Self-love is important, but we mammals are stuck on sex| Trending Viral hub

Yeah Galentine’s Day If I had a pet animal, it would have to be one of those species whose females can reproduce without a partner. Almost all animals develop best in the traditional way, combining eggs and sperm. But some have an alternative called parthenogenesis: no males are needed.

However, no matter how many romantically frustrated mammals have wished they could go it alone, a genetic quirk means we still need sexual reproduction. For now, parthenogenesis is for birds (and bees), fish, and reptiles.

One of the most famous recent cases of parthenogenesis involved California condors, an endangered species. In 2013, Leona Chemnick, then a researcher with the San Diego Zoo Wildlife Alliance, discovered that two male chicks in the condor breeding program had DNA that did not match that of the parents in their cages, nor with that of no other male. The chicks’ DNA only matched that of their mothers.

Ms. Chemnick surprised Oliver Ryder, the zoo’s director of conservation genetics, on the way to his car and asked him about the strange data he was seeing. She explained to Ms. Chemnick that such condor chicks must have come from eggs that were not fertilized by sperm.

“We were literally walking to the parking lot and we had this eureka moment,” Dr. Ryder said. “We didn’t have time to dance or anything.”

When the two scientists and other colleagues published Following their discovery of parthenogenesis in 2021, the two unusual chicks, or parthenotes, had already disappeared. Both had died young, at almost 2 years old and almost 8. However, their mothers had many other children, conceived with their partners in the usual way (despite headlines declaring virgin births).

Each conception of the condor is a miracle of another kind. In 1982, with only 22 California condors left on the planet, conservationists began trapping all the birds and bringing them into captivity in a desperate attempt to save the species. In 2022, the birds numbered 561, most of them free in the wild.

A crucial part of growing that healthy condor population has been tracking the birds’ genetics, which led to the discovery of parthenote chicks. Since he found the first two, Dr. Ryder said, his team has discovered two more, although they died before hatching.

How their moms made them is a little murky.

Condors, like most animals, carry two copies of each gene: one copy from each parent. To produce a sperm or egg, an animal must split its genetic material in half. When the egg and sperm meet during sexual reproduction, they combine their genes to create a completely new genome.

To have chicks without sperm, condor mothers must have duplicated the DNA of an egg. There are a few ways this could have happened, Dr. Ryder said, and his team is conducting further analysis that should solve the mystery.

Other birds, including chickens and turkeys, have also accomplished the feat. Then there are the reptiles, including komodo dragons and another smart girls, which have been found to reproduce in this way. Last year, scientists reported Parthenogenesis in an American crocodile. There are even some species of snakes and lizards that reproduce only through parthenogenesis and have completely abandoned sex.

Many insects and other invertebrates can reproduce without males. Certain sharks and other fish can do this too. A white-spotted bamboo shark in captivity had several parthenotes, and one of them grew to have your own fatherless offspring.

At Chicago’s Shedd Aquarium, a female zebra shark named Bubbles had two parthenote cubs in 2016, although both died shortly after birth. Like the California condors, Bubbles surprised scientists with her near-virgin birth because she was not alone at the time. She lived with two male sharks, who presumably wouldn’t have minded sharing her sperm.

No one knows whether a female can choose to reproduce on her own (for example, if her current reproductive options are unsatisfactory) or whether parthenogenesis occurs outside of her control.

“It would be fascinating if they could decide to do it voluntarily,” Dr. Ryder said.

Humans have only noticed parthenogenesis when single females had young or when researchers monitored the genes of a population. However, given the number of different branches of life that have demonstrated this ability, many more types of female animals could secretly reproduce on their own.

“It’s probably much more widespread than we think,” Dr. Ryder said.

However, scientists are confident that no mammalian mother will have fatherless babies. We are hampered by something called genomic imprinting.

To understand imprinting, remember that animals split their paired genes in half to form a sperm or egg. Mammalian parents add one more feature to this process: they place chemical tags on certain groups of genes. The labels make those genes illegible, as if the genetic instructions were crossed out with a black marker.

After a mammal’s sperm and eggs combine, those marked genes will remain silent. That means that even if the offspring still have two copies of each gene, they can only use their mother’s or father’s copy, because the other copy is unreadable.

We can see imprinting in action when, for example, a lion and a tiger breed together in captivity. The resulting big cat looks different – ​​a bulky liger or a small tigon – depending on which species is the mother and which is the father. In printed sites, the hybrid is all lion or all tiger.

“It’s really difficult to understand why this process evolved,” said Anne Ferguson-Smith, a developmental geneticist at the University of Cambridge.

Scientists have suggested that imprinting reflects a kind of evolutionary battle between parents. This is because many imprinted genes affect growth. Genome modifications made by the father generally make his offspring grow larger, while the mother’s changes keep the babies at a more manageable size.

However, Dr Ferguson-Smith suspects the real story is more complex. Some imprinted genes affect the brains and behavior of offspring, or even how they will care for their own offspring in the future.

Regardless of why we print our genomes, the result is that mammalian sperm and eggs need each other.

If a mammalian mother tried to have a baby like Bubbles the shark did, duplicating the genes of her own egg, her offspring would not develop. The genes she silenced would be completely absent. Other genes would be present at twice the usual dose, because the offspring would be missing the normally silent copy from the father. This can also cause serious problems, Dr. Ferguson-Smith said.

Mammals, then, are stuck in sex. But some scientists are experimenting with ways to rescue endangered animals whose dating pools are small or nonexistent.

Dr. Ryder of the San Diego Zoo, for example, is involved in efforts to create embryos using frozen cells and then place the cloned embryos into surrogates of closely related species. He has so far helped create a black-footed ferret clone called Elizabeth Anne and two Przewalski’s horses. The youngest cloned foal was born last year and was named olliein honor of Dr. Ryder.

Dr. Ryder’s colleagues are also using genetic technology to try to save the northern white rhino, a subspecies in serious trouble: only two are alive. A few years ago, he said, researchers at the San Diego Zoo Wildlife Alliance took a step in that direction.

They convinced frozen cells from northern white rhinos to become stem cells. Ultimately, those stem cells could become eggs and sperm. But first, as a test, the researchers told the cells to become heart muscle.

When Dr. Ryder saw northern white rhino heart cells beating in a dish, it was as good as a Valentine’s Day.

Check Also

The CUTE mission: an innovative design allows observing extreme exoplanets from a small package| Trending Viral hub

Of the approximately 5,500 exoplanets discovered to date, many have been found to orbit very …

King Tut’s central scarab may have a cosmic connection| Trending Viral hub

It has been just over a century since the British archaeologist Howard Carter discovered the …

Lead-Contaminated Applesauce Highlights Flaws in Food Safety System| Trending Viral hub

Contaminated applesauce might have gone undetected for longer if it hadn’t been for one North …

Leave a Reply

Your email address will not be published. Required fields are marked *