Is the Decrease in Genetic Diversity the Cause of the Disappear-Ance of Tagetes lucida in Yautepec?

Pericon (Tagetes lucida) is an important medicinal and traditional plant used widely in ceremonies and considered as biocultural heritage. In Yautepec (Pericon Hill, in Nahuatl), Morelos, people report the extinction of this emblematic species. The extinction causes are until now not known. Nevertheless, the decline of populations may be attributable to a combination of factors, including alterations in land use, the utilisation of herbicides, habitat degradation, and overexploitation of resources. This decline could be exacerbated by the species ' inability to adapt to environmental changes. Genetic diversity is crucial to maintain the population’s adaptability in the face of diseases, environmental changes and other stressors and has an impact on population persistence. We tested the hypothesis that reduced genetic diversity in pericon populations caused the extinction of this species in Yautepec hills. The genetic diversity of six populations of Tagetes lucida were evaluated using PCR-based inter-simple sequence repeat (ISSR) markers. Ten ISSR primers produced a total of 1677 fragments with 100% polymorphism. The mean values of PIC, EMR and Rp were 0.34, 2.51 and 2.18, respectively. The results indicate that evaluated populations of Tagetes lucida have a high genetic diversity (79%), showing that the genetic factors are not the drivers of the species local extinction, and suggesting, that nongenetic factors such as overexploitation, overkill by herbicides, habitat destruction and fragmentation, the introduction of invasive species, rapid climate change, or pollution, reduce the growth rates of species and cause their populations to decline. These results show that T. lucida is a sensitive species that may require urgent conservation interventions.