BOTANICAL MUSEUM LEAFLETS 
HARVARD UNIVERSITY 
CamBripGr, Massacnusetts, ApriL 3, 1959 VoL. 18, No. 9 
THE ORIGIN OF CORN 
III. Mopern Races, tHE PRopucT OF 
TEOSINTE INTROGRESSION 
BY 
Paut C. MANGELSDORF AND Rosert G. REEVES 
Tue third postulate of our tripartite hypothesis (35) that 
certain modern races of maize are the product of teosinte 
(Zea mexicana) introgression has been the least contro- 
versial of the three. There is now almost unanimous 
agreement among those who have studied the problem 
that corn and teosinte are constantly hybridizing in Mex- 
ico and Guatemala and that this introgression of one 
species into the other necessarily has had substantial ge- 
netic effects. The exception to this unanimity is repre- 
sented by Randolph (41) who has offered the following 
objections: (A) There is little natural crossing between 
maize and teosinte. (B) The extent to which hybridiza- 
tion between the two species has resulted in gene ex- 
change is open to question. (C) There is no cytological 
evidence of the introgression of teosinte into maize. (D) 
There is no evidence that introgression, if it occurs, leads 
toimprovement. (KE) Characters found in maize varieties 
which have been attributed to teosinte introgression can 
be equally well explained as the result of parallel muta- 
tions. 
How valid are these objections and to what extent 
are they supported by the evidence? 
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