UM Researcher: How Animals Adapt to Climate Change Depends on What They Build

MISSOULA – Across the globe, rising levels of carbon dioxide in the Earth’s atmosphere are causing temperatures to rise and precipitation patterns to shift. For biologists, a key problem is understanding the current effects of climate change on animal species and predicting future effects, such as the shifting of species’ ranges and their relative risks of extinction.

In a new paper in Trends in Ecology and Evolution, a group of researchers from the University of Montana, the University of Wyoming, the University of Tours in France and Stellenbosch University in South Africa argue that understanding how animals modify their own, local experience of climate can help predict the impacts of climate change. 

Many animals dig burrows, construct nests for themselves or their offspring, build homes for entire colonies, induce plants to produce galls that protect insect eggs, build leaf mines or simply modify the structure or texture of their local environments. These modifications, known as extended phenotypes, filter climate into local sets of conditions immediately around the organism – their microclimate.

“In our view, those microclimates represent an underappreciated and highly understudied set of processes that may reveal how species will respond to climate change,” said Art Woods, a professor in UM’s Division of Biological Sciences.

Bird nests keep eggs and nestlings warm during cool weather and cool in hot conditions. Termites build mounds that capture wind and solar energy to drive airflow through the colony and stabilize its temperature, relative humidity and oxygen level. Mammals that sleep or hibernate in underground burrows experience stable, moderate temperatures and avoid above-ground extremes. 

Woods said as microclimates typically strongly differ from nearby climates, the area climate provides little information about what animals experience in their microhabitats.  Because extended phenotypes are built structures, animals can modify them in response to local climate variation and potentially in response to climate change. These kinds of responses are known as phenotypic plasticity.

Ultimately biologists don’t know how species will respond to a changing climate – whether they will move or alter their phenotypes or evolve new traits through natural selection, Woods said.

Species most vulnerable to climate change usually have small ranges and population sizes and live in areas that are isolated without other nearby habitats.

“Some high elevation species are at risk because as their habitats warm, they may try to migrate uphill – but sometimes there is no suitable uphill habitat,” Woods said.

In the Rockies, tent caterpillars are particularly vulnerable to climate change.

“They are interesting because siblings hatch out together and, working communally, build a silk tent,” Woods said. “That silk tent provides a central platform for organizing their feeding patterns, and the tents often warm up far above ambient air temperature. The tents act like solar collectors that help the caterpillars warm up and feed and grow faster during cool spring conditions.”

Woods said, however, that higher future temperatures may injure or kill the caterpillars in their tents.

Understanding how species adapt, Woods said, will provide insights on the spread of disease vectors, the health of marine and terrestrial biomes around the world, and whether agriculture and fishing can continue supporting human populations.   

“Humans have a long history of developing tools and technologies based on observing how animals solve problems – something called ‘bioinspiration,’” Woods said. “As our climates continue to change, it would be smart to keep an eye out for whether and how animals are solving their local climate problems.

“The vast diversity of animal and plant life on the planet can serve as a kind of evolved knowledge reservoir,” he said, “if only we can study it, and perhaps leverage some of it, before there is too much disruption.”