Thursday, 07 April 2011

WA cockatoos and parrots get 454 sequencing treatment

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MURDOCH researchers have used DNA sequencing technology to map the evolutionary lineage of the cockatoo family.

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“What people previously believed was the birds that looked more alike were probably more closely related to each other.” —Ms White. Image: iStock

Biological Sciences and Biotechnology PhD student Nicole White undertook the project after noting a lack of data on cockatoo evolution.

The research used new generation sequencing – also known as 454 sequencing – to generate long fragments of DNA sequences in large volumes.

“We were actually able to generate whole mitochondrial genomes and then we were able to actually date them,” says Ms White.

“So we can do molecular time plots to examine when cockatoos and parrots first branched away from each other.”

According to Ms White, the results provide an accurate family tree, charting the development and speciation of many cockatoo species.

“We estimate that what we call the most recent common ancestor before parrots and cockatoos split away from each other was about 40 million years ago.

“So we can see from our research that the variation and the diversity of species that we have in cockatoos today really started to change between the 10–20 million year ago time frame in Australia,” says Ms White.

The data also yielded a few surprises. The accuracy and detail provided by DNA sequencing has led to changes in the way taxonomists group species.

“What people previously believed was the birds that looked more alike were probably more closely related to each other,” says Ms White.

“What the DNA is showing us is that you can’t necessarily judge a book by its cover until you get in and read the DNA code.”

Dr Michael Bunce, head of Murdoch’s Ancient DNA Lab, says the research has further reaching consequences for the area of forensics.

“About a year and half ago someone was caught smuggling (cockatoo) eggs through Perth airport, and we DNA tested [the eggs] because it was very hard to determine what species [of bird] based on egg morphology as many cockatoos share similar egg traits.

“But if you have a defined family tree and every species within the genetically typed, we have a better likelihood of being able to say ‘that egg belongs to that species’.

“Although it seems like a big jump from doing a family tree into actually policing this material through forensics, it’s not actually such a large leap.

“We need a robust family tree that we can assign unknown DNA sequences to, so we are able to make definitive identifications,” says Dr Michael Bunce”.

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