Genetic variation in the threatened South American conifer Pilgerodendron uviferum (Cupressaceae), detected using RAPD markers

Pilgerodendron uviferum (Cipres de las Guiatecas, Cupressaceae) is a long-lived conifer, endemic to southern Chile and Argentina, reaching a southern limit in Tierra del Fuego. Remnant populations are generally fragmented and highly disturbed because of exploitation for timber, grazing and fire. The extent of genetic variation within and between 16 populations of this species, distributed throughout its range, was assessed using random amplified polymorphic DNA (RAPD) markers. Eight 10-mer primers produced a total of 84 scorable markers, 30 of which (35.7%) were polymorphic. AMOVA indicated that 18.6% of the variation recorded was attributable to differences between populations, a relatively high value compared with other conifers from the region. Pair-wise Phi_st comparisons between populations were all significant at P<0.05, with one exception, highlighting a high degree of population differentiation. Values of Shannon's diversity index (S) differed significantly among populations (P=0.002, ANOVA), values ranging from 0.337 to 0.716, suggesting that some populations are currently characterised by very low genetic variability. Current patterns of genetic variation were related to biogeographic history and human impact. The high degree of population differentiation recorded here highlights the need for additional conservation measures for this species, both in terms of incorporating further populations into the protected areas, and the restoration of severely degraded populations, to ensure their continued viability.