Teosinte Distribution in Mexico - CIMMYT: Seeding innovation ...

30 Teosinte distribution in Mexico
Herbarium specimens and ethnobotanical
information
Figures 1 to 13 and Table 1 list information on
teosinte populations from botanical samples or other
varied sources. Farmers and cattle ranchers are the
most common sources, but information has also come
from taxonomists and agronomists who work
directly with farmers and ranchers. The information
in the figures and table is considered reliable and of
potentially great use in planning exploration and
collection trips. Sites in the states of Chihuahua,
Jalisco, Oaxaca, and Chiapas are of particular interest;
confirmation of teosinte’s existence there would
permit the study of genetic diversity in a latitudinal
continuum, covering a large number of ecosystems
beginning in Chihuahua at almost 30° N and ending
in Nicaragua close to 13° N.
Potential areas of teosinte
distribution
The preceding describes locations where teosinte’s
presence is either reported by non-technicians or
where its presence has been confirmed through direct
observation by a recognized expert. It is widely
believed, however, that heretofore undescribed
teosinte populations exist in Mexico. One approach
for encountering such populations would be to define
ideal environments and then search for areas and
locations that fit the parameters defined, using a
geographic information system. The following
section describes an experiment which follow this
approach to identify potential areas of teosinte
distribution in Mexico, outlining the methodology
and preliminary results for the Balsas and Central
Plateau races in the Central Pacific Region of Mexico.
First, altitude, temperature, and precipitation
parameters were defined for teosinte for sites where
seed of the maize wild relative has been collected in
the states of Colima, Jalisco, Michoacán, and Nayarit
(Table 2 lists requirements for Balsas and Central
Plateau races — results for these two races are
presented, because data are available from many
sites). To search for potential areas of teosinte
distribution, an INIFAP geographic information
database for the Central Pacific region was used,
working at resolutions of 900 x 900 m. Using this
database and the IDRISI system, altitude, annual
temperature, and annual precipitation maps were
reclassified as a function of the ranges listed in Table
2. The reclassified maps were then overlaid to find
potential areas of distribution for Balsas and Central
Plateau teosinte (Figs. 14, 15). For the Balsas race,
21,014 km2 of possible teosinte areas, representing
12% of the region, was found in four states (9,425 km2 in Jalisco, 7,883 km2 in Michoacán, 3107 km2 in
Nayarit, and 599 km2 in Colima). For the Central
Plateau race, 2,151 km2 (1.2% of the region) of new
areas was detected; 1,307 km2 in Jalisco and and 843
km2 in Michoacán.
Common names of teosinte
in Mexico
Closely related to the issue of teosinte distribution in
Mexico and of considerable importance in study or
collection efforts are the common names given the
species (Table 3). These names are generally based on
some resemblance of the plant to maize, or on the
names of birds which, according to the local
Table 2. Altitude, temperature, and precipitation
for the distribution areas of two
teosinte races.
Average annual Average annual
Altitude temperature precipitation Slope
Race (masl) (°C) (mm) (%)
Balsas 620-1550 19.8-27.7 840-1265
Central
Plateau 1530-2000 15.9-19.6 800-916 < 4