Agroforestry systems with native vegetation enhance climate adaptation and mitigation by improving coffee farm resilience, carbon storage, and income diversification. Seven native tree species were pre-selected as shade providers for Veracruz coffee agroforestry systems based on ecological, cultural, and economic criteria. The present study evaluated their physiological performance through above-ground biomass, carbon stocks, and in-situ chlorophyll fluorescence and gas exchange measurements under controlled light and temperature conditions. Five Coffea arabica varieties were also assessed under these shade canopies using the same leaf-level parameters, and leaf nitrogen and moisture content. Erythrina americana and Persea schiedeana had the highest carbon sequestration per tree. E. americana showed the highest water-use efficiency, whereas P. schiedeana showed the lowest transpiration and stomatal conductance, indicating a water-saving strategy via stomatal restriction. These traits reflect their ecological adaptations to shade and microclimate conditions in agroforestry systems. Inga inicuil achieved the highest carbon capture per hectare due to high tree density, despite lower individual performance. Species-specific strategies were identified: Psidium guajava and P. schiedeana exhibited high transpiration but limited carbon gain. E. americana and Inga punctata formed a drought-resilient group, having a high carbon assimilation and low water loss. Intermediate species (Heliocarpus appendiculatus, Inga vera, I. inicuil) balanced moderate CO2 assimilation rates with adaptable stomatal response. Photochemical efficiency remained stable across species. Shaded Coffea arabica var. Oro Azteca had significantly higher leaf nitrogen, moisture, and water-use efficiency than unshaded ones. These differences coincided with lower PAR under shade, aligning with known variations in shaded versus unshaded coffee plants. Principal component analysis showed that PC1 correlated strongly with stomatal conductance and transpiration, driven by P. guajava and P. schiedeana. PC2 showed a carbon economy trade-off between CO2 assimilation and internal concentration, dominated by E. americana. Collectively, these components highlight stomatal regulation and carbon management as adaptive strategies. Coffee PCA revealed contrasting water-use strategies: PC1 showed inverse stomatal regulation (especially in shaded varieties), and PC2 an energy allocation trade-off between photochemical efficiency and carbon assimilation, with shaded plants maintaining stable CO2 assimilation regarding unshaded ones. These results demonstrate notable interspecific variation in carbon storage, water-use efficiency, and light conditions among shade trees, offering empirical support for species selection in Veracruz coffee agroforestry.

Agroforestry systems, such as shade-grown coffee plantations are particularly well suited to address the challenges of climate change, due to potential synergies between adaptation and mitigation strategies. The traditional knowledge of coffee producers can play a critical role in optimizing agroforestry approaches and shade tree selection to balance biodiversity conservation and local needs. This knowledge was used in a two-stage hybrid methodology identifying the shade tree species that help coffee growers in central Veracruz, México, face multiple challenges including climate change, biodiversity conservation, and improved livelihoods. Multi-criteria decision analysis using the distribution and conservation traits and agroecological information available of the native tree species of Veracruz, helped generate a preliminary list of 50 prioritised species, which was refined by incorporating local knowledge of each species in participatory workshops involving smallholder producers, where gender equality and social inclusion principles were applied. Species with the highest priority score were those belonging to the genus Inga (I. jinicuil, I. vera, I. punctata), which provides shade, soil fertility, bird habitat, and food. Domesticated species of the genera Persea (P. americana, P. schiedeana, P. longipes) and Psidium (P. guajava), were also prioritised as they are considered as important elements for shade and fruit production. This methodology combines distribution and conservation and ecological traits with local knowledge to prioritise native tree species for use in shade-grown coffee plantations in the central region of Veracruz. This multidisciplinary approach could be replicated more broadly in México and other coffee growing regions.

