Should at Least Make Evolutionists Consider

[Purple Knight]

Question for Debate: Why, and how, does the muntjac deer have only seven pairs of chromosomes?

Please don't look this up, at least until you've considered for a moment how weird this is. Imagine you have 20 pairs of chromosomes, and you have a baby that has sixteen pairs. He shouldn't be able to breed with the rest of your species.

Is this at least weird? A regular deer has around 40-70 chromosomes. Is it at least strange that he can even be alive having lost that much genetic information? One more halving and he'll be a fruit fly (they have 4 pairs).

[Difflugia]

Please don't look this up, at least until you've considered for a moment how weird this is. Imagine you have 20 pairs of chromosomes, and you have a baby that has sixteen pairs. He shouldn't be able to breed with the rest of your species.

Is this at least weird? A regular deer has around 40-70 chromosomes. Is it at least strange that he can even be alive having lost that much genetic information? One more halving and he'll be a fruit fly (they have 4 pairs).

The number of chromosomes and amount of genetic information aren't the same thing. Depending on exact details, people with two chromosomes fused or split can successfully have kids as long as the chromosomes can match up and undergo crossover. It's weird and definitely uncommon, but not unheard of.

Human chromosome 2 is actually the result of the fusion of two chromosomes that are still separate in other great apes, apparently fixed in humans through genetic drift rather than fitness. Chimpanzees have 24 pairs of chromosomes and humans have 23 pairs. At some point during humanity's history, there were proto-humans with 46, 47, and 48 chromosomes in the same population. Since meiosis is already error-prone, anything that makes it more so is deleterious and the population will ultimately fix on 23 or 24 pairs, but as long as the unfused chromosomes can pair up with the fused ones, reproduction is still efficient enough prior to fixation. We fixed on 23, chimpanzees fixed on 24. We therefore have fewer chromosomes than chimpanzees, but not fewer genes across those chromosomes.

[Purple Knight]

We fixed on 23, chimpanzees fixed on 24. We therefore have fewer chromosomes than chimpanzees, but not fewer genes across those chromosomes.

So would you predict that a chimpanzee/human hybrid would be possible and itself reproductively viable?

[Difflugia]

We fixed on 23, chimpanzees fixed on 24. We therefore have fewer chromosomes than chimpanzees, but not fewer genes across those chromosomes.

So would you predict that a chimpanzee/human hybrid would be possible and itself reproductively viable?

Not anymore, but not because of chromosome number. Orangutans and gorillas also have 48 chromosomes, but gorilla-chimpanzee hybrids are equally unlikely.

[The Barbarian]

Turns out, the evidence shows a chromosome fusion sometime after humans and chimps diverged from a common ancestor. The fused chromosome shows the remains of telomeres (chromosome ends) right where they would be in a fusion.

[The Barbarian]

So would you predict that a chimpanzee/human hybrid would be possible and itself reproductively viable?

It's rare, but not unknown for that to happen. Mules are occasionally fertile. But it's very, very unlikely.

[Purple Knight]

So would you predict that a chimpanzee/human hybrid would be possible and itself reproductively viable?

It's rare, but not unknown for that to happen. Mules are occasionally fertile. But it's very, very unlikely.

What I heard is that a fertile mule is not actually a fertile mule - not an opportunity to fix the best donkey genes and the best horse genes in a truebreeding population of mules.

But she is actually a fertile horse. In other words, the chromosomes she gives to her offspring is verbatim the set that she got from her horse parent, and she can make another horse, or another mule mule (sterile or perhaps fertile but only the way she is) but she will never have the ability to make truebreeding mules.

Alternatively, a cross between an African serval and a housecat, which have different numbers of chromosomes, the F1 males will be sterile. But, from the fertile F1 females, you DO have an opportunity to fix the best serval genes, and the best domestic cat genes, in a truebreeding population. And they did. And it's called a savannah. However, what is generally accepted is that these fertile truebreeders you make, while they are an opportunity to pick and choose traits and then fix them, you will never get quite the size of the serval, and this is because part of the serval's size is due to the fact that he has more chromosomes, and the truebreeding savannah will always fix on the smaller number of chromosomes, from the housecat.

[The Barbarian]

What I heard is that a fertile mule is not actually a fertile mule - not an opportunity to fix the best donkey genes and the best horse genes in a truebreeding population of mules.

But she is actually a fertile horse.

No. Genetically, she is only half horse. Her offspring could be genetically a horse, a mule, or a hydrid like herself.

In other words, the chromosomes she gives to her offspring is verbatim the set that she got from her horse parent, and she can make another horse, or another mule mule (sterile or perhaps fertile but only the way she is) but she will never have the ability to make truebreeding mules.

Since it's remarkably rare for a mule to be fertile, it seems just about impossible to produce a viable species of mule by hybridization. Speciation by hybridization is fairly common in plants, but not so frequent in animals. It was recently observed in the Galapagos among finches.
https://www.science.org/doi/10.1126/science.aao4593

In all of these cases, the fertile mule is female (and some have produced several foals) – no male mules have ever been known to produce offspring. However, some male offspring of these mule mothers are fertile, and go on to sire more foals themselves.
https://www.helpfulhorsehints.com/can-mules-reproduce/

[Purple Knight]

[Replying to The Barbarian in post #8]

There seems to be some evidence of the phenomenon in mules, though.

https://www.horseandman.com/horse-stori ... 8/06/2017/
Dr. Oliver Ryder, associate director of the Conservation and Research of Endangered Species division at the San Diego Zoo, said the answer to how Kate could give birth could be surprising. There were very unexpected – and still unexplained – findings when a molly mule gave birth to two foals in Nebraska in the mid-1980s. The event prompted notice from the local pulpit and a flurry of scientific investigation, including the first genetic testing of a mule’s offspring.

Ryder said that tests in the Nebraska case showed there was no evidence the mother passed along any genetic markers from her father – a donkey that was also the father of the foals. The phenomenon is called “hemiclonal transmission,” which in simple terms means that the mare’s genes canceled out the male’s genes as if they didn’t even exist.

That phenomenon has been observed in amphibians but not in mammals.

“No recombinations took place. There was no reassortment. We looked at markers on every chromosome,” Ryder said. “This was an extremely unexpected finding.”

[The Barbarian]

However, what is generally accepted is that these fertile truebreeders you make, while they are an opportunity to pick and choose traits and then fix them, you will never get quite the size of the serval, and this is because part of the serval's size is due to the fact that he has more chromosomes, and the truebreeding savannah will always fix on the smaller number of chromosomes, from the housecat.

Do you have a link for that? I don't see a correlation between size of animal and chromosome count.
https://en.wikipedia.org/wiki/List_of_o ... some_count