Plant evolved a bat beckoning beacon

31st Jul 2011

A rainforest vine has evolved dish-shaped leaves to attract the bats that pollinate it, scientists have found.

Tests revealed that the leaves were supremely efficient at bouncing back the sound pulses the flying mammals used to navigate.

When the leaves were present the bats located the plant twice as quickly as when these echoing leaves were removed.

A team of scientists in the UK and Germany reported its findings in the journal Science.

The study is the first to find a plant with "specialised acoustic features" to help bat pollinators find them using sound.

Most bats send out pulses of sound to find their way around; the way they sense objects in their environment by sensing how these pulses bounce off them is known as echolocation.

"We already knew that plants used their brightly coloured petals to attract pollinators," explained Marc Holderied from the University of Bristol, one of the researchers involved in the study.

"What we've found is the echolocating equivalent to colourful flowers.

"We have a shape that produces an echo - an 'echoacoustic beacon'."

The scientists first notice the Caribbean plant, Marcgravia evenia, in a photograph in a Natural History magazine.

"We immediately recognised that this dish-shaped leaf could be a perfect bat attractor," he recalled.

He and his colleagues brought the plant into their laboratory and bounced to measure its acoustics - essentially firing sound pulses at it to see how they echoed.

The next step was to test how the bats responded to it.

The researchers set a test for a group of nectar-feeding bats (Glossophaga soricina) to measure how long it took them to locate a small feeder in a dark room.

They adorned the feeder either with the plants' dish-shaped leaf or with a normal (much flatter) foliage leaf from the same plant.

"Once we added the leaf, that really did the trick," said Dr Holderied. "The bats found the feeder in half the time."

"Now we know that the acoustic clues are important for pollination."



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