Mapping the diversity of maize races in Mexico (original) (raw)
Related papers
A test of ecological and ethnolinguistic determinants of maize diversity in southern Mexico
While prevailing theories of crop evolution suggest that crop diversity and cultural diversity should be linked, empirical evidence for such a link remains inconclusive. In particular, few studies have investigated such patterns on a local scale. Here, we address this issue by examining the determinants of maize diversity in a local region of high cultural and biological richness in Southern Mexico. We collected maize samples from villages at low and mid elevations in two adjacent municipalities of differing ethnicity: Mixtec or Chatino. Although morphological traits show few patterns of population structure, we see clear genetic differentiation among villages, with municipality explaining a larger proportion of the differentiation than altitude. Consistent with an important role of social origin in patterning seed exchange, metapopulation model-based estimates of differentiation match the genetic data within village and ethnically distinct municipalities, but underestimate differen...
Race diversity in dryland maize (Zea mays L.) landraces from southern Nuevo León, Mexico
2021
Objective: To analyze the race diversity and geographic distribution of the native maize landraces currently cropped at southern Nuevo León, México. Design/Methodology/Approach: Data was obtained from 41 accessions which represent the commercial production in the dry land area, where fertilization and pest control are scarcely used. Landraces were classified according to the CONABIO guidelines for ear traits. Results: The measured accessions correspond to seven maize races and to seven interracial crosses. The two most frequent maize races were Ratón and Cónico Norteño, mostly located in the dry areas with less rain. Study Limitations/Implications: Three races, Celaya, Tablilla de Ocho and Elotes Cónicos, had not been previously reported; while two formerly reported races Tabloncillo and Olotillo, were no longer found. This study did not include the grain-colored accessions. Findings/Conclusions: Three collections stood out for producing large ears with large kernels, thus showing a...
A maize landscape: Ethnicity and agro-biodiversity in Chiapas Mexico
Agriculture Ecosystems & Environment, 2007
The ecology of maize (Zea mays L.) in Mexico, its center of domestication and diversity, has been researched for several decades. While the broad outlines of diversity and dynamics of native maize populations are known at the farm and national levels, these topics are less well known at the landscape level. Although environmental factors are the principal forces behind the overall diversity of the species in Mexico, recent research suggests that social origin, for instance community of residence or ethno-linguistic group, influences maize population structure at more local levels. A landscape perspective can help to determine whether these social factors operate in a consistent fashion across different environments. Case study data from Chiapas are presented and used to illustrate the role of ethnicity in understanding the ecology of maize diversity in Mexico. The paper contrasts the maize populations and management practices of Spanish speaking mestizos and Mayan language speaking indigenous people across four altitude zones in Chiapas. Environmental differences are primary in determining the overall pattern of maize diversity across the Chiapan landscape, but social origin has a significant effect on maize populations in all environments. #
Genetic diversity and structure of native maize races from Northwestern Mexico
Pesquisa Agropecuária Brasileira
The objective of this work was to evaluate the genetic diversity of nine maize races (Zea mays ssp. mays) from Northwestern Mexico and one population of teosinte of the Balsas race (Zea mays ssp. parviglumis). A total of 649 alleles were identified, with an average of 20.9 alleles per locus using 31 microsatellite loci; 84.3% of them were polymorphic loci with a 0.49 expected heterozygosity. Graphic representation of principal coordinate analysis (PCoA) showed broad variation and population distribution. The highest probabilistic value obtained with the ∆K criterion confirmed the existence of five population groups clustered by the Bayesian model. This grouping coincided with the population distribution observed in the PCoA graph. Maize races examined retain broad genetic diversity among and within the evaluated populations.
Estimation of Genetic Diversity in Seven Races of Native Maize from the Highlands of Mexico
Agronomy
Characterizing the genetic diversity of maize (Zea mays L.) populations by their morphological and molecular attributes makes it possible to place populations into specific groups; thus, facilitating the design of procedures for their optimum and sustainable use. In this study, data from two lines of evidence were analyzed simultaneously to robustly classify maize populations and to determine their genetic relationships. Seven maize races of the central high plateau of Mexico were characterized using a combined analysis of 13 morphological traits and 31 microsatellite loci. The germplasm assessed included samples of 119 accessions held at Mexican germplasm banks. Cluster and principal component analyses were performed. Also, genetic and geographic relationships among the accessions were determined. Principal component analysis separated the different accessions into well-defined groups using first three principal components. The accessions of Arrocillo Amarillo and Elotes Cónicos ra...
