GAMETOPHYTE ONTOGENY, SEX EXPRESSION, AND GENETIC LOAD AS MEASURES OF POPULATION DIVERGENCE IN BLECHNUM SPICANT

摘要: Early gametophyte ontogeny was quantitatively distinct for Olympic Peninsula, Alaskan, and disjunct Idaho populations of the homosporous fern Blechnum spicant (L.) J. Sm. Although variable, ganmetophyte sex expression shown to have a genetic component. Statistically different patterns characterize each population. The Peninsula were from other but consistent in having predominantly unisexual pattern. population bisexual at time when comparable field collected gametophytes bear sporophytes. Preliminary experiments suggest that an antheridogen operates this species. Increased sowing density favors maleness, extract soil cultures shifts exclusively male pattern after dramatic suppression growth. Mating revealed all are interfertile, although fertility highest test underwent intergametophytic-selfing. evidenced low level load with predictions based on its expression. apparent high some experiments, failure produce abundant sporophytes suggested additional cultural factors operated reduce sporophyte formation. Moderate mating produced single collections. Isolated polyembryony delay proliferation. Cultural conditions which allow formation isolated without or proliferation must be sought before further analysis is undertaken. RECENT WORK has biology pteridophytes varies intraspecifically new emphasis requiring samples studies (Pray, 1968; Klekowski, 1970a, 1972, 1973a; Saus Lloyd, 1976). Pray (1968) discovered substantial variation early sexual apogamous Pellaea andromedaefolia gametophytes. One insular especially distinct, differences among not correlated generation. This suggests potential degree independent evolution two generations (Cousens, prep.). When extensive, proportions types (Lloyd Gregg, 1975) (Saus 1976) may Galapagos Pteridium aquilinum Kuhn ssp. caudatum Bonap. var. arachnoideum (Kaulf.) Brade 1 Received publication 8 December 1977; revision accepted 14 August 1978. Support work provided by N.D.E.A. predoctoral fellowship awarded through Botany Department, Washington State University. Appreciation extended Dr. David Wagner Alaskan material. demonstrated genetically South American populations, they morphologically similar (Klekowski, 1973b). hypothesis generation vary adaptively stands represent range vigor vitality will introduced elsewhere In study, vegetation four stands, northern stand described, observations natural Lake Quinault (LQ) stand, represented modal site species, presented. addition (LQ), North Fork, (NF), Twanoh (T) optimal Hoh (H), characterized dwarfed sporophytes, Mason Mtn. (MM) xeric edge tolerance described. Spores 9-21 these five spore cQllection, results laboratory comparisons ontogeny, expression, assessment presented here.