Global warming is faster than evolution

December 14, 2020

The world is getting warmer, and life has to adapt to new conditions. But if the warming continues, many species may have trouble keeping up.

"It looks like evolution is slower than global warming in this case," says Fredrik Jutfelt, an associate professor at the Norwegian University of Science and Technology's (NTNU) Department of Biology.

Jutfelt is a senior author of a new article in the Proceedings of the National Academy of Science, PNAS. He and his research group at NTNU have spent four years studying how a tropical fish species called zebrafish (Danio rerio) adapts to a warmer climate, especially with regard to extreme warm periods. Dr. Rachael Morgan, now at the University of Glasgow, is the lead author.

"This is the largest artificial evolution experiment that has been performed on vertebrates with a focus on heat tolerance," says Jutfelt.

Bred to cope with particularly warm periods

The research group used zebrafish that were caught in the wild for their experiments. The fish were then deliberately bred based on their ability to cope with the most extreme warm periods. The researchers followed roughly 20,000 individuals over six generations.

"We see that zebrafish can develop heat tolerance, and we have developed lines of zebrafish that can better withstand the heat. That's good news," Jutfelt says.

What's impressive is that researchers have actually been able to measure evolutionary adaptation to a warmer world in vertebrates in the laboratory.

"The problem is that evolution takes many generations. Evolution only increased the heat tolerance in the fish by 0.04 degrees C per generation. This is slower than the warming experienced by many fish in many places," Jutfelt said.

"Now the globe is warming so fast that the fish may not be able to adapt to the warmest periods efficiently enough," Morgan said.

Warm periods are becoming more common

Evolution means that the individuals which are best adapted to environmental conditions produce more fertile offspring than other members of their species. Over several generations, these changes can accumulate and alter the species itself.

Particularly hot periods can harm some of the fish, or make them unable to reproduce. Above a certain temperature, most of the fish will die.

Climate change is increasing the Earth's average temperature, and additionally cause more frequent and intense heat waves.

"How organisms adapt to these new conditions depends on their ability to withstand heat, to acclimatize, and the ability to pass on beneficial characteristics to the next generation," Jutfelt says.

Evolution may not save species

One group of zebrafish also spent two weeks in warmer water prior to artificial selection, to see if evolution could increase their capacity to acclimatize. It did not.

"Instead, the greater the ability of the fish to cope with the worst warm periods, the more their ability to acclimate decreased. So the gain in the form of higher heat tolerance was partly offset by a lower ability to acclimate. All in all, the rate of evolution was probably faster under the conditions in our laboratory than in nature," Morgan said.

"It's unlikely that some zebrafish populations, and other tropical fish species, will be able to cope with the temperatures that the planet may experience by the end of this century. Some species that already live at the limit of what they can tolerate may not be saved by evolution. That is surprising and sad, and it means it is important that we stop warming the planet" Jutfelt said.
Reference: Rachael Morgan, Mette H. Finnøen, Henrik Jensen, Christophe Pélabon and Fredrik Jutfelt. Low potential for evolutionary rescue from climate change in a tropical fish. PNAS.

Norwegian University of Science and Technology

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to