The origin of Carya illinoinensis?

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samson'sseed
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The origin of Carya illinoinensis?

Post by samson'sseed » Tue Nov 15, 2016 8:57 am

I read that hickory trees originated during the late Cretaceous. Early hickory species had thin shells, but most species grew thick shells as an evolutionary response to squirrels and other animals feeding upon them.

I wonder why pecan trees still had thin shells.

Were they a rare relic of more ancient species of hickory that were then spread by native Americans?

Or is there some kind of evolutionary advantage to having a thin shell? Maybe squirrels will bury pecans first before other species because they have the most food value.

I can't decide whether pecans are a very ancient species of hickory or a recent mutation spread by Indians.

What do you think?

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Larry Tucei
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Re: The origin of Carya illinoinensis?

Post by Larry Tucei » Tue Nov 15, 2016 12:20 pm

Man cultivated hard shell back into soft shell in the late 1800's. Larry

samson'sseed
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Re: The origin of Carya illinoinensis?

Post by samson'sseed » Fri Nov 18, 2016 9:28 am

I've been doing some more research on this, and I found 1 advantage pecans have over other hickories.

They ripen later.

Pecan weevils (Curculio caryae) are more likely to infest early ripening species of hickories.

Though squirrels favor pecans, this is balanced by pecan weevils attacking earlier ripening hickories in mixed stands of pecans and hickories.

I'm leaning against the hypothesis that Indians had much influence over the thickness of the pecan shell. There is a large genetic diversity within populations of pecans. If pecans evolved thin shells recently, they would have a much smaller genetic diversity.

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Rand
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Re: The origin of Carya illinoinensis?

Post by Rand » Fri Nov 18, 2016 6:19 pm

There are a scattering of planted Pecan up here in Ohio and they all have quite thick shells. I presume its some sort of cold hardy variety that has not had the thin shell traits bred into it.

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