Sea fish are descendants of river fish?

New research in the US has shown that marine fish are now evolving from freshwater fish. Scientists believe that this is why the ocean accounts for 75% of the Earth's surface but contains very few fish and organisms, from 15% to 25% of the estimated global species.

The study was conducted by Dr. John J. Wiens and students of the Department of Ecology and Evolution, Stony Brook University, USA; The results were published in the journal Proceedings of the Royal Society.

Wiens and students looked at the biodiversity of the rays, the most abundant species of all vertebrates in the saltwater environment and accounted for 96% of all planet fish species. .

The sea has many strange species but does not have rich species diversity by land.

They analyzed evolutionary plants based on fossils and DNA data (genetic material of the organism). They also analyzed on a large database of habitats for almost all fish species that exist today.

The analysis shows a surprising difference in biodiversity between freshwater and saltwater habitats.'There are many species of fish in the freshwater environment in saltwater environment, although freshwater environment only accounts for about 2% of the earth's surface. More surprisingly, most of the living saltwater fishes today are descendants of freshwater fish ancestors , Physorg quoted Dr. Wiens.

This result at first glance seems to contradict the 'postulate' that life originates from the sea. However, the hypothesis is that, major extinctions in saltwater environments hundreds of millions of years ago have affected the 'migration' and evolution of fish journey.

He explained in detail that it is true that freshwater fish species were initially diversified from saltwater ancestors, but then the saltwater ancestors were completely extinct. Then, freshwater fish return to the ocean, evolving into saltwater fish like today (and thus the descendants have less time to develop biodiversity). This is the reason why the oceans are so poor for creatures, even fish.