Developing a long lived foundation line

[reesesturtles]

So I want some advice on how to develop a long-lived gerbil line from Trouble, my foundation male. Trouble is now somewhere between 5 and 5.5 years old and doing remarkably well. He shares a habitat with one of his sons, 1.5 year old Gentry.

That exact time ago, Awaiting Abyss and I partnered on breeding him into her lines, though I also want to create my own line from Trouble. But this would be an entirely new endeavor for me and I need to work out the genetic/breeding schematics. I currently have 7 of Trouble's offspring--2 are nonbreedable: one due to a physical deformity and the other due to aggressive behavioral issues. That leaves 5 males (1.5 years old) that could be bred, 3 of which seem to be the best health/behavior candidates.

Originally my plan was to stick with only breeding males in the line once they exceeded 3 years old, outbreeding to non-related females (as in obtained from outside Trouble's line) in each generation. This would mean only 2 outbred litters in the line every 3-4 years.
There are issues with this scheme though:
1) I have no idea at this point if Trouble's good health and longevity are due to a fluke, a dominant inherited trait, a recessive inherited trait, or some other complex genetic or epigenetic form of inheritance. It will take a another 2 years at least to rule out the first 2 possibilities.
2) If it is hereditary, the multigenerational outbreeding, though helping maintain line diversity, could also dilute the trait.
3) Only breeding the males in the line raises the possibility that I am biasing the longevity trait to only males, and not line females.

Hence, some line breeding at some point would be necessary. However this means utilizing line females, but I would not be comfortable breeding a female who is over 2 years old for her own health's sake. At least not in the earliest generations of the line until the life span and health and the line females was known. Also, what would be the best away to attempt to preserve the longevity trait (assuming it is hereditary):

1. My initial plan of just selecting for long lived sires in each generation (which would be several years apart)
2. Cross Trouble one more time with an outside gerbil, breed a mature female from that cross to one of the males from my project with Awaiting Abyss, then outcross and line-breed imtermittently every 3-ish or more years
3. Cross one of Trouble's offspring (in another year or two) with an outside female, then line breed her with one her uncles, intermittently outcrossing and line breeding every couple years.
4. Something else I'm not thinking about?

[ninestone]

If you only breed males that means the trait must be on the Y chromosome. Seems like that cuts the odds of success in half at the start.

Note that even some "male" traits (like baldness in humans) are carried in the X chromosome.

[reesesturtles]

If I only breed males in the line, it's because I choose to. It has no bearing on which chromosome (if any) the trait may be located on. My reasoning for only breeding males in the line (in the beginning anyway) is that I personally don't feel comfortable waiting for a female to reach 3-4 years before breeding her, without knowing what effect the aged pregnancy would have on her and on her litters. It's not my intent to cause stress or harm in developing this line. So early on, for my own conscience, I must select for long-living males, and if I do use females in the line, do so at a young age so as to preserve beneficial traits (particularly any recessive ones) without stressing the female or her offspring. So the trait could be on any of the chromosomes; my selection of older line males for breeding is specifically for ethics sake.

[Demonic Hope]

I'm no breeder but what about this

Take your old male of choice, breed him to an unrelated female, and then back to one of his daughters. Keep back a male pup from this pairing, wait until he's olde enough and repeat. This would make it so if its carried on either chromosome you'd have it, and with no stress on an older female.

So Trouble to unrelated female. Then back to one of his daughters. Continue next generation with one of Trouble's Son/grandsons. One thing is you have to have multiple males to continue your line. Not just one. You could have a totally freak accident. Declanning, choked to death on food, gerbil broke of out cage, and jumped off a 4ft table. I had a hamster do that. So you need to have backups or else your whole line would be destroyed by loosing the male.

[betty]

I would imagine you would be keeping records of births and deaths along the whole line, so you would be able to tell if any of the offspring ARE living longer than average.

And by keeping some of the female offspring you mated earlier on, you can see if this longevity gene is being passed into the female offspring too. Also, I'm not sure if this was mentioned elsewhere, but most females need to have been mated before they are a year to still be fertile later in life so waiting until they are 3+ might not yield pups anyway - and most breeding females I know are only fertile up to about 2 years.

I suppose all you need to know is that the females are long lived at some point, and so all their earlier (younger) offspring should be carrying these 'genes' and so you can breed them back into the line. This means lots of gerbils though...

But Demonic Hope is right - you can't just rely on single gerbils for this line. As we see in humans; you may have the genes for a long life - but you have to stay alive until then! How many 100+ people have a story about 'not being on that plane that crashed with the rest of the gym team cos I broke my leg' or 'missing that derailed train because....'. You need to keep yours safe for a very long time.

[reesesturtles]

Well, I've decided to try and do this with Trouble's current sons, rather than rebreed him. Even though healthy, he and his son Gentry are strongly bonded and I've decided it's in their best interest not to separate them before Trouble finally passes along. Once that happens, I plan to pair Gentry up with an unrelated female. I would either take a female from that litter and breed her to one of her uncles (Troubadore), or I could also outbreed Gentry's brother, Troubadore, then cross the offspring between Troubadore and Gentry.