Maize diversity associated with social origin and environmental variation in Southern Mexico
Heredity, 2016
While prevailing theories of crop evolution suggest that crop diversity and cultural diversity should be linked, empirical evidence for such a link remains inconclusive. In particular, few studies have investigated such patterns on a local scale. Here, we address this issue by examining the determinants of maize diversity in a local region of high cultural and biological richness in Southern Mexico. We collected maize samples from villages at low and middle elevations in two adjacent municipalities of differing ethnicity: Mixtec or Chatino. Although morphological traits show few patterns of population structure, we see clear genetic differentiation among villages, with municipality explaining a larger proportion of the differentiation than altitude. Consistent with an important role of social origin in patterning seed exchange, metapopulation model-based estimates of differentiation match the genetic data within village and ethnically distinct municipalities, but underestimate differentiation when all four villages are taken together. Our research provides insights about the importance of social origin in structuring maize diversity at the local scale.
Maize diversity and ethnolinguistic diversity in Chiapas, Mexico
Proceedings of the …, 2005
The objective of this study is to investigate whether ethnolinguistic diversity influences crop diversity. Factors suggest a correlation between biological diversity of crops and cultural diversity. Although this correlation has been noted, little systematic research has focused on the role of culture in shaping crop diversity. This paper reports on research in the Maya highlands (altitude > 1,800 m) of central Chiapas in southern Mexico that examined the distribution of maize (Zea mays) types among communities of two groups, the Tzeltal and Tzotzil. The findings suggest that maize populations are distinct according to ethnolinguistic group. However, a study of isozymes indicates no clear separation of the region's maize into two distinct populations based on ethnolinguistic origin. A reciprocal garden experiment shows that there is adaptation of maize to its environment but that Tzeltal maize sometimes out-yields Tzotzil maize in Tzotzil environments. Because of the proximity of the two groups and selection for yield, we would expect that the superior maize would dominate both groups' maize populations, but we find that such domination is not the case. The role of ethnolinguistic identity in shaping social networks and information exchange is discussed in relation to landrace differentiation.
Economic Botany
Oaxaca is one of the areas of early maize diversification, with 28 to 35 recognized agronomic races. Campesinos (farmers) cultivate at least ten different races in the Los Loxicha region. There is evidence of introgression between them; however, some traditional practices have promoted further differentiation evidenced by the presence of different landraces, clearly recognized by various morphological and phenological characteristics. Therefore, moderate levels of genetic diversity and low levels of population differentiation are expected. Seven communities belonging to two municipalities were selected in 2005. In total, 140 semistructured interviews were administered, inquiring about cultural practices, which included questions about maize seed, ear, and cob management and selection and maize cultivation. Based on interviews and permissions, 30 maize plants from each of 28 fields (milpas) with maize crop belonging to five landraces (Conejo, Hueso, Tablita, Tepecente, and Pinto) wer...
Plant Genetic Resources, 2015
Transformations that farmers bring to their traditional farming systems and their impacts on the conservation and evolution of maize varieties over a 12-year period are investigated using a longitudinal analysis. Despite the increased introduction and supply of improved maize variety seeds in the Yucatan Peninsula, Mexico, over the last 12 years farmers continue to maintain a substantial amount of traditional maize variety diversity. Even with the increased availability of hybrid seeds, farmers in the community of Yaxcaba on average plant more than three quarters of their milpa fields to traditional maize varieties, with the latter one fourth predominately planted to a locally improved varietyNal Xoy, a farm cross of a traditional variety and an improved variety. We observed a significant reduction in yellow –x-Nuuk nal, a long-cycle traditional landrace, paralleled by an increase in short- and intermediate-cycle locally adapted improved maize varieties. We found great differences i...
Maydica
In Mexico there is a broad diversity of maize. To design schemes of genetic improvement and germplasm conservation, this diversity must first be assessed. In this context, an analysis of microsatellites was conducted to estimate the degree of variation and to analyze the structure and genetic diversity of seven maize (Zea mays L) landraces from the High Central Valleys of Mexico (Arrocillo Amarillo, Cacahuacintle, Chalqueño, Cónico, Elotes Cónicos, Palomero Toluqueño and Purépecha) as well as the teosinte races Chalco [Zea mays ssp. mexicana (Schrader) Iltis] and Balsas [Zea mays ssp. parviglumis (Iltis and Doebley)]. Seed from 107 accessions kept in Mexican germplasm banks was used. We analyzed 31 SSR loci to estimate genetic variation based on the number of alleles per locus, proportion of polymorphic loci and index of expected heterozygosity, and genetic structure using Wright F statistics. Races were grouped based on principal component and cluster analyses. A total of 636 alleles were identified, averaging 20.52 alleles per locus, 92.75% of which were polymorphic loci. Also found were 100 alleles exclusive of some of the studied populations. Occurrence of these alleles was low, representing 16% of the total alleles found. It was determined that 76.3% of the genetic diversity of the cultivated landraces of the High Valleys of Mexico resides within populations and the remaining 23.7% is between populations. Well-defined groups of the races Cacahuacintle and Purépecha, as well as two groups of the Chalqueño race, were observed. The Purépecha race formed a compact group separate from the rest, while a large sample of the Elotes Cónicos race group was placed intermediately among one of the groups of the Chalqueño race.