Beth Shapiro uses DNA to see how animals fared in ancient climate

Shapiro believes her work provides a valuable perspective into the interactions between the animals and environment of the past. “Anytime we can see the beginning, the middle, and the end of a process, such as passing through the peak of the last Ice Age, we get significant insights into how populations can respond to climate change,” says Shapiro.

Beth Shapiro: We really have very little information about how populations and species respond to climate change.

Beth Shapiro is an evolutionary biologist at Penn State University and 2009 winner of a ‘genius’ grant from the MacArthur Foundation. Dr. Shapiro uses ancient DNA – dating back over 50,000 years – to follow long-lived species through their experience of past climate change.

Beth Shapiro: I think anytime we can see the beginning, the middle, and the end of a process, such as passing through the peak of the last Ice Age, we get significant insights into how populations can respond to climate change.

Shapiro extracts DNA from ancient bones belonging to animals like horses or bison. She then analyzes their genes.

Beth Shapiro: If a population in a particular species has a lot of genetic diversity, we infer that the population is big, and has been big, for quite a long time. But if we see it losing diversity through time, we infer that it’s getting smaller.

For example, her research found that bison lost their genetic diversity shortly before the last Ice Age, when climate was changing. Shapiro said more advanced scientific tools are needed to make predictions about how modern species will respond to today’s climate change.

Beth Shapiro: You can look at how much diversity is in a population today and guess what happened in past to result in that much diversity. But with ancient DNA, you can go back in time and directly sample that population as these environmental changes are actually happening.

This field of evolutionary biology – working with ancient DNA – is relatively young. Shapiro believes it provides a valuable perspective into the interactions between the animals and environment of the past.

Beth Shapiro: One of the most important insights we can gain from this is actually to compare the trends in how these populations were growing or declining, responding to climate change, between the species that didn’t survive and those that did.

Shapiro said that comparing genetic diversity before and after the last Ice Age, for example, can show how a species responded to the change.

Beth Shapiro: There are species that survived the last mega-faunal mass extinction that happened 10,000 years ago, that we thought just went through the whole extinction event without any genetic consequences to them. But we now know because we can look prior to this event and after this event, that’s not true. These species were genetically decimated as far as diversity was concerned, at this time period. So just because they survived, didn’t mean that there wasn’t an influence of whatever it was that was going on.

For example, her research found that bison lost their genetic diversity before the last Ice Age, rather than with the arrival of human hunters, as popularly thought. That’s part of a big debate in evolutionary biology, about whether climate change, or human predators, caused the most recent mass extinction. Shapiro believes it’s a combination, and that her research could yield more answers.

Beth Shapiro: Hopefully, by looking at the patterns that we see in these different species we can learn something about how species respond to climate change, why some species survive than others, what specific environmental changes might be important for different types of species.

Shapiro said the science needs better tools for working with the old DNA, and older specimens, in order to make more specific conclusions about past climate change, and how species might respond to future climate change.

Lindsay Patterson