CONSERVING GENETIC-VARIATION IN BRITISH POPULATIONS OF LOBELIA URENS

Conservation of genetic variation in a species which occurs as a few d isjunct populations poses particular problems related to both the sepa ration of those populations and their size. Lobelia urens is rare in B ritain and occurs in only six widely separated populations. The distri bution of genetic variation within and among these populations was exa mined using enzyme electrophoresis. The results showed that much of th e variation was held among populations (G(ST) = 0.265) and that gene f low among populations was low. The populations therefore require conse rvation as independent units. No link was found between geographical d istance and genetic distance, adding weight to the theory that the Bri tish populations were established independently. Evidence was found th at the smaller, unmanaged, populations contained less variation, altho ugh all had passed through a series of bottlenecks during the past 50 years. As surrounding vegetation becomes more dense, fewer individuals contribute to variation in population size and it is suggested that p eriodic disturbance should be used as a management tool in order to re lease variation accumulated in the seed bank and so prevent depletion of genetic diversity. Copyright (C) 1996 Elsevier Science Limited