Intraspecific genetic structure and niche modeling are auxiliary data for species conservation. The Mexican endemic cactus Mammillaria candida is listed as an at-risk species at both global and national levels; however, formal ecological and genetic assessments are lacking. We integrated fieldwork surveys, ecological niche modeling, and molecular variation levels (DNA sequences and microsatellites) to identify conservation issues in this study. The results verified that M. candida is distributed in Coahuila, Nuevo León, San Luis Potosí, and Tamaulipas. The climatic + soil model had the best predictive power (pROC = 1.93, AICc = 2639.12), and the highest contributions were from isothermality (23.44%), cation exchange capacity (19.7%), and precipitation seasonality (17.5%). The DNA sequences showed weak variation; however, the populations were divided into two groups: San Luis Potosí and Nuevo León-Tamaulipas. In contrast, microsatellites segregated Nuevo León from Tamaulipas. Genetic diversity was high, and significant inbreeding was estimated for the species, which may be caused by the small number of adults and pollination patterns. Only 1.45% of the projected habitats are included in Natural Protected Areas. This taxon should be maintained in the list of at-risk species, and formal taxonomic treatment is necessary to elucidate taxonomic circumscription.
Solórzano et al. (Thu,) studied this question.