Carleton PhD candidate Danielle Fraser and co-authors Christopher Hassall of the University of Leeds, Root Gorelick of Carleton’s Department of Biology, and Natalia Rybczynski of the Canadian Museum of Nature recently released a paper that shows the fossil record can help predict how animal communities will react to climate change. The paper concludes that the fossil record is a valuable resource in understanding how animals will react to climate change.
Fraser and her colleagues looked at North American mammals to understand climate change’s effect on the diversity and spread of animals on the landscape. The paper looked specifically at latitudinal diversity gradients, or the difference in the number of animals in the north and south parts of the continent.
Today, North American animals are not spread evenly over the landscape. There is a much higher diversity of animals living in southern tropical areas than there are in northern polar regions.
Fraser and her colleagues discovered the spread of animals on the landscape varied a great deal in the fossil record. They show that historically, during cooler, dryer times, animals were distributed similarly to today. But during warmer times with more rainfall, animals were spread more evenly on the landscape and were especially more prevalent in polar regions.
After looking back, Fraser was able to look ahead using both climate change projections from the Intergovernmental Panel on Climate Change and Species Distribution Models that are commonly used by researchers. The Species Distribution Models look at where animals live now and try to predict how they will react to changing climate conditions.
“We can predict, based on the fossil record, that we will get a more even spread of animals on the landscape as climate warms,” said Fraser. “We already know this is happening. We already have species appearing in places where they haven’t before.”
The fossil record, which is the totality of the preserved remains of animals, plants and other organisms, tells us that these changes, both today and historically, are driven by loss of polar ice. As polar regions warm up and become more habitable, animals move into and survive in them.
The major takeaway from this study is that the data from the Species Distribution Models are incomplete because they do not account for evolution. Although her study of fossils predicts that, as climate change makes North America warmer and wetter, animal communities will begin to spread out more evenly, the data from the Species Distribution Models did not show this. This became more apparent the further into the future that Fraser and her team tried to look.
“These models, that are used commonly to make predictions about how animals will respond, are valuable in the short term,” said Fraser. “But when it comes to trying to understand what our grandchildren are going to see, the situation 100 years from now, they become less valuable because they exclude things like evolution and body size. Evolution happens on small timescales – in 100 years, evolution absolutely can happen.”
In other words, excluding evolution makes it difficult to project what the animal landscape will look like 100 years or more from now. The fossil record is therefore incredibly valuable because it can help us better predict the outcomes of climate change in the long term.
When discussing the implications of the study, Fraser said:
“The fossil record provides information that is relevant to making better predictions of climate change response in the future because it includes many climate change events and many evolutionary changes. However, the models we use to predict animal response to future climate change exclude evolution. Using the study of fossils, we can hopefully develop new models that will allow more accurate predictions.”
The paper was released in the scholarly journal PLOS One. You can find it here.
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