CENTAUREA CORYMBOSA, A CLIFF-DWELLING SPECIES TOTTERING ON THE BRINK OF EXTINCTION - A DEMOGRAPHIC AND GENETIC-STUDY

Centaurea corymbosa (Asteraceae) is endemic to a small area (less than or equal to 3 km(2)), and <500 individuals reproduce in any given yea r, Nevertheless, enzyme polymorphism was found within and among the si x local extant populations, the most distant at 2.3 km, Levels of gene flow among populations and seed and pollen dispersal data indicated v ery low dispersal capacity, Rarity of long distance dispersal events c oupled with traits such as prolonged juvenile period, monocarpy, and s elf-incompatibility precludes the establishment of new populations and thus the evolution toward colonization ability through increased disp ersal rate, polycarpy, or self-compatibility, The species thus appears to be trapped on an evolutionary dead-end toward extinction, even tho ugh, from a preliminary introduction experiment, we conclude that seve ral nearby unoccupied sites would be suitable for the species.