Santa Cruz, Calif. – A new study led by an ecology and evolutionary biologist at UC Santa Cruz finds that temperature changes due to climate change have a doubly detrimental impact: Not only do they destabilize animal populations, but the impacts accelerate as temperatures change more rapidly.
In the study , published on January 29 in Nature, the international team of researchers found that changing temperatures—either warming or cooling—drive changes in the composition of species in an ecosystem. The results also suggest that behavioral adaptation and changing species interactions are not enough to preserve species composition in the face of higher rates of temperature fluctuations.
"It's like shuffling a deck of cards, and temperature change now is shuffling that deck faster and faster," said lead author Malin Pinsky, associate professor of ecology and evolutionary biology at UC Santa Cruz. "The worry is that eventually you start to lose some cards."
The study's findings are unique because the impacts of temperature change have often not been clear on land or in freshwater ecosystems. While impacts on ocean species have been more overt, and therefore easier to measure, plants and animals on land adapt in subtler ways, the researchers said.
Unlike ocean animals, those on land can often move short distances to find new locations that better suit their temperature needs. Though this can mitigate the effects of temperature change a bit, this research finds that terrestrial creatures are still susceptible to destabilization and replacement due to temperature change. In their paper, the researchers focus on the rates of species replacement, which refers to the loss and gain of species over time. While this happens naturally, they found that the rate of replacement is increasing due to faster temperature changes.
If that trend continues, species could be lost and ecosystems could begin to break down, the study concludes. The most effective ways to avoid these outcomes are to avoid further global warming, preserve landscapes with a diversity of temperatures, and reduce the alteration of natural environments. Benefits could include more abundant wildlife, clean water, and clean air.
"Temperature affects everything from how fast the heart beats to how flexible and porous our cell membranes are; from how much food animals eat to how fast plants grow," said Pinsky. "Temperature is in many ways the metronome for life."
Why diverse environments are important
In addition, the researchers found that species in ecosystems with less-varied habitats were more sensitive to temperature change than those with more diverse temperatures nearby. For example, if a person stood in an open field during summer and started to overheat, there would be nowhere cooler to hide. But if a forest were nearby, one could simply move into the shade of a tree to cool down. The paper concludes that plants and animals take advantage of habitat variation to buffer themselves against major temperature swings. Living near these temperature escapes allows organisms to move nearby for relief, rather than going extinct or being replaced entirely.
Whether due to natural conditions or human interference, not all environments have a diversity of temperatures to help protect the species that live in them. It is these animals that are most at risk due to faster temperature changes. Understanding the differing needs of species living in more or less varied environments can help society identify which ecosystems need the most attention and protection, the study concludes.
"Establishing this explicit link between rates of climate change and rates of species turnover allows us to better understand how changing temperatures can impact different ecosystems," said senior author Shane Blowes, from Germany's Centre for Integrative Biodiversity Research (iDiv) and Martin Luther University Halle-Wittenberg. "Pinpointing factors that impact the rate of local species replacement can help prioritise conservation actions."
How human activity impacts turnover
Importantly, the researchers found that human impacts like land use, pollution, and introduction of invasive species exacerbate the impacts of temperature change on species replacement. This is possibly due to human activity reducing the diversity of landscapes and increasing stress on species that are already near their temperature limits.
To conserve ecosystems and their benefits to people, humans can help by "preserving more natural habitats, reducing pollution, and reducing the spread of invasive species," Pinsky said. "In the ocean, factors like reduced fishing pressure and protecting habitats are important and helpful."
The paper's other authors include Helmut Hillebrand at the University of Oldenburg in Wilhelmshaven, Germany; Jonathan Chase, also from iDiv and Martin Luther University Halle-Wittenberg; and researchers from the Institute of Biodiversity at Friedrich Schiller University in Jena, Germany, the Research Centre for Ecological Change at the University of Helsinki, and the Scottish Association for Marine Science in the UK.
Main funders for the study, "Warming and cooling catalyse widespread temporal turnover in biodiversity," include the National Science Foundation, iDiv, and the Helmholtz Institute for Functional Marine Biodiversity.
