Genes turn on to help fish adapt to climate change

The research improves understanding of which genes are involved in “transgenerational acclimation”. Knowing how the genes’ expression is regulated should enlighten us on how they respond to rapid environmental change, say the researchers.

“[It will] help [us] identify which coral reef species are most at risk from climate change and which species are more tolerant,” says computational biologist, Timothy Ravasi,  from King Abdullah University of Science and Technology (KAUST). “This will help to design better strategies for coral reef conservation.” 

Previous studies found that variations in water temperatures – just a few degrees above the summer average – reduced fishes’ capacity to take up oxygen when active. This capacity is unimpaired in fish whose parents were also hatched in water at the same higher temperatures; known as transgenerational acclimation. 

The team analysed and compared the RNA sequences in two groups of reef fish: those hatched in water 1.5°C or 3°C warmer than normal (the “developmental” group) and fish whose parents had also been exposed to higher temperatures since they were hatched (the transgenerational group). Comparing the two groups allowed the researchers to pinpoint changes in gene expression across generations.

They identified 53 key genes involved in optimizing fishes’ capacity for oxygen uptake and adapting to higher temperatures. 

The main function of one large group of genes was related to metabolism, suggesting genes are “turned on” in transgenerational fish to enable more efficient energy use in warmer water temperatures. 

Other genes that were “turned on” in transgenerational fish pertained to immune responses and inflammation, stress, maintaining normal physiological processes, organ development and maintaining DNA integrity. 

A third group of genes was “turned off”, apparently to favour other more beneficial genes for transgenerational acclimation.

Ravasi says further study should reveal whether other coral reef inhabitants employ similar mechanisms to rapidly adapt to the effects of climate change. Scientists also need to learn how adaptation at the molecular level is passed through genomes from one generation to the next via non-genetic inheritance. “The same team is now analyzing new data that will most likely answer this question,” says Ravasi.

The sequencing and computational analyses for the study were done at KAUST while fish rearing, metabolic measurements, and sample-taking were done at the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University in Queensland.

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