The present work is aimed to review the concepts of continuity and discontinuity in the reproductive processes and their impact on the evolutionary outcome, emphasizing on the plant model. Let be stated that evolutionary changes need to pass down generation after generation through the cellular reproductive mechanisms, and these mechanisms can account for changes from single nucleotide to genome-wide mutations. Patterns of continuity and discontinuity in sexual and asexual species pose notorious differences as the involvement of the cellular genetic material from single or different individuals, the changes in the ploidy level, or the independence between nuclear and plastid genomes. One relevant aspect of the plant model is the open system for pollen donation, which can be driven from every male flower to every female flower in the neighborhood, as well as the facilitated seed dispersal patterns, that may break or restore the contact between populations. Three significative processes are distinguishable, syngenesis, anagenesis, and cladogenesis. The syngenesis refers to the reproduction between individuals, either if they pertain to the same species, from different populations or even from different species. The anagenesis refers to the pursuit of all the possible rearrangements of genes and alleles pooled in a population of individuals, and the cladogenesis represents the absence of reproduction that leads to differentiation. Recent developments on the genomic analysis of single cells, single chromosomes and fragments of homologous chromosomes could bring new insights into the processes of the evolution, in generational time and in a broad spectrum of spatial/geographic extents.

Background and aims – Endemism may be defined according to the time of origin of taxa. Neo-endemics refer to relatively recent species that have not dispersed outside their ancestral areas. In contrast, paleo-endemics refer to species of ancient origins, which are currently geographically restricted but probably were more widespread in the past. Geographically, endemism areas may also be based on the co-occurrence of more than one species. We aimed to qualitatively identify the neo-endemism and paleo-endemism of endemic Cactaceae of the Tehuacán-Cuicatlán Valley, as well as to quantitatively assess paleo- and neo-endemics areas. Material and methods – Using a dated molecular phylogeny of endemic Cactaceae, we defined paleo- and neo-endemics using an arbitrary boundary of 2.6 million years ago; we also assessed the significance of concentrations of these species using a categorical analysis of paleo- and neo-endemism. Key results – Our results showed that most endemic Cactaceae in the Tehuacán-Cuicatlán Valley arose throughout the Pleistocene, while categorical analysis indicated localised mixed- and super-endemism (including both paleo- and neo-endemics) areas. Conclusion – We suggest that paleo- and neo-endemics, as well as localised mixed-endemism areas, may have originated due to a probable high climatic stability in the Tehuacán-Cuicatlán Valley, which in addition to topographically rugged and ecologically complex zones (e.g. ecotones, isolated habitat patches) may have allowed it to function as a refuge throughout Pleistocene climatic changes, mainly promoting the speciation of neo-endemics, as well as the persistence of relatively few paleo-endemics.

Mexico harbors ~45% of world's cacti species richness. Their biogeography and phylogenomics were integrated to elucidate the evolutionary history of the genera Coryphantha, Escobaria, Mammillaria, Mammilloydia, Neolloydia, Ortegocactus, and Pelecyphora (Mammilloid Clade). We analyzed 52 orthologous loci from 142 complete genomes of chloroplast (103 taxa) to generate a cladogram and a chronogram; in the latter, the ancestral distribution was reconstructed with the Dispersal-Extinction-Cladogenesis model. The ancestor of these genera arose ~7 Mya on the Mexican Plateau, from which nine evolutionary lineages evolved. This region was the site of 52% of all the biogeographical processes. The lineages 2, 3 and 6 were responsible for the colonization of the arid southern territories. In the last 4 Mya, the Baja California Peninsula has been a region of prolific evolution, particularly for lineages 8 and 9. Dispersal was the most frequent process and vicariance had relevance in the isolation of cacti distributed in the south of Mexico. The 70 taxa sampled as Mammillaria were distributed in six distinct lineages; one of these presumably corresponded to this genus, which likely had its center of origin in the southern part of the Mexican Plateau. We recommend detailed studies to further determine the taxonomic circumscription of the seven genera.

