DNA sequencing of brown trout to improve conservation: Scientists

An international team of scientists have completed the genome sequencing of the wild brown trout (Salmo Trutta) — one of the most genetically diverse group of vertebrates.

This can identify genetic traits that helped the species cope with environmental pressures and boost wildlife conservation during climate change, according to scientists, including those from the Institute for Global Food Security (IGFS) at Queen’s University Belfast.

While only three to 50 species, based mainly on appearance, are commonly referred to as brown trout, scientists noted that the DNA sequencing will answer a long-standing debate about whether they are a single species or several.

The genome sequencing of the wild brown trout is part of an ambitious project to track the DNA of tens of thousands of lifeforms in the United Kingdom.

Brown trout has 38 to 40 chromosomes and multiple copies of those chromosomes within its genome. But, for the DNA sequencing, scientists from the Institute of Marine Research in Norway bred specimens with only one set of chromosomes.  

“Given the variability of brown trout in the wild, it was important that we could create a number of genetically identical individuals to build the reference genome,” said Tom Hansen, principal scientist at the Marine Research Institute. 

“Now that we have the genome, we can begin to learn more about how trout adapt to different conditions, helping the management of wild and farmed fish stocks in future,” he added.

The findings will also reveal the mythical ‘superpowers’ of the iconic brown trout that made them one of the first species to recolonise previously frozen freshwater areas from the sea at the end of the last Ice Age.

Their unique genetic adaptations, for instance, helped “different populations to exploit particular biological niches, with some living their whole lives within a 200-metre stretch of freshwater stream while others migrate from the stream to the open sea,” the researchers said.

Identifying these genetic variations, which help trouts adapt to relatively acidic waters, may also guide conservation efforts to protect marine populations affected by growing acidity in rivers and oceans due to climate change, said Paulo Prodöhl, a fish-genetics expert from IGFS.

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