Genetics Question

[lisie]

I tried to read up on this a lot and I -think- I got some of the answers I was looking for, but I hope you genetics buffs don't mind me asking questions anyway.

Male:
Father was a steel butterfly DTHM.
Mother was a royal blue butterfly HM.
This fish is a solid royal blue HM. (I think he's solid; I didn't get him and his spawn sister yet but I will be.)

If I spawned him with his sister:
If one of them has the dt geno, but the other doesn't, I'll get 50% singletails and 50% dt genos.
If neither of them has the dt geno (possible, right?) I'll get all singletails.
If both of them have the dt geno, I'll get 25% singletails, 50% dt genos, and 25% doubletails... more or less.
Correct?
How many would be butterfly if they're both solid? Any marbles?

If I spawned the male with a marble DT female:
If he's dt geno, I'll get 50% dt genos, and 50% doubletails.
If he's not, I'll get mostly dt genos.
How many butterflies, marbles, and solids? Or will it just be a random mix?

Okay, I think that's everything I wanted to know, lol. Thanks in advance for any replies. I'm totally new to betta genetics, and I'm dying to breed, still haven't decided if I will yet but we'll see.

Oh, and if anyone has or knows of a marble DT male or female for sale, pleeeease let me know! Thanks.

 

[fawnmodel]

Hi:

I don't have alot of exp with dt's so I will leave that one...but it is readily avail in books and online

Breeding two fish with butterfly or marble geneticls doesnt mean any will have it. I have had spawns of two bf or one, and had none show up with it...technically bf or varigation is dominant...but it doesn't always pop up. I have also had marbles produce no marbles....

 

[TimCAD]

If father is a double tail and mother is not, he and his sister will be double tail genos. Each will get a double tail from father and a non-double tail from mother. With a double tail geno cross, 25-50-25 is the correct ratio.
I find the butterfly gene to be tricky. As father and mother are both butterflies and the butterfly gene is dominant he and his sister should also be butterfly phenotype. I suspect they show the butterfly effect to varying degrees, little or none in some cases.

 

[kali426]

so you inbreed hey.thats something i wanted to know about.I know dog breeders will inbreed once they have dogs of very high qualites that they wish to maintain.but fish have less chromo's then dogs so would inbreeding them cause problems?
i was thinking about doing the same thing with my fish but wanted to find out details first.

 

[TimCAD]

One more thought on butterflies:

Butterfly phenotypes can be dominant for one or both variegated fin genes. If father and mother are both VF/vf, then, he and his sister could possibly be vf/vf (non-butterfly).

kali426 - I believe Betta Splendens have 21 chromosomes.

 

[Synirr]

kali426 -- The number of chromosomes doesn't have anything to do with problems caused by inbreeding, it is the increase in homozygosity of bad genes. By selecting good quality animals you avoid this to some degree, but inbreeding always increases homozygosity, even if you are selecting against bad traits. For the record, inbreeding when selecting for good traits is usually called linebreeding . You usually only want to linebreed splendens for about 3 generations before outcrossing to an unrelated fish, otherwise you start to see some problems like weaker fish. With dogs and other animals problems can arise much sooner and linebreeding is usually discourage altogether, one generation maximum.

lisie -- Your ratios for DT are correct
Butterfly and marble are very unpredictable traits, so there's absolutely no telling. Chances are you'll get a few, but as to how many, who knows.

 

[lisie]

Thanks guys! I'm hoping they're both dt genos, but according to Victoria Parnell, just because their father was dt, doesn't necessarily mean they have the genotype. That's why I'm on the lookout for a good dt match for one of them.

This genetics stuff is pretty fun.

 

[TimCAD]

I think you may have misunderstood V.
If one parent is a double tail (DT/DT) the offspring can only receive a DT gene from that parent. That parent has no dt gene to give.
If the other parent is single tail (dt/dt) all the offspring will be double tail geno (DT/dt).
If the other parent is double tail geno (DT/dt), all the offspring will be either double tail geno (DT/dt) or double tail (DT/DT).

 

[lisie]

Man, now I'm confused, lol! What did I misunderstand?

On her site she says that a doubletail crossed with a singletail will result in all singletails but only 75% will be doubletail genotypes.

 

[lisa_perry75]

Right using S as the dominant single trait and d as the recessive
SS x dd is single tail mum and double tail dad

The F1 Offspring will be Sd, single tail is dominant and will show dominance
So cross Sd x Sd
Will result in the following f2:
SS Sd and dd in the ratios
1 2 1
so as S is dominant, the actual ratio of single to double tails in your mating will be
3:1

Does that make sense? I bet butterfly is part of more than one gene, and if its linked to the double tail gene may do funny things in the offspring. So I don't know the ratio of butterflies.

The information is based on mendels laws of independent segregation and independent assortment. His first and second laws basically!

 

[lisie]

That's what it would be if you work it out, but... okay I'll just quote what I'm talking about, lol.

The mutation that causes DT is recessive to the normal Singletail (ST). Breeding a DT with a ST will result in 100% ST offspring, approximately 75% of which will carry the DT recessive. It used to be thought that DT x ST would produce 100% DT genotypes, but I have had experience in breeding the same male fish (ST/dt) to two females who were full sisters from the same spawn. One of the females produced 25% DT from her cross with this male, and the other female produced none. Later I took a DTM from the first spawning and crossed him to a ST sister, and was rewarded with a large spawn that yielded no DT offspring - not one! So I can only conclude that the DT gene doesn't affect all members of a spawn, as previously assumed.

http/bettysplendens.com/articles/page.imp?articleid=879

 

[TimCAD]

I just looked at V’s site again. That is an interesting hypothesis. I’m not sure how she calculates 75%, although, she has a new article on double tails that states “most” are DT geno. I wonder if other breeders have experienced this.

 

[lisie]

Well, I at least hope this pair carries the DT gene! The breeder says that she thinks they both do. I guess I'll have to find out.

 

[kali426]

thanks again synirr,your very helpful.thats been on my mind for weeks now,i just always forgot to ask someone

 

[Synirr]

Normally I trust the info on BettySplendens.com, but the part about fry from a DTxST cross being only 75% DT carriers is just complete BS, I'm sorry, and it is incredibly unscientific to make such an assumption when you consider that all the fish she talks about in that example are related -- those numbers could very well be the result of a chromosomal abnormality carried only in that line.

The fact is that DT is a simple Mendelian recessive trait, so if a fry has one parent that was DT it is guaranteed to be DT geno unless there is something very strange going on in that genepool


....Ok actually, re-reading the quote from the site, those results don't seem to implausible even for a line without a genetic abnormality. The first two spawns were between DT geno fish, so you'd expect 25% DTs from both of them, but only the first produced 25% DTs... well how large was the second? If it was relatively small it's possible to get none by pure chance. If it was large, chances are the female had one of a number of possible genetic abnormalities that voided the DT gene from her genome. In the third spawn mentioned the parental fish were taken from the first spawn that did produce 25% DTs.... apparently the author forgot that that spawn also produced 25% pure STs that were not DT carriers, hence the complete lack of DTs when crossing that DT male to a ST sister -- the sister was not DT geno in the first place, duh.