Abstract Phylogenetic and geographic distances were estimated to produce a combined Distancing Index as a measure of historical reproductive isolation in the genus Cephalocereus. Geographic and climatic barriers were inferred from potential and observed distributions. Distances were extracted from a Bayesian tree for seven chloroplast regions and 26 terminals, and from the geolocation dataset for the exact same sampling. Distance matrices were relativized, and a Mantel test was applied to identify deviations between phylogenetic and geographic distances. Heatmaps and scatterplots were implemented to visualize combined trends. Two basal clades show patterns of differentiation or complete isolation; the first includes C. scoparius, C. apicicephalium, C. nizandensis, and C. totolapensis, and the second includes C. parvispinus, C. polylophus, and C. euphorbioides. The species C. fulviceps, and C. sanchezmejoradae appear in a differentiated grade as sisters of a well-defined clade that includes C. mezcalaensis, C. macrocephalus, C. tetetzo, C. senilis, C. columna-trajani, C. multiareolatus, and C. nudus, where geographic or phylogenetic distances lie below the mean, indicating a diversification process in absence of hard barriers. At the generic level, separation is related to climatic factors as temperature and moisture, while factors as the altitude could be determinants of separation at the species level. The steady accumulation of variants may lead to opposed evolutionary outcomes: differentiation or diversification, in isolated and non-isolated lineages, respectively. More studies are needed on how genetic variation is transferred or interchanged between and among lineages, and how morphological differentiation of diverging lineages account for reproductive isolation.

Twenty-one years have elapsed of the 21st Century and within the framework of the celebration of the 100th volume of Botanical Sciences, it is relevant to assess the progress of the research on conservation and on the activities undertaken for protecting the plants of Mexico, including the complementary in situ and ex situ approaches. By means of a systematic search of scientific articles related to the conservation of the Mexican flora on the Web of Science database, for the 2000–2021 period, we identified different scientific inputs, all showing specific objectives for undertaking conservation activities. The publications that resulted from this search were classified into six categories: (a) Regions and Ecoregions; (b) Communities or Ecosystems; (c) Taxonomic Groups; (d) Species and Populations; (e) Botanical Gardens; and (f) Seed Banks. For these categories, the results are presented under the headings “in situ conservation” and “ex situ conservation.” Additionally, we assessed by a random examination, the bibliography used to support touristic development projects. The results show that, despite the wide temporal range considered in this review, and even though there is a vast number of publications related to the characterization of the Mexican biodiversity, the production of scientific work oriented to the development of plant conservation strategies and activities is still scarce. Also evident is the lack of connection and communication among researchers of different disciplines, highlighting the disciplinary or multidisciplinary activities that they undertake. Finally, ten conclusions are presented, and some future research activities are suggested for conserving the Mexican flora.

It is well known that bruchids and legumes generally have ecological relationships, such as parasitism and predation; however, little is known about the effects of such relationships on the initial life cycle stages of wild legumes. This study evaluates the effect of Stator pruininus infestation on the germination and early growth of Acacia berlandieri. Germination tests were performed under controlled conditions on healthy seeds, seeds with physical scarification, chemical scarification, damage from larvae, and seeds with eggs. A one-way analysis of variance was used to analyze the germination of seeds (percentage, rate, and mean germination time), as well as the early growth of the seedlings (survival, size, and biomass). The percentage of germination in all of the seed categories was greater than 85%, with significant differences (p < 0.05) between seed categories. However, there were no significant differences between seed categories in germination rate or average germination time (p > 0.05). In the early growth of the seedlings, there were significant differences (p < 0.001) between seed categories in the size of the seedling, stem, and root, and in the aboveground and belowground biomass. Based on these results, S. pruininus is not a predator of A. berlandieri, but the damage done to the cotyledons by this insect species can reduce seedling growth and accumulation of biomass in the first days of growth.

