UBC Theses and Dissertations

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UBC Theses and Dissertations

Phylogenetic analysis of chromosome numbers and genetic markers Zhan, Shing Hei


A phylogenetic tree captures the evolutionary relationships among sampled taxa – major taxonomic groups, species, infraspecific taxa, or isolates. Phylogenetic analysis is a central component of evolutionary and ecological studies, as it lends a unifying framework to draw inferences about evolutionary and ecological processes that form biodiversity. Via phylogenetic comparative methods, trait data (for example, morphological or physiological data) and geographical data may be analyzed jointly with a given phylogeny to test specific hypotheses about the evolution and ecology of focal groups of organisms. In this thesis dissertation, I present four studies demonstrating how phylogenetic analysis can yield new evolutionary and ecological insights. In the first two studies, I compare the evolutionary fates of polyploid versus diploid lineages in fish and to test whether polyploidization coincides with speciation events in land plants. Polyploid species arise from whole genome duplication and often exhibit morphological, physiological, and ecological differentiation from their diploid parents. Understanding their evolutionary patterns in the background of diploid species help us to understand why polyploidization is abundant in some organisms (plants) but not in others (fishes). In the other two studies, I explore the biodiversity of freshwater red algae in the wild and aquarium shops, using phylogenetic analyses to reveal potential introductions of these organisms via the global aquarium trade. Furthermore, I identify candidate genetic markers that may be more suitable than commonly used markers to facilitate future studies of phylogenetic community ecology of the red algae. Not only do these studies illustrate the utility of phylogenetic analyses to tackle diverse questions in evolution and ecology, but they also have forwarded the discussion on those four distinct topics.

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