Fabiola Parra

Plant Management in the Tehuacán-Cuicatlán Valley, Mexico1

Plant Management in the Tehuacán-Cuicatlán Valley, Mexico. Plant management types currently practiced in the Tehuacán-Cuicatlán Valley, México, were documented and analyzed based on ethnobotanical studies conducted in 13 villages with six indigenous groups and Mestizo people. The information was organized in a data base, and then detailed and guided to a consensus through six workshops carried out by ethnobotanists working in the area. From a total of 1,608 useful plant species, we identified 610 with at least one management type other than simple gathering. Managed species are mainly used as food, fodder, medicinal, and ornamental, and they belong to 101 plant families. The higher species numbers were recorded in Cactaceae, Asteraceae, Fabaceae, Crassulaceae, and Agavaceae. Nearly 60% of the managed species are native to the region and the rest are introduced from other regions of Mexico and the world. In total, 400 species are ex situ managed out of their natural environments through seed sowing and/or planting their vegetative propagules or entire young plants; 373 species are in situ managed in their natural habitats as follows: all these species are deliberately left standing during vegetation clearance, 76 species are also enhanced intentionally favoring their abundance through modifications of their habitat, or directly by planting their propagules, and 51 receive protection through regulations, particular strategies of extraction, and actions against herbivores, competitors, freezing, radiation, and drought. Most management forms involve artificial selection at different intensity levels. The information allows visualizing co-occurrence of incipient and advanced forms of management at different intensity levels within and among species, which helps to postulate testable hypotheses on factors influencing plant management and domestication in an important area for studying the origins of agriculture.Manejo de plantas en el Valle de Tehuacán-Cuicatlán, México. Se documentaron los diferentes tipos de manejo de plantas que practican actualmente los pobladores del Valle de Tehuacán-Cuicatlán, México. El análisis se basa en estudios etnobotánicos llevados a cabo en 13 comunidades campesinas con seis grupos indígenas y poblados mestizos. La información se organizó en una base de datos, la cual posteriormente se detalló y se consensó a través de seis talleres en los que participaron los etnobotánicos trabajando en la región y cuyos trabajos son la base de esta investigación. De un total de 1,608 especies de plantas útiles, identificamos 610 con al menos un tipo de manejo distinto a la recolección simple. Las especies manejadas pertenecen a 101 familias botánicas y se utilizan principalmente como alimento, forraje, medicina y ornamentales. Los mayores números de especies manejadas se registraron entre las Cactaceae, Asteraceae, Fabaceae, Crassulaceae y Agavaceae. Aproximadamente 60% de las especies manejadas son nativas de la región y el resto son introducidas de otras regiones de México y del mundo. En total, 400 especies se manejan ex situ, fuera de sus ambientes naturales, mediante la siembra de sus semillas y la plantación de sus propágulos vegetativos o plantas juveniles; 373 especies se manejan in situ en sus hábitats naturales como sigue: todas estas especies se dejan en pie deliberadamente durante el aclareo de la vegetación; 76 especies son además promovidas intencionalmente, favoreciendo sus abundancias mediante modificaciones a sus hábitats o directamente plantando sus propágulos; y 51 especies reciben protección a través de reglas comunitarias, estrategias particulares de extracción y acciones contra herbívoros, competidores, heladas, radiación solar y sequías. La mayor parte de las formas de manejo involucran selección artificial a diferentes niveles de intensidad. La información permite visualizar la ocurrencia de formas de manejo incipientes y avanzadas a diferentes niveles de intensidad, simultáneamente dentro de una misma especie y entre especies. Esto permite postular hipótesis probables sobre los factores que influyen el manejo de plantas y su domesticación en una región importante para el estudio sobre el origen de la agricultura.

Evolution under domestication: ongoing artificial selection and divergence of wild and managed Stenocereus pruinosus (Cactaceae) populations in the Tehuacán Valley, Mexico

