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El presente trabajo se desarrolló de julio a diciembre de 1999 en la comunidad de Yaxcabá, Yucatán, con el objetivo de describir la diversidad morfológica in situ y determinar la relación entre la clasificación de los chiles que hacen los agricultores y la variabilidad morfológica fenotípica. Durante la exploración se tomaron datos in situ de una serie de caracteres de planta, flor y fruto de 75 poblaciones o muestras en 43 parcelas de cultivos (milpa) y solares de la comunidad objetivo. De acuerdo con la denominación de los agricultores las muestras descritas se clasificaron en siete morfotipos; los primeros seis pertenecen al Capsicum annuum L. nominados como Ya’ax ic, Xcat’ic, Cha’huá, Dulce, Sucurre y Maax o Maaxito, éste último C. annuum var. Aviculare (Dierb.). Además, un morfotipo de la especie C. chinense Jacq. conocido ampliamente como Habanero. A través de la clasificación que hacen los agricultores, se reconocen tres niveles de diversidad; entre y dentro de especies, y la diversidad dentro de los morfotipos o variedades criollas, aunque ellos los llamen simplemente como tipos. Los análisis de componentes principales, conglomerados y de discriminante determinaron que existente alta consistencia, en mas de 80 % de los casos, entre la denominación que hace el agricultor de los chiles y los diferentes grupos morfológicos, incluyendo ciertos complejos fenotípicos.

El sistema tradicional milpa, manejado mayormente bajo temporal en Yucatán, México; es importante a nivel social, biológico y ambiental. La milpa ha perdurado a través del tiempo por los conocimientos ancestrales transmitidos por generaciones. Por lo anterior, el objetivo fue conocer las estrategias de manejo realizadas por los milperos en su actividad agrícola y la conservación de la diversidad biológica. La investigación se efectuó en la comunidad maya de Xoy, Peto, Yucatán aplicando encuestas semiestructuradas al 30% de la población ejidataria que siembra maíz. La diversidad de cultivos reportada en Xoy fue de 22 variedades nativas: ocho de maíz, siete de frijol lima, cuatro de calabaza y tres de frijol común. Se detectó que la familia es el determinante para la conservación de la diversidad de especies cultivadas en la milpa con una prioridad en la conservación de semillas nativas entre los milperos.

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 in the distribution of maize varieties by soil type, with modern varieties being targeted for the rarer, deeper and fine-grained soils, while traditional varieties predominate on the more prevalent stony and thin soils. Our results provide a picture in which most traditional maize varieties in Yaxcaba continue to be maintained by farmers, coexisting with locally adapted improved varieties on the same landscape, and allowing the continued evolution of maize populations.

The recent economic development of the tourism industry in the Riviera Maya on the Caribbean beaches of the Yucatan Peninsula has involved a dynamic regional...

For small-scale farmers who maintain genetically diverse crop populations, aspects of the storage of their seeds and harvest may be just as important for successful farming as those related to productivity. The community of Yaxcaba, Yucatan, Mexico was studied to understand how the conditions under which Maya farmers store their maize harvests influence their seed selection practices and the diversity of maize varieties grown. Most farmers select their maize seed based primarily on ear characteristics and secondarily on grain characters. Farmers incorporate storability concerns by selecting for an archetypal healthy ear and by conducting selection in several steps between harvest and planting of the subsequent crop generation. Most farmers store their maize harvest in the husk, initially in the field and then in rustic granaries constructed of logs and palm thatch, in which farmers conserve separately their different seed lots. All local landrace populations show morphological adaptation (principally husk characteristics) for local storage conditions, indicating that storability has been an important selection pressure on traditional maize. Storability also appears to be a key factor working against the straightforward adoption of improved maize seed in Yaxcaba. Local farmers value many qualities of improved maize varieties, but their principal complaint is that improved maize cannot be conserved reliably under local storage conditions. Nearly all farmers who utilize improved seed stock in Yaxcaba grow locally adapted or ‘creolized’ versions of improved varieties, displaying characteristics of local maize landraces that facilitate their storage.

In this chapter, we develop new indicators and statistical tests to characterize patterns of crop diversity at local scales to better understand interactions between ecological and socio-cultural functions of agroecosystems. Farms, where a large number of crops (species or landraces) is grown, are known to contribute a large part of the locally available diversity of both rare and common crops but the role of farms with low diversity remains little understood: do they grow only common varieties—following a nestedness pattern typical of mutualistic networks in ecology—or do ‘crop–poor’ farmers also grow rare varieties? This question is pivotal in ongoing efforts to assess the local-scale contribution of small farms to global agrobiodiversity. We develop new network-based approaches to characterize the distribution of local crop diversity (species and infra-species) at the village level and to validate these approaches using meta-datasets from 10 countries. Our results highlight the sources of heterogeneity in crop diversity at the village level. We often identify two or more groups of farms based on their different levels of diversity. In some datasets, ‘crop–poor’ farms significantly contribute to the local crop diversity. Generally, we find that the distribution of crop diversity is more heterogeneous at the species than at the infra-species level. This analysis reveals the absence of a general pattern of crop diversity distribution, suggesting strong dependence on local agro-ecological and socio-cultural contexts. These different patterns of crop diversity distribution reflect an heterogeneity in farmers’ self-organized action in cultivating and maintaining local crop diversity, which ensures the adaptability of agroecosystems to global change.

