To save the future, conservationists look to the past
The marriage between two scientific disciplines – conservation and paleobiology – could guide efforts to preserve life on Earth.
Conservationists often look to historical data to determine the baseline population or range of a species threatened by human activity, information that is then used to set goals for protecting that plant or animal.
But scientists have only recorded this kind of data for decades, perhaps a century in some cases – a significantly shorter amount of time than humans have been having an impact on biodiversity. As a result, conservationists and policymakers are working with just a "snapshot" of a species or ecosystem, says Elizabeth Hadly, faculty director of the Jasper Ridge Biological Reserve at Stanford University, when a "moving picture" would be more useful.
Dr. Hadly is part of a growing movement of scientists advocating for a new perspective in conservation. She and her colleagues say the fossil record holds key insights into how a species or ecosystem might respond to changing conditions, and therefore might help guide more effective management efforts.
And as paleontologists, biologists, and ecologists are catching onto this new perspective, a new subdiscipline of science has been born: conservation paleobiology, or "conservation paleo."
"We're really interested in taking the past and applying it to the present," said Rowan Lockwood of the College of William and Mary, who applied it in a study of Chesapeake Bay oysters that she presented at the the annual meeting of the American Association for the Advancement of Science (AAAS) last month.
Conservation paleobiology can take many different forms and applications, which an interdisciplinary, international team that included Hadly outlined in a paper published in the journal Science ahead of the AAAS meeting last month.
Dr. Lockwood, for example, has studied fossil oyster shells to determine what oyster reefs in the Chesapeake Bay looked like before European colonists arrived, as a way of creating a baseline for modern oyster conservation. By studying these old shells, Lockwood has gained new insights into the biology of oysters and she has put together a set of recommendations for ecological managers who want to support the restoration of a healthy oyster reef, which she presented at the AAAS meeting.
But it's not always so straightforward. Two types of ecosystems currently call for conservation attention, says Anthony Barnosky, Hadly's husband and the first author of the Science paper, in a phone interview with The Christian Science Monitor.
In addition to the classic historical ecosystem that has experienced little human impact, novel ecosystems created by human activity also contain biodiversity worth preserving, explains Dr. Barnosky, who is the executive director of the Jasper Ridge Biological Reserve at Stanford University.
In the case of a historical ecosystem, Barnosky, Hadly and their co-authors suggest that conservation paleobiology efforts focus on determining how resilient the system may be to change.
If it's not particularly vulnerable, they advise that conservation efforts focus on maintaining the same ecosystem.
But if a given historical ecosystem is more vulnerable to change, they recommend nurturing the ecosystem's adaptive capacity. In other words, conservationists can allow the ecosystem to change, but they can also help a species move into a new range. And the fossil record can help biologists determine what conditions will be best for a given species, as they won't all be shifting north with warmer conditions.
For example, when Hadly's research team excavated a site by Shasta Lake in Northern California, they found that while some species' ranges shifted north under warming conditions over the past 10,000 years, others moved west, probably seeking wetter conditions, she recalls in a phone interview with the Monitor.
Because novel ecosystems are shaped by human activity already, conservationists can take different tactics that are less wedded to species-specific models.
"Maybe you want to build that ecosystem into something that is functioning more or less naturally so that you don't have to constantly manage it," Barnosky says. To do this, conservationists can look to the fossil record to understand what types of species are necessary to perform different ecosystem roles. For example, a particular ecosystem might need some top predators, some herbivores, some microbes, and so on to be healthy.
"If you're thinking about building an ecosystem, it's kind of like thinking about building a house," Barnosky says. "You need a certain number of carpenters, a certain number of plumbers, a certain number of electricians, but it really doesn't matter too much who those people are, as long as they can do the job."
There are limitations to a paleobiological perspective for conservation, points out Joseph Bennett, a conservation biologist at Carleton University who was not involved in the Science paper or the AAAS panel.
"The fossil record can be patchy," Dr. Bennett warns. Some species preserve quite well in paleontological records, like pine tree pollen, he says. But other species from the very same ecosystem might not preserve so well, like insects or fungi, so paleobiologists might not be able to recreate the full picture of a historical ecosystem.
That said, he says, "If we didn't use past data, then we would be throwing out all of this potential context," so paleobiological data is an important tool for conservation biologists. He sums it up by saying, "The past can be a guide, but it's not a perfect guide to what we have to do in the future."
Conservation paleobiology may be a newly coined term, but Hadly and others have been applying paleontological data to modern-day conservation issues for their entire careers. Hadly was responsible for finding evidence that gray wolves were indeed native to Yellowstone National Park, which she reported in 1994 – just one year before the wolves were reintroduced to the park.
"Wolves weren't part of the early picture," Hadly recalls. She began excavating Lamar cave in the 1980s in search of elk fossils from before European settlers arrived in the region. That's because there had been some debate as to whether elk (and wolves as well, despite them having been hunted to decimation in the early 20th century) were native to the region or were actually plains animals. So Hadly set out to settle the issue.
By the time Hadly reported that she had found elk and wolf fossils, the debate over reintroducing gray wolves to the park was already raging. "It was a very simple thing for me to find elk bones and wolf bones in these fossil deposits, they were a minor subset of all the fossils I found, but they turned out to be very significant," she says.
The reintroduction of wolves to Yellowstone National Park has actually shifted many aspects of the ecosystem, from the elk to the beavers to the paths of rivers.
So was the reintroduction of gray wolves to Yellowstone a conservation paleo success story?
"Absolutely," Hadley says. "I think wolves would probably have been reintroduced without the fossil record," but, she says, her work was able to describe much of the pre-colonial ecosystem in the region and now park managers can truly say they have an intact ecosystem. "Yellowstone now has basically all of its native mammals present. And it's one of the only places in the country, in the world, that has evidence to back that up."