Hybrides

[jac]

Can any one please tell me if an hybrid can breed itself or not?
There is a long going discussion about this matter on several forums in holland at the moment and no one seems to know the real answer to this question. I'm very curious if it is possible or not.

If it is or isn't please explain your answer.


I myself hate the idea of crossbreeding different species because it makes ID even more difficult than it already is....

[Bijn]

Some hybrids are fertile and some are infertile. To make it even more complex: certain hybrids that are usually unfertile do have fertile individuals.

Generally you can say: the closer the parents are related how bigger the chance the hybrid offspring is fertile.

[jac]

Thanks for the quick reply!
That would be a summery of what I was starting to read here on the site..... I found the topic from DJ-don about cross breeding....... At page 2 I started to get really confused...have to take more time to read the rest.

I find it quite disappointing to read that Hypancistrus could already have cross bred in the wild to make the species we have called L173, L260, L399 and L400 and others...

Comes as quite a shock to me

[MatsP]

As already explained, there is no simple answer here.

As a simple rule, mammals do not produce fertile hybrids - so for example mule (Horse + Donkey), and Zorse (Horse + Zebra) are both infertile - I think Lion + Tiger produces (at least sometimes) fertile off-spring. On the other hand, we know that Hypancistrus hybrids are definitely fertile. Other fishes may or may not be fertile. I'm pretty sure there are Ancistrus species that CAN NOT hybridize, because they are so far apart genetically (vast number of different chromosomes).

I wouldn't be surprised if at least some of the hybrid Synos are fertile.

[Sorry, fire-alarm went off - it was just an exercise to see if we do get out when it goes off!]

In nature, species doesn't exist. It's a man-made concept to distinguish one group of animals from another. Naturally occurring hybrids, therefore, aren't quite the same thing as man-made hybrids [whether that is caused by keeping two different species in the same tank or by injecting the fish with hormones and squeezing the reproduction products into a bowl and mixing there].

--
Mats

[Shane]

On the other hand, we know that Hypancistrus hybrids are definitely fertile.

Firstly I agree with Mats' comments above. It is important to remember that "species" is a man-made concept and the definition of what a "species" is has changed over time as we learn more about how organisms are related. Also, not everyone agrees as to what exactly defines a species.

This may sound like a technicality, but a hybrid, when speaking about taxonomy, refers to offspring resulting from the interbreeding between two animals of different taxa. So in Mats' example above Equus caballus (horse) X Equus asinus (donkey) is a hybrid. However spawning L XXX with L XXX is not a hybrid as L Numbers are NOT scientific taxa (despite what many aquarists have come to think). L Numbers are assigned by ornamental fish importers and are not the result of taxonomic study.

If two two different L Numbers spawn and produce offspring, it is just as likely (or more) that the spawning reflects the unscientific nature of L Number assignments rather than a case of hybridization between two taxa.

-Shane

[jac]

Thanks very much for the reply's Mats and Shane.

It makes it clear anough for me for the moment.

Just for the biological side of things: could you than conclude that when the offspring of a crossbreed (take hypancistrus for instance) is infertile that would mean that the adults would be 2 different species or taxa as you say?
Genetics is really interesting

I have an other question for you if you don't mind. This was told to me but don't really understand how it works.
If breeding Lnumbers it isn't very good to breed the offspring with the parents again. But breeding brothers and sisters (if you start a breeding group out of a group of the same offspring) isn't so bad. I know that it is best to start your breeding group up with different genes.
But I just wanted to know how it works as I want to start a breeding group of my own offspring or F1's.

Jacqueline

[MatsP]

On the other hand, we know that Hypancistrus hybrids are definitely fertile.

Firstly I agree with Mats' comments above. It is important to remember that "species" is a man-made concept and the definition of what a "species" is has changed over time as we learn more about how organisms are related. Also, not everyone agrees as to what exactly defines a species.

