For reef fish, tolerance for warming waters comes from their parents’ DNA

May 1 (UPI) — New research suggests reef fish can inherit the genetic tools to adapt to rising water temperatures.

In lab tests, scientists found the offspring of parents who were exposed to water temperatures increases were better able to adapt water temperatures increases than fish spawned by parents exposed to stable temperatures.

“When parents are exposed to an increase in water temperature, we found that their offspring improved their performance in these otherwise stressful conditions by selectively modifying their epigenome,” Philip Munday, researcher with the ARC Centre of Excellence for Coral Reef Studies and James Cook University, said in a news release.

Epigenetic changes in the DNA are biochemical changes that alter the expression of genes, causing certain genes to be turned on or off. A growing amount of evidence suggests a variety of environmental factors — including stressors like disease and famine — can trigger small epigenetic changes in humans and animals.

In 2015, researchers found worms exposed to famine conditions altered the genes they passed onto their offspring. The next generation of worms were smaller, less fertile and more likely to be male, but they were also hardier and better able to survive famine and heat stress.

In the most recent lab tests, scientists measured selective DNA methylation changes in fish parents and their offspring after being exposed to water temperatures increases. These shifts allowed the offspring to better adapt to heat stress.

Researchers shared the test results in a new paper published this week in the journal Nature Climate Change.

“We reared spiny chromis damselfish, a common Indo-Pacific reef fish, for two generations under three different water temperatures, up to 3 degrees Celsius warmer than current-day ocean temperatures,” said Timothy Ravasi of King Abdullah University of Science & Technology. “The next generation appeared to be advantaged by parental exposure to elevated temperatures. The offspring’s altered gene expression, also referred to as ‘acclimation,’ allowed them to maximize oxygen consumption and energy use.”

These subtle genetic changes may help species protect themselves against sudden shifts in climate and environment, and allow for populations to adopt more significant genetic adoptions over a longer timespan.

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