In Yucatan, Mexico, the cultivation of different native maize populations in the system milpa, promote the interchange of pollen. To evaluate the relationship between the flow of pollen and the dynamics of genetic diversity in 2005 and 2006, a white kernel population and another yellow, both of the Xmejen-nal and Xnuc-nal types, were grown associated with squash. The yellow kernel variety was planted surrounded by the white kernel variety, 540 ears were harvested in 8 directions, from the periphery to the center, and the percentage of yellow grain in the white variety was used as indicator of out crossing rate. For each direction, regression analysis was performed between distance and yellow kernel percentage. The largest out crossing rates in Xmejen-nal (44 %) and Xnuc-nal (42 %) were obtained in the direction northeast-southwest in 2005; and in direction southeast-northwest in Xmejen-nal (37 %) and Xnuc-nal ( 41 %) in 2006. Both direction and intensity of dominant wind determined trajectories of pollen, and the out crossing rate was reduced with the distance to the source of pollen. Genetic interchange is promoted by management and genotype distribution in both time and space, and gene flow among populations promotes intrapopulation diversity.

Foodways have changed substantially over the past several centuries in the Yucatan Peninsula and other areas of Mesoamerica, but one constant is the presence of maize (Zea mays) at the heart of rural economy, ecology, and culture. The domestication and diversification of maize – the world’s most productive grain crop – by indigenous farmers ranks as one of the greatest accomplishments of plant breeding. Remains of ancient maize cobs in the archeological record suggest that maize was first brought into cultivation roughly 7,000 years ago in the highlands of central Mexico, where its closest wild relative, teosinte (Zea mays ssp. parviglumis), also grows (Wilkes 1977; McClung de Tapia 1997; Smith 2001; Piperno and Flannery 2001; Matsuoka et al. 2002.). From that starting point, maize was gradually selected and diversified over time by farmers into an impressive array of different forms, sizes, and colors. Maize appears to spread out of central Mexico rapidly in the context of regional trade and exchange networks, and farmers selected and adapted maize populations to thrive in new environments. Archeobotanical evidence from northern Belize suggests maize arrived in the Yucatan Peninsula by about 5,000 years B.P. (Colunga-Garcia Marin and Zizumbo-Villarreal 2004).

Varietal data from 27 crop species from five continents were drawn together to determine overall trends in crop varietal diversity on farm. Measurements of richness, evenness, and divergence showed that considerable crop genetic diversity continues to be maintained on farm, in the form of traditional crop varieties. Major staples had higher richness and evenness than nonstaples. Variety richness for clonal species was much higher than that of other breeding systems. A close linear relationship between traditional variety richness and evenness (both transformed), empirically derived from data spanning a wide range of crops and countries, was found both at household and community levels. Fitting a neutral “function” to traditional variety diversity relationships, comparable to a species abundance distribution of “neutral ecology,” provided a benchmark to assess the standing diversity on farm. In some cases, high dominance occurred, with much of the variety richness held at low frequencies. This suggested that diversity may be maintained as an insurance to meet future environmental changes or social and economic needs. In other cases, a more even frequency distribution of varieties was found, possibly implying that farmers are selecting varieties to service a diversity of current needs and purposes. Divergence estimates, measured as the proportion of community evenness displayed among farmers, underscore the importance of a large number of small farms adopting distinctly diverse varietal strategies as a major force that maintains crop genetic diversity on farm.

Este trabajo se desarrolló en la comunidad de Yaxcabá, Yucatán, México, de agosto 2001 a junio 2002, con el objetivo de entender los sistemas de almacenamiento de semillas de frijol (Phaseolus spp.) y calabaza (Cucurbita spp.), los métodos de control de plagas que utilizan los agricultores y sus estrategias de selección de semilla. Se aplicaron entrevistas directas a 61 productores tradicionales de la comunidad, en el lugar donde tenían almacenadas sus semillas. Primeramente se recorrieron las milpas de los productores, posteriormente el solar (alrededor de las casas) y, cuando fue necesario, sus casas. Las entrevistas se hicieron en español o en maya yucateco. Los agricultores de Yaxcabá utilizan diversas estrategias de almacenamiento. El frijol puede almacenarse sin trillar (46.8 %) o trillado (53.2 %), mientras que la calabaza siempre se conserva en semilla (100 %). Éstas se depositan en diferentes contenedores, como sacos o costales, bolsas de nilón o recipientes de plástico. Los contenedores con semillas de frijol y calabaza pueden ser almacenados en la cocina (63.9 % y 40 %, respectivamente), o en otra parte de la casa (27.9 % y 54.5 % , respectivamente), y ocasionalmente en las casas construidas en la milpa (8.2 % para frijol y 5.5 % para calabaza). Durante el almacenamiento los agricultores utilizan distintas medidas de control de los insectos plagas en el almacén, como humo del fuego (al colocarlo cerca de éste), insecticidas, recipientes de plástico bien cerrados, o cal. Pero algunosagricultores (32 % en frijol y 71 % en calabaza) no usan método alguno de control. La mayoría de los productores seleccionan sus semillas cada ciclo agrícola (86 % para frijol y 76 % para calabaza), proceso que puede realizarse a la cosecha (45.6 % y 62 % para calabaza y frijol, respectivamente) o antes de la siembra (54.4 % para frijol y38 % para calabaza) del próximo ciclo agrícola.