Fouquieriaceae consists of a single genus Fouquieria with eleven species occurring in arid and semiarid regions in Mexico and the southwestern USA. A recently developed phylogeny based on chloroplast DNA sequences provided strong support for the monophyly of the genus and the evolutionary species relationships. However, details of its evolutionary history remain unclear. Due to this uncertainty, additional information such as the evolution on its growth habit, reconstruction of the ancestral habitat, and on chromosome evolution is needed for a clear understanding of its evolutionary history. Different hypotheses concerning the shift of growth habits (succulent or woody) and the occupation of the ancestral habitat, and the chromosomal evolution in the family were analyzed. We assessed the ancestral distribution by fitting different biogeographic models. Our results suggest that Fouquieriaceae may have originated in two regions at the margins of the present geographic distribution of the genus: the Sonoran Desert and desert areas south of the Mexican Transvolcanic Belt. However, our results suggest that the ancestral lineage of Foquieriaceae was originated in desert habitats in central–southern Mexico with a basal chromosome number of n = 12, and a succulent habit, all of which may have allowed the dispersion of polyploid species to newly developed dry environments during the Late Miocene.

We analysed gynostemium development and morphology of 13 species of Spiranthinae to understand the structure and homology of this organ. Flowers and flower buds in different developmental stages were examined with scanning electron and light microscopy. Gynostemium ontogeny is similar in the early stages among the analysed species, and most of the differences arose at later developmental stages. Gynostemium development starts with the appearance of the anther primordium, followed by the median carpel and finally by the lateral carpel apices. The last emerges as two congenitally united, crescent-shaped prominences located between the median carpel apex and the labellum, eventually forming a rim of tissue on the proximal margin of the stigma. The rim can be receptive or not. The base of the median carpel apex contributes mostly to the receptive stigmatic zone and its apical region develops into the viscidium. The entrance of the stylar canal is located between the two partially non-receptive lateral carpel apices and the receptive base of the median carpel apex, refuting the idea that in Sarcoglottis it is located above the stigmatic area. There are no staminodal primordia, and the membranaceous appendages at each side of the column apex represent extensions of the clinandrium margins.

Background Mexico is one of the most floristically rich countries in the world. Despite significant contributions made on the understanding of its unique flora, the knowledge on its diversity, geographic distribution and human uses, is still largely fragmented. Unfortunately, deforestation is heavily impacting this country and native tree species are under threat. The loss of trees has a direct impact on vital ecosystem services, affecting the natural capital of Mexico and people’s livelihoods. Given the importance of trees in Mexico for many aspects of human well-being, it is critical to have a more complete understanding of their diversity, distribution, traditional uses and conservation status. We aimed to produce the most comprehensive database and catalogue on native trees of Mexico by filling those gaps, to support their in situ and ex situ conservation, promote their sustainable use, and inform reforestation and livelihoods programmes. Methods A database with all the tree species reported for Mexico was prepared by compiling information from herbaria and reviewing the available floras. Species names were reconciled and various specialised sources were used to extract additional species information, i.e. endemic status, threat status, availability in seed collections, reports on plant uses and conservation actions currently in place. With this information, a comprehensive catalogue of native trees from Mexico was redacted. Available georeferenced records were used to map each species distribution and perform spatial analyses to identify gaps of information and priority areas for their conservation and exploration. Results Mexico has at least 2,885 native tree species, belonging to 612 genera and 128 families. Fabaceae is the most represented family and Quercus the most represented genus. Approximately 44% of tree species are endemic to the country. The southern part of the country showed the highest values of species richness. Six hundred and seventy-four species have at least one documented human use. In terms of conservation assessment, ca. 33% of species have been assessed by either the IUCN Red List (919) or the National protection catalogue “NORMA Oficial Mexicana NOM-059” (29) or both (45). Additionally, 98 species have been included in the CITES listing for protection. In terms of existing conservation efforts, 19% of species have ex situ protection in seed banks, while protected areas overlap with all the identified peaks of species richness, except for those in the states of Veracruz and Chiapas. This work constitutes a key milestone for the knowledge, management, and conservation of the Mexican native trees. The two areas with high density of tree species identified in Veracruz and Chiapas represent two priority areas for tree conservation in Mexico, where integrated in situ and ex situ conservation efforts should be focused.

