**Author details**

*Natural History and Ecology of Mexico and Central America*

facilitate reproduction [46].

ing and gene drift [6].

**Acknowledgements**

**5. Conclusions**

recurrent mutations or gene flow by pollen dispersal at great distances [50]. These alleles may benefit from genetic drift promoted by population size reduction. AMOVA indicates a high differentiation in seedlings (FST = 0.26), probably due to the reduction in gene flow, which has led to inbreeding within the populations. Simultaneously, in adults and juveniles, the values are very similar and may be maintained by self-incompatibility that creates a dependence on pollinators to

Some populations share some alleles, suggesting that they were connected by natural corridors some time ago, mainly in the vicinity of the Sierra Gorda in the northern of Querétaro and south of San Luis Potosí. However, in the current generations of seedlings, the Fst values indicate that the populations analyzed are becoming isolated. The isolation is probably caused by physical barriers associated with anthropic activities increasing in the area. This situation diminishes the habitat conditions and leads to higher mortality, affecting pollinators and favoring inbreed-

Some *Dioon edule* populations have declined substantially due to land-use change, primarily for sugar cane fields and cattle pastures, but the overall decline is relatively low. Populations genetic diversity suggests that at some time, they were connected by natural corridors. However, when combining the own high mortality of the species in the seedling and juvenile stages, the reduction and fragmentation of its habitat, and the decrease of pollinators, it favors endogamy and genetic drift,

GRM thanks the support of CONACYT (Scholarship for Postgraduate Studies 290685) and the PMPCA-UASLP. The Cycad Society financed the research through the project "The chamal (*Dioon edule* Lindl.) in the state of San Luis Potosí" and CONACYT (104739), granted to LYE. IICA financed the project "The Chamal, a toxic but also edible cycad" granted to AP. We thank Raymundo Mora for his

whose effects are more pronounced in small populations.

support in the field and Marc Hersh for his laboratory support.

**108**

Gabriel Rubio-Méndez1 , Alberto Prado2 , Jacqueline C. Bede3 , José Arturo De-Nova4 , Joel Flores<sup>5</sup> , Juan Antonio Reyes-Agüero4 and Laura Yáñez-Espinosa4 \*

1 Faculty of Natural Sciences, Autonomous University of Queretaro, Queretaro, Mexico

2 Juriquilla Unit, National School of Superior Studies, Queretaro, Mexico

3 Department of Plant Science, Macdonald Campus, McGill University, Sainte-Anne-de-Bellevue, Canada

4 Institute for Research on Desert Zones, Autonomous University of San Luis Potosi, San Luis Potosi, Mexico

5 Consortium for Research, Innovation and Development for Arid Zones, San Luis Potosi, Mexico

\*Address all correspondence to: lyaneze@uaslp.mx

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
