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Ferns adapt their phenological characteristics such as leaf production, leaf fertility and leaf mortality to the habitat conditions optimizing their opportunities to grow, reproduce, and disperse. The leaf phenology of the herbaceous, dimorphic fern Danaea geniculata was studied in a Brazilian submontane tropical forest and compared with several other fern species worldwide. Plants of D. geniculata held an average of 8.11 ± 2.16 leaves that were produced and died at similar rates of 4.44 ± 2.16 leaves y−1 and 4.20 ± 2.28 leaves y−1, respectively. Leaf lifespan was 24.7 ± 7.5 mo for sterile leaves and 5.6 ± 0.6 mo for fertile leaves. Leaf production and fertility increased with rainfall, but decreased with temperature, because of the local climate, which is characterized by higher rainfall during the colder winter months. On the other hand, leaf mortality increased during drier and hotter months. Leaf production and fertility of other species were fit into three categories and compared with D. geniculata. The leaf phenology of D. geniculata neither coincided with species at the same site nor with species within the same family (Marattiaceae), indicating that even coexisting or closely related species can adapt individually to the macro- and microclimatic parameters of their habitats.
In this study, mating system, genetic diversity, and genetic structure of the endangered endemic aquatic lycophyte Isoëtes yunguiensis in China was investigated using AFLP markers. The estimates of outcrossing rates (tm = 1.200) indicate that diploid I. yunguiensis is a predominantly outcrossing species. Six selected AFLP primer pairs used in the study amplified 195 reproducible bands, 160 of which were polymorphic (PPB = 82.05%), indicating significant genetic diversity at the species level. AMOVA revealed that 40.12% of the genetic variation was attributable to differences between populations and the rest (59.88%) to variability within populations. High outcrossing rates and the historical accumulation of genetic variation may be responsible for the high levels of genetic diversity observed in the I. yunguiensis population. To maintain the current level of genetic diversity for this species, we recommend increasing in situ conservation sites.