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
Return to the MNL 56 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page