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Adenophorus periens is a rain forest-dwelling epiphytic fern and is known only from one population on the island of Hawaii (Kahaualea) and from a few scattered individuals on the islands of Kauai and Molokai. A genetic survey was conducted of the Kahaualea population employing protein electrophoresis. The individuals sampled expressed extremely high levels of allozymic variability compared to two more widespread congeneric species ( A. tamariscinus and A. tripinnatifidus ). All individuals examined were produced via sexual recombination. Given the extremely young volcanic substrate upon which the Kahaualea forest has developed, 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 in combination with its perennial life cycle. Because the lack of neighboring populations precludes the influx of new genetic variability via gene flow, the population must rely solely on the appearance and incorporation of new mutations as sources of new variability. The data suggest that this genetically diverse population is not likely to suffer genetically from minor reductions in population size over the short term. The most obvious potential threats to A. periens are those affecting the demography of the population and include habitat destruction by lava flows, death of host trees through stand-level dieback, chance loss of individuals by a variety of mechanisms, and the adverse effects of gaseous emissions from volcanic activity and geothermal development. The State of Hawaii should undertake an artificial propagation and transplantation program to establish populations in less threatened, suitable habitats. |
