Why Does F1 Hybrid Vigour Occur?

[cryptolab]

Hello Denizens,

I find this whole topic of F1 Hybrid Vigour, particularly interesting.
I understand what F1 Hybrid Vigour is, as a description of its effect.
And I understand under what circumstances it will happen.
What i don't understand, is 'why' ?

Why does F1 Hybrid Vigour occur ?

The picture below, pretty much sums up the effect:

I'm sure many of you have spent plenty of time studying and working
on issues relating to plant breeding and hybridization... Perhaps you
can offer a perspective on this issue that sheds light and understanding
on the whole topic.

Thanks to those who offer a reply

have a nice day

cryptolab

 

[Jackalope]

I'm not going to give any answers lol. Just add more questions. Not only does the Hybrid effect happen in plants it also happens in animals. Mackenzie Valley Timberwolves are a cross between a Timberwolf and a German Sheppard. The offspring are bigger than both parents.
So I am waiting with Cryptolab for more info. Note: A explanation in layman's terms would be best

 

[cryptolab]

I'm not going to give any answers lol. Just add more questions. Not only does the Hybrid effect happen in plants it also happens in animals. Mackenzie Valley Timberwolves are a cross between a Timberwolf and a German Sheppard. The offspring are bigger than both parents.
So I am waiting with Cryptolab for more info. Note: A explanation in layman's terms would be best

hi Jackalope,

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 first generation 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' genes from 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.

Perhaps this 'growth hormone' scenario is also at work in the example
you cite of large F1 hybrids of Timerwolves and German Sheppards in the
MacKenzie Valley.

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.
The F1 hybrid vigour 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 and Indian lions.

 

[Icemud]

hi Jackalope,

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 first generation 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' genes from 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.

Perhaps this 'growth hormone' scenario is also at work in the example
you cite of large F1 hybrids of Timerwolves and German Sheppards in the
MacKenzie Valley.

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.
The F1 hybrid vigour 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 and Indian lions.

I think its because these animals are different species bred together...

Hybrid vigor in my understanding is 2 of the same species, that are inbred 5 or more generations and then crossed, which then results in hybrid vigor.

The difference being the animals above are not imbred for 5 to 7 generations and then crossbred, and they are a different species all together.

Plants, such as the corn in the photo typically are imbred to be homozygous (breeding true) and then crossed with another plant of the same species also that has been imbred multiple times to be homozygous and then crossbread.

I think that it takes at least 5-7 generations of selective breeding to reach a homozygous state.

I may be way off, but this is my understanding of how it works.

 

[cryptolab]

I think its because these animals are different species bred together...

Hybrid vigor in my understanding is 2 of the same species, that are inbred 5 or more generations and then crossed, which then results in hybrid vigor.

The difference being the animals above are not imbred for 5 to 7 generations and then crossbred, and they are a different species all together.

Plants, such as the corn in the photo typically are imbred to be homozygous (breeding true) and then crossed with another plant of the same species also that has been imbred multiple times to be homozygous and then crossbread.

I think that it takes at least 5-7 generations of selective breeding to reach a homozygous state.

I may be way off, but this is my understanding of how it works.

hi Icemud,

A+ You're absolutely right.

Two requirements:
1. The parental strains must be from the same species
2. The parental strains must be 'true-breeding' (inbred & homozygous for given traits)

best wishes

cryptoLab

 

[Jackalope]

I can't help bet think. How many animal crosses or hybrids went terribly wrong? Thank god that playing with plant genetics is one heck of a lot safer. Who wouldn't love a 3 headed plant.
Marijuana Botany is a great book that breaks down breeding marijuana scientifically. Pretty sure these same technics are used in animals and plants. Probably the same info used in the hybrids mentioned above. Great info for anyone trying to breed a true and great strain. Way to much info for my little mind lol.