Fish species are not the only things that can change over time.
A new study has shown that over the past five decades, a number of species have actually evolved in such a way that their genetics are no longer the same.
The researchers believe this is due to an “evolutionary process whereby species evolve to meet a particular needs of the environment”.
The key finding of the new study is that there are more and more fish species that are no more similar to each other than there were in the past.
For example, there are now a range of species of tuna that are much smaller and far more variable in size.
The research team says these species are able to adapt in response to environmental conditions and environmental threats.
These include warmer seas, the introduction of new fishing methods, and changes in climate.
“The new study shows that there is a huge range of new species, both from the same source species but new to the community and even species that were introduced to the oceans by humans,” said Dr Matthew Kewell, a senior research fellow at the University of Sydney and lead author of the study.
“There is no single cause for this diversification but many factors are likely to be contributing to this.”
In the study, published in Nature Ecology & Evolution, Dr Kewel and his team examined the genetic history of some of the most important fish species, including bluegill, hammerhead, tigerfish and terraria.
They found that the genetic diversity of these species was not always the same, which is unsurprising as fish have such different genomes.
These are species that evolved to be different from one another in response for many reasons including climate change and changing habitat conditions.
“For example, we have seen that hammerhead and tigerfish populations have undergone rapid declines due to overfishing and overfished fishing techniques,” Dr Kephart said.
“In the future, we need to understand how fish species can adapt to new conditions and how they can maintain genetic diversity in response.”
Dr Kebell said there was evidence to suggest that fish could be evolving to be more tolerant of environmental threats, such as climate change.
“Some species can live on the edge of extinction, whereas others will survive and will thrive on certain habitats, but they are all changing their ecology and are adapting to those changes,” he said.
In the past, there have been many species that had a relatively low genetic diversity, but the authors believe that now we are starting to see some species that can actually be more resilient to environmental changes.
“This is a time when we need all fish species to change their DNA to adapt to these changing environmental conditions,” Dr C.E.M. Kewill said.
The authors also say that while this is a significant change in the genetic composition of some species, it is not the end of the world.
“What is important is that we should not forget the many species which have already adapted to these conditions, so that we can continue to have a diversity of species to choose from,” Dr R.L. Kebill said, referring to the diversity of fish species.
“I do think that there will always be a range in the gene pool of each species that is still the same and that we must work together to find new ways of adapting and to create new fisheries.”
Dr Cesar Novelli, a research fellow with the Australian Institute of Marine Science, said the new research was “a fantastic contribution to our understanding of the evolution of fish”.
“This study is a really exciting and important contribution to the field,” he added.
“It has been shown for the first time that species can respond to environmental challenges and are changing their genetic makeup.
This shows that these changes are not irreversible and that the gene pools of these fish species will continue to diversify as they adapt to different ecological and environmental conditions.”