ETH Zurich –
An international research team from ETH Zurich and French universities has studied genetic diversity among fish around the world for the first time. Their research produced a map that will serve as a tool in improving the protection of species and genetic diversity in the future.
In a population of animals or plants, genetic diversity can decline much more quickly than species diversity in response to various stress factors: disease, changes to habitat or climate, and so on. Yet not much is known about fish genetic diversity around the world.
The researchers have also identified the environmental factors instrumental in determining the distribution of genetic diversity in their new study.
To begin their study, the researchers analyzed a database that contained the data of over 50,000 DNA sequences representing 3,815 species of marine fish and 1,611 species of freshwater fish. From this sequence data, they estimated the average genetic diversity in sections of bodies of water, each section measuring 200 square kilometers (about 77.2 square miles).
Their analysis revealed that genetic diversity is unevenly distributed throughout marine and freshwater fish. They found the greatest genetic diversity among marine fish in the western Pacific Ocean, the northern Indian Ocean, and the Caribbean. Among freshwater fish, genetic diversity was greatest in South America, but comparatively low in Europe.
Further, researchers determined that temperature is a key factor influencing genetic diversity among marine fish: as the temperature rises, so does diversity. By contrast, the key determinants of genetic diversity in freshwater fish were the complexity of their habitat structure and how their habitats have changed over time.