Corals clone in bad weather

2012-03-02 12:00

Sydney - Coral offspring spawned from Australia's Great Barrier Reef clone themselves when rough weather hits with not all of the fragile embryos perishing in big waves, research showed on Friday.

Scientists from the Australian Institute of Marine Science discovered the previously unknown reproductive strategy, which shows that coral offspring can form genetic clones of themselves before they settle and mature.

Coral "offspring" are usually the result of sexual reproduction - fragile eggs fertilised either before or after being released into the water - and are then carried by ocean currents before settling at new locations.

The new study, published in the journal Science, found that if there was some turbulence in the water such as a storm, these offspring often cloned to create genetic replicas of themselves rather than break up.

"We originally thought that if the embryos were fragmented by wave action that that the fragments may not develop into larvae," said researcher Andrew Negri.

"However, when we investigated this we found that a high proportion of the fragments were successful in developing into smaller viable clones of the original embryo.

"Although smaller, these clones developed normally into coral larvae, eventually attaching and metamorphosing into coral polyps."

'Maximising impact'

The researchers said they suspected the fact that fertilised coral eggs lacked a protective outer-layer or membrane, unlike most animal embryos, could be an evolutionary tactic to ensure reproduction.

"It appears that the lack of protective membrane is no accident," said Negri.

"Almost half of all these naked embryos fragmented in our experiments, suggesting that this has long been part of the corals' repertoire for maximising the impact of their reproductive efforts."

Fellow researcher Andrew Heyward said the coral, under threat from changing ocean temperatures, could benefit simultaneously from the advantages of both sexual and asexual reproduction.

"Much like humans, it is important that the offspring of corals have genetically distinct parents," he said.

"But these embryos also readily clone to form multiple versions of themselves, and it helps to explain how coral maximise their chances of finding a suitable habitat in which to settle and survive.

"In human terms this is the equivalent of giving birth to identical twins, triplets, quadruplets and so on."