between those three regions.

The MacDonnell Ranges cycad is a species unique to central Australia and is the only cycad in the region.

Mr Ingham says, until now, researchers have generally believed that the MacDonnell Ranges cycad has survived in central Australia since the Eocene period, more than 30 million years ago when Australia's climate was much wetter and rainforest much more widespread.

Because cycad fossils from the Jurassic period look very similar to cycads living today, it was previously assumed that cycads have remained more or less unchanged for millions of years.

Overall, the study supports two other recent studies indicating that living cycad groups have been around for only the past 10-20 million years, much younger than during the Jurassic when cycads served as dinosaur food.

James Ingham is a UQ PhD candidate whose research focuses on the evolution of Macrozamia. He has a strong interest in the conservation of threatened species, and nearly a third of Macrozamia species are threatened.

are a group of non-flowering that look like palms but reproduce with cones and have existed as a group since about 270 million years ago.

Explore further: Fewer students study botany, more plant collections closing

Related Stories

Scientists find new Australian frog

Jul 26, 2011

(PhysOrg.com) -- A new miniature frog species or ‘toadlet’ has been discovered in the resource-rich Pilbara region of Western Australia, an area previously thought to support very few of the amphibians.

Australia 'has two distinct white shark populations'

Jun 05, 2012

(Phys.org) -- A new scientific study has identified two distinct populations of white shark at the east and west of Bass Strait in Australian waters, prompting researchers to suggest the huge fish may need regional conservation ...

Recommended for you

Birds time breeding to hit 'peak caterpillar'

12 hours ago

When oaks burst into life in spring populations of oak-leaf-eating caterpillars boom: this offers a food bonanza for caterpillar-munching birds looking to raise a family.

11 new species come to light in Madagascar

19 hours ago

Madagascar is home to extraordinary biodiversity, but in the past few decades, the island's forests and associated biodiversity have been under greater attack than ever. Rapid deforestation is affecting the ...

Birds 'weigh' peanuts and choose heavier ones

May 23, 2015

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.