Science blog
Map of the universe years in the making
Rogue bug may cause IVF failure
Technology decodes Alhambra inscriptions
Sonar causes deafness in dolphins
GM stem cells treat autoimmune disease
Nickel crash kick-started evolution
GPS inhalers track asthma triggers
Urban design turning kids off being active
Cleaning up oil spills can be bad for fish
Fluoro sensors to monitor recycled water
First cloned camel born in Dubai
Cephalopods share common toxic armoury
New evidence of aspirin risk for elderly
Salmonella vaccine could come from space
Porpoise-like sub swims with the current
Microbes thrive on iron under the ice
Blinking tower lights could save birds
Tradition can curb climate change: meeting
Coolest brown dwarf in universe found
'Silent' heart attacks quite common: study
World's land slipping in quality
Warning over 'natural' menopause therapies
Complex life pushed back in time
Lice may suppress asthma, allergies
  Seagrass link to seahorse upright posture
Seahorses evolved their upright posture some 25 million years ago, thanks in part to an expansion of vertical seagrass habitat, Australian researchers have found.

Associate Professor Luciano Beheregaray of Flinders University and Dr Peter Teske of Macquarie University report their findings in the journal Biology Letters today.

Seahorses are unique fish with a horse-shaped head and a habit of swimming upright.

Beheregaray says it has been hard for scientists to work out when exactly seahorses evolved to swim upright.

This is because there are only two known fossils of seahorses - the oldest dating back to 13 million years - and no link between these and horizontally-swimming fish had been found.

"When you look back in time, you don't see intermediate seahorse-like fish," says Beheregaray.

But, he says, there are fish alive today that look like horizontally-swimming seahorses and these could provide clues as to when seahorses evolved to be upright.
Pygmy pipehorses

Beheregaray and Teske compared the DNA of seahorses and other species from the same family to find out which was the closest living relative to seahorses.

"The pygmy pipehorses are by far the most seahorse-like fish on earth. They do look like the seahorses, but they swim horizontally," says Beheregaray.

He and Teske used molecular dating techniques, which relies on the accumulation of differences in the DNA between the two species to work out when they diverged.

The researchers used the two existing fossil seahorses to calibrate the rate of evolution of DNA in their molecular clock.

And they discovered that the last common ancestor of seahorses and pygmy pipehorses lived around 25 to 28 million years ago.
Seagrass habitat

Beheregaray says at the time that seahorses arose during the Oligocene epoch coincided with the formation of vast areas of shallow water and expansion of seagrass in Australasia - where Teske has previously showed seahorses first evolved.

Seagrass was the perfect habitat for an upright-swimming seahorse, which could camouflage itself in the vertical seagrass blades, he says.

The horizontal-swimming pygmy pipehorses, by contrast, thrived in large algae on reefs and didn't have the need to evolve the upright posture.

"The two groups split in a period when there were conditions favouring that split," says Beheregaray.

"It's like us. We started walking upright when we moved to the savannahs. On the other hand, the seahorses invaded the new vast areas of seagrass."
Roads kill more than malaria: study
Seagrass link to seahorse upright posture
Black band disease hits Great Barrier Reef
Hobbit feet reignite debate
Lizards soak up sunshine vitamin
Canada sequences swine flu virus
Termites are a miner's best friend
'Hide and seek' costly to HIV
Giant trilobites had complex social lives
Midnight sun too much for some
More toxics added to 'dirty dozen' list
Rogue galaxies prompt rethink on Newton
Acupuncture relieves back pain: study
Blazars shed light on black hole physics
Unfaithful offspring get head start
Daydreamers might solve problems faster
Coal supply may be vastly overestimated
Science and unis are winners in the budget
Heartbeat key for blood growth in embryos
Neck pain worse for women in the office
Busty figurine a 'Paleolithic Playboy'
Plant cells help bees get a grip
Space trio to give sharper view of cosmos
Sea creatures inspire CO2 sponge
Genetic link between period onset and BMI
Researchers find bacteria in clouds
Sustainable farm research 'under threat'
Tree leaves monitor pollution levels
Stay upright during labour, say experts
Antarctic ice growth linked to ozone hole
Fires fuelling global warming: study
Methane climate shock 'less likely'
Genome map reveals cow's genetic makeup
Microbe bubble machine stores energy
Stress gives reef fish wonky ears
Swine flu remains a mystery
Perception is in the ear of the beholder
Solar wind gives asteroids a tanning
Researchers find grain's memory gene
PET bottles potential health hazard
Researchers find first common autism gene
Fossil fuel use must fall to 25%: study
'WaveRider' poised for hypersonic flight
Big cuttlefish 'at risk' from desalination
Glaciers show north-south climate divide
Mobile phones help cardiac rehab
Dancing birds feel the beat
Mushrooms may yield vitamin D bonanza
Dingoes may be a native's best friend
Dud treatments more easily spread
U2 comet dust predates solar system
Australian CO2 delay sends 'mixed message'
Visit Statistics