This may sound like a technicality, but a hybrid, when speaking about taxonomy, refers to offspring resulting from the interbreeding between two animals of different taxa. So in Mats' example above Equus caballus (horse) X Equus asinus (donkey) is a hybrid. However spawning L XXX with L XXX is not a hybrid as L Numbers are NOT scientific taxa (despite what many aquarists have come to think). L Numbers are assigned by ornamental fish importers and are not the result of taxonomic study.

If two two different L Numbers spawn and produce offspring, it is just as likely (or more) that the spawning reflects the unscientific nature of L Number assignments rather than a case of hybridization between two taxa.

-Shane

Ok, so technically,

Hypancistrus sp(L201)

x

Hypancistrus sp(L260)

is not a hybrid. Whilst scientists may not have got round to defining them as separate species, they are clearly not [by reasonable defintion of species, as not only do they have different body patterns, they also have fairly different body shape] the same species. Yet, if that particular combination hasn't been bred, I'm 99% sure there were pictures of similar "hybrids" at the L-Welse meeting in Germany last year.

What I'm trying to say is that whilst technically it may not (currently) be hybrids produced from various L-numbered species, at least in some cases, that is purely because scientists have yet to define these as individual species.

I am not, by the way, saying that every L-number represents different speceis. There are certtainly several examples of L-numbers that are definitely or most likely the same species from different locations.

--
Mats

[racoll]

I find it quite disappointing to read that Hypancistrus could already have cross bred in the wild to make the species we have called L173, L260, L399 and L400 and others...

This is complete nonsense! Speciation via hybridisation has been demonstrated, but to assume that this is the case without any evidence whatsoever (other than "the fishes look quite similar") is entirely ludicrous.

could you than conclude that when the offspring of a crossbreed (take hypancistrus for instance) is infertile that would mean that the adults would be 2 different species

Yes, it is strong evidence to support that. However the opposite is not true, and two different species are perfectly able to have fertile hybrid offspring.

Also, not everyone agrees as to what exactly defines a species.

I think an important paradigm shift occurred after biologists gave up trying to define a species, as there are so many exceptions to each rule. Now, we recognise species as independently evolving units, and can be defined using the most appropriate data to resolve that question.

P.S. I agree with Mats on the L number thing.

[Bas Pels]

Now, we recognise species as independently evolving units, and can be defined using the most appropriate data to resolve that question.

for quite some time now, I'm starting to pay less and less attention to the species - in favour of the genus and location

So I don't care so much about the species my Ancistrus which I found in the arroyo Aquas Blancas in Uruguay - it's an Ancistrus (which tells me a lot about how to take care of them - feeding, behaviour) from the arroyo Aquas Blancas - which tells me the rest of how to take care of them (waterflow, water values, temperature)

Therefore, whether this fish is the same species as the Ancistrus from the arroyo Tropa Vieja (60 km apart) or not - I keep them separated, as they would not mingle in nature

Do you agree, Racoll that the cited piece would ultimately define 'species' as 'population'?

[racoll]

So I don't care so much about the species my Ancistrus which I found in the arroyo Aquas Blancas in Uruguay - it's an Ancistrus (which tells me a lot about how to take care of them - feeding, behaviour) from the arroyo Aquas Blancas - which tells me the rest of how to take care of them (waterflow, water values, temperature)

Therefore, whether this fish is the same species as the Ancistrus from the arroyo Tropa Vieja (60 km apart) or not - I keep them separated, as they would not mingle in nature

Seems like a sensible approach with all these undescribed species.

Do you agree, Racoll that the cited piece would ultimately define 'species' as 'population'?

Difficult question, as there are many examples of single species with huge ranges, comprising hundreds of "populations", yet all individuals are morphologically and genetically conservative.

[Mike_Noren]

However the opposite is not true, and two different species are perfectly able to have fertile hybrid offspring.

Ability to interbreed is a plesiomorphy, a primitive inherited trait, and as such is not informative. Inability to interbreed is an autapomorphy, a derived trait, and as such is informative. In other words: if two groups of animals can interbreed and have fertile offspring, that means nothing; if they can not interbreed or their offspring has reduced fitness, then they are different species.

Inability to interbreed is not normally selected for, but merely an accidental by-product of cumulative changes. However, when hybrids have significantly reduced fitness, there may be an evolutionary pressure to limit interbreeding - there are a handful of such cases known.

