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GuppyDude

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ok, im not sure if i know of any hybrids, im rely tired at the moment and if i did i couldn't remember. Heres my question, can hybrid fish reproduce? u know when u cross a horse with a donkey u get a mule right? mules because of this are sterile. does it work the same with hybrid fish?
 

JustinSane

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Vip said:
All hybrid fish breed as far as i know, from blood parrots to flowerhorns.
Usually the problems start occuring in the F2 generation.
As in you breed cichlid x and y and the result is hybrid z (F1 generation) the if you breed two z's their offspring (F2 generation) is sterile (usually). Though some F2 generations are able to breed, the problem is that the because of the small size of the original population, the gene pool is very small and sooner or later this starts causing problems (crippled and deformed fry, internal organ failures etc. look at goldfish, most of this day forms are results off heavy inbreeding).
Though with fish (lower vertebrates) this isn't as much as a problem as it is with higher vertebrates (mammals, birds), it doesn't mean that it isn't an issue at all. All breeders should take this into consideration (as most pro's do).
 

Doggfather

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look at goldfish, most of this day forms are results off heavy inbreeding).

My science isn't too flash, but from my understanding goldfish have been interbred for tails and colour forms from well before the 1700's, if your arguing that the problem occur with the F2's, due to problem with the whole gene pool, how is it that the goldfish have managed to survive all this time? If problem occur within the second generation, how could an interbred fish have lasted hundered of years?
 

JustinSane

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Doggfather said:
look at goldfish, most of this day forms are results off heavy inbreeding).

My science isn't too flash, but from my understanding goldfish have been interbred for tails and colour forms from well before the 1700's, if your arguing that the problem occur with the F2's, due to problem with the whole gene pool, how is it that the goldfish have managed to survive all this time? If problem occur within the second generation, how could an interbred fish have lasted hundered of years?

Obviously it isn't. Well, kids a lesson in basic genetics is about to begin, please take your seats *teacherish voice*

I didn't take goldfish as an example of hybrids but as an example of the downsides extended inbreeding. It is commonly known (or it least it should) that the gene pool of the "wildest" (as in the most heavily "mutated") forms of Carassius auratus is majorly screwed up. This shows as internal organ failures (on some forms the organs are too tightly "packed" because crooked spine. Also swimming bladder problems are more than common and the disease resistance has been greatly lowered when compared to the wild form. Longevity has also majorly decreased.

It is obvious that you don't posses much knowledge in genetics so I'll have to introduce a few common terms, but I'll have to take some shortcuts here in order to keep this simple. Anyway, here goes. (in order to quicken things up, I'll use wikipedia for explainin the terms, so therefore I take no responsibility of the possible errors in the text)

Genotype and phenotype.

The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual.

The phenotype of an individual organism is either its total physical appearance and constitution, or a specific manifestation of a trait, such as size or eye color, that varies between individuals.

Alleles

An allele is any one of a number of alternative forms of the same gene occupying a given locus (position) on a chromosome

Recessive and dominant qualities

1) A recessive quality needs both parents to have it in order to be inherited. (to be a phenotype)
An organism which has two different alleles of the gene is said to be heterozygous.
if only one parent has it, it remains in the genotype of the offspring.

2) A dominant quality needs only one parent to be inherited. (to be a phenotype)
An organism in which both copies of the gene are identical - that is, have the same allele - is said to be homozygous for that gene.

The gene pool

The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. A large gene pool indicates a large genetic diversity, which is associated with robust populations that can survive bouts of intense selection. Meanwhile, low genetic diversity (see inbreeding and population bottlenecks) can cause reduced fitness and an increased chance of extinction.

Inbreeding

Inbreeding is breeding between close relatives. If practised repeatedly, it typically leads to a reduction in genetic diversity


So let's imagine that from a 100 natural goldfish 10% is of a phenotype that gives them extended fins.
Of these 10 specimens 20% carries a recessive allele which causes increased vulnerability to have a tumor.
So you take these 10 specimens and breed them together to get offspring with extended fins.
So, you're lucky and you get 50% offspring with extended finns but you also have 30% offspring that have that harmful recessive gene in their genotype.
So you further breed these offspring together the bigger and bigger the possibility to have homozygous offspring with the harmful genotype now as phenotype.

