HIGH GENETIC DIFFERENTIATION AMONG REMNANT POPULATIONS OF THE ENDANGERED CAESALPINIA-ECHINATA LAM. (LEGUMINOSAE-CAESALPINIOIDEAE)

Forest fragments along the Atlantic coastland of Brazil have been high ly impacted by extensive human activities for the last 400 years. Caes alpinia echinata (Leguminosae-Caesalpinioideae), brazilwood, was overe xploited during this period due to its economical importance as a dye. As a result, the species has become endangered and today its total po pulation size is very restricted. We have assessed the distribution of genetic variation between five natural populations of brazilwood by m eans of RAPD (random amplified polymorphic DNA) markers. Of the total genetic variability, 28.5% was attributable to differences between two geographical groups, 29.6% to population differences within groups an d 42.0% to individual differences within populations. The high level o f population differentiation observed is in contrast to that expected for a primarily outcrossed woody perennial plant, and suggests that th ere may be a degree of inbreeding. Our results are in agreement with p revious studies which postulated that C. echinata has always occurred in clumps, being common in some places but rare in between. From a con servation point of view, different populations representing different regions should be protected and, yet, plants with different origins sh ould not be synthesized into populations in a recovery process at the risk of loss and dilution of genetic information. This study demonstra tes that RAPD markers were effective in establishing a clear correlati on between genetic and geographical distance and in identifying areas of maximum diversity, and may be used as an initial approach to assess the partitioning of genetic variation in this endangered species.