The restriction of vascular plants to gypsum-rich soils under arid or semiarid climates has been reported by many authors in different parts of the world. However, factors controlling the presence of gypsophytes on these soils are far from understood. We investigated the establishment of Lepidium subulatum, a gypsophyte, in a nondisturbed semiarid gypsum-soil landscape in central Spain, both from spatial and temporal perspectives. Over 1400 seedlings were tagged, and their growth and survival were monitored for a 2-yr period. Several biotic and abiotic variables were measured to determine the factors controlling the emergence and early survival. These variables included the cover of annual plants, bryophytes, lichens, litter, gypsum crystals, bare fraction and cover of each perennial plant, and several soil properties (gravel, fine gravel, and fineearth fraction, conductivity, pH, gypsum content, organic matter and penetrometer soil resistance). Our results support the linkage of gypsophily with some physical properties of the surface crust. Seedlings tended to establish on the gypsum surface crust, and their survival was size dependent, probably as a consequence of the necessity of rooting below the surface crust before summer drought arrives. However, once seedlings emerged, a higher survival rate occurred on the alluvial soils of the piedmont-slope boundary where soil crusts are absent or thinner. We conclude that Lepidium subulatum may be considered a refuge model endemic with a distribution range that occupies a reduced fraction of a wider habitat from which it is probably excluded by competition.

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This chapter investigates the potential linkages between in situ and ex situ conservation, how ex situ conserved germplasm, particularly of crop wild relatives, might be better used in support of in situ and ecosystem conservation, and how in situ conserved germplasm might be better utilized. Both the complementary nature of in situ and ex situ conservation and the desire to link conserved diversity to use are emphasized in the methodology for plant genetic conservation proposed by Maxted et al. (1997a).

This chapter presents a set of quality standards for the conservation of crop wild relative taxa in genetic reserves (GRs) or areas designated for the active, long-term in situ conservation of wild populations where the primary consideration is to preserve its genetic diversity. The criteria for the establishment of GRs and management considerations to optimize GR efficacy are also discussed.

Thirteen allozyme loci and 68 random amplified polymorphic DNA (RAPD) markers were analyzed to assess the genetic diversity and population structure of threatened Antirrhinum microphyllum (Scrophulariaceae), a narrow endemic of central Spain known from only four populations. According to allozyme data, species genetic diversity (p = 46.15%, A = 2.61, and H(e) = 0.218), as well as within-population genetic diversity (p = 44.23%, A = 2.10, and H(e) = 0.204), were high when compared to average estimates for other narrowly distributed plant species. Ninety-four percent of species genetic diversity corresponded to within-population genetic diversity. Nevertheless, significant differences were found among populations in allele frequencies of four of the six polymorphic loci, and three private alleles were detected. Inbreeding coefficients (F(IS)) suggest that populations are structured in genetic neighborhoods. The RAPDs also showed high levels of genetic diversity (p = 89.71% and H(e) = 0.188 at the species level, and p = 67.65% and H(e) = 0.171 at the population level). Nei's genetic distances estimated both from allozymes and RAPDs indicated low differentiation among populations. In spite of this, the low frequencies of certain alleles and the presence of private alleles indicate that efforts should be made to conserve all four remaining populations.