Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Department

Biology

First Advisor's Name

Suzanne Koptur

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Daniel F. Austin

Third Advisor's Name

Bradley C. Bennett

Fourth Advisor's Name

Steven F. Oberbauer

Fifth Advisor's Name

Jorsre E. Pena

Date of Defense

11-5-1998

Abstract

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. Euryiides 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 Jona than 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 the fire treatments, BURN and CUT&BURN, significantly increased flowering. Mechanical treatments cutting and mulching had no significant effect.

Identifier

FI14061532

Included in

Biology Commons

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