In my last post I quoted one of my favorite sayings, “When the bow is beneath the waves, follow the rats,” which is based on a slightly less melodious quote by Claude Swanson–a lifelong politician and Secretary of the Navy under FDR.
The obvious interpretation is that it’s wise to abandon ship when even the rats know it is a lost cause. It turns out that it’s also wise advice to follow the rats when it comes to a sinking gene pool as well:
Female mice can identify inbred males by their scent
Liverpool, UK – 18 April 2008: Scientists at the University of Liverpool have found that female mice avoid mating with inbred males by ‘sensing’ the diversity of a protein type in their urine.
Researchers found that major urinary proteins (MUPs) – the main protein component of mouse urine – are less varied in inbred male mice compared to outbred males, a distinction female mice are able to make through ‘counting’ the protein types in the urine.
So far MUPs have only been discovered in rodents – where they function as a genetic signal for social and mate choices – but scientists believe that similar signals are likely to be present in other vertebrates.
Dr Michael Thom, from the University’s Mammalian Behaviour and Evolution Group, explains: “Inbreeding is often avoided in animals because it can lead to health problems in offspring, but despite this inbreeding can sometimes still occur. Why female mice would want to avoid inbred males is still uncertain, however, but it is interesting that it is certainly something of importance to them. The work raises the question, if this is important in mice, are there mechanisms in place to help others animals and humans make similar distinctions between outbred and inbred males?
How fitting that the humble little rodent–who has done as much good for the advancement of human health in recent years as they did evil by harboring the flea that carried the black plague in past centuries–is once again showing us the way.
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Anton
Christopher
Lawrence Dillard
Lech
Stephanie
Essere
Of course if a female mouse produced offspring with an inbred male then there would be no inbreeding unless the female and male had been related. In other words the inbreeding done by male’s parents has no bearing on his offspring as long as his mate is unrelated to him.
Yes, a completely unrelated female will cut the COI to 0% at once. But that’s just the COI and the pretty big assumption of unrelatedness.
It only unwinds much of the damage already done though, by ~50%.
Worst case scenario, it only helps the grand kids. For instance, if the male is so inbred that he’s 100% homozygous, and if those genes are 100% dominant, then even the children will be the same phenotype as their father.
They’d actually *look* like clones.
But it is ridiculously unlikely that all of the male’s genes would be dominant. And even if the offspring did look like clones you would still eliminate the effects of the negative recessive genes that would have been affecting the male.
The the concept of breeding a male with homozygous genes to a female lacking genetic diversity to the same extent would produce consistent offspring. But there is nothing really wrong with this unless you a breeder who is used to picking the best from a litter.
Yes, of course, I’m just making a point that COI is more of a snapshot than an absolute measure. It absolves you for all of the inbreeding it doesn’t see.
For instance, if we had identical twins, a boy and a girl (yes, I know, mostly identical given the XX and XY on one set) and they bred and we took all their children and split them into two groups and interbred them for 7 generations and did a COI6, we could devise a COI of 0% even though the true number could be ~100% or something substantially higher than 0.
Any COI drops off that last generation and the assumption becomes perfect unrelatedness… So the COI only measures how likely it is to have the same allele at any given spot based only upon how far back we look.
I recall reading somewhere that where as we assume that all founders are unrelated, for most breeds if we take any two dogs, the odds of finding the same allele in any given spot is much closer to 100% than it is to 0% or even 50%. For some reason the number 93% comes to mind.
Closer to 100% than to 50% does sound way too high for comfort. I think we should allow Australian, and English Shepherds to be integrated into the breed of Border Collies if the number is CIO is even close to twenty percent.
But either way the most important issue is whether or not any negative traits affect the dog. But I wonder if the AKC would consider the mixing of breeds to some extent.