BioColloquium 2016 Begins with Lizard Ecology

By  Ronald Hanaki

Sports Editor

Last Friday, ESU’s Department of Biological Sciences presented the first BioColloquium of the spring 2016 semester, inside Moore Biology Hall.

This was the first of three BioColloquiums. There will be two more in March and early April.

ESU’s Dr. Howard Whidden introduced the day’s speaker, Dr. Renee L. Rosier.

Rosier is a professor of biology at Penn State Wilkes-Barre and studies lizard ecology behavior.

Her research presentation was entitled “Impacts of Early Social Environments on Behavior and Ecology of a Lizard.”

Rosier uses eastern fence lizards to study animal behavioral development.

She finds that lizards are good animals to study because they are pretty much mature and ready to go after they hatch.

Rosier explained that animals use different behavioral strategies to meet their needs.

When predators look for prey, some look for movement.

For example, if a lizard is seen to be moving, they might become more conspicuous to predators.

Rosier also cited that there is a growing body of evidence indicating that atypical animal behaviors develop partly because members of the species become isolated.

This has implications for both animal husbandry purposes and ecological behavior.

Rosier noted that predation can select for risk-taking behavior. Predation is also considered to be a driving force in the development of the boldness variation.

Needless to say, every animal needs to eat. If a lizard chooses not to expose itself to predators in order to stay safe, it would eventually starve to death.

On the other hand, a lizard can choose to be bold, but then

it would have to expose itself as it looks for food. The lizard would be risking predation.

Thus, the lizard is faced with a Shakespearean dilemma: to eat, or not to eat—that is the question.

In order for the lizard to sate its hunger, it needs to expose itself to predation as it looks for food.

For the lizard, the question is not just how hungry is it, but also how much risk it is willing to take.

Furthermore, Rosier was interested in investigating how competition and social interaction factor into this type of animal behavior.

Rosier’s first experiment was to have one small lizard and one bigger lizard compete for food.

She then showed a video where the two lizards competed for a cricket. Both lizards got the cricket, but to Rosier’s surprise, the one that got most of the cricket was the smaller lizard.

This got Rosier excited because although there were no predators, there was evidence that there might still be selection factors that affected animal behavior.

Perhaps an animal’s social experience could increase boldness in behavior over time.

Rosier developed two research questions: does the presence of competitors in early life lead to risk-taking behavior, and do risk-taking individuals have a competitive advantage?

For Rosier’s next experiment, she took eight lizards and split them into two groups.

Four lizards were housed together, allowing them to socially interact with each other.

The other four lizards were grouped and housed individually, and those four lizards had no social interaction with each other.

Rosier then conducted what is called an open field test. This experiment takes place over an open area.

The center zone of that open area is considered the riskiest place to be because being in the center leaves the animal the most exposed.

Therefore, any movement toward the center of an open area is considered to be bold or risk-taking behavior.

Rosier found that lizards that were housed together were more likely to go to the most exposed area in the center.

The lizards that were housed individually and did not have any social interaction with each other were less likely to move toward the center of an open area and were classified as “shy” or less bold.

So does the presence of competition and social interaction in early life lead to risk-taking behavior? Rosier’s experiment suggests that it might—but does that necessarily result in a competitive advantage?

In order to answer that question, Rosier conducted a feeding trial.

There were two trials. The first was a high competition trial where four lizards competed over one cricket. The sec ond was a low competition trial where four lizards competed over eight crickets. Rosier found that boldness did not seem to matter. Instead, what mattered the most was which lizard saw the crickets first.

Therefore, the answer to Rosier’s second research question, of whether or not risk-taking individuals have a competitive advantage, was the following: maybe not.

After these experiments, Rosier’s major finding was that predation is not required for the development of the boldness variation.

She also found that if lizards were housed together, they tended to become bolder overtime.

In other words, the lizards did not necessarily need the selective pressure of predation to exhibit so-called bold behavior. Rosier’s experiments led to more questions: is it competition that is driving this relationship, or is it social interaction?

Moreover, is visual interaction sufficient for the development of the boldness variation?

Because if it is, then group and individually housed lizards should exhibit similar bold behavior.

Further experimentation by Rosier led to the finding that group-housed lizards showed the most exploratory behavior, so the conclusion was that being isolated has more of an impact than visual interaction.

Therefore, visual interaction may not be sufficient for the boldness variation.

The next BioColloquium at ESU will be held in March.

Email Ronald at: