| Abstract: | Sporophytes from natural populations of ferns occupying pioneer lava and mature rainforest habitats on the island of Hawaii, Hawaiian Islands, were investigated to determine their mating system and frequency of recessive lethal genes (genetic load). Species dominant in pioneer lava habitats were found to have intragametophytic mating systems and to be devoid of lethal genotypes. Species from intermediate and mature rain-forest habitats exhibited complex intergametophytic mating systems and higher levels of genetic load. It is suggested that natural selection has favoured intragametophytic mating and homozygosity in species of less diverse and less competitive pioneer habitats and intergametophytic mating and heterozygosity in species of more mature habitats. |