In plants, partial DNA sequences of chloroplasts have been widely used in evolutionary studies. However, the Cactaceae family (1500–1800 species) lacks molecular markers that allow a phylogenetic resolution between species and genera. In order to identify sequences with high variation levels, we compared previously reported complete chloroplast genomes of seven species of Mammillaria. We identified repeated sequences (RSs) and two types of DNA variation: short sequence repeats (SSRs) and divergent homologous loci. The species with the highest number of RSs was M. solisioides (256), whereas M. pectinifera contained the highest amount of SSRs (84). In contrast, M. zephyranthoides contained the lowest number (35) of both RSs and SSRs. In addition, five of the SSRs were found in the seven species, but only three of them showed variation. A total of 180 homologous loci were identified among the seven species. Out of these, 20 loci showed a molecular variation of 5% to 31%, and 12 had a length within the range of 150 to 1000 bp. We conclude that the high levels of variation at the reported loci represent valuable knowledge that may help to resolve phylogenetic relationships and that may potentially be convenient as molecular markers for population genetics and phylogeographic studies.

The complete sequence of chloroplast genome (cpDNA) has been documented for single large columnar species of Cactaceae, lacking inverted repeats (IRs). We sequenced cpDNA for seven species of the short-globose cacti of Mammillaria and de novo assembly revealed three novel structures in land plants. These structures have a large single copy (LSC) that is 2.5 to 10 times larger than the small single copy (SSC), and two IRs that contain strong differences in length and gene composition. Structure 1 is distinguished by short IRs of <1 kb composed by rpl23-trnI-CAU-ycf2; with a total length of 110,189 bp and 113 genes. In structure 2, each IR is approximately 7.2 kb and is composed of 11 genes and one Intergenic Spacer-(psbK-trnQ)-trnQ-UUG-rps16-trnK-UUU-matK-trnK-UUU-psbA-trnH-GUG-rpl2-rpl23-trnI-CAU-ycf2; with a total size of 116,175 bp and 120 genes. Structure 3 has divergent IRs of approximately 14.1 kb, where IRA is composed of 20 genes: psbA-trnH-GUG-rpl23-trnI-CAU-ycf2-ndhB-rps7-rps12-trnV-GAC-rrn16-ycf68-trnI-GAU-trnA-AGC-rrn23-rrn4.5-rrn5-trnR-ACG-trnN-GUU-ndhF-rpl32; and IRB is identical to the IRA, but lacks rpl23. This structure has 131 genes and, by pseudogenization, it is shown to have the shortest cpDNA, of just 107,343 bp. Our findings show that Mammillaria bears an unusual structural diversity of cpDNA, which supports the elucidation of the evolutionary processes involved in cacti lineages.

Antecedentes La clasificación de la familia Poaceae ha cambiado a lo largo de los años, por la evolución de distintas áreas del conocimiento de la sistemática, tanto en sus aspectos teóricos como prácticos. La morfología y anatomía siguen siendo fuentes importantes de información taxonómica en las gramíneas. Sin embargo, en los últimos 20 años, los trabajos moleculares que buscan inferir la filogenia de los diferentes taxa, han dominado el escenario de la sistemática de la familia, lo que ha derivado en cambios y re-arreglos a todos los niveles taxonómicos. Objetivo: Realizar la revisión y actualización de la información taxonómica y geográfica de las Poaceae de México, presentando un listado de especies, en el que se señalan los taxa nativos, introducidos y endémicos, los logros alcanzados en el conocimiento del grupo, así como los retos que se habrán de enfrentar en el futuro para adelantar en el conocimiento de las gramíneas de México.Métodos: Se tomó como base de referencia el trabajo de Dávila et al . (2006). Se revisó tanto la literatura especializada disponible de 2006 a la fecha y distintas bases de datos nomenclaturales y taxonómicas. El trabajo también incluye la revisión de ejemplares de 29 herbarios entre 2006-2017. La lista de las especies se presenta con base en la clasificación de Soreng et al . (2015).Resultados: Se registran en México 11 subfamilias, 205 géneros, 1,216 especies y 207 categorías infraespecíficas. Se presenta el listado alfabético de las especies, resaltando su distribución a nivel estatal y en particular las endémicas e introducidas. Se incluye también la distribución de las especies a nivel estatal. Asimismo, se presentan los avances alcanzados en relación a los estudios de las diferentes subfamilias con diversos enfoques de estudio, tanto metodológicos como conceptuales, y los retos que se habrán de enfrentar en los próximos años.