Speciation can not occur while there is significant gene-flow between two groups of organisms. The gene-flow has to be cut off or at the very least fall below the threshhold at which the populations genetics are homogenized, at which point there has been speciation. The species can however not be detected until they've accumulated any autapomorphies.

As is probably obvious from these examples speciation can be reversible if gene flow is cut off but later resumed.

There is no qualitative difference between population and species; they grade into each other with diminishing level of interbreeding.

[Bas Pels]

Do you agree, Racoll that the cited piece would ultimately define 'species' as 'population'?

Difficult question, as there are many examples of single species with huge ranges, comprising hundreds of "populations", yet all individuals are morphologically and genetically conservative.

Thank you. Conservatism is an aspect I did not take into account. And yes, a fish (or any other creature) should be sufficiently different in order to become another species. That's obvious

[Shane]

So I don't care so much about the species my Ancistrus which I found in the arroyo Aquas Blancas in Uruguay - it's an Ancistrus (which tells me a lot about how to take care of them - feeding, behaviour) from the arroyo Aquas Blancas - which tells me the rest of how to take care of them (waterflow, water values, temperature)

I long ago came to this same conclusion myself. 9 times out of 10 genus tells you all you need to know. Combine that with some basic habitat info and, for an aquarist, it is a lot more meaningful data than a binominal name.

I am hardly suggesting anyone throw all their L numbers together to breed freely since they are not described spp and thus can't produce "technical" hybrids. I just wanted to point out the actual definition, from a taxonomic standpoint, of a hybrid. Also, since L Number designations have no basis in science it is not applicable to come to scientific conclusions based on their behavior.

-Shane

[jbmm]

I'm 99% sure there were pictures of similar "hybrids" at the L-Welse meeting in Germany last year.

make it 100%, that was an interesting topic in Hannover!
You might be able to find some sheet photo's on the website

Anyone with interest should visit the next event!
Mats? you gonna be there?

grtz
Jeroen

[MatsP]

I was planning to go last year, but a new washing machine needed as well as a bit of difficulty finding good transport - direct flights to hannover were all at odd hours or VERY expensive when I looked. And other flights were affordable, but a long way away...

But with some better planning, yes, I should be able to do that.

--
Mats

[Bijn]

So I don't care so much about the species my Ancistrus which I found in the arroyo Aquas Blancas in Uruguay - it's an Ancistrus (which tells me a lot about how to take care of them - feeding, behaviour) from the arroyo Aquas Blancas - which tells me the rest of how to take care of them (waterflow, water values, temperature)

I long ago came to this same conclusion myself. 9 times out of 10 genus tells you all you need to know. Combine that with some basic habitat info and, for an aquarist, it is a lot more meaningful data than a binominal name.

and this is why I hate it when people use numbers instead of names (the numbers are for fishes without a name!). A fish that has a name shouldn't be called by it's number. I even try to mention the genus if it's an undiscribed species because that gives a lot off information. I have 3 Hypostomus sp. L117 not 3 L117.

[racoll]

Ability to interbreed is a plesiomorphy, a primitive inherited trait, and as such is not informative. Inability to interbreed is an autapomorphy, a derived trait, and as such is informative. In other words: if two groups of animals can interbreed and have fertile offspring, that means nothing; if they can not interbreed or their offspring has reduced fitness, then they are different species.

Inability to interbreed is not normally selected for, but merely an accidental by-product of cumulative changes. However, when hybrids have significantly reduced fitness, there may be an evolutionary pressure to limit interbreeding - there are a handful of such cases known.

Speciation can not occur while there is significant gene-flow between two groups of organisms. The gene-flow has to be cut off or at the very least fall below the threshhold at which the populations genetics are homogenized, at which point there has been speciation. The species can however not be detected until they've accumulated any autapomorphies.

As is probably obvious from these examples speciation can be reversible if gene flow is cut off but later resumed.

There is no qualitative difference between population and species; they grade into each other with diminishing level of interbreeding.

Really nicely explained here Mike.