Gliding Bristletails Give Clues On Evolution Of Flight

Yanoviak and his co-authors, Mike Kaspari of the University of Oklahoma and Robert Dudley at the University of California-Berkeley, observed how arboreal bristletails -- evolutionary precursors to insects -- in the Amazon Forest can leap tree trunk to tree trunk by manipulating a filament on their bodies as a primitive rudder system.

“Directed aerial descent, such as gliding and maneuvering, may be an important stage in the evolution of winged flight,” Yanoviak said.

The scientists conducted drop tests in tropical forests in Peru, the Smithsonian Tropical Research Institute at Barro Colorado Island, Panama; and Gamba, Gabon, from 2005 to 2007. They quantified the directed descent behavior of jumping bristletails by dropping individuals from tree branches while perched high above the ground in the rainforest canopy.

The bristletails were dusted with orange fluorescent power to track their movement. Approximately 90 percent of them successfully landed on an adjacent tree branch. When the median caudal filament – the structure thought to control its gliding ability – was removed, the percentage of tree trunk landings was significantly reduced.

“The existence of aerial control ability in a wingless insect and its habitat in trees is consistent with the hypothesis of a terrestrial origin for winged flight in insects,” Yanoviak said.

Last year, Yanoviak, Kaspari and Dudley, in collaboration with nematode specialist George Poinar, Jr. at Oregon State University, made waves in the bug world with their research about a parasite that can so dramatically transform the look of its host – an ant – that the ant comes to resemble a juicy red berry, ripe for the picking in the jungles of Central and South America.

Their research, first published in the American Naturalist, may be the first example of how a lowly parasite can manipulate the look of a host to such an extent that birds can’t tell the difference between a red berry and an ant.