Genetic diversity and differentiation in Zamia furfuracea (Zamiaceae): an endangered, endemic and restricted Mexican Cycad

Authors: FAVIAN-VEGA, ENRIQUE - University Of Veracruzana; MEEROW, ALAN - Retired ARS Employee; OCTAVIO-AGUILAR, PABLO - Universidad Autonoma Del Estado De Hidalgo; IGLESIAS-ANDREU, LOURDES - University Of Veracruzana

Submitted to: Biodiversity and Conservation Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2022
Publication Date: 5/21/2022
Citation: Favian-Vega, E., Meerow, A.W., Octavio-Aguilar, P., Iglesias-Andreu, L.G. 2022. Genetic diversity and differentiation in Zamia furfuracea (Zamiaceae): an endangered, endemic and restricted Mexican Cycad. Biodiversity and Conservation Journal. 67(3): 302310.
DOI: https://doi.org/10.6165/tai.2022.67.302

Interpretive Summary: Zamia furfuracea belongs to Zamiaceae family and is the second most traded cycad in the horticultural market worldwide. Illegal extraction of seedlings and seeds from the natural habitats of Z. furfuracea led them to endangered and endemic status. Their population distribution is highly fragmented restricting them to coastal habitats of southeast Mexico. Understanding levels of genetic diversity and structure in natural populations of threatened and endangered plants is a priority for plant germplasm conservation biology. Loss of genetic diversity in conservation programs and restoration of threatened populations can only be addressed through detailed population genetic studies. Using simple sequence repeat (SSR) molecular markers, the genetic variations of natural populations of Z. furfuracea were studied. The results highlighted the grouping of populations with a reduction in effective population size and a decrease in genetic diversity. The study highlights the basis to establish an effective strategy for the management of valuable endemic germplasm that is highly threatened.

Technical Abstract: Zamia furfuracea is a cycad endemic to coastal habitats of southeast Mexico and of high ecological and horticultural importance. It is threatened with extinction due to the declining population size, caused mainly by livestock raising, urban development, and poor environmental management. This work aimed to determine the genetic diversity and structure of six natural populations of Z. furfuracea throughout their known distribution range. To determine the genetic variation, ten molecular markers of repeated simple sequences (SSR) were used. A Bayesian assignment model, molecular variance analysis and bottleneck tests, and identification of loci with non-neutral heritage were also performed. A lower genetic diversity was identified in the southern population (Capulteolt). Four genetic groups were identified (K = 4). Ancestral polymorphism and management resulted in an increased genetic similarity between the populations of "Ciénega del Sur," "Toro Prieto," and "Playa Escondida". "Capulteolt" was the most differentiated population; a historical reduction in the population size was observed, leading to the loss of some alleles by putative directional natural selection. This study reveals the "Capulteolt" population's low genetic diversity as well as the presence of increased differentiation in the geographical limits of the species' distribution range.