Thesis Title

Breeding System, Heterozygosity, and Seed Germination in a Population of Missouri Bladder-Pod, Lesquerella Filiformis Rollins

Date of Graduation

Fall 1996

Degree

Master of Science in Biology

Department

Biology

Committee Chair

John Heywood

Subject Categories

Biology

Abstract

Lesquerella filiformis Rollins, a federally endangered species, is a rare endemic of limestone glades in southwest Missouri. Although highly restricted in its range, populations of L. filiformis are highly polymorphic and significant genetic differentiation occurs among them (Graham 1994). To better understand the presence of such high levels of genetic diversity in this geographically-restricted species, allozyme genotypes for seeds produced from one generation of natural breeding were used to estimate the breeding system and to examine the fitness consequences of heterozygosity. Both multilocus and single-locus estimates of the outcrossing rate (tm=1.000, ts=0.996) indicate a primarily outcrossing species. Among viable seeds, the smaller seeds were more prone to germinate. However, neither seed size nor germination behavior was related to multilocus or single-locus heterozygosity. With high levels of gene flow promoted by outcrossing and an extensive seed pool, effective population sized in L. filiformis may be very large despite its restricted geographic range. Thus, the high levels of genetic variation may be stable under current conditions. There is as yet no evidence to suggest that L. filiformis was more broadly distributed in historical or prehistoric times.

Copyright

© Michiko Brenda Smart

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Dissertation/Thesis

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