Mating Systems and Distribution in some Tropical Ferns

Applying mating system genetics as the tool, three tropicalferns, namely, Ceratopteris thalictroides, Pseudodrynaria coronansand Pityrogramma calomelanos were examined for their distributionalpatterns. Absence of recessive lethals in the sporophytes ofP. colomelanos allows its spores to function as a single propagulein the colonization of open habitats through intra-gametophyticselfing and it is widely distributed. The phenomenon of leakylethality and ultimately recessive sporophytic lethality inP. coronans is associated with a restricted distribution ofthe species in the forest. Ecological specialization in thecase of C. thalictroides also renders it a poor colonizer thoughits mating system is directed towards intergemetophytic selfingwith capacity in time for intra-gametophytic selfing.