Mexico: Sierra de Manantlán

Sue Stolton and Jorge Alejandro Rickards-Guevara

Maize isone of the world’s major crops, cultivated globally on 130 million ha. There are currently five recognized species of teocintle, the ancient ancestor of modern corn: Zea diploperennis, Z. luxurians, Z. mays, Z. nicaraguensis and Z. perennis. The maize gene pool consists mainly of cultivated Z. mays and the related wild species, which form an important genetic source for breeding and adaptation. Zea diploperennis and Z. perennis are perennial, while other species are annual.Virtually all populations of wild teocintle are either threatened or endangered (FAO, 1997). This case study tells the story of how two of these species have been saved from exinction.

Seeking Zea

In 1976, Professor of Botany, Dr Hugh Iltis, at the University of Wisconsin-Madison in the US, sent a New Year’s card in the form of a poster to botanists around the world with a picture of Zea perennis against which he wrote “extinct in the wild”. Wild populations of Z. perennis had last been seen in 1921 inWestern Mexico, by two US Department of Agriculture botanists, who introduced the species to university greenhouses. Since then several other botanists had tried, and failed, to relocate the wild population.One poster was placed on a bulletin board at the University of Guadalajara by a local taxonomist, who urged her students: “Go and find this teocintle, and prove that gringo Iltis wrong”. One undergraduate student took the challenge and went back to the plant’s last known location in Western Mexico and found the long-lost Z.Perennis (Stolton et al, 2006).

This one find led to an even more important discovery. On being told that Z. perennis was growing in another location the student, Rafael Guzman, collected more seed. This teocintle (known locally as ‘milpilla’) however turned out to be a new species – Z. diploperennis. Unlike Z. perennis, this species freely interbreeds with corn, which raised the possibility that the crop could be grown for several years from one rootstock and, perhaps more importantly, it appeared to be tolerant of seven corn viruses and the only member of Zea that is immune to three of them (Stolton et al, 2006).

Protection

Following this discovery, years of negotiations led eventually to the creation of the Sierra de Manantlán Reserve under the direction of the University of Guadalajara– thefirst protected area established principally for the preservation of a wild crop relative, along with traditional agricultural systems and cultivars (Iltis,1994). Steps towards protection began in 1984, when the State of Jalisco purchased land which included a large population of Z. diploperennis. The following year this area became the Laboratorio Natural Las Joyas de la Sierra de Manantlán run by the Universidad de Guadalajara. The area was recognised by UNESCO’s Man and the Biosphere Programme in 1988 and is currently under the administration of the National Comission for Protected Areas (CONANP).

Apart from the Laboratorio Natural Las Joyas de la Sierra de Manantlán, none of the land in the Biosphere Reserve has been purchased by governmental authorities – at present 20 per cent is owned by indigenous communities, 40 per cent is community-owned (‘ejido’) lands and 40 per cent privately owned (Sheean-Stone, 1989).Around 33,000 people live in the Biosphere Reserve, and some 400,000 rely on the Sierra’s water catchment for industry, agriculture and other purposes (Stolton et al, 2006).

Understanding conservation management

The discovery of Z. diploperennisand the subsequent declaration of a biosphere reserve have together led to intensive research into the biodiversity, and specifically the flora of the reserve, which includes tropical humid forest and temperate grasslands. Over 2,700 plant species have been recorded, of which 40 per cent are endemic to Mexico. Agricultural fields and associated secondary vegetation in hillsides and small valleys in the reserve and surrounding area have been found to contain CWR of beans (Phaseolus coccineus and P. vulgaris) as well as maize. The Sierra de Manantlán is also an important refuge for animals, including threatened species such as the jaguar (Panthera onca). So far, 108 species of mammals have been recorded in the region – at least 12 of which are endemic to montane areas of western Mexico and 2 subspecies to the reserve (Cuevas-Guzmán et al, undated).

Protection strategies for Z. diploperennis began with gathering baseline information on the species’ habitat requirements. Surveys revealed that all known Z. diploperennis populations were found near highland farming villages and that the plants invariably occur in clearings surrounded by pines, oaks and broadleaf cloud forest. Z. diploperennis was found in areas created by small-scale clearance for maize cultivation and subsequently abandoned, or in actively cultivated fields.Further research found that Z. diploperennis cover and stem abundance appeared to be highest in sites that had not been cultivated for at least 15years. However, these sites also showed the first incursion of young woody trees that could eventually shade out the plant,suggesting that long-term conservation of the species would depend upon regular small-scale forest openings like those produced by shifting agriculture(Stolton et al, 2006).

Community knowledge

Sierra de Manantlán’ssuccess as a protected areais not just due to the work carried out by scientists and conservationists. Mexicans call teocintle the ‘grain of the gods’ and the crop is of great importance to food security in the region. The reverence accorded to the species has clearly helped to preserve its diversity.

The local rural communities in the region have considerable knowledge of the area’s diversity and their agricultural practices have helped to retain species richness. The existence of Z. diploperennis and other CWRs is likely to be due to the traditional agricultural practices of slash-and-burn cultivation (‘coamil’) and cattle-ranching. The management practices and objectives of the reserve thus stress the necessity of conserving traditional agricultural systems and it is planned to continue the coamil system in areas within the reserve, so that the Z. diploperennis populations can survive(Stolton et al, 2006).

References

Biodiversity Leadership Awards (undated) , accessed 1st August 2009

Cuevas-Guzmán, R., Benz, B. F. Jardel-Peláez, E. J. and Herrera-MacBryde, O. (undated) Fact Sheet, Sierra de Manantlan Region; Smithsonian Institution, SI/MAB Program, Washington, DC, USA, accessed 1st August 2009

FAO (1997) The State of the World’s Plant Genetic Resources for Food and Agriculture, FAO, Rome, Italy

Iltis, H. (1994) New Year’s Card Leads to Newly Discovered Species of Enormous Economic Potential, R&D Innovator, 3:6, June 1994 at: accessed 1st August 2009

Sheean-Stone, O. (1989) Mexico’s wonder weed, WWF Reports, Gland, Switzerland, Aug-Sept: 9-12

Stolton, S., Maxted, N. Ford-Lloyd, B.V., Kell, S.P. and Dudley, N. (2006); Food Stores: Using Protected Areas to Secure Crop Genetic Diversity, WWF International, Gland, Switzerland