Momma is giving birth, and the babies are coming in one, two, three, four, five, six, seven, and eight. Whew! Momma is exhausted, but she’s taking care of her babies. Babies are fine.
Meiosis includes recombination
Your chromosomes’ two copies—one from each parent—are divided into gametes (eggs or sperm) during the meiotic process. Think of your chromosome pairs as red and blue marbles. Meiosis starts with the process of segregation. In the case of the marbles, segregation would entail randomly selecting one marble from each pair. That produces a ton of marble combinations, but what if we wanted even more variety, like marbles in multiple colors or marbles of various sizes? That’s where recombination comes in.
Recombination is the process by which a parent’s DNA in a pair of chromosomes is shuffled before being passed to their offspring. Every generation, this shuffle takes place to add more genetic variation This explains why you and your sibling don’t look exactly alike, as well as how related puppies can have different appearances from one another.
Let’s examine the procedure in greater detail by going from beginning to end.
How recombination works
Here’s a quick refresher: humans have 23 pairs of chromosomes. Our mother contributed half of our chromosomes, and our father contributed the other half. Dogs, who have 39 pairs of chromosomes, are the same. Though inheritance isn’t as straightforward as an equal split of chromosomes, Recombination occurs before chromosomes are transferred to egg and sperm cells.
A chromosomal pair in the parent that was equally inherited from the grandmother and the grandfather splits in two during recombination. The two chromosomes have the chance to exchange DNA while they are splitting. The amount of exchange between the maternal and paternal chromosomes is random, but different pieces do so. A more extreme ratio, such as 90-10, or a 60-40 split between the grandparents’ chromosomes could be seen in the offspring.
Research shows under which conditions a litter can have mixed parentage.
While a litter’s puppies typically all have very similar appearances, on occasion you may come across some that stand out and look out of place. It appears that there is a fascinating explanation for this.
I was surprised to find myself entering the driveway of a farm owned by a spouse-friend. My wife wanted to make blueberry pies and freeze them so we could have them over the winter, so I was there to pick up a few boxes of blueberries. A woman with a long ponytail was standing next to Marion, the farm’s owner, in the yard. “This is Jess, and she’s our veterinarian,” she said, waving me over to her companion. She came to see one of my cows, but Jess thought it would be convenient to give the puppies their first set of shots while she was here since Kate [Marions dog] just had a litter a few weeks ago. “.
Marion had set up a wire pen in the mudroom next to the kitchen for Kate and her puppies when we entered. Kate had medium-sized V-shaped ears and blonde curly hair. She was some kind of poodle cross, also known as a “doodle.” It therefore came as no surprise when four of her six puppies also had light-colored curly coats and comparable ears. Two of the pups, however, stood out from the others due to their short hair, somewhat Beagle-like coat, and ears that appeared to eventually form the pendant-shaped ear flaps typical of hounds.
“It looks like Kate is a bit of a party girl,” Jess said with a smile. I’d wager that this litter is the result of matings with more than one sire, so she must have been having fun with the neighborhood dogs. “.
You don’t mean to say that the puppies in this litter have more than one father, do you? Is that really possible? Marion asked with a surprised expression.
Of course, there is only one mother and one father for each puppy. However, female dogs typically give birth to litters rather than single puppies because they produce multiple eggs at once. Bitches also continue to be in heat (i.e., have eggs that are ready for fertilization in the uterus) for about 10 days.
“You have to realize that dogs are not the best example of fidelity.” They generally are devoted to their human family and are loyal to them, but when it comes to mating, they act much more like feisty swingers. Due to the fact that many eggs are released at once, if a bitch has multiple partners, different eggs may be fertilized by various sires.
But promiscuity with multiple partners doesn’t always produce a litter of children with mixed parents, Less than 1% of puppies in the resulting litter will be born to different fathers if a female dog is inseminated by more than one sire, especially if the semen from both sires is deposited at almost the same time. That is so that a sperm competition can occur when the sperm of two different male dogs is combined. Typically, only one sire’s sperm succeeds in fertilizing all of the available eggs. Therefore, each insemination must be spaced apart by 24 or 48 hours for a litter to have more than one sire, and even then, the outcomes are not always predictable. “.
I brought up that I had recently read an article by a research team led by Fiona Hollinshead from the College of Veterinary Medicine and Biomedical Sciences at Colorado State University in Fort Collins, Colorado, at that point. They investigated the issue of multiple sires using both natural and artificial insemination because they were curious about it. When there were two sires, they spaced out the inseminations and discovered that 90% of the bucks actually gave birth to one or more puppies. (In actuality, this is significantly more than the 76% whelping rate when there is only one sire. Only 31% of the litters from the successful breedings following the insemination by two sires revealed signs of mixed parentage, which means that in the remaining 69% of the litters, the sperm competition resulted in just one successful father. The sire who inseminates the female second, as opposed to the first sire, is more likely to father a higher proportion of puppies (73% versus 27%) in the mixed parentage litters, which is an odd finding in this study. The study’s final intriguing finding was that when there were two sires, the litter sizes were actually noticeably larger.
You know some breeders actually purposefully breed a female dog to two different studs, Jess said as she nodded. They contend that it’s advantageous because more genetic diversity will be produced in a single litter, and I would anticipate that the larger litter size is another advantage (especially if there is a worry that one of the sires has low sperm count or poor quality semen). The majority of kennel clubs historically prohibited the registration of puppies from multi-sired litters. But in 1998, the American Kennel Club decided that Multiple Sired Litters (MSL) could be registered with the AKC if the mother and both sires were purebred dogs, and other kennel clubs quickly agreed. However, compared to puppies born into the more typical single-fathered litters, the MSL pups’ registration process is significantly more difficult. For the specific sire and dam to be noted on the pedigree form for each puppy, it is necessary to have the DNA profiles of all the parents and all of the puppies. “.
But of course our Katie is not going to tell us who she had her extramarital affairs with, Jess laughed and ruffled Kate’s hair. But if we could track down the culprits and use DNA testing to determine which of her pups belongs to which father, we could then reveal that information on a racy episode of our very own canine Jerry Springer Show!
Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission.
Hollinshead FK, Ontiveros M, Burns JG, Magee C, Hanlon DW (2020). Factors influencing parentage ratio in canine dual-sired litters, Theriogenology, doi: https://doi.org/10.1016/j.theriogenology.2020.08.030.
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FAQ
Can puppies from the same litter look completely different?
No two offspring receive the same set of chromosomes from their parents due to segregation and recombination. This explains why puppy siblings can differ so greatly in appearance. One puppy from the same litter might inherit a genetic variation for black fur, while another might inherit a variant for yellow fur.
What are the signs of fading puppy syndrome?
- Low birth weight or no weight gain.
- Decreased activity.
- Neglect from the mother.
- Stomach pain indicated by paddling movements.
- Diarrhea or soft stools.
- Vomiting.
- Continuous crying.
- Trouble breathing.
Do puppies get their color from Mom or Dad?
Each allele has a 50% chance of being passed down to the pups when dogs breed because the mother and father each randomly contribute one allele from each locus. Each locus has a dominant allele that determines the traits, such as coat color, that the dog exhibits.
What does littermate syndrome look like?
Fear of strange people, dogs, and other novel stimuli (neophobia) are symptoms of littermate syndrome, as are severe anxiety when separated, even for a short time, and difficulty picking up simple obedience commands. In some cases, the two dogs will fight incessantly.