Ethnobotanical biocultural diversity by rural communities in the Cuatrociénegas Valley, Coahuila; Mexico.

BACKGROUND: Cuatrociénegas, part of the Chihuahuan Desert, is a region of unique biological, geological, geographical, and evolutionary importance. Its current population is mestizo; nevertheless, it has high national historical, cultural, and touristic relevance in Mexico. It has been cataloged as nationally significant for its flora and fauna by Mexican law, as well as being designated a High Protection site by the World Wildlife Fund and UNESCO. Because of its diverse and complex biological and sociocultural characteristics, we considered it important to determine, identify, and analyze various aspects of the traditional ethnobotanical knowledge and practices in this region. METHODS: Between 2016 and 2019, seven field trips were made to document the knowledge and use of flora. Cuatrociénegas is a protected area, collecting botanical material is regulated, so specimens were photographed and collected in neighboring communities, and in public and private gardens. Later permission was obtained to complete the collection of specimens (2019-2020). The plants were identified and entered into the flora database of the state of Coahuila, and deposited in the Herbarium of the Faculty of Forest Sciences, Autonomous University of Nuevo León, Mexico. One hundred ten local residents (50 men and 60 women), aged between 27 and 91 years, were interviewed (semi-structured interviews). The cultural importance of ethnobotanical resources (cultural significance index) and its significance with respect to ethnobotanical richness in other Biosphere Reserves in Mexico (Mann-Whitney test), and similarities in the diversity of exotic species (Sørensen index) were studied. RESULTS AND DISCUSSION: The ethnobotanical information registers 158 species and 132 genera in 57 vascular and non-vascular families, documenting a greater knowledge and use of cultivated species (84) with respect to wild species (74). The diversity of plants reported is compared to other ethnobotanical studies carried out in Mexican Biosphere Reserves. These results are highly relevant, in spite of unique exotic species. The people local pay special attention to medicinal and ornamental plants. The species that presented the highest use values are Larrea tridentata, Jatropha dioica, and Machaeranthera pinnatifida, three species characteristic of the desert region. CONCLUSIONS: The particular diversity of wild flora in Cuatrociénegas Valley, combined with the varied introduced flora, is an important multifunctional resource. Special attention to introduced species is associated with harvesting use restrictions in the protected area as well as the high value of ornamental species that are difficult to maintain in desert areas. The extensive use of ethnobotanical knowledge is an example that biocultural diversity (at the conceptual level) is also strongly associated with socio-ecological systems incorporating mestizo groups and semi-urban rural landscapes, thus ceasing to be an exclusive focus of indigenous communities and regions.

RESUMEN: ANTECEDENTES: Cuatrociénegas es una región de singular importancia biológica, geológica, geográfica y evolutiva. Forma parte del Desierto de Chihuahua, su población actual es mestiza; sin embargo, posee una alta relevancia histórica, cultural y turística. Ha sido catalogado como Área de Protección de Flora y Fauna por la ley mexicana, así como un sitio de Alta Protección por el Fondo Mundial para la Naturaleza y la UNESCO. Por sus complejas características biológicas y socioculturales, consideramos importante conocer, determinar, identificar y analizar los conocimientos y prácticas etnobotánicas tradicionales en esta región. MéTODOS: Entre 2016 y 2019 se realizaron siete viajes de campo para documentar el conocimiento y uso de la flora. Cuatrociénegas es un área protegida, la recolección de material botánico está regulada, por lo que se fotografíaron y colectaron especímenes en comunidades aledañas, y en jardines públicos y privados. Posteriormente se obtuvo el permiso para completar la colección de ejemplares (2019-2020). Las plantas fueron identificadas e ingresadas a la base de datos de flora del estado de Coahuila, y depositadas en el Herbario de la Facultad de Ciencias Forestales de la Universidad Autónoma de Nuevo León, México. Se entrevistó a ciento diez vecinos (50 hombres y 60 mujeres) de entre 27 y 91 años (entrevistas semiestructuradas). Se evaluó la importancia cultural de los recursos etnobotánicos (índice de importancia cultural) y su significancia con respecto a la riqueza etnobotánica en otras Reservas de Biosfera en México (prueba de Mann-Whitney) y la similitud en la diversidad de especies exóticas (índice de Sørensen). RESULTADOS Y DISCUSIóN: La información etnobotánica registra 158 especies y 132 géneros en 57 familias vasculares y no vasculares, documentando un mayor conocimiento y uso de las especies cultivadas (84) con respecto a las silvestres (74). La diversidad de plantas reportada, en comparación con otros estudios etnobotánicos realizados en Reservas de la Biosfera, es altamente relevante, sin embargo, las especies exóticas son únicas. Los pobladores locales tienen una especial atención a las plantas medicinales y ornamentales. Las especies que presentaron mayores valores de uso son Larrea tridentata, Jatropha dioica y Machaeranthera pinnatifida, tres especies características de la región desértica. CONCLUSIONES: La particular diversidad de flora silvestre del Valle de Cuatrociénegas, combinada con la variada flora introducida, es un importante recurso multifuncional. La especial atención a las especies introducidas está asociada a las restricciones de aprovechamiento; así como a la alta valoración de especies ornamentales, dificiles de mantener en las zonas desérticas. El amplio conocimiento y uso de la etnobotánica son un ejemplo, que la diversidad biocultural (a nivel conceptual) también, está fuertemente asociada socio-ecologicamente a grupos mestizos y paisajes rurales semiurbanos, dejando de ser exclusiva de las regiones indígenas.

