Great white shark genes refute the scientific explanation.
The genome of the animal may be deeply revealed, but since the researchers began decoding Great white shark (Carcharodon Carcharius) DNA More than 20 years ago, their discoveries raised more questions than answers.
2024, a to study Confirmed that, unlike usual, this fierce ocean predator does not belong to one global species.
There are three different groups that all come from the common population living 10,000 years ago until the last glacial period reduced their numbers. One of the modern groups is in the North Pacific, one in the southern Pacific Ocean and the Indian Ocean, and one in the North Atlantic and Mediterranean.
Related: The discovery of a surprise reveals that there are 3 different excellent white shark species
No matter how researchers are trying to explain those groups using evolutionary modeling, they continue to stroke after a deadlock.
“The honest scientific answer is that we can’t even imagine” says Senior Senior Author Gavin Naylor, Director of Florida Shark Research Program at the Florida Natural History Museum.
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Although the nuclear DNA of all three groups of sharks is usually the same, their mitochondrial DNA is surprisingly different.
The nuclear DNA is packed in the cell’s nucleus (and hence the name), but the mitochondrial DNA is packed in mitochondria that secrete energy to the cell.
Unlike the nuclear DNA, which is inherited from both parents, most mitochondrial DNA (MTDNA) is inherited from the mother. Multicellular animals – Sharks;
Because MTDNA can trace the mother’s line, protection biologists have used it for many years to set the boundaries of the population and migration paths.
But when it comes to great white sharks, this method does not work.
Even with one of the largest data sets on great white sharks, researchers worldwide appeared empty -handed.
In the past, scientists suspected that MTDNA changes were due to the fact that women’s sharks returning to their homeland to recreate – the concept, known as female philopathy.
The hypothesis is even confirmed by the latest evidence of observation that thread While both men and women are traveling long distances, women come home when it comes time to mate.
However, when Naylor and colleagues tried the idea, but it failed to explain the MTDNA groups. Naylor and his team will follow a sequence of 150 white shark genes, Naylor and his team found no female philopathy evidence.
Nuclear DNA is expected to be a small signal if women breed only with certain populations. “But it did not reflect at all in nuclear data” says Naylor.
Even when the team performed evolutionary modeling, showing how sharks could divide into three groups from their last common ancestor, the female philopathy hypothesis did not stand.
“I have come up with the idea that gender relationships may be different – that only a few women contribute to populations from one generation to another,” explains Naler.
It also did not explain the genetic differences. This is how random genetic changes that accumulate over time are called genetic drifting.
A team of scientists says that “the alternative mechanism of evolution must be functional”.
However, the only known explanation is that natural selection could have improved the MTDNA of each group, and it looks far. There are only 20,000 great white sharks in the world, which is a very small population, relatively speaking. If there is something useful in some of the evolution of some MTDNA forms, then the sharks should save from something “brutally fatal”, says Naylor.
He doubts that this is the case. Some puzzles are clearly lacking.
“The variability of mitochondria observed in natural populations has never been restored in any modeling – even with extreme female philopatries, which indicates that other forces contributed to strife,” the authors – authors – authors The conclusion;
“The same approach would be useful for other types of shark, where the philopathy of women was previously thought to have been considered to be based on genetic data.”
The investigation has been published Pna;