FINCHforum

Hi everyone,

I've been a bit quiet on here lately as I have had a busy summer plus my birds have been quite quiet and not breeding these past few months.

Well my question relates to Javas. I have had a silver female reproduce a silver male son who is now matured and old enough to breed. Is it bad to consider pairing these two up so I can reproduce more silvers?

Normally I wouldn't breed such close family members but I was wondering how bad this really would be or is it considered 'ok'?

I have never found fawn Java's and silvers are not that common here so would like to try making more but with a silver and grey pair I only get about 1 in 4 coming out silver so thought 2 silvers would make more, obviously, however they are mother and son.

Thanks.

I'm not a Java breeder nor am I an expert, but such Oedipal inbreeding would significantly increase the risk of recessive diseases.

I heard that was true of nest mates but that other combinations were OK.
Is that not true GG?

Again no finch expert (yet) but my background will hopefully help. Simple Mendelian genetics states that a child possesses 50% of each parent's genes.

Father with genotype PP;
Mother with genotype Pp;
Where P is autosomal (not sex-linked) dominant and p is autosomal recessive. Assuming that a genotype of pp leads to a lethal or maladaptive phenotype:

____|__P_|__P_
__P_|_PP_|_PP_
__p_|_Pp_|_Pp_

50% of offspring will be the same genotype as the father PP, and 50% will be the same as the mother Pp

Therefore, if the son is Pp (50% chance) then:

____|__P_|__p_
__P_|_PP_|_Pp_
__p_|_Pp_|_pp_

25% of offspring will be PP, 50% Pp, and sadly, 25% will be pp (lethal/disease).

IF this were sex-linked, and in birds, being wacky, the male carries two X chromosomes and the female only carries one, she would theoretically not be able to carry a recessive lethal gene as she would be forced to express it (Like hemophilia A in humans). However, if the father carries the recessive sex-linked gene and passes it to the son, with X being dominant, x being recessive (lethal), and Y being the "useless" female Y chromosome, then:

____|__X_|__Y_
__X_|_XX_|_XY_
__x_|_Xx_|_xY_

50% of males would be XX, 50% would be Xx, and 50% of females would be XY and 50% of females would express the recessive gene.
NOW if the son were to be XX, then the recessive trait would be lost to the ages. If the son is Xx, you would have repetition of the above Punnett square, leading to a theoretical 50% recessive phenotype in your female offspring.

I'm not saying it can't be done. I'm not saying it shouldn't be done. It just might be best to breed in a few outsiders to make splits and then cross those (Cousin with cousin; or better 2nd cousin with 2nd cousin) to reduce the odds of a recessive gene with bad outcomes being expressed.

Thanks for the detail. Always good to introduce new genes to the flock.
My canaries in particular are banded with a year color (numbered ) and a family color so the following year there aren't any miss-matched. I also keep notes on the parents success rate.

Finches are harder for me to keep track of in an open flight so the babies just get banded with the numbered year color. This year it's blue. If the bands on a pair are the same color but numbers far apart, (like a 4 and an 18), I'm OK with that. If they're two different colors then I guess I'm taking my chances because that just means they're from two different years. Could be mom or dad with an off-spring from last year.

Paul

And I'm sure this happens in the wild. But in the wild they also have the benefit of large flocks. The numbers reduce the odds.

I guess to all bird owners their birds are like royalty... you feed them, clean them, house them... why not allow a little inbreeding

Good point about the numbers. My Gouldians are at about 25 and Canaries about 50 in their flock. Still like to trade blood lines whenever I can.

Sue, basically you could do it, but then you should really pair the resulting offspring with unrelated birds as repeated inbreeding could cause problems.

This has been really helpful and although I just about kept up with what GouldianGuy explained so I have received enough information and guidance to decide not to breed the mother to her son. I have other normal grey females I can use to breed with the silver male so will hopefully create splits or more silvers and then I can start building up a line of silvers where they are not so closely related and be able to put 2 silvers together in the end. The great thing about finches is the ease they breed and how quickly they grow. Its a quick turnaround hehe.

Thanks all again. Very very helpful.