摘要
Galium cracoviense is a narrow endemic diploid species with a highly restricted natural range of occurrence, confined to a system of limestone outcrops in an area covering ca. 25?km2 in southern Poland. It is an excellent example of a naturally very rare species which most probably has persisted in the same area since its divergence. We used the first exhaustive inventory of its subpopulations, range-wide fine-scale sampling and AFLP fingerprinting to examine the genetic structure of G. cracoviense. The aims of the study were to verify whether this ‘old rare-species maintains high levels of genetic variation despite low population resources; to infer from the spatial pattern of genetic relatedness of individuals any limitations on dispersal and gene flow that may contribute to maintenance of its highly restricted range; and to place our results in the context of conservation strategies for G. cracoviense. Based on AMOVA and PCoA we found high genetic variation (80?% polymorphic markers) and weak divergence among subpopulations, despite the spatial isolation of subpopulations (ΦST?=?0.11). The high genetic variation found in most subpopulations makes them equally important reservoirs of genetic diversity. In view of the microspatial genetic structure of the subpopulations revealed by autocorrelation analyses, we recommend that if plant material or seeds of this species are collected for ex situ conservation, multiple sampling of neighboring plants (distances of the first lag in autocorrelation analysis) should be avoided so that the largest range of diversity can be covered by sampling.