Abstract

Traditional evolutionary models depict evolution as a bifurcating pattern with a single ancestor diverging to form two lineages. However, reticulate species resulting from hybridization and recombination have unique histories shared with two independent lineages, not one. Accounting for the genetic histories of reticulate species increases the power and ability to recover biologically meaningful relationships. The genus Collomia (Polemoniaceae) is used to explore issues of reticulation and the importance of accounting for gene histories in a phylogenetic analysis. The issue of reticulation within species trees is discussed with a multilabeled, network approach being explored to better represent the genus's evolutionary history. Wherry's hypotheses regarding the relationships that exist within Collomia are addressed and the need for a new intrageneric section is recognized based on support from multiple, independent genes and morphology. Sections Collomiastrum and Courtoisia remain as previously circumscribed. Section Collomia is modified with removal of two species, C. grandiflora and C. biflora from the section and by erecting a new section, Calyperona. A morphological key is included for each section and their corresponding species, followed by sectional discussions. Finally, the evolution of lifecycle duration, seed morphology, and pollen morphology are discussed based on the phylogeny of the genus.

Degree

College and Department

Life Sciences; Biology

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