Like this
Original parents
P1 With the allele X that causes extended fins and the allele Y that causes a tumor
P2 With the allele X that causes extended fins but without the allele Y
Offspring:
Generation F1: Since they received the allele X from both parents, they are now homozygous for that gene. Extended finns are now their phenotype. Some of them also received the allele Y and for that gene they are heterozygous and it is in their genotype

Further breeding
P1 (from F1): X is now dominant and has Y in it's genotype
P2 (from F2): X is now dominant and has Y in it's genotype
Generation F2: X still remains in the phenotype but now also Y is inherited from both parents so the offspring are homozygous for that gene too. They are now more vulnerable to tumor.

Now this was making it reaaally simple, obviously it isn't quite that straightforward but simplification was needed in order to ensure your understanding.

The rarer the mutation/quality originally is, the more probable it is, that is is a recessive quality ie. there are only a few original specimens to make up the basic population

So what I meant is, with hybrids the F2 generation's ability to breed is most probably recessive so it is fairly rare to begin with. This means that only few specimens have it and so the original population is small. This means that the more generations pass, the more probable it is for harmful recessive qualities to become homozygous too within the offspring.


Sorry to keep you in excitement and sorry if you didn't understand :p
(I've mainly studied these in finnish so there may be errors just because the translation)
 

Doggfather

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It is obvious that you don't posses much knowledge in genetics

Well, which 16 year old kid does :lol:

Thanks for your 'lesson', i know the basics and thanks for re-enforcing the little knowledge i had :lol: as well as teaching me a few things in the process! Hopefully i'll learn a lot more next year when i take up biology and chemistry as seperate subjects, not like science this year, a whole lot of little things rolled into one class :)
 

JustinSane

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Doggfather said:
Well, which 16 year old kid does :lol:

Thanks for your 'lesson', i know the basics and thanks for re-enforcing the little knowledge i had :lol: as well as teaching me a few things in the process! Hopefully i'll learn a lot more next year when i take up biology and chemistry as seperate subjects, not like science this year, a whole lot of little things rolled into one class :)

No no, I didn't mean it as an insult, I can hardly blame people for not having much knowledge with these matters since they are quite complicated and to be quite honest, I'm having difficulties with them myself too :D
I'm sort of "forced" to study these things since I intend to apply to Helsinki University to study biology and some knowledge in genetics is required in the entrance examination, so I need to study MORE MORE! :crazy:
 

Doggfather

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:lol: i didn't take it as an insult, it's just a sign telling me to pay more attention in class next year :nod:

Well, if you need anymore practise, i'm sure theres a lot of genetic mis-information all over the forum :thumbs:

Good luck with your exam, sounds as thought you'll do fine!
 
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GuppyDude

GuppyDude

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yes mules are sterile due to the cross breeding. i have heard that F2 generations were sterile in fish before, i dunno how tru exactly it is or what kinda fish do it but its sertainly interesting. thanx to all who helped ( and u guys who juts said blah zah and wat not....y?) -_- :D

Dah!
 

Opcn

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To answer the origional question, Sometimes!

It depends on the hybrid, the reason mules are sterile has little to do with there makeup genetically it has to do with how its packaged, Asses have 26 chromosomes and horses 24 So when it comes time for miosis (when genetic information is equally devided in a random fasion for the purpose of mateing) they cant match up there 25 chromosomes and they fail to reproduce. Some plants can handle this by there tolerance of polysome (More than 2 copies of a chromosome) For instance the wheat that is farmed for cerial is the mix of three different types of wheat I've forgetten the names but for simplicities sake I'll lable them A, B, and C

Now first they cross A with B Now each one has two identical (Mostly) sets of genetic data so A will be AA and B will be BB

AAXBB=AB which is sterile because it cant devide its genetic information, But if Miotic Error occurs and you end up with AABB then the genetic information can be devided eqqually and you now have a viable hybrid. Now You Decide To cross AABB with CC And you get ABC (AABB devides its A and B equally and then CC gave a C) But now ABC cant reproduce, its scuttled unlessit gets a miotic error, and it does and we end up with a viable AABBCC. Yay!

Now if your breeding a sword tail and a platy they are very closely related and the offspring will be able to reproduce (Esspecially considering the Barr bodies (Extra chromosomes floating around in the nucleous of the cell) of the platy)
 

Daveo

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The only hybrids I know of is drum rudimental hybrids :thumbs:


Daveo
 

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