Certain fish species adapt to warmer oceans without ADN changes
2016-11-04 10:34:26   copyfrom:    hits:

Winter skate (Leucoraja ocellata) (Photo: DFO)UNITED KINGDOMFriday, November 04, 2016,01:50 (GMT + 9)Researchers fro
 

Winter skate (Leucoraja ocellata). (Photo: DFO)

 

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Friday, November 04, 2016, 01:50 (GMT + 9)

 

Researchers from the University of East Anglia (United Kingdom) andDalhousie University (Canada) have found that some fish species are adapting to survive environmental changes without significant genetic evolution.

These scientists stress that such changes mean species threatened by climate change may find ways to adapt far quicker than through changes in DNA, which come with evolution.

To reach these conclusions these researchers studied the winter skate (Leucoraja ocellata), in waters that are around 7000 years old and significantly warmer than those where the rest of the species range is found. They observed many physical and functional adaptations which allow the species to cope with the significantly different set of environmental conditions observed in this shallow, warm habitat.

Dr Jack Lighten from UEA’s School of Environmental Sciences says this type of adaptation is due to epigenetic changes – caused by modification of gene expression where instructions in DNA are converted into a functional product, i.e. protein.

These adaptations are particularly important for species with long maturation times and low reproductive potential, as typically these life-history characteristics result in slow evolution. Rapid changes in gene expression, irrespective of changes in the DNA sequence, can allow rapid modification of an organisms biological characteristics and fuel a form of rapid adaptation.

In Dr Lighten's opinion, there is a wealth of fossil evidence which suggests rapid climate shifts do not provide enough opportunity for many species to adapt, meaning they became extinct or restricted to smaller areas of suitable habitat.

“But adaptations in evolutionary potential through gene expression can enable species with long maturation and low reproductive output (and so low evolutionary potential) to survive and adapt to different environments – something which may be vital for the future survival of sharks, skates, and rays in the light of future climate change,” the scientist pointed out.

To carry out the study, two populations of the winter skate in Atlantic Canada were studied - one an endemic and endangered population in the southern Gulf of St Lawrence, and a large population on the Scotian Shelf.

It has been found that the southern Gulf of St. Lawrence winter skate has reduced its body size dramatically, by 45 per cent compared to those in the other population, and has a significantly shorter life span with a faster maturation time. Investigation of this miniaturized endemic skate’s genes showed thousands of changes in gene expression.

The adaptive changes in life history, physiology and phenotype have occurred through epigenetic regulation causing changes in gene expression, enabling the species to respond rapidly to environmental challenges.

The importance of genetic versus epigenetic changes in adaptive evolution is hotly debated and the results of this study are significant in demonstrating the value of studying these variations, not only in fish but other species facing similar challenges.

“Our work suggests that some success of sharks, skates and rays over very long evolutionary time scales may be due to their ability to respond rapidly to environmental changes through regulation of gene expression. The biggest threat today for many of these species is overfishing. We are only just beginning to understand how they may be affected by climate change. We hope our findings will open the door for more detailed research on the role that epigenetics may play in allowing vulnerable and ecologically important fish to persist during this period of rapid global warming,” the scientist concluded.

The study was published in the journal Royal Society Open Science.

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