Niche conservatism promotes speciation in cycads: the case of Dioon merolae (Zamiaceae) in Mexico.

Niche conservatism is the tendency of lineages to retain the same niche as their ancestors. It constrains biological groups and prevents ecological divergence. However, theory predicts that niche conservatism can hinder gene flow, strengthen drift and increase local adaptation: does it mean that it also can facilitate speciation? Why does this happen? We aim to answer these questions. We examined the variation of chloroplast DNA, genome-wide single nucleotide polymorphisms, morphological traits and environmental variables across the Dioon merolae cycad populations. We tested geographical structure, scenarios of demographic history, and niche conservatism between population groups. Lineage divergence is associated with the presence of a geographical barrier consisting of unsuitable habitats for cycads. There is a clear genetic and morphological distinction between the geographical groups, suggesting allopatric divergence. However, even in contrasting available environmental conditions, groups retain their ancestral niche, supporting niche conservatism. Niche conservatism is a process that can promote speciation. In D. merolae, lineage divergence occurred because unsuitable habitats represented a barrier against gene flow, incurring populations to experience isolated demographic histories and disparate environmental conditions. This study explains why cycads, despite their ancient lineage origin and biological stasis, have been able to diversify into modern ecosystems worldwide.

The phylogeography of the cycad genus Dioon (Zamiaceae) clarifies its Cenozoic expansion and diversification in the Mexican transition zone.

Background and Aims: Biogeographic transition zones are promising areas to study processes of biogeographic evolution and its influence on biological groups. The Mexican transition zone originated due to the overlap of Nearctic and Neotropical biota, which promoted great biological diversification. However, since most previous studies in this area were focused on revealing the phylogeography of Nearctic plants, how historical biogeographic configuration influenced the expansion and diversification of the Neotropical flora remains almost unknown. Using the cycad genus Dioon (Zamiaceae), this study aimed to test whether the biogeographic provinciality of the Mexican transition zone reflects the history of diversification of Neotropical plants. Methods: Two chloroplast DNA (cpDNA) regions were analysed from 101 specimens of 15 Dioon species to reveal the distribution of haplogroups. In addition, genome-wide single nucleotide polymorphisms (SNPs) from 84 specimens were used to test the concordance between phylogenetic clusters and the biogeographic provinces. An ultrametric tree was constructed from the sequences containing SNPs to reconstruct the biogeographic events of vicariance and dispersal of Dioon across the Neotropical biogeographic provinces. Key Results: Four Dioon lineages with strong phylogeographic structures were recognized using both cpDNA and SNP data. The lineages correspond to two clades that originated from a common ancestor in Eastern Mexico. One clade expanded and diversified in South-east Mexico and Central America. Another clade diversified into three lineages that dispersed to North-east, South and North-west Mexico. Each lineage was biogeographically delimitated. Biogeographic provinces might have provided disparate ecological conditions that facilitated speciation in Dioon since the Miocene. Conclusions: The current genetic structure and species diversity of Dioon depict the history of expansion and diversification of the northernmost Neotropical provinces. Past biogeographic connectivities were favoured by elevated topographies, since mountain systems served as corridors for the migration of Dioon and as refugia of tropical communities that diversified during the formation of modern Neotropical forests.

Ethnobotany in Rayones, Nuevo León, México.

BACKGROUND: Trough collections of plants and interviews with 110 individuals, an ethnobotanical study was conducted in order to determine the knowledge and use plant species in Rayones, Nuevo Leon, Mexico. The aim of this study was to record all useful plants and their uses, to know whether differences exist in the knowledge about the number of species and uses between women and men, and to know if there is a correlation between the age of individuals and knowledge of species and their uses. METHODS: A total of 110 persons were interviewed (56 men, 56 women). Semistructured interviews were carried out. The data were analyzed by means of Student t test and the Pearson Correlation Coeficient. RESULTS: A total of 252 species, 228 genera and 91 families of vascular plants were recorded. Astraceae, Fabaceae and are the most important families with useful species and Agave and Opuntia are the genera with the highest number of useful species. One hundred and thirty six species are considered as medicinal. Agave, Acacia and Citrus are the genera with the highest number of medicinal species. Other uses includes edible, spiritual rituals, construction and ornamentals. There was a non-significant correlation between the person's age and number of species, but a significant very low negative correlation between the person's age and number of uses was found. CONCLUSIONS: Knowing their medicinal uses is an important issue for the people of Rayones. Boiling and preparing infusions are the main ways of using plants by residents. The leaves, the branches, and the fruits are the most commonly used parts. Almost 18% of the flora is used for wood and construction purposes. Several uses such as cosmetic, shampoo, firming skin tonics and health hair products recorded in Rayones has not been reported for other areas in the state of Nuevo León. In Rayones, women have a greater knowledge about plants and their uses than men, particularly, medicinal plants, but, men have a greater knowledge about wood and construction species.