ASU Research E-Magazine: Evolution of a Biologist

David Pearson never set out to be a conservation biologist. But the shiny, colorful tiger beetle led him down a new career path.

Blame it on a beetle.

David Pearson never set out to be a conservation biologist. An ecologist by training, he began his career studying tropical bird communities. But when birds could no longer answer the questions he was asking, he followed the shiny, colorful tiger beetle down a new career path.

"Birds were exciting and fun but I couldn't manipulate them. I couldn't even see what they were eating. I couldn't see their enemies very often," says the Arizona State University research professor. So he turned his attention to tiger beetles.

The colorful predators had always fascinated Pearson, who collected insects as a boy. The beetles soon proved as useful as they were interesting.

"I found that I could answer some important questions in ecology that weren't possible with birds. That led to some studies on conservation–trying to use tiger beetles to indicate which areas have a higher diversity of species."

Tiger beetles lend themselves easily to conservation studies. For Pearson, the switch was a little more difficult. Because conservation is a relatively new area of biology, he is learning and defining the field as he goes.

"Most people in conservation biology came from some other field, just like I did. They studied genetics, ecology, or behavior. And when we came into this new field in which none of us had been formally trained, we brought with us our organisms–whatever we were working with. Very few people thought to consider whether this was really appropriate," Pearson explains.

That's why the ASU scientist has put together a checklist for researchers to use in selecting organisms for use as bioindicators. A bioindicator is a species that serves as a representative sample of its ecosystem. Bioindicators allow scientists to make predictions about the ecosystem without studying every species in that system.

"The ideal, of course, would be to have all the information on everything, but that's years and years of work," Pearson says. "In conservation biology we're always short of money, time, and personnel. And we always need the information yesterday. We need to make policy decisions. Bioindicators provide a quick way to find answers with a high degree of accuracy."

The items on the checklist are weighted according to their importance. Pearson's goal is to create a grading system, like a report card, that would indicate a species' overall usefulness as a bioindicator.

"You can't just choose them because you like them, because they're soft and furry, which is the way many have been chosen in the past," he explains.

Pearson says that researchers need to look at a whole suite of bioindicators to get a good picture of any area. Ideally, scientists should choose an organism from each level of the food chain.

"I have to be careful because I do understand that tiger beetles are not the only bioindicator. I often sound like that's all I'm pushing!" he laughs.

Still, there is no denying that tiger beetles do make excellent bioindicators, for a variety of reasons. First, the insects are remarkably easy to study.

Second, a huge base of information on the beetles already exists. That is because the insects are extremely popular among amateur entomologists. Often brightly colored in greens, maroons, or metallic colors, tiger beetles are the beauty queens of the insect world.

Also, Pearson has found that he can collect data on tiger beetles much more quickly than on other animals.

"We've done surveys in Peru and Ecuador with bird people, mammal people, and frog people all working together. I can determine the number of tiger beetles in about 55 hours of work," Pearson says. "The bird people working with me may take as long as 10 years to do the same thing at the same site. The butterfly people may take three or four years."

Why this discrepancy? "There are fewer species [of tiger beetles] and they're more obvious," Pearson says.

"We've been able to show that in many cases, the number of butterflies, the number of birds, and the number of tiger beetles are all correlated. Yet I can get that information much faster and at a lower price."

Tiger beetles are also highly sensitive to changes in their environment, an important characteristic for a bioindicator.

"This is kind of like the canaries in a coal mine," explains Pearson. "The canaries were very sensitive to methane gas–much more so than human beings. Big burly miners would carry down these little cages with canaries. If the canary all of a sudden keeled over, people ran quickly out of the mine, because they didn't have a lot of time. The dying birds provided a warning."

One such warning occurred in the 1960s, when brown pelicans began disappearing from southern California.

"The die-off happened in just a couple of years," says Pearson. "All of a sudden–bam!–the brown pelicans were gone. It was a warning we probably wouldn't otherwise have seen for years. We learned that DDT was affecting the calcium deposited in their eggs. The shells were paper-thin. The pelicans would sit on them and just squash them."

