Updated: Oct. 16, 2019 at 10:17 p.m.

A professor co-authored a paper that compared how current worldwide decreases in ecosystem biodiversity mirror similar trends in prehistoric ecosystems.

Andrew Barr, an assistant professor of anthropology, examined how the loss of large animals like wooly mammoths and saber-toothed tigers during the last ice age influenced species interactions, according to a GW Today release earlier this month. Paleoecology experts said observing how prehistoric species responded to large animal extinctions can baseline research on how biodiversity loss will affect present ecosystem interactions.

“We have this modern-day biodiversity and climate crisis that we know is having profound impacts and can feel sometimes that we don’t really know what’s happening because it’s a new problem,” Barr said. “If we study the past, we actually have a record of how mammal communities have reacted.”

The research team examined 93 species spanning from the Pleistocene era — the last ice age — to the present day to understand how mass extinctions of keystone species, or organisms on which other species in an ecosystem depend, can alter species abundance within ecosystems.

The team found that removing predators at the top of the food chain, like the woolly mammoth, caused species to inhabit certain areas based on abiotic instead of biotic factors.

Barr said the paper was part of the Smithsonian Institute’s Evolution of Terrestrial Ecosystems working group, a research program that studies how terrestrial land ecosystems have evolved, which provided the research team with funding.

He said eliminating keystone predator species leads to a rapid increase in “common species,” like rats, and biodiversity loss. He said human activities, like clearing land for agricultural use, has contributed to biodiversity loss and biotic homogenization – when separate communities of organisms become more similar.

Factors like climate change and pollution have led to decreases in biodiversity worldwide, according to a United Nations report released in May. The average abundance of native species in most major land-based habitats has fallen by at least 20 percent since 1900, according to the report.

“We know a really common pattern that’s been shown in a lot of different studies is that the species that are very common in different sites become even more common,” Barr said. “Things like raccoons or opossums do really well in sort of these human modified ecosystems that we have today.”

Biodiversity loss weakens ecosystem productivity, according to a release from Conservation International. Decreasing species diversity reduces ecosystems’ capacity to store excess carbon and act as water and food sources, the release states.

Paleoecology experts said examining how prehistoric ecosystems changed in response to large animal extinctions can serve as a guideline for how modern ecosystems will respond to the current biodiversity crisis.

Emily Lindsey – an assistant curator and excavation site director at the La Brea Tar Pits and Museum, which is a collection of tar pits in California that contain fossil remains – said human activity can hinder species’ ability to survive climate change. She said animal biodiversity would decrease more slowly if humans did not intercede in natural habitats, like how endangered animal populations can be confined in national parks.

Lindsey added that biodiversity loss has taken place over millions of years, but recent human impacts on the environment have expedited mass species extinctions.

“It’s only very recently – just in the last few tens of thousands of years – that really dramatically changed,” she said. “The second thing that’s important to recognize is that event very likely represents the beginning pulse of the extinction crisis that we’re in today.”

Lindsey said ecosystem conservation can mitigate the effects of human activity and climate change on species abundance.

“The most important thing that we can do is protect large swathes of land,” she said. “That includes corridors, or significant say, elevational or longitudinal gradients where the animals will be able to migrate and track the ecosystems that they rely on.”

Lindsey said challenges like climate change that animal species face today are also affecting humans. She said humans now face more difficulty extracting necessary resources, like food and water, from the environment.

“Human populations are also being stressed exorbitantly by climate changes, like major weather events, drought, crop die off and ocean die off are impacting communities that rely on resources from the sea,” Lindsey said.

Warren Douglas Allmon, a professor of paleontology at Cornell University, said removing any species from an ecosystem disrupts the food chain, which can “radically” transform interspecies interactions, which he said negatively affects ecosystem productivity.

“If you get rid of species in any ecosystem or you get rid of large-bodies species, then you are going to change the dynamics within the ecosystem because you’ve removed an energy processor,” Allmon said.

This post has been updated to correct the following:

Due to inaccurate information from a source, the Hatchet wrongly reported that Andrew Barr is a visiting assistant professor. He is an assistant professor.