Designing ex-situ conservation strategies through the assessment of neutral genetic markers: Application to the endangered Androcymbium gramineum

Recent anthropogenic habitat perturbationsrelated to the unsustainable development of thetwo areas of distribution of Androcymbiumgramineum in Almería (South of Spain) andthe Atlantic coast of Morocco are outweighingthe intrinsic biological survival assets ofthis narrow Ibero-Moroccan endemic. We usedpopulation genetic data on 18 isozyme loci for13 populations to design a comprehensivesampling strategy for ex-situ conservation thatstraddles the results of independenttheoretical developments and the indications ofseveral genetic polymorphism parameters.Regressions based on the probabilities of lossestimate that sampling one population would beinsufficient to represent the variationattributable to the rare alleles found in thepopulations surveyed from Almería orMorocco and suggest that the relationshipbetween the number of populations sampled ineither area should conform to the proportion0.6:0.4, respectively. The estimate of thenumber of populations that need be targeted torepresent 99% of the genetic variationdetected indicates that it would be necessaryto sample eight populations intensively. Fivepopulations from Almería and three fromMorocco were selected through the ranked valuesof the average number of alleles per locus andthe expected heterozygosity on the grounds thatthese parameters provide unambiguousindications of polymorphism that, in the caseof heterozygosity, are less likely to beinfluenced by sampling error. Spatialautocorrelation surveys in the largestpopulation known indicate that seeds should becollected at a minimum separation of 15 m toavoid the sampling of close relatives.