Surprisingly, Research Shows Blue Whales Interbreed with Other Species

  • Recently, researchers discovered the fact that there is a hanky panky or 'affair' between blue whales (Balaenoptera musculus) and fin whales (Balaenoptera physalus) and gave birth to 'flue' whales or 'chimney' whales.
  • Researchers suspect the mating system is outside the blue whale species to avoid inbreeding.
  • This research provides new insights into the population structure and demographic history of blue whales.
  • From the data collected, the current population of blue whales, which are vulnerable to extinction, is estimated to be only 15,000 in the world. The blue whale population plummeted due to massive hunting at the beginning of the 20th century.

Recently, researchers discovered the fact that there is a hanky panky or 'affair' between blue whales ( Balaenoptera musculus ) and fin whales ( Balaenoptera physalus ). Interestingly, this phenomenon has been going on for a long time.

The researchers found 3.5 percent of blue whale DNA was in fin whales. This certainly sparked curiosity that the largest creatures on earth could actually mate with animals that were 85 tonnes smaller than them.

The blue whale population plummeted due to massive hunting at the beginning of the 20th century. As a result, blue whales are included in the list of endangered species by the International Union for Conservation of Nature ( IUCN ). However, based on the latest data their population is slowly increasing throughout the world.

Regarding their DNA, in the journal Conservation Genetics published January 6 2024, researchers began analyzing the blue whale genome to look for signs of inbreeding. But instead they found crossbreeding of genes outside the species.

"Our results provide new insights into the population structure and demographic history of blue whales from the North Atlantic, as well as documenting the extent of fin whale introgression," said Sushma Jossey of the Royal Ontario Museum, Canada.

The surprising part, he says, is that most hybrid animals (the offspring of two different species) tend to be infertile. Because this animal is similar to a mule (a hybrid of a donkey and a horse) and a liger (a hybrid of a lion and a tiger).

The reason is that the hybrid parent does not have viable genetic material to produce sperm or egg cells. Indeed, there are also certain genetic factors that make it capable of hybridization or producing infertile (barren) offspring.

Research on fin whales has found no evidence that this species inherited blue whale DNA through introgression. So, it appears that only blue whales are capable or perhaps willing to reproduce with these whale hybrids.

In the case of blue whales and fin whales, it turns out that both have 44 pairs of chromosomes which tend to be identical when genetic tests are carried out. Even though they both come from different genera.

For example, the case of a hybrid whale was first discovered in Icelandic waters in 1986. Where the hybrid fin whale was identified as containing a fetus fertilized by a blue whale.

Since then, researchers have learned that blue whales mate with fin whales and produce hybrid offspring known as 'flue' or 'chimney' whales. However, this hybrid marine mammal is still a mystery regarding its evolution.

In 2021, this hybrid whale appeared. According to researchers, its appearance looks like a fin whale but is larger in size with a color and jaw structure similar to a blue whale.

Until now it is still assumed that hybrid whales are infertile and cannot have offspring. However, many believe that hybrid whales resulting from crossing blue whales and fin whales are capable of reproducing.

According to scientists, although interbreeding can sometimes be detrimental, it may help blue whales. Or perhaps, the ability to breed with other whale species could be to avoid inbreeding among blue whales.

From the data collected, the population of blue whales is estimated to be only 15,000 in the world. About 2,000 blue whales roam the Pacific coast, from Alaskan waters to Central America.

Speciation or the process of forming new types is quite an important part of genetic diversity. So far, there are no signs that the fin whale DNA present in blue whales is causing them any problems.

However, Jossey and his team are worried. Blue whale DNA was originally lost as a result of climate change.

“Our sequencing and population structure analysis provides a genomic basis to inform conservation strategies for this iconic species,” he said.

Through baru

This phenomenon led researchers to create a 'de novo' genome or a genome whose reference was not yet known. To get the data, they then used blueprints to put together pieces of DNA from different individuals in the blue whale population.

Regarding this unusual marriage, the researchers argue, it is likely that this method is part of the salvation that the entire species needs. Or it could be a form of adaptation to environmental changes.

"This will be a long and tedious process, like solving a puzzle," said Mark Engstrom, an ecological geneticist at the University of Toronto, as quoted by Live Science .

Based on the genome, Engstrom said there was much less inbreeding among North Atlantic blue whales than expected. Instead the research team found results from fin whale DNA sequencing among the blue whale genome.

“The amount of introgression between species is much higher than previously reported. We don't know why introgression appears to be unidirectional. "However, it could be because there are more fin whales than blue whales," he added.

Engstrom considers these results good news. That means whale populations are interconnected and more genetically diverse. This could further show that blue whales do not always mate with their own species.

“This gives me hope that with continued conservation efforts, the Atlantic population can recover,” he concluded.

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