In the Tehuacán-Cuicatlán Valley (TCV) a total of 1605 useful plant species have been recorded. All of them, anthropologically speaking, are very important and thus, it is worthy to explore various options for ensuring their conservation. Accordingly, the aim of this work was focused in identifying potential areas for the conservation of useful plant species of the TCV. For doing so, we compared two databases from the TCV. The known and potential distributions were identified for 272 species, using MaxEnt. The distribution data was intersected with a grid of 153 operative geographic units (OGUs) that were used to elaborate the species presence matrixes. An optimization algorithm was applied for both the known and the potential distribution and their respective species accumulation curves were compared. A list of 583 useful plant species of the TCV was obtained. These species are heterogeneously distributed in 111 of the 153 recorded OGUs. Ten families contribute with 55.06% of the overall plant richness of the TCV. In addition, the analysis revealed that at least, 13 OGUs are needed to conserve 81% of the useful flora, which represents approximately 30% of the flora, in only 8.5% of the total TCV surface. The selected sites coincide with those areas where some incipient domestication processes, as well as, plant endemism and richness centers have been reported.

The efficient storage and germination of seeds underpin the effective use of plants for livelihoods and sustainable development. A total of 204 wild species useful for local communities of the Tehuacán–Cuicatlán Valley were collected and stored in seed banks in country for long term conservation, and 66 % (i.e., 134) duplicated in the U.K., as an effective means of ex situ conservation. Of the 204 species, 147 (122 of which also duplicated in the U.K.) were previously listed as useful plants in the ethnofloristic inventory of the Valley. Based on literature surveys, we found that one of the major impediments to the use of stored seeds of wild species is the lack of knowledge of how to germinate the seed. In detailed studies, we found that seeds of 18 useful plant species from 10 different families germinated readily and could be propagated. In contrast, four species (Actinocheita filicina, Bursera submoniliformis, Karwinskia mollis and Lippia graveolens) produced dormant seeds and therefore further studies are needed before their use can be maximised in large scale propagation programmes in support of conservation and livelihoods. Overall, this large-scale study on useful wild plant species in Mexico confirms that conventional seed banking can effectively support sustainable development and livelihood programmes.

Mexican dry environments are widespread and characterized by a rich flora and fauna in terms of both overall species diversity and endemism, but the factors that have shaped this diversity remain unclear. In this study, we evaluated hypotheses concerning the biogeographical origin and evolutionary history of Florestina (Asteraceae) in Mexican dry environments. For this, we generated a time-calibrated phylogenetic tree from the nuclear non-coding external and and internal transcribed spacers (ETS, ITS), using the program BEAST. Based on this phylogenetic tree, we employed the package BioGeoBEARS to infer the historical biogeography of the genus, comparing different biogeographical models and estimating the ancestral range probabilities. Our time-calibrated phylogenetic tree suggested that the genus Florestina diverged during the early Pliocene c. 5.2 Mya and diversification continued throughout the Pleistocene. Furthermore, results suggest that the biogeographical origin of the Hymenothrix/Palafoxia/Florestina clade was in Nearctic regions, not in Neotropical regions as previously suggested. We hypothesize that the ancestor of Florestina became disjunct and isolated in tropical dry forests of southern Mexico from Palafoxia after the rifting of the Baja California peninsula from the Mexican mainland.