BACKGROUND AND AIMS The Tehuacán Valley in Mexico is a principal area of plant domestication in Mesoamerica. There, artificial selection is currently practised on nearly 120 native plant species with coexisting wild, silvicultural and cultivated populations, providing an excellent setting for studying ongoing mechanisms of evolution under domestication. One of these species is the columnar cactus Stenocereus pruinosus, in which we studied how artificial selection is operating through traditional management and whether it has determined morphological and genetic divergence between wild and managed populations. METHODS Semi-structured interviews were conducted with 83 households of three villages to investigate motives and mechanisms of artificial selection. Management effects were studied by comparing variation patterns of 14 morphological characters and population genetics (four microsatellite loci) of 264 plants from nine wild, silvicultural and cultivated populations. KEY RESULTS Variation in fruit characters was recognized by most people, and was the principal target of artificial selection directed to favour larger and sweeter fruits with thinner or thicker peel, fewer spines and pulp colours other than red. Artificial selection operates in agroforestry systems favouring abundance (through not felling plants and planting branches) of the preferred phenotypes, and acts more intensely in household gardens. Significant morphological divergence between wild and managed populations was observed in fruit characters and plant vigour. On average, genetic diversity in silvicultural populations (H(E) = 0.743) was higher than in wild (H(E) = 0.726) and cultivated (H(E) = 0.700) populations. Most of the genetic variation (90.58 %) occurred within populations. High gene flow (Nm(FST) > 2) was identified among almost all populations studied, but was slightly limited by mountains among wild populations, and by artificial selection among wild and managed populations. CONCLUSIONS Traditional management of S. pruinosus involves artificial selection, which, despite the high levels of gene flow, has promoted morphological divergence and moderate genetic structure between wild and managed populations, while conserving genetic diversity.

Landscape management and domestication of Stenocereus pruinosus (Cactaceae) in the Tehuacán Valley: human guided selection and gene flow

BackgroundUse of plant resources and ecosystems practiced by indigenous peoples of Mesoamerica commonly involves domestication of plant populations and landscapes. Our study analyzed interactions of coexisting wild and managed populations of the pitaya Stenocereus pruinosus, a columnar cactus used for its edible fruit occurring in natural forests, silviculturally managed in milpa agroforestry systems, and agriculturally managed in homegardens of the Tehuacán Valley, Mexico. We aimed at analyzing criteria of artificial selection and their consequences on phenotypic diversity and differentiation, as well as documenting management of propagules at landscape level and their possible contribution to gene flow among populations.MethodsSemi-structured interviews were conducted to 83 households of the region to document perception of variation, criteria of artificial selection, and patterns of moving propagules among wild and managed populations. Morphological variation of trees from nine wild, silviculturally and agriculturally managed populations was analyzed for 37 characters through univariate and multivariate statistical methods. In addition, indexes of morphological diversity (MD) per population and phenotypic differentiation (PD) among populations were calculated using character states and frequencies.ResultsPeople recognized 15 pitaya varieties based on their pulp color, fruit size, form, flavor, and thorniness. On average, in wild populations we recorded one variety per population, in silviculturally managed populations 1.58 ± 0.77 varieties per parcel, and in agriculturally managed populations 2.19 ± 1.12 varieties per homegarden. Farmers select in favor of sweet flavor (71% of households interviewed) and pulp color (46%) mainly red, orange and yellow. Artificial selection is practiced in homegardens and 65% of people interviewed also do it in agroforestry systems. People obtain fruit and branches from different population types and move propagules from one another. Multivariate analyses showed morphological differentiation of wild and agriculturally managed populations, mainly due to differences in reproductive characters; however, the phenotypic differentiation indexes were relatively low among all populations studied. Morphological diversity of S. pruinosus (average MD = 0.600) is higher than in other columnar cacti species previously analyzed.ConclusionsArtificial selection in favor of high quality fruit promotes morphological variation and divergence because of the continual replacement of plant material propagated and introduction of propagules from other villages and regions. This process is counteracted by high gene flow influenced by natural factors (pollinators and seed dispersers) but also by human management (movement of propagules among populations), all of which determines relatively low phenotypic differentiation among populations. Conservation of genetic resources of S. pruinosus should be based on the traditional forms of germplasm management by local people.

Evolutionary Ethnobotanical Studies of Incipient Domestication of Plants in Mesoamerica

