Primatologist Nate Dominy tries out the Pedestrian Canopy Lidar in preparation for a trip to Africa as Jess Parker discusses its features with researchers from Florida who hope to use the system in mangroves.

Tales of the Forest

How one primatologist is using forest ecology to reveal primate behavior and evolution

A lot can be said about a person by the house they keep. Likewise, an awful lot can be learned about animals through studying their environment. That's why Forest Ecologist Jess Parker has been helping Primatologist, Nate Dominy learn how to use his tools to study the forest.

Dominy studies primate behavior and evolution at U.C. Santa Cruz, and he's particularly interested in how environmental factors influence both. He hopes a better understanding of forest structure will help him describe how and why primates in different regions of the world evolved different methods of movement. It may even shine some light on the origins of bi-pedalism.

A little over 20 years ago, Smithsonian scientist, Louise Emmons and her colleague Alwyn Gentry of the Missouri Botanical Garden, noted that tropical forest animals in South America tend to swing through the trees, while those in Asia jump and glide. Additionally, South America is the only region of the world where a prehensile or grasping tail has evolved in many animals, including primates. Emmons and Gentry presumed these things had something to do with the structure of the forest, and scientists have been trying to pin down an answer ever since.

If forest structure is at the root cause of differences in locomotion and the evolution of a prehensile tail, then "you would expect forests in South America to be characterized by vines that are fragile, so an animal needs to hold the tree crown that it's leaving and grab the one it's going to. Relying on fragile vines, means needing to distribute weight more broadly" He said. A prehensile tail would serve just this purpose.

In contrast, "The forests in South East Asia should be much more gappy, and the forest should be much taller in general" he said, "because animals needed to jump or glide to move through the canopy." In Africa, where neither swinging with the aid of a tail nor gliding has arisen, Dominy expects something entirely different again.

"The density of vines in Africa is similar to that of South America, but the vines are much bigger and stronger and can support an animal's whole body weight," he said. "This may also describe why primates are much larger in Africa."

According to Dominy, no one has been able to accurately test these theories because it requires a detailed, quantifiable picture of the inside of a forest. That's been nearly impossible to get until recently. "Jess Parker is a leader in this," Dominy said.

Over the past few years, Parker has been creating detailed images of the interior structure of forests in Asia and Latin America with a unique device he developed. Called the Pedestrian Canopy Lidar (PCL), it resembles a laptop strapped to a person's torso like a tray of peanuts or popcorn vendors wear to work the crowd at a ballgame. With it, a scientist walks through a forest rapidly capturing data about the height, size, shape and distance of its interior structures. "Think of it as sort of a CAT scan of the forest," Parker said.

"The nice thing about Jess's device is we can measure all of these factors, tree height, vine density, gappiness, in one go," Dominy said.

Dominy recently visited Parker at SERC to learn how to use the PCL for a trip to Congo and Cameroon. He intends to compare the data he gathers with data Parker has taken in Panama, Brazil, Borneo, and Australia. With the PCL's first journey to Africa, Dominy may gain a better insight into how and why primates there have evolved their various means of getting around the forest.

 

For more information, or to reach Dr. Parker, please contact SERC science writer Kristen Minogue.