[cryptolab]

What makes this whole F1 Hybrid Vigour topic more puzzling...
is that the effect doesn't always show up.

So, perhaps the most famous example, of an F1 hybrid, is a mule.
Which is a hybrid between a horse and a donkey.
(Mules are normally sterile so you very rarely get second generation mules)

These animals are not more 'vigourous' than donkeys or horses.
These animals are not bigger than donkeys or horses.
However, they are longer lived, than horses and donkeys.

In contrast, ligers (a cross between a male lion and a female tiger)
are usually at least double the size of their parents.
Lions and tigers weigh 500 to 600 kilos (Tigers are generally slightly bigger)
Ligers get 'growth hormone' from genes in both parents and consequently they weigh
in at around 1000 kilos. The heaviest recorded liger was 1,600 kilos...
That's about 3 times the average weight of lions and tigers.

See the image below to get an idea of how massive ligers are:



Male and female ligers look most similar to (very large) female lions.
An odd detail about male ligers, is that, despite having a male lion as a father,
they don't have the shaggy lion's mane.

You might be forgiven for assuming that the genes for a male lion's shaggy
mane would come from 'dad'... but apparently, it comes from 'mum'.
Evidence for this can be seen in the picture of a male tigon shown below.
You can see that this animal obviously has a very pronounced lion's mane.
But tigons have a male tiger for a dad, and a lioness for a mum.
And since tigers don't have a 'mane'.. the tigon's mane must have come via mum.

A second interesting detail, is that tigons are either the same size as lions
or slightly smaller than lions (all depending on who's articles you read). But in
any event, tigons aren't bigger than either lions nor tigers.
Interestingly, the F1 hybrid vigour effect shows up for ligers but not for tigons.



The third detail about these cats concerns tigon rarity. Ligers are quite
abundant, tigons are much rarer. The reason for this is that tigon cubs
are often still born. Tigons have a tiger dad and a lioness mum. Out of
the 4 cats (lion, lioness, tiger, tigress) tigers are the biggest
and lionesses are the smallest. An explanation for the tigon still births
is that cubs are physically too big to fit comfortably inside a lioness' womb.
This third detail, makes me wonder if the mixing of these genes is actually
haphazard and chaotic.

I wonder if, lions and tigers are simply not similar enough for the
'F1 Hybrid Vigour' effect to apply. Perhaps it would apply
much better, to the F1 hybrids of Bengal tigers and Siberian tigers.
Or perhaps to the F1 hybrids of African lions and Indian lions.

[Betterhaff]

cryptolab, that link downloads as a pdf so maybe that's the issue why it doesn't work. I have it as a pdf file but the site doesn't let pdf's be attached. Search "Heterosis: Theory and Estimation". The authors are Kendall R. Lankey and Jode W. Edwards.

On the lion/tigon mane thing, in humans most male baldness comes from the maternal side’s contributions.

Also, lions and tigers are not the same species, they are in the same family and genus so other things at play there.

[hyposomniac]

Two selves locked in a single plant in a constant battle for dominance. Your mother's powerful family demands that you behave like a blueberry, meanwhile you look up to your father who is a ninja and a big wave surfer. You want to please them both. Such internal struggle can drive a plant to greatness and usually madness. Its metaphysical dudes.

[Yard dog]

Originally Posted by Weird

https://www.icmag.com/ic/showthread....ight=heterosis

and old thread I made on the topic

Genetic discovery points the way to much bigger yields in tomato, other flowering food plants
Scientists learn how tweaking a 'hybrid vigor' gene generates higher crop yields

Didn't they find that with tomatoes that vigor was due to over dominance?def not pseudo but true over dominance...

[Natural high]

The explanation for hybrid vigour lies in the fact that recessive alleles tend to be the "weaker" or "less fit" alleles in an evolutionary sense, as opposed to dominant alleles.

All inbred lines have a high level of homozygousity. This means that many alleles which could be considered as sub-optimal will be expressed, as there is no overriding dominant allele.

When two inbred lines are brought together, the percentage of homozygous alleles is reduced as many are now paired up with a new different allele from the other parent. Of these new heterozygous pairings, the allele which is relatively "stronger" or "more fit" is more often than not the dominant one, hence the one which influences the final phenotype.




.

[cryptolab]

Originally Posted by Betterhaff

cryptolab, that link downloads as a pdf so maybe that's the issue why it doesn't work. I have it as a pdf file but the site doesn't let pdf's be attached. Search "Heterosis: Theory and Estimation". The authors are Kendall R. Lankey and Jode W. Edwards.

On the lion/tigon mane thing, in humans most male baldness comes from the maternal side’s contributions.

Also, lions and tigers are not the same species, they are in the same family and genus so other things at play there.

Super! Thank you Betterhaff

[MaryMaven]

Originally Posted by Natural high

The explanation for hybrid vigour lies in the fact that recessive alleles tend to be the "weaker" or "less fit" alleles in an evolutionary sense, as opposed to dominant alleles.

All inbred lines have a high level of homozygousity. This means that many alleles which could be considered as sub-optimal will be expressed, as there is no overriding dominant allele.

When two inbred lines are brought together, the percentage of homozygous alleles is reduced as many are now paired up with a new different allele from the other parent. Of these new heterozygous pairings, the allele which is relatively "stronger" or "more fit" is more often than not the dominant one, hence the one which influences the final phenotype.

.

I'm sure there are more things at play than this in the grander scheme of things when it comes to hybrid vigor, but this quote from Natural high is quite eye/mind opening in its simplicity yet 'profoundness'


Thank you, all, for your contributions to this thread. Very, very interesting and a lot to think about!


I am just learning SOOOO much here at IC mag. It really is quite a unique site. I just love that so many here take their 'gardening' so seriously and their learning to the next level. The willingness of so many of you to share so much amazing, hard-earned knowledge with virtual strangers at no benefit to yourselves is 'philanthropy' at its very finest. I am so glad I found this site.


Peace
Maven

[aridbud]

Originally Posted by Natural high

The explanation for hybrid vigour lies in the fact that recessive alleles tend to be the "weaker" or "less fit" alleles in an evolutionary sense, as opposed to dominant alleles.

All inbred lines have a high level of homozygousity. This means that many alleles which could be considered as sub-optimal will be expressed, as there is no overriding dominant allele.

When two inbred lines are brought together, the percentage of homozygous alleles is reduced as many are now paired up with a new different allele from the other parent. Of these new heterozygous pairings, the allele which is relatively "stronger" or "more fit" is more often than not the dominant one, hence the one which influences the final phenotype.




.

Yup.

[Farm Hero]

Yes, hybrid vigor is real. In making UK Cheese X Black Widow, the first round was wild with variety and the vigor, now after S1F2 generation, the plants are quite stable and predictable. It's fun to witness hybrid vigor first hand, just be sure to use two very different yet stable genetic lines.


To me it is like both parents recognize they are very different and somehow put their most vigorous genetic expression forefront? Hybrid vigor plants have made great clone only varieties retaining the vigor over many years.

[Natural high]

Originally Posted by Farm Hero

To me it is like both parents recognize they are very different and somehow put their most vigorous genetic expression forefront? Hybrid vigor plants have made great clone only varieties retaining the vigor over many years.

It's not that they recognize that they are very different, but rather it happens inherently because of the dominance of some alleles over others as outlined in my post above. It is analogous to two card players combining average hands to make a better one.

UK cheese x black widow would make some awesome phenotypes i'd imagine.