Human cultures that occupied the area currently known as Mesoamerica developed a broad repertory of technologies for managing the biotic resources and ecosystems of the surrounding areas they lived. These technologies emerged from early experiences and had long time, enough for leading to the first forms of agriculture of the New World. Mesoamerica is actually recognized as one of the regions where agriculture and domestication of plants originated, with nearly 10,000 years of antiquity. This chapter summarizes ethnobotanical, ecological, and evolutionary information documented in different regions of Mexico, combining different research approaches in order to understand the human motives for managing plant resources, and the ecological and evolutionary consequences of management of plants and ecosystems. We therefore analyse those processes involving domestication as part of general design of nature according to human needs and desires, occurring at the levels of plant population of particular species, but also at the level of ecosystems and landscapes. We pay particular attention in the analysis of plant species that in the Mesoamerican area have wild and domesticated populations and maintain reproductive interactions. These interactions allow exploring practices and natural processes intervening in conforming populations in which divergence populations guided by natural and artificial selection and other evolutionary forces are occurring. Because natural processes continually weaken the human activities, the divergence is relatively slight and we have therefore called these processes incipient domestication. We analyse the cases of traditional greens called ‘quelites’ such as Anoda cristata and Crotalaria pumila in which people distinguish favourable and unfavourable morphs and practice artificial selection resulting in the abundance of the favourable morphs in areas more intensively managed. Similarly, some examples are analysed of trees (Leucaena esculenta, Crescentia spp. Spondias purpurea, S. mombin, and Sideroxylon palmeri), agaves (Agave inaequidens and A. hookeri), and columnar cacti (Escontria chiotilla, Myrtillocactus schenckii, Pachycereus hollianus, Polaskia spp., Stenocereus spp.). In the cases studied we analysed divergence in morphology, reproduction, population genetics, and germination patterns, among other features, between wild, silvicultural managed and cultivated populations. These case studies allow demonstrating that evolutionary divergence influenced by humans occurs not only under agriculture but also under silvicultural management and we hypothesize that domestication under silvicultural systems could have leaded to the origins of agriculture.

Ethnobotany for Sustainable Ecosystem Management: A Regional Perspective in the Tehuacán Valley

Different indicators of global change identify that industrial processes are principal causes of the severe human impact on ecosystems of Earth. However, although industrial processes predominate in the world, numerous rural societies with a different rationality and organization coexist with the hegemonic mode of production. In indigenous communities the traditional botanical, zoological and ecological knowledge as well as traditional technologies of local resources and ecosystem management are particularly rich, as product of hundreds or thousands of years of experience. Indigenous communities have historically built diverse forms of managing the socioecological systems and the biocultural diversity adapted to local conditions, which are generally much more environmental friendly than other intensive forms of management. In this study we document the management of plant resources by peoples of the Tehuacan Valley, Mexico. We have inventoried more than 1600 plant species used for satisfying a broad spectrum of needs. People gather nearly 90 % of those species from wild populations, but practice different forms of incipient management (tolerance, enhancing, transplantation and seed sowing) in order to increase availability of nearly 400 important plant resources. The indigenous communities may adopt some modern techniques of managing resources and ecosystems, and select those according with their conditions and views. Based on these processes people construct hybrid techniques that may be adapted to the local environments. Agroecologists and ethnobotanists have visualized the high value of traditional management systems for generating technological viable alternatives for designing forms of sustainable management adapted to satisfy local needs and conserving biodiversity and ecosystems, and the continuous innovation tested by local people. It has been recognized that, in general, the traditional management systems have higher capacity for conserving biodiversity and ensuring the resilience of socioecological systems than industrial systems and that both traditional and modern techniques may contribute to better forms of management, but the form that the process adopts is crucial. Understanding traditional management systems are therefore the opportunity to reproduce valuable experiences, models and lessons for sustainable management and participatory adoption of new techniques may help to solve problems not traditionally solved. This chapter shows a general panorama of ethnobotanical information about resources and local traditional management strategies among Nahua, Mixtec, Mazatec, Cuicatec, Popoloca, Ixcatec and Mestizo peoples of the Tehuacan Valley, in order to analyse their role in designing a future for the region based on sustainability, an experience that may be useful for this and other regions of Mexico.

Ethnobotany in Mexico: History, Development, and Perspectives

Ethnobotany is defined as the study of the traditional botanical knowledge of different cultures, the techniques utilized in the use and management of plant resources, and the place they have in their cultural Cosmo vision. This study aimed to review the development and perspectives of ethnobotany in Mexico, based on an extensive review of all ethnobotanical studies showed at the Mexican Botanical Congress (MBC), the main forum of ethnobotanical studies in Mexico, between 1963 and 2010. We systematized a total of 897 works, identifying their progressive increase in the generation of investigative papers up until 1990, then a decrease until 1995 and a new increase from 1995 to the present. The main Mexican institutions studying ethnobotany are the Universidad Nacional Autonoma de Mexico, Universidad Autonoma Chapingo, Instituto Politecnico Nacional, Universidad Autonoma Metropolitana, and the Universidad Autonoma de Nuevo Leon, which produced nearly half of all the studies recorded. The best represented cultural groups studied were the Maya, Nahua, Otomi, Totonac, and Mixtec, studied under the predominant approach of descriptive ethnobotany. Ethnobotany in Mexico is in a stage of growth and therefore in the phase of consolidating its approaches, particularly in the areas of ecological, economic, quantitative, and evolutionary ethnobotany. In order to achieve the development of sustainable management strategies of plant resources, it is of the highest priority to consolidate ethnobotanical research and direct it towards the analysis of environmental degradation and solutions.