Patricia Dávila

Biological diversity in the Tehuacán-Cuicatlán Valley, Mexico

A general overview of the biological knowledge of the floristic province of the Tehuacán-Cuicatlán Valley in central-southern Mexico is presented. Floristic and faunistic richness and endemism, as well as uses of the flora are analyzed and discussed for this area, recently declared a biosphere reserve. The analysis shows that, in approximately 10 000 km2 the Tehuacán-Cuicatlán Valley contains between 10 and 11.4% of the Mexican flora. In addition, the valley possesses 365 endemic species that represent 13.9% of its flora. With respect to the fauna diversity, the available information is less comprehensive than for plants. Nevertheless, the study shows that the 11 species of amphibians, 48 species of reptiles, and 91 species of birds recorded for the valley surpasses the diversity found in other dry-lands of the world. In relationship to the mammals of the region, the available data are poor for most of the groups except for bats, for which 24 species have been reported. Regarding the use of the flora, the analysis revealed that 815 species are utilized by the people in the valley. A discussion related to future research activities is also included.

Plant resources of the Tehuacán-Cuicatlán valley, Mexico

Information on richness of plant resources, and their forms of use and management in the biosphere reserve Tehuacan-Cuicatlan, Mexico is analyzed. This 10 000 km2 region hosts nearly 2700 vascular plant species, and it is acknowledged as one of the arid areas with the highest floristic diversity in North America. The seven indigenous ethnic groups that live in this region have cultural roots that date back almost 10 000 years. Based upon ethnobotanical and floristic studies, as well as bibliographical sources, a total of 808 useful plant species were identified, most of them (90%) being native, and 44 species being endemic to the region. A total of 681 species are wild plants, 109 are weeds and ruderal plants, and 86 are domesticated crops. However, it was noted that considerable overlap exists between the species of these 3 categories. For example, while wild and ruderal plants (706 species) are foraged by both humans and domestic animals, 59 species of this group are also managed in situ. On the other hand, 168 wild, ruderal and domesticated species are cultivated. The Tehuacán-Cuicatlan Valley is one of the richest regions of Mexico in plant resources. Local knowledge on use and management of plants is a valuable source of information for designing conservation and social development strategies for the biosphere reserve.ResumenSe analiza informatión sobre la riqueza de recursos vegetales, así como sus formas de uso y manejo en la reserva de la biosfera Tehuacán-Cuicatlán, México. Esta región, con una extensión de 10 000 km2, alberga a cerca de 2700 especies de plantas vasculares y es reconocida como una de las zonas áridas con mayor diversidad florística de Norteamerica. Incluye además a siete grupos étnicos indigenas con una historia cultural iniciada hace aproximadamente 10 000 años. Con base en estudios etnobotánicos y floristicos, así como informatión bibliográfica, se identificaron un total de 808 especies de plantas útiles, la mayor pane de las cuales (90%) son nativas y 44 son endémicas para la region. Un total de 681 especies son silvestres, 109 son arvenses y ruderales, y 86 son domesticadas, con algunas especies presentando al mismo tiempo conditión de silvestres, arvenses y domesticadas. En total, 706 especies de plantas silvestres, arvenses y ruderales son forrajeadas tanto por humanos como por animales domésticos en las áreas donde se encuentran, pero 59 de ellas son también manejadas in situ, mientras que 168 especies silvestres, arvenses y ruderales, asi como domesticadas, son cultivadas. El Valle de Tehuacán es una de las regiones de Mexico con mayor diversidad de recursos vegetales. El conocimiento indígena sobre uso y manejo de las plantas locales es una fuente de informatión valiosa para el diseño de estrategias de conservatión y desarrollo social para la reserva de la biosfera.

Phylogenetic relationships of aroids and duckweeds (Araceae) inferred from coding and noncoding plastid DNA

