Viruses struggle to adapt to climate change

Mohan Yin_Scitech Viruses_0205
Photo by Mohan Yin.

The severe heat waves and blizzards incurred by climate change have caused even viruses to have trouble adapting to randomly fluctuating temperatures.

A study published Jan. 31 in the journal Evolution demonstrated that viruses cannot adapt well to an environment with erratic temperature shifts within a range of 8 degrees Celsius, though they thrived when subjected to predictable fluctuations in temperature or incubated at either temperature extreme.

After the viruses were subjected to a given temperature pattern for around 100 generations, a sample of the evolved virus population was tested at both high and low temperatures — 37 degrees Celsius and 29 degrees Celsius, respectively — to gauge how well it could cope with those temperature extremes.

When exposed to a constant temperature, viruses evolve to become “specialists” for that temperature, surviving and reproducing best at that specific temperature. When exposed to regular patterns of temperature change, viruses instead become generalists that can withstand a wide range of temperatures. On the other hand, viruses that experience random temperature fluctuations are subject both to periods of relatively constant temperatures and to periods of rapid heating or cooling. Thus, they are unable to adapt either as generalists or as specialists.

“The virus populations are chasing a moving target,” said Barry Alto, lead author of the study and University of Florida professor of arbovirology. “So certain molecular changes in the virus that are beneficial in one environment may be detrimental in other.”

There has been relatively little research on how well organisms can adapt to different patterns in the environment. Even though the temperature fluctuations were not designed to simulate those observed or predicted by climate change, this study represents a preliminary demonstration that the random nature of environmental change may hinder organisms’ abilities to adapt, said senior author Paul Turner, chair of Yale’s Ecology and Evolutionary Biology Department.

This may be bad news for Earth’s flora and fauna, as viruses typically adapt to new environments more quickly than animals and plants can do so. If viruses do not readily adapt to environments with randomly fluctuating temperatures, it seems unlikely that animals would fare any better.

“It’s reasonable to believe that organisms that mutate at a lower rate may have more trouble adapting,” Alto said.

But the current experimental setup is a far cry from a simulation of climate change, and Alto and Turner said they are not jumping to conclusions yet. Next, Turner said he wants to replicate the experiment using more realistic scenarios, including methods of virus transport. His next study will test how similar temperature patterns affect viruses transported by mosquitoes rather than pure viruses.

Turner added that he hopes these findings may encourage other researchers to examine experimental variables that fluctuate randomly in the environment.

“Relatively few studies in evolutionary biology look at random changes in environmental conditions,” Turner said. “This opens up a lot of possibilities to investigate [random] processes.”

In the United States, 2,558 monthly heat records and 272 monthly snow records were broken over the past 365 days.

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