Mammillaria groups 200 species. Mexico harbors 164 species, 85 % are endemic and 113 are listed in the Official Mexican Standard NOM-059 SEMARNAT-2010. In spite of their importance in biodiversity and serious conservation crisis, the scarce information documented for these species does not allow proposals for protection strategies. Our objective was to estimate the population genetic diversity levels of M. hernandezii, M. kraehenbuehlii and M. napina to identify genetic conservation units. Twenty-four individuals from two M. hernandezii populations and 120 individuals from five populations for the other two species were genotyped with ten microsatellite loci. In the three species the observed heterozygosity levels were lower than the expected ones (M. hernandezii 0.58, 0.65; M. kraehenbuehlii 0.61, 0.73; and M. napina 0.56, 0.74). The allelic diversity ranged from five (M. hernandezii) to eight alleles in the other two species. The three species showed heterozygotic deficiency possibly due to genetic drift since their populations are small, but selfing may also be involved. Gene flow levels were high for the three especies indicating that genetic drift, pollen and seed dispersal systems determine the genetic structure. Three genetic groups are proposed for M. kraehenbuehlii and M. napina to be considered as reference for conservation programs of the species and their habitats. The main threats for the three species are severe landscape transformation, which isolates the populations, and looting. For M. hernandezii, the number of studied populations should increase to guarantee conclusive results of its population genetic diversity. Currently, the geographic distribution pattern in small patches indicates severe habitat fragmentation that urges to take actions for its protection and management.

Mammillaria agrupa a 200 especies, 164 registradas en México, 85 % son endémicas y 113 están en la Norma Oficial Mexicana NOM-059 SEMARNAT-2010. A pesar de su importancia en la biodiversidad y de su grave crisis de conservación, la escasa información documentada en estas especies no permite proponer estrategias para protegerlas. Nuestro objetivo fue estimar los niveles de diversidad genética poblacional en M. hernandezii, M. kraehenbuehlii y M. napina para identificar unidades genéticas de conservación. Se genotiparon con 10 loci de microsatélites 24 individuos de dos poblaciones de M. hernandezii y 120 individuos de cinco poblaciones para cada una de las otras dos especies. En las tres especies se estimaron niveles de heterocigosidad observada menores que los esperados (M. hernandezii 0.58, 0.65; M. kraehenbuehlii 0.61, 0.73; y M. napina 0.56, 0.74), la diversidad alélica varió de cinco (M. hernandezii) a ocho alelos en las otras dos especies. Las tres especies mostraron una deficiencia de heterocigotos que puede deberse a deriva genética porque sus poblaciones son pequeñas, aunque la autofecundación también podría participar. Entre las poblaciones de las tres especies los niveles de flujo génico fueron altos, lo que indica que podría ser la deriva genética y el sistema de dispersión de polen y semillas lo que determina la estructura genética. Para M. kraehenbuehlii y M. napina se proponen tres grupos genéticos para que sean considerados como referencias para programas de conservación de estas especies y de sus hábitats. Las principales amenazas para las tres especies son la severa transformación del paisaje que aisla a sus poblaciones y el saqueo. En M. hernandezii se debe incrementar el número de poblaciones estudiadas para tener resultados concluyentes de su diversidad genética poblacional, por el momento el patrón de distribución geográfica en parches pequeños indica una severa fragmentación que insta a tomar medidas urgentes para su protección y manejo.

The endemic plant species with extremely narrow geographical range (<100 km2) often have few populations of small size and tend to be more vulnerable to extinction by genetic drift and inbreeding effects. For these species, we tested if intraspecific genetic diversity can be applied to identify conservation priorities. The biological model was Mammillaria albiflora—a Mexican cactus that numbers ~1000 individuals distributed in four nearby patches covering 4.3 km2. A total of 96 individuals were genotyped with 10 microsatellite loci to describe the genetic substructure and diversity. There is significant population substructure: the genetic diversity is distributed in three genetic neighbors and varies among the patches, the genotypes are not randomly distributed and three genetic barriers restrict the gene flow. The current population size is 15 times smaller than in the past. The restricted gene flow and genetic drift are the processes that have shaped population substructure. To conserve the genetic diversity of this cactus we recommend that two patches, which are not private property, be legally protected; to include M. albiflora in the Red List Species of Mexico in the category of extinction risk; and a legal propagation program may help to diminish the illegal harvesting.