Familial, subfamilial, and tribal monophyly and relationships of aroids and duckweeds were assessed by parsimony and Bayesian phylogenetic analyses of five regions of coding (rbcL, matK) and noncoding plastid DNA (partial trnK intron, trnL intron, trnL-trnF spacer) for exemplars of nearly all aroid and duckweed genera. Our analyses confirm the position of Lemna and its allies (formerly Lemnaceae) within Araceae as the well-supported sister group of all aroids except Gymnostachydoideae and Orontioideae. The last two subfamilies form the sister clade of the rest of the family. Monophyly of subfamilies Orontioideae, Pothoideae, Monsteroideae, and Lasioideae is supported, but Aroideae are paraphyletic if Calla is maintained in its own subfamily (Calloideae). Our results suggest expansion of the recently proposed subfamily Zamioculcadoideae (Zamioculcas, Gonatopus) to include Stylochaeton and identify problems in the current delimitation of tribes Anadendreae, Heteropsideae, and Monstereae (Monsteroideae), Caladieae/Zomicarpeae, and Colocasieae (Aroideae). Canalization of traits of the spathe and spadix considered typical of Araceae evolved after the split of Gymnostachydoideae, Orontioideae, and Lemnoideae. An association with aquatic habitats is a plesiomorphic attribute in Araceae, occurring in the helophytic Orontioideae and free-floating Lemnoideae, but evolving independently in various derived aroid lineages including free-floating Pistia (Aroideae).

Pollination biology of two columnar Cacti (Neobuxbaumia mezcalaensis and Neobuxbaumia macrocephala) in the Tehuacan Valley, central Mexico

We document the pollination biology and mating systems of Neobuxbaumia mezcalaensisand Neobuxbaumia macrocephala, two Mexican giant columnar cacti. These two species form mixed forests in the western Tehuacan Valley, Mexico. The flowers of both N. mezcalaensisand N. macrocephalaexhibit nocturnal anthesis, are self-incompatible, and are pollinated primarily by three species of nectar-feeding bats (Choeronycteris mexicana, Leptonycteris curasoae,and Leptonycteris nivalis). Neobuxbaumia mezcalaensisis androdioecious, a breeding system that appears to be uncommon among Cactaceae. Neobuxbaumia macrocephalais hermaphroditic. We hypothesize that columnar cacti show a geographical dichotomy in floral biology specialization that probably can be related to predictability in pollinator abundance.

Morphological variation and the process of domestication of Stenocereus stellatus (Cactaceae) in central Mexico

Morphological variation was analyzed in wild, managed in situ, and cultivated populations of the columnar cactus Stenocereus stellatus in central Mexico. The purpose was to evaluate whether morphological divergence between manipulated and wild populations has resulted from domestication processes. Variation of 23 morphological characters was analyzed among 324 individuals from 19 populations of the Tehuacán Valley and La Mixteca Baja. Multivariate statistical analyses were used to group individuals and populations according to their morphological similarity. Individuals grouped according to the way of management and fruit characteristics were the most relevant for grouping. Within each region, sweet fruits with pulp colors other than red were more frequent in cultivated populations, where fruits were also larger, contained more and bigger seeds, and had thinner peel and fewer spines than fruits from wild individuals. Phenotypes common in managed in situ and cultivated populations generally occur in the wild but in lower frequencies. Artificial selection has thus operated by enhancing and maintaining desirable rare phenotypes in managed in situ and cultivated populations, causing divergent patterns of morphological variation from wild populations. Cultivation has caused the strongest level of divergence, but divergence has also been significant with management of wild populations in situ.

Reproductive biology and the process of domestication of the columnar cactus Stenocereus Stellatus in Central Mexico

Pollination biology, breeding system, and floral phenology of the columnar cactus Stenocereus stellatus were studied in wild, wild managed in situ and cultivated populations of central Mexico, in order to examine whether these aspects have been modified under domestication and whether they determine reproductive barriers between wild and manipulated individuals. Individuals of both wild and manipulated populations are self-incompatible, indicating that artificial selection has not modified the breeding system. Their pollination biology is also similar. Anthesis is mainly nocturnal, with a peak of nectar production between 0200 and 0400 when the stigma presents maximum turgidity. Nocturnal visitors are the effective pollinators. Nearly 75% of flowers exposed for nocturnal pollination set fruit, while none of the flowers exposed for diurnal pollination produced fruits. The bats Leptonycteris curasoae, L. nivalis, and Choeronycteris mexicana (Glossophaginae) are the most likely pollinators, and their time of foraging is synchronized with the time of nectar production and stigma receptivity in S. stellatus. Bats potentially move pollen over a considerable distance, so there is apparently no spatial isolation to prevent pollen exchange between wild and cultivated populations. Phenological studies showed that there are also no apparent temporal barriers. However, manual cross pollination failed between some domesticated and wild phenotypes, suggesting that gene flow between wild and cultivated populations might be limited by pollen incompatibility.

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.

