Date of Award

1998

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biological Sciences

First Advisor

Doust, J. L.

Keywords

Biology, Botany.

Rights

CC BY-NC-ND 4.0

Abstract

The majority of angiosperms produce more flowers than fruits and more ovules than seeds. Yet, most studies of the population biology of flowering plants tend to follow the fate of seeds starting from the time of seed dispersal or time of germination, while ignoring the development or failure of ovules before they reach seed maturity. Potentially, the mortality of plant embryos may be the most severe during the period of seed development between fertilization and seed maturity. In several field and laboratory experiments, I investigated the variation in ovule development within and among fruits in garlic mustard, Alliaria petiolata, and eight other species of mustards (Brassicaceae) in order to determine how these plants regulated their investment in fruits and seeds. I observed that the production of many more fruits and seeds than could be matured by a plant is a common phenomenon. I also found that plants regulated their investment in seeds by varying seed mass, and the number of fruits and seeds. Investment in seed mass directly influenced seedling fitness components. In addition, the maturation and abortion of plant embryos did not occur at random in mustards. The linearly ordered arrangement of ovules within their fruits permitted an assessment of positional effects on the developmental fate of ovules. In A. petiolata, patterns of seed maturation and abortion varied nonrandomly within and among fruits, individuals (of different sizes), sites, and geographic regions. In addition, by manipulating the availability of parental resources through nutrient supplementation, deradication, defoliation, and fruit removal experiments, I demonstrated that these patterns were dependent on the resource status of the plant. By examining the fate of ovules in eight species of mustards, I observed that patterns of seed maturation and abortion differed with respect to breeding system. Breeding system may influence the extent to which patterns of ovule fate are affected by availability of resources and by sexual selection. In the future, patterns of seed maturation and abortion may serve as useful descriptive tools for estimating the breeding systems of species, as well as for quantifying the extent of outcrossing within and among individuals and sites.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1998 .S87. Source: Dissertation Abstracts International, Volume: 61-09, Section: B, page: 4511. Adviser: Lesley Lovett Doust. Thesis (Ph.D.)--University of Windsor (Canada), 1998.

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