Thursday, June 13, 2019

The evolution of the apple

Apples are from Kazakhstan. But how did they get from there to circle the globe?


How did they evolve from the wild, and in response to what evolutionary imperatives?

One part of the story: the Silk Road. Another: horses.

The Max Planck Institute for the Science of Human History recently summarized research into large fruits by Robert Spengler. (Spengler's original work was published in the May issue of Frontiers of Plant Science.)

The Silk Road hypothesis is not new: that trade routes brought the original wild apples (Malus sieversii) together with three other subspecies to create the modern version of the fruit.

Before the Silk Road

But even before that transportation and hybridization, the wild apples of the Tien Shen mountains were large and red. Why?

Many other fruits (such as rose hips, berries, and cherries) evolved small, to be swallowed and spread by birds. However, the Plank Institute notes, some fruits

such as apples, pears, quince, and peaches, evolved in the wild to be too large for a bird to disperse their seeds. Fossil and genetic evidence demonstrate that these large fruits evolved several million years before humans started cultivating them. So whom did these large fruits evolve to attract?

Spengler's answer: "large fruits are usually adaptations for large mammalian dispersal."

Not just horses (or proto-horses) but other megafauna. Spengler names "humans, bear, and possibly deer." Planck's summary again:

The evidence suggests that large fruits are an evolutionary adaptation to attract large animals that can eat the fruits and spread the seeds.

Spengler's work, based on genetic data and recent archaeological finds of ancient preserved apple seeds, challenges the dominant model of gradual domestication that is based on grains and grasses.

Works Cited
Spengler, Robert. 2019. "Origins of the Apple: The Role of Megafaunal Mutualism in the Domestication of Malus and Rosaceous Trees" Front. Plant Sci., 27 May 2019. 

Max Planck Institute for the Science of Human History. 2019. "Exploring the Origins of the Apple" press release, May 27, 2019.

Links


5 comments:

  1. I have several Kazakhstan apples in my orchards grown from scion obtained from GRIN. One PI 6140000 is bearing a half dozen fruit this year.

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    1. Thanks, Greyphase. That is very cool!

      I wonder where the orchard that grew your budwood is located. I notice that GRIN has a station in Geneva, New York.

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  2. Naturally occurring M. sieversii were selected by local market-traders - they would know the location of a 'good' one and harvest it for market. A seed collected from one of these was brought back to England and trees are now available for sale as Grandpa Ailes. Mine has yet to fruit so can't vouch for how good it is. There are several others doing the rounds.

    Also, in the US, see
    https://www.widespreadmalus.com/
    http://www.cultivatingdiversity.org/

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    Replies
    1. Thank you, Orchard Thing. That is fascinating and raises so many questions.

      Are these wild apples less heterozygous than domestic varieties and more likely to breed true? I see that Grandpa Ailes is propagated by grafting.

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  3. I love this history. A lot of stuff opened up along the silk road when Alexander the Great made his rounds in the 300s BC. The English/Persian Walnut has a near history too, probably very similar to the apple.

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