Reconstruction of the missing links between teosinte and maize

The key traits of maize, namely a many-ranked (decussate) spike and paired female spikelets, were individually transferred to teosinte in order to examine the hypotheses of a common ancestor between a wild maize and teosinte or that of intermediate steps in the presumed domestic transformation of teosinte into maize.

A joining of the fruit cases of teosinte into yokes with a decussate arrangement is non-adaptive as a wild trait because it reduces the number of dispersal units by half. It must, therefore, represent a domestic trait. When the paired condition of female spikelets in maize is transferred to teosinte, the effectiveness of the fruit case as a protective device is destroyed.

The conclusion is that, when the key traits of maize are individually transferred to teosinte, the product is no more adaptable as a wild type than that of the eight-rowed ear of the oldest maize. Furthermore, these modified teosintes are like maize in not fitting into a logical early position in the sequential steps leading toward the cupulate fruit case. They must represent transitional forms in corn's origin by domestication.

Walton C. Galinat

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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