July 20, 2009

Tracing The Origins Of The Venus Flytrap

Scientists have traced the origin of the Venus flytrap and another predatory plant back to a single ancestor with sticky leaves.

Botanists told BBC Earth News that the plants' evolution was a result of the need to devour larger animals. This evolution caused the plants to develop new forms of weapons, including teeth and sensor hairs.

There are several plants known to man that hunt prey using an array of tools.

Scientists focused on the Venus flytrap and the waterwheel plant. The waterwheel plant is an underwater counterpart of the Venus flytrap.

Charles Darwin considered the Venus flytrap "one of the most wonderful plants in the world" due to its ability to trap its prey in 0.3 seconds or less.

"Darwin was fascinated by carnivorous plants in general and the Venus flytrap in particular, I think, partly because they go against type," Don Waller, a botanist at the University of Wisconsin, in Madison, told the BBC.

"In his time and ours, most of us feel that plants are passive, harmless, and can't move. But the Venus flytrap acts like an animal, it moves fast and eats fresh meat."

However, botanists have had trouble tracing the evolutionary origins of the flytrap and the waterwheel.

However, writing in the journal New Phytologist, Waller and colleague Thomas Gibson said they found evidence to show that both plants underwent a series of steps to develop them into the professional hunters they are today.

Waller and Gibson compared the structures of the flytrap and waterwheel with another type of predatory plant known as the sticky trap.

Ken Cameron of the University of Wisconsin conducted DNA analysis of the plants to show that the Venus flytrap and the waterwheel are related, with the closest ancestor being a species of sticky trap known as Drosera regia.

Waller and Gibson have laid out the series of steps they believe were involved in the plant's development to becoming an experienced predator.

First, they believe the plant gained the ability to move its tentacles and leaves in the direction of its prey.

Second, researchers said the plant was likely to increase the time between detecting its prey and attempting to capture it.

Next, they assume that the plant would have to learn how to determine whether or not its prey was live or simply something unintended to be devoured.

And lastly, Waller and Gibson say the plant's tentacles evolved into sensory hairs and teeth to detect its prey.

However, the question remained as to why the plants were forced to adapt.

"Capturing big prey provides big rewards to any carnivorous plant, and snap-traps can immobilize and digest these bigger prey far more effectively than the sticky fly-paper type traps we see in sundews," Waller told the BBC.

"A bug twice as long as another has more like eight times the biomass and nutrients, so these rewards accelerate as prey get bigger. This is why flytraps build bigger traps as soon as they can, unlike almost all other plants where the size of leaves or traps remains the same as plants get bigger."


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