DNA sequences and fossils show Proteaceae spread by continental drift and transoceanic dispersal to modern continents

Aug 08, 2007

Using DNA sequence data, botanists have shown that the large southern hemisphere plant family Proteaceae lived on the super-continent Gondwanaland almost 120 million years ago.

As Gondwanaland broke up, it was originally thought that these plants merely moved with the newly formed continents. But now a new study published in the Journal of Biogeography has shown that, while this is the case for some of these plants, others are far too recent to have lived at the time when the super-continent broke up. They must therefore have dispersed across oceans to reach their current distribution ranges.

Barker et al. apply a technique known as molecular dating to DNA sequences from over 40 representatives of the family from all southern continents. Using carefully selected fossils that are of known age and affinity, the mutation rate of the DNA sequences was calculated, allowing these scientists to provide age estimates for evolutionary events in the family.

“Our results show that ancestors of some of the modern Proteaceae must have crossed the Atlantic and Indian Oceans. Thus, in Africa, for example, the spectacular genus Protea is truly Gondwanan, but 250 species from other genera that occur in the ‘fynbos’ vegetation (literally, ‘fine leaved shrubs’) of the highly diverse south-western Cape biodiversity hotspot are much younger, and have Australian relatives” says Nigel Barker of Rhodes University, South Africa.

This new finding is important, as it challenges the dogma that gondwanaland’s biota merely moved in situ with the continents as they broke up. “We have to reconsider the possibility of transoceanic dispersal, as unlikely as it sounds for these plants” says Peter Weston, a researcher at the Royal Botanic Gardens, Sydney, Australia. While this is not the first study to invoke dispersal, it is the first on a major and diverse Gondwanan plant family with complex distribution patterns.

These results are not only relevant to botanists. Ornithologists will be intrigued to find that the age of the Embothriinae, a bird-pollinated group of Proteaceae in Australia, coincides with the estimated age of the Honey-eaters, Australian nectar-feeding birds.

Nigel Barker, the first author of the work enthuses “this study is the culmination of 11 years of work. I generated much of the data while working with Peter Weston at the Royal Botanic Gardens in Sydney in 1996. It was only when I met up with Frank Rutschmann in Zurich, who had the expertise on molecular dating, and Hervé Sauquet, a postdoc at the Royal Botanic Gardens, Kew, United Kingdom with an extensive knowledge of the fossil record of the Proteaceae, that it became possible to undertake this rigorous analysis. Sometimes science is about getting the right people with the right skills together in order to make advances”.

Source: Blackwell Publishing

Explore further: Rising temperatures can be hard on dogs

add to favorites email to friend print save as pdf

Related Stories

Google worker shows early-draft glimpse of Chrome OS

7 minutes ago

The Chrome OS is in for a future look. Athena, a Chromium OS project, will bring forth the new Chrome OS user experience. Google's François Beaufort on Friday, referring to the screenshot he posted, said," ...

Firefighters battle wild blazes in Spain

3 hours ago

Spanish firefighters on Saturday battled forest blazes that have destroyed hundreds of hectares of parched land and forced scores of people from their homes, authorities said.

Kingston, Jamaica hybrid project to harness sun and wind

14 hours ago

A hybrid energy project in Kingston, Jamaica, aims to satisfy the need for money-saving renewable energy. U.S.-based WindStream Technologies recently announced the wind solar hybrid installation commissioned ...

Archaeologists excavate NY Colonial battleground

14 hours ago

Archaeologists are excavating an 18th-century battleground in upstate New York that was the site of a desperate stand by Colonial American troops, the flashpoint of an infamous massacre and the location of the era's largest ...

Google eyes Chrome on Windows laptop battery drain

21 hours ago

Google Chrome on Microsoft Windows has been said to have a problem for some time but this week comes news that Google will give it the attention others think the problem quite deserves. Namely, Google is to ...

Recommended for you

Rising temperatures can be hard on dogs

15 hours ago

The "dog days of summer" are here, but don't let the phrase fool you. This hot time of year can be dangerous for your pup, says a Kansas State University veterinarian.

Monkeys fear big cats less, eat more, with humans around

19 hours ago

Some Monkeys in South Africa have been found to regard field scientists as human shields against predators and why not if the alternative is death by leopard? The researchers found the monkeys felt far safer ...

User comments : 0