Traditional Knowledge and Useful Plant Richness in the Tehuacán-Cuicatlán Valley, Mexico

Traditional Knowledge and Useful Plant Richness in the Tehuacán–Cuicatlán Valley, Mexico. This study systematizes ethnobotanical information about the interactions between people and plants, ethnofloristic richness, the relative importance of useful species richness in relation to general species richness, and plant management in the Tehuacán–Cuicatlán Valley of central Mexico. The study recorded a total of 1,605 useful vascular plant species (61.2% of the total species richness of the regional vascular flora), this being the region with the highest absolute richness of useful plant species in Mexico. The null hypothesis that plant families with a higher number of useful species would be those having a higher general species richness was analyzed through residuals method. The plant families richest in useful species were Poaceae, Asteraceae, Cactaceae, Cyperaceae, Mimosaceae, and Solanaceae, most of which also have the highest general floristic richness. However, analyses of use categories did not generally corroborate our hypothesis. About 1,335 of the useful species are wild, more than 500 species are submitted to some type of management (62 species are tolerated, 34 protected, 50 enhanced, and 358 cultivated), but only a few have been studied to document their process of domestication. This information can be useful for developing regional strategies of sustainable management of plant resources.Conocimiento tradicional y riqueza de plantas útiles en el Valle de Tehuacán-Cuicatlán, MéxicoConocimiento tradicional y riqueza de plantas útiles en el Valle de Tehuacán-Cuicatlán, México. Este trabajo sistematiza información etnobotánica sobre las interacciones entre la gente y las plantas, la riqueza etnoflorística, la importancia relativa de las especies útiles con respecto a la riqueza florística general, y sobre el manejo de plantas en el Valle de Tehuacán–Cuicatlán, en el centro de México. Se registró un total de 1,605 especies de plantas vasculares útiles (61.2% de la riqueza total de la flora vascular de la región), lo que identifica a la región como la de mayor riqueza de plantas útiles de México en términos absolutos. Mediante el método de residuales se analizó la hipótesis nula de que las familias con mayor número de especies útiles serían las de mayor riqueza florística. Se encontró que las familias con mayor número de especies útiles fueron Poaceae, Asteraceae, Cactaceae, Cyperaceae, Mimosaceae, y Solanaceae, las cuales en su mayoría son las de mayor riqueza florística en la región. No obstante, al efectuar el análisis por categorías de uso no siempre se confirmó nuestra hipótesis. Casi 1,335 de las plantas útiles son silvestres, pero alrededor de 500 están sometidas a algún tipo de manejo (62 especies son toleradas, 34 protegidas, 50 fomentadas y 358 cultivadas), pero sólo para algunas de ellas se ha estudiado cómo operan los proceso de domesticación. La información generada en el trabajo puede ser útil para el desarrollo de estrategias regionales de manejo sustentable de los recursos vegetales.

The chaparral vegetation in Mexico under nonmediterranean climate: the convergence and Madrean-Tethyan hypotheses reconsidered

A comparative study between an unburned evergreen sclerophyllousvegetation located in south-central Mexico under a wet-summer climate,with mediterranean regions was conducted in order to re-analyzevegetation and plant characters claimed to converge under mediterraneanclimates. The comparison considered floristic composition,plant-community structure, and plant characters as adaptations tomediterranean climates and analyzed them by means of a correspondenceanalysis, considering a tropical spiny shrubland as the external group.We made a species register of the number of species that resproutedafter a fire occurred in 1995 and a distribution map of the evergreensclerophyllous vegetation in Mexico (mexical) under nonmediterraneanclimates.The Tehuacán mexical does not differ from the evergreensclerophyllous areas of Chile, California, Australia, and theMediterranean Basin, according to a correspondence analysis, whichordinated the Tehuacán mexical closer to the mediterranean areasthan to the external group.All the vegetation and floristic characteristics of the mexical, aswell as its distribution along the rain-shadowed mountain parts ofMexico, support its origin in the Madrean-Tethyan hypothesis of Axelrod.Therefore, these results allow to expand the convergence paradigm of thechaparral under an integrative view, in which a general trend to ariditymight explain floristic and adaptive patterns detected in theseenvironments.

Isolation, characterization and cross-amplification of polymorphic microsatellite loci in the threatened endemic Mammillaria crucigera (Cactaceae)

The cactus Mammillaria crucigera is a threatened species endemic to central Mexico. As a means of assessing population genetic status of these species, eight microsatellite markers were developed. These primers were tested in 40 individual from two wild populations. The results showed that these primers will be useful to describe population structure and aid to the conservation of species. The eight primers were tested in other Mammillaria species and most of them showed successful amplification.