Phenotypes and floral variation: A phylogenetic approach

Biological diversity is created by evolution. To adequately explore biodiversity and examine processes in evolution, scientists need perspective on past evolutionary events. In this study, phenotypic diversity was investigated at several taxonomic levels by examining floral morphological characters against a backdrop of phylogenetic hypotheses. Floral traits were measured and phylogenetic hypotheses were generated across the species' Pedicularis densiflora and Pedicularis aurantiaca, within the tropical genus Cantua, and throughout the family Brassicaceae.; Floral morphological variation among populations of P. densiflora s.l. was examined and two distinct floral morphological groups were determined. Phenotypic analysis was then combined with a phylogenetic hypothesis in order to examine the number of times different floral morphs arose, relationships among populations in different localities, and potential pollinator shifts. An investigation of the floral diversity and phylogentics among populations in the species P. densiflora s.l. warranted the splitting of the group into two distinct species, P. densiflora and P. aurantiaca.; Scanning electron microscopy was used to examine pollen grain morphology within the genus Cantua. Pollen characteristics were then assessed relative to a strongly supported molecular phylogenetic hypothesis. Pollen grain morphology was found to be highly conserved within the genus and synapomorphies in pollen grain characteristics supported relationships hypothesized in the phylogenetic analysis. In addition, a potential correlation between pollen diameter and style length was examined using independent contrast and found to be insignificant. This investigation confirmed the phylogenetic utility of pollen characters and provided no support for the hypothesis that pollen grain diameter is functionally integrated with style length.; Floral morphological traits in the Brassicaceae were used to examine phenotypic variance-covariance matrix (P-matrix) stability relative to a comprehensive phylogenetic hypothesis. The P-matrix stability was highly conserved among some genera in the family and more labile among others. This examination of P-matrix stability within the Brassicaceae used a phylogenetic hypothesis to confirm that matrix stability did not follow a stepwise pattern of similarity corresponding to taxonomic rank.; Although each chapter of the dissertation used a different group of plants, and varied statistical techniques, they all showed the utility of combining both morphological and molecular analysis to examine patterns of floral diversity. The objectives of each study focused on different aspects of patterns of floral diversity. Ultimately, all of the investigations contained a phylogenetic hypothesis that provided a unique historical perspective to the questions being addressed.