948 L. Martínez‐Domínguez et al.
Mexican herbaria and elsewhere, lack of taxonomic revi- sions and limited knowledge of the taxonomic relationships of species within the genus. To study the biology of spe- cies, delimit species distributions and assess extinction risk, correct identification and naming of species is im- portant (Wheeler et al., 2012; Mota-Vargas & Rojas-Soto, 2016), but the distribution of the various species of Cera- tozamia in the Sierra Madre Oriental remains poorly known. Some Ceratozamia species occur within desig- nated protected areas, but how many or which ones is unknown. Ecological niche modelling predicts the distribution of
species using spatial analysis of environmental variables (Holt, 2009). It is a valuable tool for the development and evaluation of conservation strategies (Peterson et al., 2006) and has been shown to be effective in studies of the distribu- tion of many taxa (Mota-Vargas & Rojas-Soto, 2012; Peterson & Soberón, 2012), but has rarely been used in analyses of the distribution of cycads. Evidence of the effectiveness of current conservation
actions for Mexican Ceratozamia species is lacking. Out- comes of ongoing conservation programmes, which involve participation of local communities in the propagation and care of nursery plants, have not been evaluated (Vovides et al., 2010), and potential conceptual and methodological shortcomings that could restrict their success have not been considered (Bottrill & Pressey, 2012). In addition, there is a disconnect between conservation policies and management strategies recommended by biologists and the needs and activities of local communities. This calls for collaborative, multidisciplinary approaches, with the aim to implement conservation strategies in partnership between local com- munities and conservation biologists/managers (Orlove & Brush, 1996). Here, we evaluate the conservation and management
strategies for Ceratozamia in the Sierra Madre Oriental, using multidisciplinary methods from both natural and social sciences (Halme et al., 2015;Bennett, 2016). Specifically, we examine the taxonomy and biogeographical characteris- tics of the genus, and local perceptions of, and attitudes towards, existing conservation programmes. We also dis- cuss prospects for additional multidisciplinary approaches for the conservation of cycads.
Study area
The Sierra Madre Oriental is amountain range that emerges from the coastal plain of the Gulf of Mexico towards the central high plateau of Mexico. It is 800 km long and 80– 100 km wide (Eguiluz de Antuñano et al., 2000). Ceratozamia species occur at an altitude of 600–2,000mon karstic rocks. People living in this area are ethnically diverse and prac- tice subsistence- and market-oriented production (Toledo et al., 2003).
Methods
Species data Weobtained occurrence records for Ceratozamia by review- ing the 323 specimens available in the following herbaria: CHAPA, CIB, ENCB, FCME, FTG, GH, HEM, IEB, K, LE, LSU, MB, MICH, MEXU, MO, NY, P, SERO, SLPM, U, UAT, US, XAL, and XALU (acronyms according to Index Herbariorum; Thiers, 2019). This review was based on the taxonomic concepts of species proposed by Nicolalde- Morejón et al. (2014) and Martínez-Domínguez et al. (2018). We also included information collected in the field during 2014–2017. We conducted fieldwork on 41 Ceratozamia populations throughout the Mexican Sierra Madre Oriental, to corroborate existing records and/or obtain new localities for species. Because of the clustered distribution of species, we used preliminary information on distribution and eco- logical requirements to locate Ceratozamia populations. In 22 localities we interviewed local people, showing them photographs and describing the morphological characters representative of the genus, and asking about potential sites in the vicinity thatmay have suitable habitat for cycads, such as karstic rocks. We recorded the geographical coordi- nates of each site where we located cycad plants and com- piled this information in a database in ArcMap 10.2 (Esri, Redlands, USA). Records without precise locality data, or with coordinates that could not be corroborated during fieldwork, were omitted. To examine the distribution of Ceratozamia in the Sierra Madre Oriental,we superimposed the points of occurrence on the biogeographical province proposed by Paniagua & Morrone (2009).
Environmental layers, ecological niche modelling and distribution
We used interpolated climatic layers of 19 bioclimatic vari- ables from WorldClim (Hijmans et al., 2005) at a spatial resolution of 30" (c. 1km2 cell size) to characterize ecological niches.Wereduced dimensionality and collinearity between the bioclimatic layers by applying principal component analysis (PCA) with the function PCARaster in the R 3.3.1 package ENMGadgets (Barve & Barve, 2013; R Development Core Team, 2018). We retained the first six components for modelling because they explained c. 95% of the overall variance in environments for all species. Niche modelling was performed with Maxent (Phillips et al., 2006) because of its high predictive capability with presence-only data (Elith et al., 2010), and the dismo package (Hijmans et al., 2011)in R. Because the seeds of cycads are dispersed mainly by gravity (rarely by rodents, and then only over short distances), watersheds could be barriers to the dispersion of the species. We calibrated models within the accessible area (i.e. the area where the species could occur considering
Oryx, 2021, 55(6), 947–956 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320000204
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