Evolution by Individual Trees

[Amelanchier]

So an Oak lives for hundreds of years. Defoliating insects might have two generations a year. You'd think that the insects have the upper hand, they're mobile, breed fast, and can adapt over generations to any defences the tree might have. So how come the tree gets to live out its days???

 

It evolves. Trees can't run away from trouble or look for better environments. They change or die (or struggle for years then die).

 

Trees (as you're probably aware) are generating systems. They don't heal wounds, they seal them with new tissue. The damage is always there just compartmentalised.

 

Trees are also modular. Stems, limbs, branches, twigs, leaves and buds are in competition with each other - the perfect capitalist market economy. Those parts that are profitable last another day. Those parts that can't pull their weight get surbordinated or binned.

 

 

Ok - I've been rambling, but there is a point.

 

Every part of a tree, grows from meristematic tissues. Those tissues can mutate during normal cellular division. This means that a bud can be genetically different to the others.

 

This means that whatever that bud turns into will be genetically different as well. So bud becomes leaf, flower, twig. All the parts that arise from that new growth will be genetically distinct also.

 

This means that mature trees can be made up of a 'mosaic' of genes.

 

This allows natural selection to act on parts of the tree. Reversion is a good example, reverted leaves are more productive and will outcompete the variegated, purple, cut-leafed types. Buds mutate back to their wild type and just do their thing.

 

To go back to where I started - leaves under attack from defoliating insects produce chemicals to defend themself. Leaves that are better at doing it don't get eaten. A genetic mosiac of foliage keeps the tree one step ahead.

 

Also adventitous buds lie dormant until released by changes in hormones or sunlight. These can also be mutate but won't be expressed until needed. Evolution in a bottle!! Stored for a rainy day.

[Jamie]

Nice idea but, i doubt that any mutations will be that distinct though. maybe you should write a thesis on it.

 

any peer papers on this thinking?

 

Jamie

[Amelanchier]

Sorry, didn't mean to give the impression that it was my idea!

 

This 1981 paper was the synthesis that kicked off the idea.

 

Its accepted fact now.

Evolution by Individuals, Plant-Herbivore Interactions and Mosiacs of Genetic Variability_Whitham &

[Marc]

Learn something new everyday thanks posting that Tony.

[scotspine1]

Trees are also modular. Stems, limbs, branches, twigs, leaves and buds are in competition with each other - the perfect capitalist market economy.

 

Or if your a Marxist they channel photosynthates from areas of strong growth to areas of poor growth or areas that have been wounded or areas such as the heartwood for structural strength.

[Dagmar]

So an Oak lives for hundreds of years. Defoliating insects might have two generations a year. You'd think that the insects have the upper hand, they're mobile, breed fast, and can adapt over generations to any defences the tree might have. So how come the tree gets to live out its days???

 

 

Leaf signal theory?

[Amelanchier]

I knew that was a metaphor too far Tim...

 

Maybe that's a topic for another thread???

[Amelanchier]

Leaf signal theory?

 

I suppose leaf colour would be genetically determined so there's no reason why the ideas can't overlap.

[scotspine1]

I knew that was a metaphor too far Tim...

 

Maybe that's a topic for another thread???

 

Just thought I'd point it out. No need to start a new thread.

[Dagmar]

I suppose leaf colour would be genetically determined so there's no reason why the ideas can't overlap.

 

 

It would be a indicator for coevolution.

I can't find much recent work on it. I remember it fascinated me when it was first postulated!