Title of Document: POLLINATOR SPECIALIZATION AND THE EVOLUTION OF POLLINATION SYNDROMES IN THE RELATED SILENE, S. CAROLINIANA, S. VIRGINICA, AND S. STELLATA Richard James Reynolds, Ph.D., 2008 Directed By: Associate Professor, Charles B. Fenster, Biology Associate Professor, Michele R. Dudash, Biology Pollination syndromes are the convergent expression of floral traits in unrelated species refl...

A small cluster of dioecious species in the plant genus Silene has evolved chromosomal sex determination and sex chromosomes relatively recently, within the last 10 million years (MY). Five dioecious Silene species (section Elisanthe) are very closely related (1-2 MY of divergence) and it was previously thought that all five have similar sex chromosomes. Here we demonstrate that in one of these...

BACKGROUND AND AIMS Among-population differentiation in phenotypic traits and allelic variation is expected as a consequence of isolation, drift, founder effects and local selection. Therefore, investigating molecular and quantitative genetic divergence is a pre-requisite for studies of local adaptation in response to selection under variable environmental conditions. METHODS Among- and withi...

The isovitexin-O-glycosylation patterns of rosette leaves, stem leaves and petals of Silene dioica plants were investigated. The 7-O -xylosylation o f isovitexin, controlled by gene gX, only occurs in the petals. In the leaves isovitexin is 7-O-galactosylated, which is controlled by gene Xgal. Acyl groups may be linked to either the 7 -0 or the 2"-0-substituted sugar; the former only occurs in ...

*Understanding disease distributions is of fundamental and applied importance, yet few studies benefit from integrating broad sampling with ecological and phylogenetic data. Here, anther-smut disease, caused by the fungus Microbotryum, was assessed using herbarium specimens of Silene and allied genera of the Caryophyllaceae. *A total of 42,000 herbarium specimens were examined, and plant geogra...

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Understanding mechanisms of coevolution between nuclear and mitochondrial (mt) genomes is a defining challenge in eukaryotic genetics. The angiosperm genus Silene is a natural system to investigate the causes and consequences of mt mutation rate variation because closely related species have highly divergent rates. In Silene species with fast-evolving mtDNA, nuclear genes that encode mitochondr...

• Sex ratio polymorphism has been extensively studied in Silene latifolia, but it is neither known whether inbreeding (which is likely to occur under field conditions) affects it nor which of the proposed mechanisms (Y degeneration, X-linked drive) is more important. Both mechanisms predict reduced pollen performance. • In this study, females were crossed with pollen from related and unrelated ...