Comparative reproductive biology of two Florida pawpaws Asimina reticulata Chapman and Asimina tetramera Small

I investigated the phenology and breeding systems of two Florida endemic pawpaws, Asimina reticulata, widespread in peninsular Florida, and A. tetramera, a federally endangered species limited to two counties on the Atlantic Coastal Ridge. The purpose of this study was to determine if differences contribute to the rarity of Asimina tetramera compared with A. reticulata. The study was conducted in sand pine scrub sites with the largest populations of A. tetramera in the two counties. Flowering seasons differ for the two species. Both species are hermaphroditic and strongly protogynous. Pollination experiments show that neither species is autogamous and the primary breeding mechanism is outcrossing, although low levels of geitonogamous pollination occur in mature scrub habitats. High levels of inbreeding depression were noted in both species at both sites but inbreeding depression was relaxed the first year post-fire. Fruit set in mature habitats may be pollinator limited. ^ I studied insects associated with the flowers in sand pine scrub habitat in southeastern Florida from 1994–1996. The most commonly represented orders were Coleoptera (25 spp.), Lepidoptera. (3 spp.) and Hymenoptera. (3 spp.). All Coleoptera. were flower visitors; one species, Euphoria sepulchralis (Fabricius)(Scarabeaidae), visited flowers of the two Asimina species at both sites. Eurytides marcellus (Cramer) (Lepidoptera: Papilionidae) eggs and larvae were observed on both species of Asimina during each year of the study. ^ Resource management techniques were applied to a mature sand pine scrub community in Jonathan Dickinson State Park in southeastern Florida for the management of Asimina tetramera. Manipulations conducted in 1996 included combinations of fire and mechanical treatments. I measured effects of these treatments on flowering and fruit set on A. tetramera and found cutting and burning was most effective in increasing flowering, followed by burning. Mechanical cutting and mulching had no significant effect. ^