As a result, the Environmental Protection Agency banned the manufacture and use of DDT before other species suffered similar tragedies. Since then, the brown pelican populations in California have recovered.

Pearson says that most people think of bioindicators in this context, as monitors of environmental change. "But equally as useful, and probably more published, is their use for inventory," he explains.

For example, government officials may need to find areas of high species diversity to set aside those areas as national parks.

"You want to choose areas called 'centers of evolution'," explains Pearson. "Simply having a lot of species in one place isn't a lot of information. Sometimes you have high species numbers because [the area] is a crossroads or because they've dispersed from other places. They creatures didn't originate there."

Pearson determines if an area is a center of evolution by tracing the DNA of the animals living there. Then he creates diagrams showing the genetic relationships between the species. The diagrams help him see how likely it is that the area served as a point of origin.

Pearson has circled the globe for his research, studying beetles in South America, India, Africa, Europe, Indonesia, and the United States. Tiger beetles primarily live in tropical areas. They are active at the beginning of the rainy season. Pearson tries to arrive just as the rains begin.

"If I get there much later we can't get anywhere because the roads are all muddy," he explains.

Pearson hosts workshops in the countries he visits, recruiting students to help him with his work. Once trained, students can take over a large portion of the research in their areas.

"It's really obvious at a workshop which students are going to do a good job," Pearson says. "In many cases the women do a much better job than the men. Because in many countries the macho image dictates that men don't catch insects. Men become doctors or dentists. Men don't do this kind of work in the mud."

Changing these kinds of perceptions about the environment is a big part of Pearson's job. Conservation biologists need to be part public relations agent.

"I asked some businessmen in Quito, 'Have you ever been down to the Amazon?' And these people inevitably say, 'No.' There are two reasons," Pearson explains. "Some people will say, 'I haven't been there because I'm afraid of the mud, the mosquitoes, and the snakes.' The other, worse answer is, 'I haven't been there because I'm embarrassed by all that rainforest, and all those naked people living there. It reflects on my country as backward, that we haven't developed that area yet.'"

Understanding the biology of an ecosystem is pretty useless if you can't persuade people to protect it.

"You have to convince people that the forest is worth more if it's not cut down. Economic arguments, unfortunately, carry the weight. You can talk about aesthetics to young people but not to adults," says Pearson.

The ASU scientist currently promotes both the economic and aesthetic advantages of conservation in two different book series. The first is a set of ecotourism travel guides. Pearson gives a "green rating" to lodgings and provides questions for travelers to ask of lodge operators.

The second project is a series of field guides to common animals and plants found in several countries. The guides combine easy-to-understand text with stunning graphics that are meant to spark an interest in the environment. Pearson agreed to the project with one important condition–that the publisher would sell the rights to translate the book and use the images, at a very low cost, to a non-governmental organization in each country featured.

Pearson holds up a copy of the guide to Costa Rica. "Our goal is to have a copy of this book, in Spanish, in every school in Costa Rica," he says. "For the Ecuadoran book, a copy in every school in Ecuador, and so on."

The books are a two-pronged strategy for promoting conservation in the countries they cover. The ecotourism guides provide a financial incentive for conservation that appeals to policy makers, Pearson says.

"These policy makers can understand there are forests out there, with 40 tourists going every day and each tourist paying $200 a day. They can tell pretty fast how much that forest is worth if it's not cut down.

"At the same time, we can hit the students with a field guide and get them to understand on a more profound level just how significant, how important, and how interesting these treasures are in their own countries. That's the only way we've got a chance for the long-term."

Currently, Pearson is in the midst of writing four books: a tour guide to Ecuador, and field guides to Ecuador, Peru, and Amazonian Brazil. He is trying to produce at least two books per year.

"I've learned that I've got to be a lot more than a biologist," he says. "I'm a quasi-sociologist, a psychologist, and a writer. I've learned other languages. All are involved in trying to get this job done."

For a conservation biologist, it's all in a day's work.—Diane Boudreau