ORIGINAL PAPER Extinction risk of Zamia inermis: a demographic study in its single natural population Pablo Octavio-Aguilar 1 • Andre ´s Rivera-Ferna ´ndez 2 • Lourdes Georgina Iglesias-Andreu 3 • P. Andrew Vovides 4 • Francisco F. Nu ´n ˜ez de Ca ´ceres-Gonza ´lez 1 Received: 6 June 2016 / Revised: 5 August 2016 / Accepted: 13 August 2016 Ó Springer Science+Business Media Dordrecht 2017 Abstract Demographic studies of endemic and threatened plant species are essential for establishing effective conservation strategies. This paper aims to determine the structure and dynamics of the only natural population reported for Zamia inermis. All individuals were mapped to determine the spatial structure and patterns of association between cate- gories and sexes. Matrix analysis were conducted to determine the population dynamics based on three on-site visits. The population is distributed randomly, although seedlings were found to be aggregated at all scales, juveniles are aggregated in smaller radii up to 4.5 m and males at radii above 3.5 m. Seedlings and juveniles are associated with males over greater radii of 3 m, the dependence of adults from earlier categories and females is less than 1.5 m. The population growth rate confirms that the population is in decline (k = 0.963 ± 0.011). Although few juveniles were identified and no seedling survival was observed in the field, also the amount of viable seeds per female cone is low. However, inhabitants of the region are cultivating the species by germinating seeds in backyard nurseries with 92 of 954 seeds reaching the juvenile category to date. It is clear that the population has lost its regenerative potential and is simply holding on to persistence of adults, this implies a great risk to the species. Ex situ propagation is encouraged. Communicated by Daniel Sanchez Mata. This article belongs to the Topical Collection: Ex-situ conservation. & Lourdes Georgina Iglesias-Andreu xliglesias@gmail.com 1 Laboratorio de Gene ´tica, Centro de Investigaciones Biolo ´gicas, Instituto de Ciencias Ba ´sicas e Ingenierı ´a, Universidad Auto ´noma del Estado de Hidalgo, Pachuca, Hidalgo, Mexico 2 Facultad de Ciencias Agrı ´colas, Universidad Veracruzana, Xalapa, Veracruz, Mexico 3 Instituto de Biotecnologı ´a y Ecologı ´a Aplicada, Universidad Veracruzana, Xalapa, Veracruz, Mexico 4 Laboratorio de Biologı ´a Evolutiva de Cycadales, Jardı ´n Bota ´nico Fco.Javier Clavijero, Campus II, Instituto de Ecologı ´a A. C., Xalapa, Veracruz, Mexico 123 Biodivers Conserv DOI 10.1007/s10531-016-1270-z