Yeast evolution reveals limits to surviving climate change

Yeast may seem unremarkable at first glance. Most of us know it as the stuff behind bread and beverages, yet there is more to these tiny organisms than meets the eye.

A new study reveals that genetic diversity and temperature tolerance are closely linked, offering fascinating insights into how certain species might endure in a rapidly changing world.

The findings come from work led by Jennifer Molinet and Rike Stelkens, both researchers in the Department of Zoology at Stockholm University.

Yeast helps us study evolution

Yeast is actually a microorganism that belongs to the kingdom of fungi. It has been essential to humankind’s cooking and fermentation processes for centuries.

Scientists also use it in the lab to investigate big questions in ecology and evolution because it reproduces quickly and is easy to grow under controlled conditions.

These qualities helped researchers watch adaptation unfold over 600 generations. A temperature increase from 77°F to 104°F provided a model of future warming.

This setup allowed them to see how eight different yeast species, each with unique histories, handled steamy conditions without stepping outside the lab.

How yeast handles heat

The team monitored the growth and development of these yeast populations and took note of shifts in temperature tolerance. They gathered data about how each species performed at various points along the heat spectrum.

This continuous observation offered a window into experimental evolution, where small changes can accumulate into noticeable differences.

“We found that different species use different evolutionary strategies to adapt to heat: some species, already warm-tolerant, did not improve their performance, but rather expanded their temperature range,” said Molinet.

“Other species, more adapted to the cold, were able to withstand higher temperatures, but this came at the cost of reduced overall fitness,” she added. No single adaptation path appeared across all species. 

Yeast’s changing abilities

Certain yeast species excelled at handling the heat but lost out in other areas. Those with cooler preferences had room to push their upper limit, though they sacrificed maximum growth in the process.

This pattern hints that there might be trade-offs for any population facing an environmental shift. Some species broadened their tolerance without boosting their ability to thrive at hot temperatures.

Others raised their limit for warmth but ended up less efficient when it came to peak growth. That distinction may be critical when predicting how biodiversity fares in changing environments.

Warming threatens biodiversity

Biodiversity is the variety of life that enriches ecosystems around the world. Studies like this one show how organisms can adapt under stressful conditions.

The research also hints that species already equipped for warmer climates might keep improving, while those that like cooler spots could struggle to keep up. Small genetic changes can make a big difference in how a species responds to environmental stress.

Over time, genetic adaptations could alter entire ecosystems if certain microbes become more common. This raises a puzzle about who wins and who loses when heat becomes the norm.

Climate change lessons from yeast

The same group has looked at other organisms too. In a separate publication, they studied temperature adaptation in seed beetles.

This sort of comparative approach shows how different species, from insects to fungi, adjust to new extremes.

It all comes down to how well an organism’s evolutionary potential can keep pace. Genetic diversity forms the bedrock that allows populations to respond to new pressures. With more variation comes a higher chance that some individuals carry traits well-suited for a hot future.

Yeast shows how microbes may shift

One of the most interesting points of the study is that it highlights the unique paths organisms including yeast take in response to climate change. This could guide us in anticipating how microbes, and possibly pathogens, might shift their ranges or behaviors.

Early insight can help researchers stay a step ahead in tracking which strains pose threats or benefits under higher temperatures.

Adaptation isn’t uniform. We cannot assume that every organism will simply become more heat-tolerant. Some will expand their temperature ranges, while others will change their optimal growth zone.

If entire populations head in different directions, future ecosystems could look very different.

The past shapes future evolution

“If temperatures change in the future, it is still the history in our genes that determines if and how we can adapt,” said Dr. Stelkens. The past leaves a stamp on the present.

The findings underline how the unique background of a species can limit or boost its path forward. That sense of individuality is a reminder that no two species are alike. Each carries genetic memories of ancient environments.

Some are better equipped for certain extremes, while others are at a disadvantage when conditions shift too far from what their ancestors experienced.

Ongoing yeast and climate research

Experiments with yeast and other microbes allow researchers to explore how life’s building blocks respond to new challenges including climate change.

There is still much to learn about specific genetic mechanisms behind heat tolerance and how trade-offs affect survival. Future work may reveal ways to preserve vulnerable species as conditions change.

Adaptation studies can also help scientists predict whether new strains might develop harmful traits. This can be pivotal for fields like medicine and agriculture, where a small genetic tweak in a microbe can affect disease spread or crop production.

Ultimately, staying informed on such developments might protect our well-being.

The study is published in the journal Proceedings of the National Academy of Sciences.

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