When Ohio University graduate student Eric McElroy was a kid, he was disappointed that lizards were rarely the focus of the nature shows he watched. Little did he know that he would end up in Australia, catching lizards with a 9-foot fishing pole as part of his doctoral research.
Alongside Stephen Reilly, professor of biological sciences, McElroy said he tracked 18 different species of lizards as they walked or ran in order to see how a lizard's hunting method affects its movement in nature. Kristin Hickey, then an undergraduate honors student, contributed data to the study before graduating in 2002.
Biomechanics has focused on three freaks ' people
horses and dogs which stand erect and have legs underneath them Reilly said. For lizards
the speed they need for hunting is driving their mechanics.
The study stretched from fall 2003 to spring 2007, appearing in The Journal of Experimental Biology earlier this month. A $263,000 National Science Foundation grant awarded in 2005 funded the research, Reilly said.
Our study showed a physiological reason for why lizards do what they do in nature
McElroy said.
During the experiment, the team raised each lizard's body to its preferred temperature with a heat lamp and then ran the lizard on a straight, 6-meter track in the Life Science Center. The lizards could hide in a box at the end of the track, Reilly said.
As the team ran each lizard, a plate on the track recorded the force the lizard exerted and the movement itself, allowing the team to determine whether each species was walking or running, he added.
Lizards are classified into two categories of hunting: those using the sit-and-wait technique and the wide foragers, Reilly said, adding that both types were examined in the study.
Sit-and-wait lizards have wider skulls that allow them to bite with force. Found in places where food is plentiful, they wait for prey and then run to snatch it. These lizards ran in the experiment. Wide foragers, such as monitor lizards native to Asia, use their sense of smell to find prey and walked during the experiment, Reilly said.
The experiment showed a nice correlation between having to evolve slow locomotion and a shift in biomechanics
Reilly said, adding that the skulls of wide foragers elongated over time to accommodate the snake-like tongues they use for hunting.
The 18 species in the study are from all over the world, including Africa, Asia and Australia, said McElroy, who added he was careful to select lizards from all parts of the evolutionary tree for the experiment.
Although some lizards in the study were caught by hand, others were bought commercially.
McElroy said commercially-raised lizards are not always treated well, so the researchers tried to stay away from this method and caught many by hand.
They released the lizards back into the wild after the experiment, McElroy said.
After finishing his Ph.D., McElroy will teach biological sciences at the College of Charleston in South Carolina this fall, Reilly said.
17
Archives
Emily Hubbell
200805017904midsize.jpeg
