EVOLUTION OF HIGH GENETIC-VARIABILITY IN THE RARE HAWAIIAN FERN ADENOPHORUS-PERIENS AND IMPLICATIONS FOR CONSERVATION MANAGEMENT

Adenophorus periens is a rain forest-dwelling epiphytic fern and is kn own only from one population on the island of Hawaii (Kahaualea) and f rom a few scattered individuals on the islands of Kauai and Molokai. A genetic survey was conducted of the Kahaualea population employing pr otein electrophoresis. The individuals sampled expressed extremely hig h levels of allozymic variability compared to two mol e widespread con generic species (A. tamariscinus and A. tripinnatifidus). All individu als examined were produced via sexual recombination. Given the extreme ly young volcanic substrate upon which the Kahaualea forest has develo ped the historical factors leading to the high genetic variability of A. periens are somewhat obscure. The outcrossed mating system of this species may play a key, role in the maintenance of genetic diversity i n combination with its perennial life cycle. Because the lack of neigh boring populations precludes the influx of new genetic variability via gene flow, the population must rely solely on the appearance and inco rporation of new mutations as sources of new variability. The data sug gest that this genetically diverse population is not likely to suffer genetically from minor reductions in population size over the short te rm. The most obvious potential threats to A, periens are those affecti ng the demography of the population and include habitat destruction by lava flows, death of host trees through stand level dieback, chance l oss of individuals by a variety of mechanisms, and the adverse effects of gaseous emissions from volcanic activity and geothermal developmen t. The State of Hawaii should undertake an artificial propagation and transplantation program to establish populations in less threatened, s uitable habitats.