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.

BackgroundTrough 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.MethodsA 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.ResultsA 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.ConclusionsKnowing 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.

To aid in formulating conservation strategies for protection of species in mountainous regions, we studied the distribution of endemic vascular plants of northeastern Mexico’s Sierra Madre Oriental physiographic province, a massive mountain system in which different types of climate, vegetation, topography, and sedimentary soil converge. The information used in our five-year study was gathered from databases of national and international herbaria, as well as from botanical studies and floristic inventories conducted in the study area. We corroborated the nomenclature and geographical distribution of each species in the databases. A total of 1,135 species of endemic vascular plants from 369 genera and 88 families, including 177 infraspecific categories and one hybrid, were recorded in this study. The families with the most species and genera are Asteraceae (232 species, 75 genera), Cactaceae (170, 26), Fabaceae (66, 19) and Lamiaceae (66, 10). The genera with the most species are Mammillaria (43), Turbinicarpus (40), Agave (20), Salvia (20), Sedum (20) and Pinguicula (19). The families with the largest number of endangered species are Cactaceae, Zamiaceae, Pinaceae, and Fagaceae. Endemic species were most abundant in vegetation of temperate regions (554 endemic species) and in zones with dry climates or chalky soils (a total of 380 species for the two types of zones combined). The principal endemism-promoting attributes of the Sierra Madre Oriental may be its location, climate, physiography, soil types, geological age, karstic landscape, and wide range of elevations.

BackgroundCuatrociénegas is a region of unique biological, geological, geographical and evolutionary importance. It is part of the Chihuahua Desert, its current population is mestizo; however, it has a high historical, cultural and tourist relevance. It has been cataloged as a Flora and Fauna by Mexican law, as well as a High Protection site by the World Wildlife Fund and UNESCO. Because of its complex biological and sociocultural characteristics, we consider it important to know, determine, identify and analyze the traditional ethnobotanical knowledge and practices in this region.MethodsBetween 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 and 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) ware evaluated.Results and DiscussionThe 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, compared to other ethnobotanical studies carried out in Biosphere Reserves, is similar. 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 characteristic species of the desert region.ConclusionsThe 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 use restrictions; as well as the high value of ornamental species, difficult to maintain in desert areas. The extensive knowledge and use of ethnobotany are an example that biocultural diversity (at the conceptual level) is also, strongly associated with socio-ecological system with mestizo groups and semi-urban rural landscapes, ceasing to be exclusive to indigenous regions.

Summary 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.