Conservation genetics of the protected candy barrel cactus Echinocactus platyacanthus in the Chihuahuan Desert Region

Three main genetic diversity hotspots were identified in a survey of the genetic variability of the populations of the candy barrel cactus Echinocactus platyacanthus, a protected and highly sought-after cacti for ornamental, culinary and livestock water source in the Chihuahuan Desert Region, Mexico. This study identified one southern, one central, and one northern population in the Chihuahuan Desert Region as first priorities for conservation based on the analysis of a matrix of 4 ISSRs for 183 individuals from 10 localities along the 900 × 300 air km polygon of the geographic distribution of the species. The genetic structure of the 183 individuals from the 10 populations studied, showed a high degree of genetic differentiation for each of the localities with low gene flow, making each of these populations important for conservation actions. The isolation by distance analysis showed that other factors apart from the geographic distance could be playing an important role in the differentiation of the genetic structure of the populations. The UPGMA tree derived from the genetic distance matrix showed that the central and the southern populations conform a mega genetic population clearly separated from the northern populations, each with its own genetic signature.