I am keeping records of the line, including offspring longevity, health, and behavior. Right now I only have one daughter of Trouble, and she's not breedable due to being very small and having a fixed wrist. But she's in great health and has a great personality. So keeping an eye on her will give me an idea as to whether the females share the trait.

You are right though that I need to have "backups" in case of something detrimental. I don't mind that. I have no problem keeping several gerbils to ensure line prosperity and diversity.

[ninestone]

Jul 26, 2014 13:23:15 GMT -8 reesesturtles said:

If I only breed males in the line, it's because I choose to. It has no bearing on which chromosome (if any) the trait may be located on. My reasoning for only breeding males in the line (in the beginning anyway) is that I personally don't feel comfortable waiting for a female to reach 3-4 years before breeding her, without knowing what effect the aged pregnancy would have on her and on her litters. It's not my intent to cause stress or harm in developing this line. So early on, for my own conscience, I must select for long-living males, and if I do use females in the line, do so at a young age so as to preserve beneficial traits (particularly any recessive ones) without stressing the female or her offspring. So the trait could be on any of the chromosomes; my selection of older line males for breeding is specifically for ethics sake.

That's a great reason, I didn't think about that. Good luck!

[Shooting Star]

Anything related to lifespan is most likely going to be incredibly complex on a genetic level. That's not to say you can't select for longevity-- you absolutely can. But if you're serious about this, it's going to be a long, resource-intensive process.

Continuously outcrossing with females is a bad idea. First, because the females need to be bred before they've shown their longevity, you have no idea what you're adding to the line in that respect. When you need to outcross, I'd do it with a Trouble-line female and an older outcross male, so you have a better idea of what you're getting in terms of lifespan. Second, since I can 99% guarantee this not a single simple dominant or recessive gene, relying on outcrossing won't get you very far. Do outcross from time to time, to avoid inbreeding depression, but not often.

I'm assuming all of Trouble's sons that you have now came from the same mom? If you have access to a good female, I would breed him again (or at least attempt to). Keep the best couple males and the best several females from that cross. Over the next year, evaluate the females, pick the best three. Breed those three with those best three of Trouble's older sons. (The younger sons are backup, unless they turn out stellar.) You can also use just the best male and a succession of females, but if it turns out that that male dies young, or has health problems later in life, you're SOL. Keep several males and females from the second-generation litters, take a year, pick out the best. Breed them amongst each other, or back to the older (or younger) Trouble-sons. Try to avoid full-sibling crosses until you have more experience in picking which gerbils will turn out well, and which will complement each other. Rinse, lather, repeat.

All the while, keep detailed records about all the gerbils in the line. See which Trouble-sons/daughters live the longest. If one lives particularly long, use more of his/her descendants in later generations. If one dies early, or has other issues, use less of his/her descendents, in order to reduce his/her influence on the line.

Figure out a way to get good males for outcrossing. Avoid store-bought at all costs. Every few generations, put your absolute best line-female with an outside male-- in addition to your usual linebred pairs. Let the outbred offspring mature, and cross the best one or two males back into the main line when they're older (2+).

As you might have noticed, to do this right, you're going to end up with a lot of gerbils. What I've described would be the ideal course of action, but it's by no means the only way. Figure out how much time, effort, space, and resources, you're willing to commit to, and tailor the plan to your needs.

[Shooting Star]

Since I took forever to compose a reply, and missed a couple posts...
If you're not going to breed Trouble again, then branch out with his sons. With no daughters available, find three good females, ideally from three different lines. Pair each with one of Trouble's sons. Pair the offspring amongst themselves, as above. Since you're going for longevity, you can always cross a female back to a father or uncle as well. Leave yourself options. But keep in mind that males also undergo reproductive changes with age. They might still be capable of fathering litters at 3+, but those litters might be small or far apart. There's even data to show that older males are more likely to produce mutations in their offspring, and not always beneficial ones.

[reesesturtles]

Shooting Star,

This is VERY helpful! I think at this point I will follow your advice and look for unrelated females to outcross to Gentry, Troubadore, and Governor (the third quality male). I will be moving away from Atlanta sometime in September or October though for a job opportunity, though exactly which city and state I will be moving to is up in the air. I plan on renting a house though, wherever I move to, That will provide the space for developing this line. And I'm near finished with a web page for advertising the gerbils. Anyway, due to the move, I don't plan on starting any breeding until after October, or possibly even after the New Year. However, I am wondering if I should try to obtain female pups now, or wait till after the move.

I will also keep your counsel in mind regarding likelihood of smaller litters or deformities in litters from older males. I have to say that was not an issue with Trouble--He sired 3 very large litters (7-8 pups each), all healthy and surviving. Mi'Lady, the single girl in my care, is the only one with any physical defect, most likely due to womb crowding, though I can't know that for sure. However with an outcrosses, it will be something I monitor very closely.

I may pick your brain often on this! Thanks so much!

[reesesturtles]

Okay, I miscalculated Trouble's age by 1 year. I took a look at the history I documented for him. He's actually between 4-4.5 years old. Still, approximating 25 human years per single gerbil year (based on average lifespan of 3 years for a domesticated gerbil), that would make him over 100 years old in human years