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Alexander Center For Applied Population Biology

Camera-Shy Cats

Spotted Swimmers
Jaguars are not particularly choosy about where they live: their habitat
ranges from lowland jungle to temperate forest to grassland.

Some habitats are more risky than others, a factor that the population model must take into account. But whatever their habitat, the big cats need lots of space and prefer to live near water. Excellent swimmers, jaguars don’t mind taking the occasional dip.

Modeling the Wild

Models are only as good as the logic used to build them and the data fed into them. If the PHVA is going to work, it must contain the most accurate information possible about the Argentine jaguars. Because field data about wild jaguars are lacking, the team began with data gleaned from zoo records. For decades, zoos have tracked the birth rates and life spans of captive jaguars as well as a host of other “metrics” (quantifiable information) on the species. “The meetings were more exciting than you might think,” recalls Earnhardt. “One field biologist at Lisa Faust’s population biology presentation was so excited to see the data on average litter sizes that zoo scientists had collected (1.74 cubs per litter) that he got up in the meeting and shouted, ‘It’s 1.74! I’ve wanted to know that all my life!'”

Because captive jaguars live very different—and much longer—lives than their cousins in the wild, Earnhardt, Faust and Lonsdorf are incorporating data from the wild populations whenever possible. But the patchwork methods of field-data collection in the past have made some of the data on wild jaguars unusable to the modeling team. Each jaguar-research team has made different kinds of observations and used different metrics. At least for now, the modeling team must rely on tweaking the zoo data to make the model approximate what happens in the wild. “In our meeting in Brazil we had to reach consensus about how to adjust the captive data and make it wild-like,” says Lonsdorf. “We may not have the wild data but we have some wild-like
data and some very fine logic.”

Using the PHVA will improve the data-collection process across research projects and allow population biologists to understand which types of field data are essential to the jaguar population’s recovery. “Modeling teases out the best from your current data,” says Lonsdorf. “And it suggests what further information you need to collect to make the best decision about a population.” For instance, if in the model very small changes in the death rate have a dramatic impact on the population size, field biologists will focus their efforts on determining as accurately as possible what the actual death rate in the wild is and how it might be decreased. Since the zoo team is developing its model from scratch, it can uniquely tailor the model’s structure to fit the jaguar populations under study. The model can also be expanded as new data are collected and different threats to the jaguar population are studied.“Understanding all the various threats to the jaguar populations will enable scientists to create a multi-pronged approach to conservation,” says Earnhardt. Although researchers don’t have all the answers on how to save the big cats yet, the international collaboration has yielded some surprising benefits for the researchers themselves. “So often in science researchers are reluctant to share their data with each other because of the pressure to publish first,” explains Lonsdorf. “But to do this kind of work
the free flow of information is crucial. And that requires a lot of trust from those you’re working with.” Happily, sharing hasn’t been a problem for these scientists. “The collaboration between all of the scientists has been a wonderful experience,” Earnhardt observes. “We’re working with great scientists from many countries.” Unlike the animal they’re working to conserve, there’s nothing mysterious about the way this team works.

A New Breed: The Alexander Center Opens
“Frequently in science,” notes Joanne Earnhardt, Ph.D., Director of Alexander Center for Applied Population Biology at the zoo, “the commonsense solution to a roblem turns out to be wrong. The mind says ‘yes’ but the data say ‘no’ or ‘not quite.’” With the creation of the Alexander Center for Applied Population Biology, researchers around the world have a unique resource for finding solutions based on data instead of guesswork.

An exceptionally generous endowment from Emily and John Alexander established the center by supporting day-to-day operations and providing research funding to staff. Cutting across traditional disciplines, scientists at the Alexander Center apply techniques from a variety of fields—demography, population genetics, ecology, and evolution—to tackle real-world conservation problems. “A self-sustaining population is the goal of all conservation work,” says Steve Thompson, Ph.D., Vice President and Emily and John Alexander Chair of Conservation and Science.

“To create a self-sustaining population you need to understand the dynamics of that
population first.” The Alexander Center’s focus on the development of new approaches and methodologies enables researchers to tailor their analysis to the particular population under study. “When we find that the standard model doesn’t fit, we build a new one,” says Earnhardt. “For example, it turns out that the textbook equation for calculating the genetic diversity of captive populations underestimated the diversity retained.

When we started looking at our actual captive populations, they were doing better than the equation said they were. So we developed a new model that described the populations more accurately.” Lincoln Park Zoo may be used to housing rare creatures, but the Alexander Center is truly one of a kind.